Keeping a 12v battery charged above 80%

[W. eWatson]

I had a fellow out to do some electrical work that involves one 12v
marine battery. The battery will be used about 4-6 hours a night
sporadically. Maybe 15-20% of the time. He offered that it should be
recharged every day, and keeping it above 80% was important for the life
of the battery. Somehow that seems a bit high. Apparently, there's a
charger of some sort that costs about $150 that will adhere to that
schedule. Comments?

 

[krw@att.bizzzzzzzzzzzz]

On Sat, 09 Jun 2012 20:03:51 -0700, "W. eWatson" <wolftracks@invalid.com>
wrote:

I had a fellow out to do some electrical work that involves one 12v
marine battery. The battery will be used about 4-6 hours a night
sporadically. Maybe 15-20% of the time. He offered that it should be
recharged every day, and keeping it above 80% was important for the life
of the battery. Somehow that seems a bit high. Apparently, there's a
charger of some sort that costs about $150 that will adhere to that
schedule. Comments?

Yes, lead-acid batteries should be kept fully charged. The proper charger
shouldn't be that expensive. Just keep it charged. Put it on a timer, if
it'll be months without use; charge an hour or three a day.

 

[Wrecker]

On 06/09/2012 08:03 PM, W. eWatson wrote:

I had a fellow out to do some electrical work that involves one 12v
marine battery. The battery will be used about 4-6 hours a night
sporadically. Maybe 15-20% of the time. He offered that it should be
recharged every day, and keeping it above 80% was important for the life
of the battery. Somehow that seems a bit high. Apparently, there's a
charger of some sort that costs about $150 that will adhere to that
schedule. Comments?

I bought a Battery Tender Jr. for my motorcycle. A
microprocessor-controlled marvel that usually did nothing at all, but
sometimes it drained my battery below the level that it started at.
Never once did it charge the battery. The "Lifetime" warranty required
me to ship it back to Florida for repair, along with handling fees,
diagnostic fees, return shipping fees, etc. that approached the retail
cost of the charger. After a year, I smashed it with a sledgehammer and
threw it in the trash.

 

[W. eWatson]

On 6/9/2012 8:57 PM, Wrecker wrote:

On 06/09/2012 08:03 PM, W. eWatson wrote:
I had a fellow out to do some electrical work that involves one 12v
marine battery. The battery will be used about 4-6 hours a night
sporadically. Maybe 15-20% of the time. He offered that it should be
recharged every day, and keeping it above 80% was important for the life
of the battery. Somehow that seems a bit high. Apparently, there's a
charger of some sort that costs about $150 that will adhere to that
schedule. Comments?

I bought a Battery Tender Jr. for my motorcycle. A
microprocessor-controlled marvel that usually did nothing at all, but
sometimes it drained my battery below the level that it started at.
Never once did it charge the battery. The "Lifetime" warranty required
me to ship it back to Florida for repair, along with handling fees,
diagnostic fees, return shipping fees, etc. that approached the retail
cost of the charger. After a year, I smashed it with a sledgehammer and
threw it in the trash.
I can certainly sympathize with that. I've had a few instances where I

thought I might bring some faulty equipment into a mfger's office and
drop it on the floor.

 

[Jasen Betts]

On 2012-06-10, W. eWatson <wolftracks@invalid.com> wrote:

I had a fellow out to do some electrical work that involves one 12v
marine battery. The battery will be used about 4-6 hours a night
sporadically. Maybe 15-20% of the time. He offered that it should be
recharged every day, and keeping it above 80% was important for the life
of the battery. Somehow that seems a bit high. Apparently, there's a
charger of some sort that costs about $150 that will adhere to that
schedule. Comments?

I own a cheap 4A Arlec charger with electronic control (electronic
control comprises a pcb with a pair of SCRs, a transistor, a zener
diode, and some resistors)

It charges to about 14V gradually reducing the charge rate.
that would be stages 1 and 2 of the diagram here.

http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery

I use it for charging accidentally discharged car batteries, and
for charging the sealed lead acid battery in childs electric trike.
(it charges this smaller battery at 1A gradually tapering off)

It sounds like you'd want one that also does stage 3 "float charge" for your
application. $150 does sound quite expensive (about twice what I would
expect) but I don't know of a more competively priced off-the-shelf
solution.

--
⚂⚃ 100% natural

--- Posted via news://freenews.netfront.net/ - Complaints to news@netfront.net ---

 

[default]

On Sat, 09 Jun 2012 20:03:51 -0700, "W. eWatson"
<wolftracks@invalid.com> wrote:

I had a fellow out to do some electrical work that involves one 12v
marine battery. The battery will be used about 4-6 hours a night
sporadically. Maybe 15-20% of the time. He offered that it should be
recharged every day, and keeping it above 80% was important for the life
of the battery. Somehow that seems a bit high. Apparently, there's a
charger of some sort that costs about $150 that will adhere to that
schedule. Comments?

There must be dozens of good schematics for battery chargers on the
web if you want to roll your own. Schedule? there is no schedule,
but a fully charged battery will live longer. I had a Marine battery
on my boat that lasted 12 years (through two boats). I put a Heathkit
charger on it about once a month when I remembered to do it. Another
on my sailboat that went 10 years on a solar panel and shunt regulated
charger I built. It started the motor, kept the anchor light going,
and cabin lights when I was on board I only checked the electrolyte
level religiously and looked at the charger once in awhile to see that
it was limiting current when I first got on board (every weekend)
--

 

On Sat, 09 Jun 2012 20:03:51 -0700, "W. eWatson"
<wolftracks@invalid.com> wrote:

I had a fellow out to do some electrical work that involves one 12v
marine battery. The battery will be used about 4-6 hours a night
sporadically. Maybe 15-20% of the time. He offered that it should be
recharged every day, and keeping it above 80% was important for the life
of the battery. Somehow that seems a bit high. Apparently, there's a
charger of some sort that costs about $150 that will adhere to that
schedule. Comments?

Black and Decker used to have a selectable 1 and 2 amp charger. It
turned off when the battery was fully charged. I've been using one of
them for a number of years to keep the grandkids' battery-powered
vehicles charged (beats using the "battery burner" that comes with the
vehicles). The charger was about $30. I think they still have a
similar one that only has the 2 amp output. That would be OK foryour
application, but the small SLA batteries in the kiddie cars live
longer if the charge is limited to 1 amp.

Ideally, a lead acid battery is never discharged below 50% - that's
the standard used in designing the battery system for solar or other
alternate energy. The less a lead acid battery is discharged, the
longer it lasts - the electrochemical reactions (charge/discharge) are
reversible, but there is a limit.

 

[Tim Wescott]

On Sat, 09 Jun 2012 20:03:51 -0700, W. eWatson wrote:

I had a fellow out to do some electrical work that involves one 12v
marine battery. The battery will be used about 4-6 hours a night
sporadically. Maybe 15-20% of the time. He offered that it should be
recharged every day, and keeping it above 80% was important for the life
of the battery. Somehow that seems a bit high. Apparently, there's a
charger of some sort that costs about $150 that will adhere to that
schedule. Comments?

I repeat a conversation I heard recently between an ace mechanic and
regular trailer camper, and a new trailer camper with a dead battery:

Go to a place that sells RV stuff and get a float charger. Figure on
spending $20 to $25 bucks.

A "plain old" charger for lead-acid batteries will boil the electrolyte
dry (well, it'll electrolyze it into hydrogen and oxygen, but it's the
same difference to you). Go for the float charger.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

 

[Bob Engelhardt]

news@jecarter.us wrote:

...
Ideally, a lead acid battery is never discharged below 50% - ...

How is charge measured? Voltage? Does 50% mean a 12v battery at 6v?
That doesn't sound right.

 

[Sjouke Burry]

Bob Engelhardt <bobengelhardt@comcast.net> wrote in news:jr8d6d01ej8
@news3.newsguy.com:

news@jecarter.us wrote:
...
Ideally, a lead acid battery is never discharged below 50% - ...

How is charge measured? Voltage? Does 50% mean a 12v battery at 6v?
That doesn't sound right.

That is because the talk was about the charge, not the voltage.
8-10 volt means almost empty.
Below that you are trying to kill the battery.

 

[Winston]

On Tue, 12 Jun 2012 22:40:14 +0000, Sjouke Burry wrote:

Bob Engelhardt <bobengelhardt@comcast.net> wrote in news:jr8d6d01ej8
@news3.newsguy.com:

news@jecarter.us wrote:
...
Ideally, a lead acid battery is never discharged below 50% - ...

How is charge measured? Voltage? Does 50% mean a 12v battery at 6v?
That doesn't sound right.


That is because the talk was about the charge, not the voltage. 8-10
volt means almost empty.
Below that you are trying to kill the battery.

Below 12v you are trying to kill the battery.
http://batteryuniversity.com/learn/how_to_measure_state_of_charge

--Winston

 

[krw@att.bizzzzzzzzzzzz]

On Tue, 12 Jun 2012 17:43:50 -0400, Bob Engelhardt <bobengelhardt@comcast.net>
wrote:

news@jecarter.us wrote:
...
Ideally, a lead acid battery is never discharged below 50% - ...

How is charge measured? Voltage? Does 50% mean a 12v battery at 6v?
That doesn't sound right.

Integrate the current taken out of a fully charged battery (integral of
current is charge). When that number reaches ~50% of the rated capacity,
stop.

 

[Bob Engelhardt]

Sjouke Burry wrote:

Bob Engelhardt <bobengelhardt@comcast.net> wrote in news:jr8d6d01ej8
@news3.newsguy.com:

news@jecarter.us wrote:
...
Ideally, a lead acid battery is never discharged below 50% - ...
How is charge measured? Voltage? Does 50% mean a 12v battery at 6v?
That doesn't sound right.


That is because the talk was about the charge, not the voltage.
....

I know. That's why I asked: "How is charge measured?"

 

[Bob Engelhardt]

Winston wrote:

...
http://batteryuniversity.com/learn/how_to_measure_state_of_charge

More specifically:
http://batteryuniversity.com/learn/article/how_to_measure_state_of_charge

Which says basically that charge is pretty hard to measure. I.e., there
isn't a simple, accurate technique.

 

[Bob Engelhardt]

krw@att.bizzzzzzzzzzzz wrote:

On Tue, 12 Jun 2012 17:43:50 -0400, Bob Engelhardt <bobengelhardt@comcast.net
wrote:

news@jecarter.us wrote:
...
Ideally, a lead acid battery is never discharged below 50% - ...
How is charge measured? Voltage? Does 50% mean a 12v battery at 6v?
That doesn't sound right.

Integrate the current taken out of a fully charged battery (integral of
current is charge). When that number reaches ~50% of the rated capacity,
stop.

batteryuniversity calls that coulomb counting. Even that is subject to
the battery actually having its rated capacity when it's fully charged.

 

[Winston]

On Tue, 12 Jun 2012 23:27:18 -0400, Bob Engelhardt wrote:

Winston wrote:
...
http://batteryuniversity.com/learn/how_to_measure_state_of_charge

More specifically:
http://batteryuniversity.com/learn/article/
how_to_measure_state_of_charge

Quite right. Thanks!

Which says basically that charge is pretty hard to measure. I.e., there
isn't a simple, accurate technique.

'Same is true for anything else we measure, for very demanding
levels of accuracy. However, one can also take the article
to say that measuring open-circuit terminal voltage (after
allowing the battery to rest) yields accuracy that is quite
acceptable for just about anything a hobbyist is likely to do.

Yes? No?

My nice torque wrench serves perfectly fine to be within +-5%
of the *real* reading. I don't have a need to know my lug
nut torque with much better accuracy than that.
'Same is true for my ammeters. I know that there is a burden
voltage on top of calibration errors and the relative sloppiness
of all physical things, but I accept their readings if I am
comfortable that the reading that I see is likely to be
'close enough'. (Yes, rarely I *am* fooled by readings that
are not nearly 'close enough').

Why take away these tools (and hundreds of others) as being
'too imprecise' if great accuracy is not required?


--Winston

 

[krw@att.bizzzzzzzzzzzz]

On Tue, 12 Jun 2012 23:31:25 -0400, Bob Engelhardt <bobengelhardt@comcast.net>
wrote:

krw@att.bizzzzzzzzzzzz wrote:
On Tue, 12 Jun 2012 17:43:50 -0400, Bob Engelhardt <bobengelhardt@comcast.net
wrote:

news@jecarter.us wrote:
...
Ideally, a lead acid battery is never discharged below 50% - ...
How is charge measured? Voltage? Does 50% mean a 12v battery at 6v?
That doesn't sound right.

Integrate the current taken out of a fully charged battery (integral of
current is charge). When that number reaches ~50% of the rated capacity,
stop.


batteryuniversity calls that coulomb counting.

Well, the unit of charge is the Coulomb, so that makes some sense. ;-)

Even that is subject to
the battery actually having its rated capacity when it's fully charged.

If the battery is so bad that 50% isn't enough margin of error, it's done
anyway. A battery is considered "bad" if its capacity is 80% of that of a new
battery.

 

[tuinkabouter]

On 6/12/2012 11:43 PM, Bob Engelhardt wrote:

news@jecarter.us wrote:
...
Ideally, a lead acid battery is never discharged below 50% - ...

How is charge measured? Voltage? Does 50% mean a 12v battery at 6v? That
doesn't sound right.

Read the wiki: https://en.wikipedia.org/wiki/Lead%E2%80%93acid_battery
Look at the open voltage caracteristic (the name is misleding):

https://en.wikipedia.org/wiki/File:Lead-acid_voltage_vs_SOC.PNG

When a lead battery starts gassing it is full.

--
pim.

 

[amdx]

On 6/9/2012 10:57 PM, Wrecker wrote:

On 06/09/2012 08:03 PM, W. eWatson wrote:
I had a fellow out to do some electrical work that involves one 12v
marine battery. The battery will be used about 4-6 hours a night
sporadically. Maybe 15-20% of the time. He offered that it should be
recharged every day, and keeping it above 80% was important for the life
of the battery. Somehow that seems a bit high. Apparently, there's a
charger of some sort that costs about $150 that will adhere to that
schedule. Comments?

I bought a Battery Tender Jr. for my motorcycle. A
microprocessor-controlled marvel that usually did nothing at all, but
sometimes it drained my battery below the level that it started at.
Never once did it charge the battery. The "Lifetime" warranty required
me to ship it back to Florida for repair, along with handling fees,
diagnostic fees, return shipping fees, etc. that approached the retail
cost of the charger. After a year, I smashed it with a sledgehammer and
threw it in the trash.

I note Amazon.com has 761 customer reviews.
95% are 4 or 5 star and 84% are 5 star.
Leaving only *5% unhappy with the product,
looks like you got a bad one.

* I think it might be lower, as unhappy people
are more likely to complain.

Mikek

 

[Wrecker]

On 06/13/2012 10:42 AM, amdx wrote:

On 6/9/2012 10:57 PM, Wrecker wrote:

I bought a Battery Tender Jr. for my motorcycle.
....
After a year, I smashed it with a sledgehammer and
threw it in the trash.

I note Amazon.com has 761 customer reviews.
95% are 4 or 5 star and 84% are 5 star.
Leaving only *5% unhappy with the product,
looks like you got a bad one.

Yep. And when I needed the warranty (5 years I think it was, not
lifetime), I found it was laughable.

* I think it might be lower, as unhappy people
are more likely to complain.

People also like to push their choices, and rally others to follow.
Everyone likes to be an authority. I see that so often on hokey
Newegg.com reviews.

> Mikek