Battery gets hot during charging on bench

[Kestas]

I needed to trickle charge the battery of a car I have in storage. After trickle charging (2 days at 2 amps) two things caught my attention when I disconnected the charger. One, the negative battery post was black even though I shinied the post two days ago. And two, the cell immediately adjacent to the negative post was warm. All other cells were at room temperature. The battery seems to work fine; the car started right up after installation. And there may be a bulge on the side of the battery next to the negative post. What is going on? I topped off the cells before charging and they were all full after charging.

 

[dave munson]

You are boiling the battery. Overcharging. Too much voltage. You may want to invest in a better battery charger. There are several good ones reviewed at amazon.

 

[andyd]

Take the charger off the battery for two days. Check the battery voltage. If it is below 12.5 volts the battery has a bad / shorted cell.

If I leave a light on in the car and flatten the battery down to 7 volts or so and all I get is a buzz from the relay . I can charge the battery overnight at 2 Amps and the car will start in the morning. Also the charger isnt shutting off , which it should after reaching float voltage. That could indicate a short.

 

[Donald]

If its a true trickle charger toss it and get a float charger also called a battery maintainer.

A true trickle charger charges at 2 amps forever, never shuts off. While it might be OK for overnight, there are newer and better chargers out there for $20.

 

[901Memphis]

http://www.amazon.com/gp/aw/d/B00068XCQU

That's what you want. The junior model is okay too.

 

[TFB1]

Originally Posted By: Donald
If its a true trickle charger toss it and get a float charger also called a battery maintainer.

A true trickle charger charges at 2 amps forever, never shuts off. While it might be OK for overnight, there are newer and better chargers out there for $20.


This really depends on the charger, some are less...

I use a 1957 power supply designed to service tube type car radios, on 12v operation can dial up anything between zero and 10 amps(0-20A for 6V oper) ... For trickle I usually set it at approx 1/2A and have never heated a battery...

 

[Donald]

Originally Posted By: TFB1
Originally Posted By: Donald
If its a true trickle charger toss it and get a float charger also called a battery maintainer.

A true trickle charger charges at 2 amps forever, never shuts off. While it might be OK for overnight, there are newer and better chargers out there for $20.


This really depends on the charger, some are less...

I use a 1957 power supply designed to service tube type car radios, on 12v operation can dial up anything between zero and 10 amps(0-20A for 6V oper) ... For trickle I usually set it at approx 1/2A and have never heated a battery...


The main point is a true trickle charger does not shut off. Thats the problem.

 

[901Memphis]

If its not micro processor controlled it is manual and you would need a multi meter and a lot of time to properly maintain a battery.

 

[JHZR2]

The first two posts are what you need to do/look at.

I'd buy a temp compensated battery minder model 2012.

Sounds like a shorted cell or one that has had a big impedance rise that causes a lot of localized heating. Imbalanced cells is common.

If there is plenty of electrolyte in all cells, then a an equalization charge at high voltage and controlled current would be valid before condemning.

 

[Trav]

You cooked it. A 2A charger with no controller will put 96A into the battery in 48 hrs.
Your battery is probably around 50A.
I don't understand the calculation to figure CCA charging rates so i don't bother with it, i just need to know how many amps the battery has.

Look at this German site. Notice the first number is the amps of the battery, if you know the amps you know how long you can charge it at a given charger output.
Big MB diesels use a 74 -95 amp battery. A 27f is around 50A IIRC.

A 50A battery can be charged to 100% at 5A in 10 hrs, 10A in 5, or 2A in 25 hrs.
When no info is available you can use the 50A figure for most mid sized and 75A for large automotive batteries, if it doesn't charge it to 100% it will be close and start the engine.
Sorry for over simplified answer but this is the easiest way i can explain it.

http://www.atu.de/shop/kategorie/Batterien-w5722/Auto-Batterien_w5723/

 

[JethroBodine]

Originally Posted By: 901Memphis
http://www.amazon.com/gp/aw/d/B00068XCQU

That's what you want. The junior model is okay too.


I have two of those. I leave them on my kids car while she is at school all Winter. Never an issue.

 

[AVB]

Was the negative charging lead also warm? I do agree with the possible causes already mentioned, but another possible cause is high resistance in the connection causing an localized increase in temperature.

As far as the blackened battery post, that could be just from normal gas released from charging. When I was working with industrial batteries in electric fork lifts we were taught not to fill the water past the tops of the plates before charging.

 

[Donald]

Originally Posted By: Trav
You cooked it. A 2A charger with no controller will put 96A into the battery in 48 hrs.
Your battery is probably around 50A.
I don't understand the calculation to figure CCA charging rates so i don't bother with it, i just need to know how many amps the battery has.

Look at this German site. Notice the first number is the amps of the battery, if you know the amps you know how long you can charge it at a given charger output.
Big MB diesels use a 74 -95 amp battery. A 27f is around 50A IIRC.

A 50A battery can be charged to 100% at 5A in 10 hrs, 10A in 5, or 2A in 25 hrs.
When no info is available you can use the 50A figure for most mid sized and 75A for large automotive batteries, if it doesn't charge it to 100% it will be close and start the engine.
Sorry for over simplified answer but this is the easiest way i can explain it.

http://www.atu.de/shop/kategorie/Batterien-w5722/Auto-Batterien_w5723/


I do not think its quite this easy to calculate. Even some of the old manual chargers I have slow down the charge rate as the battery gets charged. The problem is they slow it down, but do not stop it. I assume they put out a constant voltage and as the battery voltage rises the current drops. These are the transformer (heavy) based chargers. Which are good to keep around to start off a charge to a dead battery as some automatic chargers will give up if the voltage is too low.

 

[Trav]

Thats true they start slowing down when the battery gets to around 80%. Some of the old 2A trickle chargers just put out 2A continuously without any control.

I had one here that would cook a MC battery if left on all night, but yes i agree its not that simple but i have used this Mickey Mouse method for years with non smart chargers and never cooked one so i stay with whats been working.

http://www.emarineinc.com/pages/Batteries-Maintenance-101.html
Quote:
Three Stage Battery Charging
The battery is normally brought up to 75% of fully charged in the Bulk Charge Phase. The Acceptance or Absorption Phase continues charging the battery until fully charged. After the battery is fully charged, just enough charge current is applied to maintain the battery in a fully charged mode (this is the Float Phase). The float phase should not be confused with "trickle chargers" which have cooked many batteries.

 

[HerrStig]

Originally Posted By: Trav
You cooked it. A 2A charger with no controller will put 96A into the battery in 48 hrs.
Your battery is probably around 50A.
I don't understand the calculation to figure CCA charging rates so i don't bother with it, i just need to know how many amps the battery has.

Look at this German site. Notice the first number is the amps of the battery, if you know the amps you know how long you can charge it at a given charger output.
Big MB diesels use a 74 -95 amp battery. A 27f is around 50A IIRC.

A 50A battery can be charged to 100% at 5A in 10 hrs, 10A in 5, or 2A in 25 hrs.
When no info is available you can use the 50A figure for most mid sized and 75A for large automotive batteries, if it doesn't charge it to 100% it will be close and start the engine.
Sorry for over simplified answer but this is the easiest way i can explain it.

http://www.atu.de/shop/kategorie/Batterien-w5722/Auto-Batterien_w5723/
Lead acid battery cycles are NOT 100 % efficient, it takes MORE than 10 amps for an hour, for example, to fully charge a 10 amp-HOUR battery. Probably more like 12 to 15 amps for an HOUR. The rest ends up as heat. The accurate test of a storage battery is how many amps it will deliver for an hour... "amp hours". Interestingly, the figure changes a bit as rrelated to discharge level, a 70 amps for an HOUR battery might give you 35 amps for 2.25 hours. With use, a battery takes more and more "amp hours" to fully charge, and more and more of the supplied current turns into heat until one day, the battery won't charge at all. Numbers like "cold cranking amps" relate to very short periods of use in cold weather when the chemical reaction is slowed, "just when you need it the most". Even a flashlight battery will output 100 amps for a small fraction of a second. "Deep cycle" trolling motor batteries are this that, designed for a slow discharge rate for long periods. Modern sealed batteries not of the deep cycle type are often damaged by being run doen to the no charge left state. It appears that "AGM batteries, a newer type of sealed battery, isn't as subject to such damage. As for Ni Cad, NMH and "LiIon type "electronic unit" batteries, they are all different in performance. Many "fast chargers" for electronic and portable tool batteries have a "thermister" built into the battery case with a lead for a charger connection, the internal temp of the battery pack is measured to so that the charger output can be controlled to prevent heat damage to the battery.