Car battery charging below float voltage?...

[Commander Kinsey]

I have 8 computers with 15 graphics cards running science projects. The graphics cards run from 12 volts, adding up to a lot of current between them. I have three 1kW power supplies connected to a big bus bar and have set those power supplies to 12.6 volts, as the graphics cards expect 11.4 to 12.6 volts, so I\'m playing safe and allowing the biggest voltage drop not to make it fall outside that range. Currently I\'m close to the limit of the power supplies, and since the current draw of the graphics cards is uneven, I thought it would be a good idea to add a car battery (actually a 130 Ah leisure battery) to the bus bars, to help out if there was too much current draw momentarily. The power supplies are current limited so don\'t mind if I try to draw too much, they will just limit the current.

My question is, is it ok to have the battery sat at 12.6 volts? This is the voltage the battery sits at with nothing connected to it when it\'s 95% full. If the battery were to supply a fair amount of current for a while and become a little discharged, would it manage to charge back up with only 12.6 volts supplied to it? Or does it require a float voltage of 13.2 volts or more?

 

[Peeler]

On Mon, 9 Jan 2023 22:57:21 -0000 (UTC), Hul Tytus, another mentally
deficient troll-feeding senile ASSHOLE, blathered:

> I\'ve found 12.6 volts

You STILL haven\'t found out that you are playing the troll\'s game, senile
idiot!

 

[Peeler]

On Mon, 9 Jan 2023 22:57:21 -0000 (UTC), Hul Tytus, another mentally
deficient troll-feeding senile ASSHOLE, blathered:

> I\'ve found 12.6 volts

You STILL haven\'t found out that you are playing the troll\'s game, senile
idiot!

 

[Peeler]

On Mon, 9 Jan 2023 22:57:21 -0000 (UTC), Hul Tytus, another mentally
deficient troll-feeding senile ASSHOLE, blathered:

> I\'ve found 12.6 volts

You STILL haven\'t found out that you are playing the troll\'s game, senile
idiot!

 

[Commander Kinsey]

I guess if that battery was half full, so 12V open circuit, you\'d get a bigger current?

On Mon, 09 Jan 2023 22:57:21 -0000, Hul Tytus <ht@panix.com> wrote:

I\'ve found 12.6 volts applied to car batteries effective, though slow, for charging. I\'ve been monitoring a battery
that\'s been charging from a current source limited to 12.6 volts. Current yesterday morning measured .029 amps & 12.55v.

Hul

In sci.electronics.design Commander Kinsey <CK1@nospam.com> wrote:
I have 8 computers with 15 graphics cards running science projects. The graphics cards run from 12 volts, adding up to a lot of current between them. I have three 1kW power supplies connected to a big bus bar and have set those power supplies to 12.6 volts, as the graphics cards expect 11.4 to 12.6 volts, so I\'m playing safe and allowing the biggest voltage drop not to make it fall outside that range. Currently I\'m close to the limit of the power supplies, and since the current draw of the graphics cards is uneven, I thought it would be a good idea to add a car battery (actually a 130 Ah leisure battery) to the bus bars, to help out if there was too much current draw momentarily. The power supplies are current limited so don\'t mind if I try to draw too much, they will just limit the current.

My question is, is it ok to have the battery sat at 12.6 volts? This is the voltage the battery sits at with nothing connected to it when it\'s 95% full. If the battery were to supply a fair amount of current for a while and become a little discharged, would it manage to charge back up with only 12.6 volts supplied to it? Or does it require a float voltage of 13.2 volts or more?

 

[Commander Kinsey]

I guess if that battery was half full, so 12V open circuit, you\'d get a bigger current?

On Mon, 09 Jan 2023 22:57:21 -0000, Hul Tytus <ht@panix.com> wrote:

I\'ve found 12.6 volts applied to car batteries effective, though slow, for charging. I\'ve been monitoring a battery
that\'s been charging from a current source limited to 12.6 volts. Current yesterday morning measured .029 amps & 12.55v.

Hul

In sci.electronics.design Commander Kinsey <CK1@nospam.com> wrote:
I have 8 computers with 15 graphics cards running science projects. The graphics cards run from 12 volts, adding up to a lot of current between them. I have three 1kW power supplies connected to a big bus bar and have set those power supplies to 12.6 volts, as the graphics cards expect 11.4 to 12.6 volts, so I\'m playing safe and allowing the biggest voltage drop not to make it fall outside that range. Currently I\'m close to the limit of the power supplies, and since the current draw of the graphics cards is uneven, I thought it would be a good idea to add a car battery (actually a 130 Ah leisure battery) to the bus bars, to help out if there was too much current draw momentarily. The power supplies are current limited so don\'t mind if I try to draw too much, they will just limit the current.

My question is, is it ok to have the battery sat at 12.6 volts? This is the voltage the battery sits at with nothing connected to it when it\'s 95% full. If the battery were to supply a fair amount of current for a while and become a little discharged, would it manage to charge back up with only 12.6 volts supplied to it? Or does it require a float voltage of 13.2 volts or more?

 

[Commander Kinsey]

I guess if that battery was half full, so 12V open circuit, you\'d get a bigger current?

On Mon, 09 Jan 2023 22:57:21 -0000, Hul Tytus <ht@panix.com> wrote:

I\'ve found 12.6 volts applied to car batteries effective, though slow, for charging. I\'ve been monitoring a battery
that\'s been charging from a current source limited to 12.6 volts. Current yesterday morning measured .029 amps & 12.55v.

Hul

In sci.electronics.design Commander Kinsey <CK1@nospam.com> wrote:
I have 8 computers with 15 graphics cards running science projects. The graphics cards run from 12 volts, adding up to a lot of current between them. I have three 1kW power supplies connected to a big bus bar and have set those power supplies to 12.6 volts, as the graphics cards expect 11.4 to 12.6 volts, so I\'m playing safe and allowing the biggest voltage drop not to make it fall outside that range. Currently I\'m close to the limit of the power supplies, and since the current draw of the graphics cards is uneven, I thought it would be a good idea to add a car battery (actually a 130 Ah leisure battery) to the bus bars, to help out if there was too much current draw momentarily. The power supplies are current limited so don\'t mind if I try to draw too much, they will just limit the current.

My question is, is it ok to have the battery sat at 12.6 volts? This is the voltage the battery sits at with nothing connected to it when it\'s 95% full. If the battery were to supply a fair amount of current for a while and become a little discharged, would it manage to charge back up with only 12.6 volts supplied to it? Or does it require a float voltage of 13.2 volts or more?

 

[Peeler]

On Mon, 9 Jan 2023 10:33:30 -0000, Brainless & Daft, the TV-watching and
pity-baiting senile \"blind\" mole, blathered again:

In my experience it would be fine, of course if the extra current charging
the battery exceeded the load for everything on the psu, you would be back
to square one if you are not careful.
These must be very power hungry cards. I would not want you electricity
bill.
Brainless & Daft

In my experience you are a sick troll-feeding senile asshole. One of the
disgusting and despicable sort who plays the \"handicapped\" card, so he can
continue with his idiotic bullshitting and troll-feeding unrestrictedly.

 

[Peeler]

On Mon, 9 Jan 2023 10:33:30 -0000, Brainless & Daft, the TV-watching and
pity-baiting senile \"blind\" mole, blathered again:

In my experience it would be fine, of course if the extra current charging
the battery exceeded the load for everything on the psu, you would be back
to square one if you are not careful.
These must be very power hungry cards. I would not want you electricity
bill.
Brainless & Daft

In my experience you are a sick troll-feeding senile asshole. One of the
disgusting and despicable sort who plays the \"handicapped\" card, so he can
continue with his idiotic bullshitting and troll-feeding unrestrictedly.

 

[Peeler]

On Mon, 9 Jan 2023 10:33:30 -0000, Brainless & Daft, the TV-watching and
pity-baiting senile \"blind\" mole, blathered again:

In my experience it would be fine, of course if the extra current charging
the battery exceeded the load for everything on the psu, you would be back
to square one if you are not careful.
These must be very power hungry cards. I would not want you electricity
bill.
Brainless & Daft

In my experience you are a sick troll-feeding senile asshole. One of the
disgusting and despicable sort who plays the \"handicapped\" card, so he can
continue with his idiotic bullshitting and troll-feeding unrestrictedly.

 

[Peeler]

On Tue, 10 Jan 2023 10:09:16 +1100, Sylvia Else, another mentally deficient
troll-feeding senile ASSHOLE, blathered:


> I would question the economics.

I question the mental sanity of every single troll-feeding senile asshole
here, who keeps humouring the KNOWN and PROVEN clinically insane Scottish
attention whore, troll and wanker!

 

[Peeler]

On Tue, 10 Jan 2023 10:09:16 +1100, Sylvia Else, another mentally deficient
troll-feeding senile ASSHOLE, blathered:


> I would question the economics.

I question the mental sanity of every single troll-feeding senile asshole
here, who keeps humouring the KNOWN and PROVEN clinically insane Scottish
attention whore, troll and wanker!

 

[Peeler]

On Tue, 10 Jan 2023 10:09:16 +1100, Sylvia Else, another mentally deficient
troll-feeding senile ASSHOLE, blathered:


> I would question the economics.

I question the mental sanity of every single troll-feeding senile asshole
here, who keeps humouring the KNOWN and PROVEN clinically insane Scottish
attention whore, troll and wanker!

 

[Commander Kinsey]

On Mon, 09 Jan 2023 23:09:16 -0000, Sylvia Else <sylvia@email.invalid> wrote:

On 09-Jan-23 3:37 pm, Commander Kinsey wrote:
I have 8 computers with 15 graphics cards running science projects. The
graphics cards run from 12 volts, adding up to a lot of current between
them. I have three 1kW power supplies connected to a big bus bar and
have set those power supplies to 12.6 volts, as the graphics cards
expect 11.4 to 12.6 volts, so I\'m playing safe and allowing the biggest
voltage drop not to make it fall outside that range. Currently I\'m
close to the limit of the power supplies, and since the current draw of
the graphics cards is uneven, I thought it would be a good idea to add a
car battery (actually a 130 Ah leisure battery) to the bus bars, to help
out if there was too much current draw momentarily. The power supplies
are current limited so don\'t mind if I try to draw too much, they will
just limit the current.

My question is, is it ok to have the battery sat at 12.6 volts? This is
the voltage the battery sits at with nothing connected to it when it\'s
95% full. If the battery were to supply a fair amount of current for a
while and become a little discharged, would it manage to charge back up
with only 12.6 volts supplied to it? Or does it require a float voltage
of 13.2 volts or more?

I would question the economics. Lead-acid batteries don\'t last very long
at the best of times, and they\'re quite pricey. Unless this is a
short-term endeavour, I expect it would be cheaper to increase your
power supply capacity.

It was £75 for 130Ah. They last for 5 years in a car, and this one won\'t be experiencing hundreds of amps to start an engine, so should last a lot longer.

I am increasing the capacity, but it takes almost a month to get a new one (they come from China). Now I\'ve put it there I might aswell leave it there. It means I have more flexibility, I can remove a supply for repair, or move it around etc.

There\'s a ripple current of 0.5A, so it\'s being a nice smoothing capacitor too. I think I might add a fuse though, I looked it up and a battery that big will give out 8000 amps if shorted with a big enough spanner. The cable is rated at only 400 amps so I think some flames would result.. I\'ll have to check what the resistance of a fuse is though, don\'t want to lose a couple of tenths of a volt.

 

[Commander Kinsey]

On Mon, 09 Jan 2023 23:09:16 -0000, Sylvia Else <sylvia@email.invalid> wrote:

On 09-Jan-23 3:37 pm, Commander Kinsey wrote:
I have 8 computers with 15 graphics cards running science projects. The
graphics cards run from 12 volts, adding up to a lot of current between
them. I have three 1kW power supplies connected to a big bus bar and
have set those power supplies to 12.6 volts, as the graphics cards
expect 11.4 to 12.6 volts, so I\'m playing safe and allowing the biggest
voltage drop not to make it fall outside that range. Currently I\'m
close to the limit of the power supplies, and since the current draw of
the graphics cards is uneven, I thought it would be a good idea to add a
car battery (actually a 130 Ah leisure battery) to the bus bars, to help
out if there was too much current draw momentarily. The power supplies
are current limited so don\'t mind if I try to draw too much, they will
just limit the current.

My question is, is it ok to have the battery sat at 12.6 volts? This is
the voltage the battery sits at with nothing connected to it when it\'s
95% full. If the battery were to supply a fair amount of current for a
while and become a little discharged, would it manage to charge back up
with only 12.6 volts supplied to it? Or does it require a float voltage
of 13.2 volts or more?

I would question the economics. Lead-acid batteries don\'t last very long
at the best of times, and they\'re quite pricey. Unless this is a
short-term endeavour, I expect it would be cheaper to increase your
power supply capacity.

It was £75 for 130Ah. They last for 5 years in a car, and this one won\'t be experiencing hundreds of amps to start an engine, so should last a lot longer.

I am increasing the capacity, but it takes almost a month to get a new one (they come from China). Now I\'ve put it there I might aswell leave it there. It means I have more flexibility, I can remove a supply for repair, or move it around etc.

There\'s a ripple current of 0.5A, so it\'s being a nice smoothing capacitor too. I think I might add a fuse though, I looked it up and a battery that big will give out 8000 amps if shorted with a big enough spanner. The cable is rated at only 400 amps so I think some flames would result.. I\'ll have to check what the resistance of a fuse is though, don\'t want to lose a couple of tenths of a volt.

 

[Commander Kinsey]

On Mon, 09 Jan 2023 23:09:16 -0000, Sylvia Else <sylvia@email.invalid> wrote:

On 09-Jan-23 3:37 pm, Commander Kinsey wrote:
I have 8 computers with 15 graphics cards running science projects. The
graphics cards run from 12 volts, adding up to a lot of current between
them. I have three 1kW power supplies connected to a big bus bar and
have set those power supplies to 12.6 volts, as the graphics cards
expect 11.4 to 12.6 volts, so I\'m playing safe and allowing the biggest
voltage drop not to make it fall outside that range. Currently I\'m
close to the limit of the power supplies, and since the current draw of
the graphics cards is uneven, I thought it would be a good idea to add a
car battery (actually a 130 Ah leisure battery) to the bus bars, to help
out if there was too much current draw momentarily. The power supplies
are current limited so don\'t mind if I try to draw too much, they will
just limit the current.

My question is, is it ok to have the battery sat at 12.6 volts? This is
the voltage the battery sits at with nothing connected to it when it\'s
95% full. If the battery were to supply a fair amount of current for a
while and become a little discharged, would it manage to charge back up
with only 12.6 volts supplied to it? Or does it require a float voltage
of 13.2 volts or more?

I would question the economics. Lead-acid batteries don\'t last very long
at the best of times, and they\'re quite pricey. Unless this is a
short-term endeavour, I expect it would be cheaper to increase your
power supply capacity.

It was £75 for 130Ah. They last for 5 years in a car, and this one won\'t be experiencing hundreds of amps to start an engine, so should last a lot longer.

I am increasing the capacity, but it takes almost a month to get a new one (they come from China). Now I\'ve put it there I might aswell leave it there. It means I have more flexibility, I can remove a supply for repair, or move it around etc.

There\'s a ripple current of 0.5A, so it\'s being a nice smoothing capacitor too. I think I might add a fuse though, I looked it up and a battery that big will give out 8000 amps if shorted with a big enough spanner. The cable is rated at only 400 amps so I think some flames would result.. I\'ll have to check what the resistance of a fuse is though, don\'t want to lose a couple of tenths of a volt.

 

[Peeler]

On Wed, 11 Jan 2023 09:06:17 -0500, legg, another brain dead troll-feeding
senile ASSHOLE, babbled:


> Get serious.

Yep, that\'s the way to admonish a proven clinically insane troll,
troll-feeding senile asshole! LOL

Some of Birdbrain\'s superhuman feats:

\"I go hillwalking barefoot for hours in the snow, my feet just go red.
Extra blood, they can\'t freeze.\"
MID: <op.y3xjmqg9js98qf@red.lan>

More from Birdbrain\'s sociopathic world:
\"I like being naked in the snow. All humans are warmblooded and it really
doesn\'t matter what temperature you are. I was swimming in the sea the
other day, not far above freezing point. It felt nice. And why do people
not like shivering?\"
Message-ID: <op.zdj2zgh5js98qf@red.lan>

Birdbrain Macaw (now \"Commander Kinsey\") about himself:
\"I can sleep outside in a temperature of -20C wearing only shorts\".
\"I once took a dump behind some bushes and slid down a hill to wipe my
arse\".
(Courtesy of Mr Pounder)

\"Having read the utter bullshit about dying if you fall in a freezing lake
for 15 minutes, I\'ve tried it on many occasions. It takes 30 minutes to
even get chattering teeth, an hour to shiver nicely, and 2 hours to shiver
hard.\"
MID: <op.yvpolqmzjs98qf@red.lan>

 

[Peeler]

On Wed, 11 Jan 2023 09:06:17 -0500, legg, another brain dead troll-feeding
senile ASSHOLE, babbled:


> Get serious.

Yep, that\'s the way to admonish a proven clinically insane troll,
troll-feeding senile asshole! LOL

Some of Birdbrain\'s superhuman feats:

\"I go hillwalking barefoot for hours in the snow, my feet just go red.
Extra blood, they can\'t freeze.\"
MID: <op.y3xjmqg9js98qf@red.lan>

More from Birdbrain\'s sociopathic world:
\"I like being naked in the snow. All humans are warmblooded and it really
doesn\'t matter what temperature you are. I was swimming in the sea the
other day, not far above freezing point. It felt nice. And why do people
not like shivering?\"
Message-ID: <op.zdj2zgh5js98qf@red.lan>

Birdbrain Macaw (now \"Commander Kinsey\") about himself:
\"I can sleep outside in a temperature of -20C wearing only shorts\".
\"I once took a dump behind some bushes and slid down a hill to wipe my
arse\".
(Courtesy of Mr Pounder)

\"Having read the utter bullshit about dying if you fall in a freezing lake
for 15 minutes, I\'ve tried it on many occasions. It takes 30 minutes to
even get chattering teeth, an hour to shiver nicely, and 2 hours to shiver
hard.\"
MID: <op.yvpolqmzjs98qf@red.lan>

 

[Peeler]

On Wed, 11 Jan 2023 09:06:17 -0500, legg, another brain dead troll-feeding
senile ASSHOLE, babbled:


> Get serious.

Yep, that\'s the way to admonish a proven clinically insane troll,
troll-feeding senile asshole! LOL

Some of Birdbrain\'s superhuman feats:

\"I go hillwalking barefoot for hours in the snow, my feet just go red.
Extra blood, they can\'t freeze.\"
MID: <op.y3xjmqg9js98qf@red.lan>

More from Birdbrain\'s sociopathic world:
\"I like being naked in the snow. All humans are warmblooded and it really
doesn\'t matter what temperature you are. I was swimming in the sea the
other day, not far above freezing point. It felt nice. And why do people
not like shivering?\"
Message-ID: <op.zdj2zgh5js98qf@red.lan>

Birdbrain Macaw (now \"Commander Kinsey\") about himself:
\"I can sleep outside in a temperature of -20C wearing only shorts\".
\"I once took a dump behind some bushes and slid down a hill to wipe my
arse\".
(Courtesy of Mr Pounder)

\"Having read the utter bullshit about dying if you fall in a freezing lake
for 15 minutes, I\'ve tried it on many occasions. It takes 30 minutes to
even get chattering teeth, an hour to shiver nicely, and 2 hours to shiver
hard.\"
MID: <op.yvpolqmzjs98qf@red.lan>

 

[Commander Kinsey]

On Tue, 10 Jan 2023 01:57:24 -0000, Paul <nospam@needed.invalid> wrote:

On 1/8/2023 11:37 PM, Commander Kinsey wrote:
I have 8 computers with 15 graphics cards running science projects. The graphics cards run from 12 volts, adding up to a lot of current between them. I have three 1kW power supplies connected to a big bus bar and have set those power supplies to 12.6 volts, as the graphics cards expect 11.4 to 12.6 volts, so I\'m playing safe and allowing the biggest voltage drop not to make it fall outside that range. Currently I\'m close to the limit of the power supplies, and since the current draw of the graphics cards is uneven, I thought it would be a good idea to add a car battery (actually a 130 Ah leisure battery) to the bus bars, to help out if there was too much current draw momentarily. The power supplies are current limited so don\'t mind if I try to draw too much, they will just limit the current.

My question is, is it ok to have the battery sat at 12.6 volts? This is the voltage the battery sits at with nothing connected to it when it\'s 95% full. If the battery were to supply a fair amount of current for a while and become a little discharged, would it manage to charge back up with only 12.6 volts supplied to it? Or does it require a float voltage of 13.2 volts or more?

Power outages, have statistics.

Here, a power outage is 1 second. Or a power outage is 2+ hours.

Do you live in India? I can\'t remember my last power outage. This battery is not for power outages.

In fact, the long power outages have been lengthening in time,
in the last decade. One lasted a day. The last one was two days plus.
The power company is on a safety kick, where power repair trucks
sit idle on the street, with staff sitting on their hands.

As such, a single leisure battery and three 80 ampere loads, that\'s
a huge load. And the 130 Ah leisure battery, you\'re not really supposed
to be running those flat. This means you have well-less than an
hour of capacity. How many BOINC units can you do in half an hour ?
Is it worth XXX pounds currency, for the privilege of doing
so few units ?

The computers are not powered by that battery. They run directly off the mains. They do nothing in a power outage.

With a UPS, the objective is to allow clean shutdown of all
computers. You could buy a consumer UPS for each 1kW supply.
Maybe this would give you 8 minutes holdup time, or 4 minutes
holdup time. You would need to send the shutdown signal,
to all the computers, so they would begin shutting down.

I have one for the computer in here, plus the screen, stereo, internet router, and lights for the whole house. That runs off two of those batteries. The pathetic little batteries inside UPSs are useless, I bought a 2nd hand one without batteries and connected the leisure batteries to it. Lasts 20 times longer.

My parents bought a 720W UPS which will power a 15W LED standard lamp for 8 hours, or that plus two fridges for 2 hours. Pathetic. I\'m trying to persuade my dad to let me connect a couple of leisure batteries to it. The original intention was to power the pumps for the oil boiler but they changed their mind and said they can just use the fireplace. For some reason he doesn\'t trust me connecting stuff to his fusebox.

You cannot buy the lowest tier of UPS either, if you
really plan on handling a full kW load. There are some
really awful UPS that will smoke if you do that.

My APC 1kW UPS can power a 1kW vacuum cleaner, even though motors at the full load rating are not supposed to be connected to a UPS (they draw 5 times the current at startup).

A commercial UPS, a double conversion rack mount, might have the
power rating to run your entire computer room. But, you will
be charged a commercial rate for such a beast.

Nah, I\'d get a 5kW solar invertor, and add lots of leisure batteries which are dirt cheap. A 240V powered relay will easily switch the load between that and the mains instantly.

Actually most of the load could run straight off the battery as it\'s 12V.

If the doom sayers are correct and we end up with mass power shortages, I may end up with the whole house on UPS.

In your IT days,
you might have had such rackmount UPS in the server room.

We did, it held the (on wheels) server cabinet very steady!

They seem to be quite common. As double conversion, they have a
cooling fan that runs constantly (unlike a consumer SPS which
runs cool until it flips to battery).

No, ours did not make any noise. If there was a fan it was totally silent when not under load.

Buying three UPS, would be an intermediate solution, compared to
buying a Tesla Powerwall (price has gone up 2x since introduction),
or some of the less well thought out consumer \"battery bank\" thingies.

Those are a stupid idea. Lithium Ion batteries?!? Way too expansive. Li Ion is for when you need light weight, otherwise lead acid is far cheaper.

There is one product, which does not even work as well as a
double conversion UPS, which would be cheaper than a powerwall,
and they\'re about 1kWh each.

*******

The video card uses 3.3V and 12V

No it does not, my video cards run entirely off 12V.

> The motherboard uses 3.3,5,12,-12,+5VSB.

A very small amount of current. The CPU is 12V for example.

The leisure battery only has one voltage, not
six or seven voltages.

You need to pick the logically correct point for
backup powering this mess.

Your plan right now, is just plain wrong.

You might care to read what I\'m doing first.