Transformer Current

Nutshell:

I have a lead acid 12V battery charging device that used a wall
transformer rated as 120 VAC 26W input, 12 VAC 1.6A out. The xformer
failed (primary opened) and I made a replacement (12.6 VAC 3A out) but
it is drawing 4.5A and blowing the secondary fuses I put in place.

Synopsis:

I have two "Basement Watchdog" battery operated sump pumps. The
batteries are 6 cell 12V lead acid batteries. The control panel on
each unit charges the batteries as well as giving status and alarming.
The controller accepts a dry contact (float) to trigger a pump cycle.
It has some led's, a piezo and a button to silence alarms/run pump.
The main load runs from the battery all the time.

One of the devices gave me an AC failed indication. I checked the
transformer and was getting nothing from it. I removed it and went on
to other things. Several days passed and w/ rain in the forecast I
decided to top the charge of on the battery by moving the wall
transformer from the (still) good unit to the one that had failed. Not
too bright on my part because poof went the other transformer. Turns
out there is a problem in the one unit that caused the transformer to
fail.

I pulled the failed control unit out and peeked inside and found a
shorted 6A bridge rectifier diode. I went to RS to get a replacement
and noticed they had a 12V 3A xformer so I decided to build a
replacement, one that would run both units. I made a simple box, wired
up the xformer (full voltage, not using the center tap), paralleled
one secondary leg to two fuses (one for each control unit). I
connected the wires to the control unit to one of the fuses and the
other secondary leg. Secondary was giving 14.6 VAC, no load.

Power up and connect to the pump control unit and all seems ok but
then after about 20 seconds the fuse goes. Investigation shows that
the control unit is drawing about 4.5 A. Remember, this unit is the
one that had zero problems at all, the repaired one is still on the
bench.

Can someone offer any ideas as to why the charger is drawing far more
than the original transformer was rated? I cut one open and could not
find any identifying marks on the transformer. The primary had failed
and the secondary was fused at 5A. The fuse was intact. Input was
labeled as 120 VAC 26W, looks like 0.2A roughly. Stepped down to 12V
that would be 2A.

I am not certain why the high draw - maybe the initial charging cycle
draws much more than 2A, for some period of time, and then bleeds
down? That would mean the original transformer was rated for much
higher than what the wall transformer was labeled. It was fused at 5A
on the secondary.

Thanks.

 

[Jamie]

usenet2@xemaps.com wrote:

Nutshell:

I have a lead acid 12V battery charging device that used a wall
transformer rated as 120 VAC 26W input, 12 VAC 1.6A out. The xformer
failed (primary opened) and I made a replacement (12.6 VAC 3A out) but
it is drawing 4.5A and blowing the secondary fuses I put in place.

Synopsis:

I have two "Basement Watchdog" battery operated sump pumps. The
batteries are 6 cell 12V lead acid batteries. The control panel on
each unit charges the batteries as well as giving status and alarming.
The controller accepts a dry contact (float) to trigger a pump cycle.
It has some led's, a piezo and a button to silence alarms/run pump.
The main load runs from the battery all the time.

One of the devices gave me an AC failed indication. I checked the
transformer and was getting nothing from it. I removed it and went on
to other things. Several days passed and w/ rain in the forecast I
decided to top the charge of on the battery by moving the wall
transformer from the (still) good unit to the one that had failed. Not
too bright on my part because poof went the other transformer. Turns
out there is a problem in the one unit that caused the transformer to
fail.

I pulled the failed control unit out and peeked inside and found a
shorted 6A bridge rectifier diode. I went to RS to get a replacement
and noticed they had a 12V 3A xformer so I decided to build a
replacement, one that would run both units. I made a simple box, wired
up the xformer (full voltage, not using the center tap), paralleled
one secondary leg to two fuses (one for each control unit). I
connected the wires to the control unit to one of the fuses and the
other secondary leg. Secondary was giving 14.6 VAC, no load.

Power up and connect to the pump control unit and all seems ok but
then after about 20 seconds the fuse goes. Investigation shows that
the control unit is drawing about 4.5 A. Remember, this unit is the
one that had zero problems at all, the repaired one is still on the
bench.

Can someone offer any ideas as to why the charger is drawing far more
than the original transformer was rated? I cut one open and could not
find any identifying marks on the transformer. The primary had failed
and the secondary was fused at 5A. The fuse was intact. Input was
labeled as 120 VAC 26W, looks like 0.2A roughly. Stepped down to 12V
that would be 2A.

I am not certain why the high draw - maybe the initial charging cycle
draws much more than 2A, for some period of time, and then bleeds
down? That would mean the original transformer was rated for much
higher than what the wall transformer was labeled. It was fused at 5A
on the secondary.

Thanks.
it's my guess your charger has a current limiter that has gone bad or

out of adjustment.

Can you get at the details of the charging circuit?

You could always put a 50 watt incandescent bulb in series
with the primary until your issues are solved. actually, I've
seen many basic charging systems do just that as a current limiter
and indication of charge!


http://webpages.charter.net/jamie_5"

 

[ehsjr]

usenet2@xemaps.com wrote:

Nutshell:

I have a lead acid 12V battery charging device that used a wall
transformer rated as 120 VAC 26W input, 12 VAC 1.6A out. The xformer
failed (primary opened) and I made a replacement (12.6 VAC 3A out) but
it is drawing 4.5A and blowing the secondary fuses I put in place.

Synopsis:

I have two "Basement Watchdog" battery operated sump pumps. The
batteries are 6 cell 12V lead acid batteries. The control panel on
each unit charges the batteries as well as giving status and alarming.
The controller accepts a dry contact (float) to trigger a pump cycle.
It has some led's, a piezo and a button to silence alarms/run pump.
The main load runs from the battery all the time.

One of the devices gave me an AC failed indication. I checked the
transformer and was getting nothing from it. I removed it and went on
to other things. Several days passed and w/ rain in the forecast I
decided to top the charge of on the battery by moving the wall
transformer from the (still) good unit to the one that had failed. Not
too bright on my part because poof went the other transformer. Turns
out there is a problem in the one unit that caused the transformer to
fail.

I pulled the failed control unit out and peeked inside and found a
shorted 6A bridge rectifier diode. I went to RS to get a replacement
and noticed they had a 12V 3A xformer so I decided to build a
replacement, one that would run both units. I made a simple box, wired
up the xformer (full voltage, not using the center tap), paralleled
one secondary leg to two fuses (one for each control unit). I
connected the wires to the control unit to one of the fuses and the
other secondary leg. Secondary was giving 14.6 VAC, no load.

Power up and connect to the pump control unit and all seems ok but
then after about 20 seconds the fuse goes. Investigation shows that
the control unit is drawing about 4.5 A. Remember, this unit is the
one that had zero problems at all, the repaired one is still on the
bench.

Can someone offer any ideas as to why the charger is drawing far more
than the original transformer was rated? I cut one open and could not
find any identifying marks on the transformer. The primary had failed
and the secondary was fused at 5A. The fuse was intact. Input was
labeled as 120 VAC 26W, looks like 0.2A roughly. Stepped down to 12V
that would be 2A.

I am not certain why the high draw - maybe the initial charging cycle
draws much more than 2A, for some period of time, and then bleeds
down? That would mean the original transformer was rated for much
higher than what the wall transformer was labeled. It was fused at 5A
on the secondary.

Thanks.

Or it might mean they don't use bullet proof design, and allow
the wall transformer to be overloaded during the initial charge.
After all, they had a 5 amp fuse in there, which is over 3 times
the 1.6 A rating you mentioned. If you intend to run 2 chargers
from the transformer, buy a bigger one. To get one working,
replace your 2 amp fuse with a 5 amp fuse. Monitor it and see
if the current draw drops, and check how long it takes. The
farther a battery is discharged, the greater the current it draws
from the charger. As the battery charges, it draws less current.
Monitoring it and watching the current drop over time may give
you a sense of how much is being demanded of your 3 amp xformer.
At least you know that the new transformer is rated at almost
double the old transformer's rating.

Ed

 

[Ross Herbert]

On Thu, 5 Feb 2009 08:50:59 -0800 (PST), usenet2@xemaps.com wrote:

:Nutshell:
:
:I have a lead acid 12V battery charging device that used a wall
:transformer rated as 120 VAC 26W input, 12 VAC 1.6A out. The xformer
:failed (primary opened) and I made a replacement (12.6 VAC 3A out) but
:it is drawing 4.5A and blowing the secondary fuses I put in place.
:
:Synopsis:
:
:I have two "Basement Watchdog" battery operated sump pumps. The
:batteries are 6 cell 12V lead acid batteries. The control panel on
:each unit charges the batteries as well as giving status and alarming.
:The controller accepts a dry contact (float) to trigger a pump cycle.
:It has some led's, a piezo and a button to silence alarms/run pump.
:The main load runs from the battery all the time.
:
:One of the devices gave me an AC failed indication. I checked the
:transformer and was getting nothing from it. I removed it and went on
:to other things. Several days passed and w/ rain in the forecast I
:decided to top the charge of on the battery by moving the wall
:transformer from the (still) good unit to the one that had failed. Not
:too bright on my part because poof went the other transformer. Turns
ut there is a problem in the one unit that caused the transformer to
:fail.
:
:I pulled the failed control unit out and peeked inside and found a
:shorted 6A bridge rectifier diode. I went to RS to get a replacement
:and noticed they had a 12V 3A xformer so I decided to build a
:replacement, one that would run both units. I made a simple box, wired
:up the xformer (full voltage, not using the center tap), paralleled
ne secondary leg to two fuses (one for each control unit). I
:connected the wires to the control unit to one of the fuses and the
ther secondary leg. Secondary was giving 14.6 VAC, no load.
:
ower up and connect to the pump control unit and all seems ok but
:then after about 20 seconds the fuse goes. Investigation shows that
:the control unit is drawing about 4.5 A. Remember, this unit is the
ne that had zero problems at all, the repaired one is still on the
:bench.
:
:Can someone offer any ideas as to why the charger is drawing far more
:than the original transformer was rated? I cut one open and could not
:find any identifying marks on the transformer. The primary had failed
:and the secondary was fused at 5A. The fuse was intact. Input was
:labeled as 120 VAC 26W, looks like 0.2A roughly. Stepped down to 12V
:that would be 2A.
:
:I am not certain why the high draw - maybe the initial charging cycle
:draws much more than 2A, for some period of time, and then bleeds
:down? That would mean the original transformer was rated for much
:higher than what the wall transformer was labeled. It was fused at 5A
n the secondary.
:
:Thanks.


Those "wall transformers" (we call 'em plug-packs) will invariably have a
thermal fuse built into the primary winding. If a prolonged overload occurs,
which may not be sufficient to cause an external fuse to rupture, the thermal
fuse blows in order to prevent a fire or other hazardhous situation.
Unfortunately, this also means the transformer is now defunct and unrepairable.

It appears to me that whatever else is connected to the output of the
transformer then it must have a low impedance or short circuit in it. When you
replaced the 6A diode did you investigate to see what caused that to blow? If
you simply replaced the rectifier without checking for other failed components
then you may now have another dead rectifier as well.

 

[Jasen Betts]

On 2009-02-05, usenet2@xemaps.com <usenet2@xemaps.com> wrote:

Nutshell:


Can someone offer any ideas as to why the charger is drawing far more
than the original transformer was rated? I cut one open and could not
find any identifying marks on the transformer. The primary had failed
and the secondary was fused at 5A. The fuse was intact. Input was
labeled as 120 VAC 26W, looks like 0.2A roughly. Stepped down to 12V
that would be 2A.

it's either the charger or the battery.
swap both until you locate the culprit.

I am not certain why the high draw - maybe the initial charging cycle
draws much more than 2A, for some period of time,

more than a few minutes would be troubling.

 

[IanM]

Jasen Betts wrote:

On 2009-02-05, usenet2@xemaps.com <usenet2@xemaps.com> wrote:
Nutshell:


Can someone offer any ideas as to why the charger is drawing far more
than the original transformer was rated? I cut one open and could not
find any identifying marks on the transformer. The primary had failed
and the secondary was fused at 5A. The fuse was intact. Input was
labeled as 120 VAC 26W, looks like 0.2A roughly. Stepped down to 12V
that would be 2A.

it's either the charger or the battery.
swap both until you locate the culprit.

I am not certain why the high draw - maybe the initial charging cycle
draws much more than 2A, for some period of time,

more than a few minutes would be troubling.



Its possible the original charging circuit is so *dumb* it relies on the

precise output voltage and internal resistance of the transformer to
limit the charging current and also to taper the charging off at the
float voltage. A transformer, measured at 10.7 V(rms) AC output off
load (15.1 V peak), connected through a simple bridge rectifier will
naturally float a 12V battery at about 14 V and if wound with thin
enough wire, could be designed to limit the current into a battery
discharged to 10 V to 1.5 A.

Check the original circuit to see if there is any active charge control.
If there are no three terminal components between the brige +ve and the
battery +ve they've designed it *DUMB*. Enter the wonderful world of
Muntzed battery chargers.

If so there are a couple of approaches to fixing this, but it would be
nice to confirm the problem first.

Its also possible a cell has failed in the battery in the good unit. If
you have an adjustable current bench supply that can run on current
limit indefinately, set it to 13.8 V out and to limit at less than C/20
A (where C is the capacity of the battery in AH) and charge on the bench
till the voltage has been at 13.8 V for 4 hours or for a maximum of 24
hours (or use a dedicated SLA charger if you have one). Let the battery
rest disconnected for 24 hours. If it measures about 12.5 V its OK. If
its 2 or more volts lower, its dead. Also check it can run a C/20 load
for 8 hours. Recharge fully immediately after testing. If the battery
out of the good unit has failed, its probable the bad unit lost two
cells which killed its charger. If you have more experience with SLA
batteries, there are shorter testing procedures, but they can damage the
battery or give misleading results so I'm not giving them here.

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
[at]=@, [dash]=- & [dot]=. *Warning* HTML & >32K emails --> NUL:

 

[Paul E. Schoen]

<usenet2@xemaps.com> wrote in message
news:353a2a4c-9d2f-4c55-a570-522681b2ed5a@t26g2000prh.googlegroups.com...

I have two "Basement Watchdog" battery operated sump pumps. The
batteries are 6 cell 12V lead acid batteries. The control panel on
each unit charges the batteries as well as giving status and alarming.
The controller accepts a dry contact (float) to trigger a pump cycle.
It has some led's, a piezo and a button to silence alarms/run pump.
The main load runs from the battery all the time.

I don't know if this is the same sort of unit that my friend had in her
basement, but it sounds similar. In her case, the battery would not stay
charged and it failed the self-test as well as the routine that was
supposed to cycle the battery and fix problems, so we got a new battery.

But I tried to test the system by pouring water into the sump where the
pump was located, and it seemed like it would only work when the water
level got very high, and then it only pumped out a small amount before
shutting off. The level sensor seemed to be very poorly designed.

She also had a regular 120 VAC sump pump, which had been disconnected, but
I saw from the nameplate that it was fairly new. I plugged it in, and it
very quickly drained nearly all the water out of the sump, as would be
expected with a 1/3 HP motor. The tiny pump in the original design was
probably about the same as your 25 watt pump, which is about 1/30 HP, so it
would take ten times as long to do the job, and apparently did not do a
very thorough job at that. I think she fell victim to a fast talking
salesman who sold her a "bill of goods" she really did not need, and he
probably installed it poorly.

So, I bought a 1000 watt inverter for about $60, and hooked it up to the
battery, which I left on the original charger, which seemed to work OK. I
could have rigged up a transfer relay to detect loss of AC power and switch
over to inverter power, but that would have taken a large power relay to
switch the 12 VDC primary at 50 amps. So I instructed my friend to simply
move the plug from the sump pump to the inverter and turn it on if power
was lost. She is home most of the time and there is fairly good drainage
anyway, so it's not as if it needs to run very often.

You could also use a heavy duty UPS for the regular pump, which I would
trust more than the wimpy backup pump. It's a good idea to check the
operation of your pump like I did, by simply pouring a 5 gallon bucket of
water in the sump and seeing how it works.

Paul

 

[Chris]

On Feb 5, 10:50 am, usen...@xemaps.com wrote:

Nutshell:

I have a lead acid 12V battery charging device that used a wall
transformer rated as 120 VAC 26W input, 12 VAC 1.6A out. The xformer
failed (primary opened) and I made a replacement (12.6 VAC 3A out) but
it is drawing 4.5A and blowing the secondary fuses I put in place.

Synopsis:

I have two "Basement Watchdog" battery operated sump pumps. The
batteries are 6 cell 12V lead acid batteries. The control panel on
each unit charges the batteries as well as giving status and alarming.
The controller accepts a dry contact (float) to trigger a pump cycle.
It has some led's, a piezo and a button to silence alarms/run pump.
The main load runs from the battery all the time.

One of the devices gave me an AC failed indication. I checked the
transformer and was getting nothing from it. I removed it and went on
to other things. Several days passed and w/ rain in the forecast I
decided to top the charge of on the battery by moving the wall
transformer from the (still) good unit to the one that had failed. Not
too bright on my part because poof went the other transformer. Turns
out there is a problem in the one unit that caused the transformer to
fail.

I pulled the failed control unit out and peeked inside and found a
shorted 6A bridge rectifier diode. I went to RS to get a replacement
and noticed they had a 12V 3A xformer so I decided to build a
replacement, one that would run both units. I made a simple box, wired
up the xformer (full voltage, not using the center tap), paralleled
one secondary leg to two fuses (one for each control unit). I
connected the wires to the control unit to one of the fuses and the
other secondary leg. Secondary was giving 14.6 VAC, no load.

Power up and connect to the pump control unit and all seems ok but
then after about 20 seconds the fuse goes. Investigation shows that
the control unit is drawing about 4.5 A. Remember, this unit is the
one that had zero problems at all, the repaired one is still on the
bench.

Can someone offer any ideas as to why the charger is drawing far more
than the original transformer was rated? I cut one open and could not
find any identifying marks on the transformer. The primary had failed
and the secondary was fused at 5A. The fuse was intact. Input was
labeled as 120 VAC 26W, looks like 0.2A roughly. Stepped down to 12V
that would be 2A.

I am not certain why the high draw - maybe the initial charging cycle
draws much more than 2A, for some period of time, and then bleeds
down? That would mean the original transformer was rated for much
higher than what the wall transformer was labeled. It was fused at 5A
on the secondary.

Thanks.

Some quick points about the Battery Watchdog:

* The worst thing you can do is disconnect the battery with power on.
A poor battery connect will do the same damage. This damages the
regulator portion of the circuit, and it will attempt to charge the
battery at a significantly higher voltage, leading to an overcurrent/
blown fuse condition, and/or burning out the battery. If you've done
this, bad on you. RTFM.

* It's very possible you may have a bad battery, too. It's a standard
marine-type deep-discharge battery, so you should be able to
troubleshoot this yourself without the Battery Watchdog. Disconnect
(please unplug the power first!), and top off the battery cells
without overfilling with distilled water. Put the battery on a known
good automotive battery trickle charger for a while. Use a DVM to
read the voltage on the battery while it's charging. You should be
seeing about 13.8-14.4V across the battery while it's charging. If
it's getting a lot higher or lower than that, your battery may be
unable to take a charge properly. Then remove the charger, wait a
minute, and read the voltage again. You should be seeing somewhere
around 12.6V. If it's lower than that, you may have a dead cell. The
last test would be connecting an automotive headlight to the battery
as a load, and then looking at the battery voltage. For a freshly
charged battery, if it drops significantly below 12V, the battery is
dead or dying. Replace it.

If you're still having problems, you can try email or calling the
Battery Watchdog technical people. They're located in Illinois
(Central Standard Time), and were reasonably helpful when I had a
problem. You can get their contact information from their website.

http://basementwatchdog.com/index.htm

Good luck
Chris

 

Chris wrote:

If you're still having problems, you can try email or calling the
Battery Watchdog technical people. They're located in Illinois
(Central Standard Time), and were reasonably helpful when I had a
problem. You can get their contact information from their website.

http://basementwatchdog.com/index.htm

Good luck
Chris

Thanks to everyone for the advice so far. I have been in contact w/
the BW people and am waiting for clarifications. A comment from a
support rep was "1.6 amp is the DC output; 5 amp is the AC input." He
also mentioned that the 5A fuse was to protect the system if a bridge
rectifier failed (as mine did but the thermal TCO in the transformer
opened, not the fuse). The wall transformer had no rectifier in it, it
is a pure transformer, although the secondary fuse was on a small PCB
with component markings for an obvious bridge rectifier setup. I did
pick the transformer apart and found an open thermal device (as Ross
mentioned). It was rated at 130C. There were no marking on the
internal transformer parts to indicate its actual rating.

I m guessing the natural draw on this device is close to 5A,
especially on a battery that has had its charge depleted somewhat. I
am thinking of simply dropping in a 10A xformer and fusing each device
at 5.

ehsjr mentioned simply dropping in a large fuse and monitoring the
current draw over time in an attempt to divulge its behavior. I was
thinking this as well but the transformer in place at the moment is
rated at 3A. If I am pulling 4.5 do I risk failing the transformer or
are they capable of significant higher current draws than indicated?

Possible silly question: Can I take a 24V xformer and use the center
tap for each of my 2 12V devices? Will the DC output from the bridge
rectifier be ok or will there be serious sags every cycle (the
rectifier feeds an LM7805 voltage regulator - I did some checks on the
repaired, unloaded, control board using my homemade transformer and
got 14.6 VAC (< 0.2 A) out, appx 16 VDC into the 7805 and a nice 5.00
VDC out of it)?

Thanks again

 

[Paul E. Schoen]

<usenet2@xemaps.com> wrote in message
news:2e264f6d-4231-4eec-85f1-a0d0f14a97ff@h20g2000yqn.googlegroups.com...

Chris wrote:

If you're still having problems, you can try email or calling the
Battery Watchdog technical people. They're located in Illinois
(Central Standard Time), and were reasonably helpful when I had a
problem. You can get their contact information from their website.

http://basementwatchdog.com/index.htm

Good luck
Chris

Thanks to everyone for the advice so far. I have been in contact w/
the BW people and am waiting for clarifications. A comment from a
support rep was "1.6 amp is the DC output; 5 amp is the AC input." He
also mentioned that the 5A fuse was to protect the system if a bridge
rectifier failed (as mine did but the thermal TCO in the transformer
opened, not the fuse). The wall transformer had no rectifier in it, it
is a pure transformer, although the secondary fuse was on a small PCB
with component markings for an obvious bridge rectifier setup. I did
pick the transformer apart and found an open thermal device (as Ross
mentioned). It was rated at 130C. There were no marking on the
internal transformer parts to indicate its actual rating.

The transformer probably was current limited to the point that the output
short circuit current was not enough to open the fuse (at least not very
quickly), so it just overheated (which caused its output current to drop
even more), and the TCO opened. Sounds like a rather poor design that was
not properly tested.

I m guessing the natural draw on this device is close to 5A,
especially on a battery that has had its charge depleted somewhat. I
am thinking of simply dropping in a 10A xformer and fusing each device
at 5.

ehsjr mentioned simply dropping in a large fuse and monitoring the
current draw over time in an attempt to divulge its behavior. I was
thinking this as well but the transformer in place at the moment is
rated at 3A. If I am pulling 4.5 do I risk failing the transformer or
are they capable of significant higher current draws than indicated?

Transformers generally can be overloaded on the basis of duty cycle up to
as much as 5x or 10x continuous rating. The duty cycle goes by the inverse
square of the overload, so a 1.4x overload is 50%, 2x overload is 25%, 3x
overload is 10%, and 10x overload is 1%. The actual on and off times are
greater at lower levels, so you might be able to do 15 minutes on and 15
minutes off at 1.4x, while for 3x you might only be able to do 1 minute on
and 10 minutes off. It all depends on the temperature rise at the hottest
point, and the rating of the insulation.

Possible silly question: Can I take a 24V xformer and use the center
tap for each of my 2 12V devices? Will the DC output from the bridge
rectifier be ok or will there be serious sags every cycle (the
rectifier feeds an LM7805 voltage regulator - I did some checks on the
repaired, unloaded, control board using my homemade transformer and
got 14.6 VAC (< 0.2 A) out, appx 16 VDC into the 7805 and a nice 5.00
VDC out of it)?

Probably best to use a FWCT with two diodes and dispense with the bridge
rectifiers. You could use a FWBR on each 12 volt winding as long as there
are no common connections in the DC output circuits.

Thanks again

Paul

 

[Ross Herbert]

On Mon, 9 Feb 2009 07:45:05 -0800 (PST), usenet2@xemaps.com wrote:

:Chris wrote:
:
:> If you're still having problems, you can try email or calling the
:> Battery Watchdog technical people. They're located in Illinois
:> (Central Standard Time), and were reasonably helpful when I had a
:> problem. You can get their contact information from their website.
:>
:> http://basementwatchdog.com/index.htm
:>
:> Good luck
:> Chris
:
:Thanks to everyone for the advice so far. I have been in contact w/
:the BW people and am waiting for clarifications. A comment from a
:support rep was "1.6 amp is the DC output; 5 amp is the AC input." He
:also mentioned that the 5A fuse was to protect the system if a bridge
:rectifier failed (as mine did but the thermal TCO in the transformer
pened, not the fuse). The wall transformer had no rectifier in it, it
:is a pure transformer, although the secondary fuse was on a small PCB
:with component markings for an obvious bridge rectifier setup. I did
ick the transformer apart and found an open thermal device (as Ross
:mentioned). It was rated at 130C. There were no marking on the
:internal transformer parts to indicate its actual rating.
:
:I m guessing the natural draw on this device is close to 5A,
:especially on a battery that has had its charge depleted somewhat. I
:am thinking of simply dropping in a 10A xformer and fusing each device
:at 5.
:
:ehsjr mentioned simply dropping in a large fuse and monitoring the
:current draw over time in an attempt to divulge its behavior. I was
:thinking this as well but the transformer in place at the moment is
:rated at 3A. If I am pulling 4.5 do I risk failing the transformer or
:are they capable of significant higher current draws than indicated?
:
ossible silly question: Can I take a 24V xformer and use the center
:tap for each of my 2 12V devices? Will the DC output from the bridge
:rectifier be ok or will there be serious sags every cycle (the
:rectifier feeds an LM7805 voltage regulator - I did some checks on the
:repaired, unloaded, control board using my homemade transformer and
:got 14.6 VAC (< 0.2 A) out, appx 16 VDC into the 7805 and a nice 5.00
:VDC out of it)?
:
:Thanks again


And thank you for responding to the group - it is much appreciated. Some others
who request help and get a string of replies fail to let the group even know
that they are following the thread they started. They often don't have the
courtesy to make any further comment following their initial request. In such
cases it is no wonder that these posters might be accused of trolling.

 

Following ehsrj's suggestion, I've dropped in a 5A fuse and am running
the 3A xformer and so far it seems quite happy. My current draw is 5a
on the secondary side, 1A on the primary (crappy RS inductive
ammeter). After 15 minutes it is only mildly warm w/ a slight buzz.
I've noticed no duty cycle though, it has been a sold 5A for the 15
minutes.

If all this pans out I think I will just get a second $8 3A xformer
and run with it. The alternative is to spend appx. $25 total for a 10A
12-0-12 one, and then I have the center tap - FWBR thing to deal with,
or spend $45 for two wall transformers from the manufacturer.

And thank you for responding to the group - it is much appreciated. Some others

I am always willing to thank and feedback so others in the future may
glean some info. Usenet is a treasure trove, still. It is getting
tougher (Comcast killing news access) but it is still available. The
noise is outrageous but this is still viable. Thanks to all who
willingly read and respond. (This probably should have been in .repair
but oh well...)

 

[ehsjr]

usenet2@xemaps.com wrote:

Following ehsrj's suggestion, I've dropped in a 5A fuse and am running
the 3A xformer and so far it seems quite happy. My current draw is 5a
on the secondary side, 1A on the primary (crappy RS inductive
ammeter). After 15 minutes it is only mildly warm w/ a slight buzz.
I've noticed no duty cycle though, it has been a sold 5A for the 15
minutes.

If all this pans out I think I will just get a second $8 3A xformer
and run with it. The alternative is to spend appx. $25 total for a 10A
12-0-12 one, and then I have the center tap - FWBR thing to deal with,
or spend $45 for two wall transformers from the manufacturer.


And thank you for responding to the group - it is much appreciated. Some others


I am always willing to thank and feedback so others in the future may
glean some info. Usenet is a treasure trove, still. It is getting
tougher (Comcast killing news access) but it is still available. The
noise is outrageous but this is still viable. Thanks to all who
willingly read and respond. (This probably should have been in .repair
but oh well...)

If the current draw stays at 5 amps, you need to do more.
The batteries draw higher current when they are discharged,
but the current should decrease as they charge. Meanwhile,
your 3A transformer can't be expected to provide 5A forever,
and the original rating you posted was 1.6A, AIRC. SO, if
the current draw stays at 5A, something else is amiss - either
the charging circuit is shot, or the battery is bad.

To diagnose, you can remove the battery, and charge it with a
regular car battery charger, then reconnect it and see if the
current draw has dropped down below ~1.6A. Then check it again
several times a day for a couple of days. Assuming it stays
below ~ 1.6A, your battery may be likely ok.

You can then discharge the battery part way with an auto headlamp.
Connect the headlamp to the battery and measure the current, then
monitor the voltage. Run it for an hour, or until the voltage,
under load, drops to 11.5 volts - no lower. Then monitor the charge
current to see that it drops down as the battery charges. If that
happens, then you're ok with the 3A xformer & your charger. If not,
the charger is bad.

After the 1 hour discharge (or until the voltage drops to 11.5) you
can compute the ampere hours used. You can compare that to the ampere
hours rating for your battery and the draw of the pump to get a sense
of the battery health.

All of that is worth doing so that you get a good sense of whether
the pump will be able to do what you need it to do when there is
a power failure. Using the 5A fuse is correct for the transformer,
but was only the first step.

Ed

 

ehsjr wrote:

usenet2@xemaps.com wrote:

If the current draw stays at 5 amps, you need to do more.
The batteries draw higher current when they are discharged,

The battery draw did drop, albeit a little, to about 4A was the last I
saw. The charging ceased less than an hour after connection. I didn't
watch it the entire time so I don't know exactly how the current
behaved. It is indicating as charged and drawing about 0.2A at the
moment.

and the original rating you posted was 1.6A, AIRC. SO, if
the current draw stays at 5A, something else is amiss - either
the charging circuit is shot, or the battery is bad.

I am trying to get this clarified from the manufacturer. The one email
I received was somewhat cryptic ("1.6 amp is the DC output; 5 amp is
the AC input."). I'm not sure what this means. The wall transformer
was labeled as a 12 VAC 1.6 output, 26W 120 VAC input, plain and
simple. There is no rectifier in the wall unit. So is the 5A the input
to the controller rectifier? If so, why was the wall unit labeled as
1.6A? If the rep us thinking the wall transformer has its own
rectifier, the 5A AC input would be roughly 600W!

The rectifier diodes were 6A, is this an indication of the power
expected or just a common practice to put in beefy components?

To diagnose, you can remove the battery, and charge it with a

Thanks, I will try some of these things. Note that this battery was
replaced last year and also all this testing is being done on the 2nd
unit - one that has had zero issues nor has it been touched in any
way. It's only sin was having an operating wall transformer that some
idiot decided to appropriate.

Thank you Ed.

 

[ehsjr]

usenet2@xemaps.com wrote:

ehsjr wrote:

usenet2@xemaps.com wrote:


If the current draw stays at 5 amps, you need to do more.
The batteries draw higher current when they are discharged,


The battery draw did drop, albeit a little, to about 4A was the last I
saw. The charging ceased less than an hour after connection. I didn't
watch it the entire time so I don't know exactly how the current
behaved. It is indicating as charged and drawing about 0.2A at the
moment.

While not a guarantee, that's an indication that you're home
free. You can do the other tests mentioned earlier, but,
assuming the battery is properly charged, the 3A xformer with
the 5A secondary fuse is a good solution.

and the original rating you posted was 1.6A, AIRC. SO, if
the current draw stays at 5A, something else is amiss - either
the charging circuit is shot, or the battery is bad.


I am trying to get this clarified from the manufacturer. The one email
I received was somewhat cryptic ("1.6 amp is the DC output; 5 amp is
the AC input.").

That's BS from them.

I'm not sure what this means. The wall transformer
was labeled as a 12 VAC 1.6 output, 26W 120 VAC input, plain and
simple. There is no rectifier in the wall unit. So is the 5A the input
to the controller rectifier?

You can have that much current when the battery is low,
as you saw with your measurements. But what their little
wall transformer can provide is a different issue.

If so, why was the wall unit labeled as
1.6A? If the rep us thinking the wall transformer has its own
rectifier, the 5A AC input would be roughly 600W!

Yep. He's wrong. ~5 amps on the 12V secondary is ~.5 amps
on the primary side. And as you mentioned, the 26W rating
means ~.2 amps.

The rectifier diodes were 6A, is this an indication of the power
expected or just a common practice to put in beefy components?

I don't know what they had in mind, but it was most likely
a cost driven decision. It's certainly not designed for
worst case, based on that transformer. I suspect the control
circuitry is not designed to protect the battery from being
discharged too far, and the charger circuitry is likely not
designed to protect itself, the diodes or the transformer.
But that is speculation - I don't know. In most situations
you probably don't need the more expensive worst case design
for this application.

Ed

To diagnose, you can remove the battery, and charge it with a


Thanks, I will try some of these things. Note that this battery was
replaced last year and also all this testing is being done on the 2nd
unit - one that has had zero issues nor has it been touched in any
way. It's only sin was having an operating wall transformer that some
idiot decided to appropriate.

Thank you Ed.

 

[Jasen Betts]

On 2009-02-12, usenet2@xemaps.com <usenet2@xemaps.com> wrote:

Following ehsrj's suggestion, I've dropped in a 5A fuse and am running
the 3A xformer and so far it seems quite happy. My current draw is 5a
on the secondary side, 1A on the primary (crappy RS inductive
ammeter). After 15 minutes it is only mildly warm w/ a slight buzz.
I've noticed no duty cycle though, it has been a sold 5A for the 15
minutes.

does not sound good, if you're measuring 5A after the rectifier on the
DC range of the meter best case is about 8A RMS

If all this pans out I think I will just get a second $8 3A xformer
and run with it. The alternative is to spend appx. $25 total for a 10A
12-0-12 one, and then I have the center tap - FWBR thing to deal with,
or spend $45 for two wall transformers from the manufacturer.

that 12-0-12 sounds better. is that 120VA or 240VA ?

perhsaps you can do half bridge rectifier thing.
__ ______----->|---.
3||( |
3||(____---(-) |--(+)
3||( |
__3||(_______---->|---'