Battery Charging Problems

[rwtomkins]

Is there something weird about Gal batteries that means ordinary battery chargers don't work properly on them? The handbook says they have a silver calcium battery, whatever that is, and my Hilka heavy-duty battery charger/engine starter says it is only to be used on lead/acid batteries. In any event, I managed to completely flatten the car battery on Saturday night and on hooking up the charger on Sunday, got very weird readings. The charger seemed to be working but it was as if the battery didn't want to take the charge - the meter on the charger didn't seem to lift off zero. After spending most of the day on the charger, the voltage across the terminals was only 7.3 volts. I disconnected the charger overnight but when I came back to look at in the morning, it was reading 10.5 volts across the terminals! So I've hooked up the charger again to see what happens and come into work. Just don't understand what's going on.

 

By the way the battery itself looks weird - it doesn't seem to have any manufacturer's brand on it and doesn't have the little letters Ca on it, unlike the picture in the owner's handoobk. It's been perfectly OK up till no, though. Only 1 year old.

[seatkid]

Probably the charger is f****d. Some chargers however have a anti reversed-connection protection system that require the battery voltage to be > 10.5 volts before they will charge.

 

If there really was only 7.3v at the battery terminals your battery might also be f****d. Silver-ca (and Ca-Ca) batteries do not like deep discharge and it can kill them.

 

You can use an ordinary charger to charge a Silver-ca battery, but it may not get fully charged or may take a long time to charge as the charging voltage is higher than the old standard batteries.

 

Use jump leads to get some charge in the battery before you try your charger again.

[rwtomkins]

Thanks for that advice, seatkid. Evidently the problem is you can't properly charge a silver-calcium Gal battery with an ordinary battery charger. I never knew that, and I can't believe they don't tell you in the owner's manual.

 

I do seem to be getting some kind of a charge into it, though, so I think I'll just persist in the hope of getting enough amps in to fire up the engine, then go on a long drive. Meanwhile, looks like I need to invest in a pair of jump leads.

[rwtomkins]

in case this helps anyone with a flat battery...

 

these silver/calcium batteries don't seem to respond to the normal trickle charge (2 amps), but my charger also has a 15 amps "booster" setting and by using that in very long bursts i eventually managed to get the battery up to 12.6 volts across the terminals. i don't know whether it's sustained any permanent damage but as seatkid says, these batteries really don't like being fully discharged - it does something nasty to the plates and can prevent the battery reaching full voltage again.

 

you probably all know this but i found the following info from www.autobatteries.com very interesting. a standard automotive battery is made up of 6 cells with 2.1 cells per cell, so it is fully charged when you have 12.6 volts across the terminals. a small drop in voltage makes an enormous difference to the charge, as follows:

 

at 12.6 volts the battery is 100 per cent charged

at 12.4 volts, the battery is 75 per cent charged

at 12.2 volts, the battery is 50 per cent charged

at 12.0 volts, the battery is 25 per cent charged

 

a car battery is considered charged at 12.4 volts or more. it is considered discharged at 12.39 volts or less.

 

it seems extremely improbable that you'd be able to turn over the engine with less than 12 volts across the terminals.

[seatkid]

Sorry rwtomkins, but I think your battery is a gonner. :(

With a 15 amp boost charge (assuming it is pumping out 15 amps) - your battery should rise to 15 or 16 volts. If it is only getting to 12.6 v you have one or two cells duff.

 

12.6-12.8v is the open circuit voltage of a rested fully charged battery at room temperature. i.e. no charging current or load for 10-20 mins+. With the engine running and no electrical loads, you will see between 14 and 15 volts on the battery.

 

Silver Ca (they are still lead acid) batteries only differ electrically in that they require a higher charge voltage

[Ivor_E_Tower]

ISTR that once a battery has gone completely flat, it sometimes will not recover with conventional charging. A high current charger may do the trick, if the battery is so new (1 year old) - alternatively get a jump start and then go for a long drive - say 40 minutes; the charging from the vehicle alternator is better than from a battery charger.

Good luck.

[rwtomkins]

thanks guys. some ray of sunshine you are, seatkid! but it's my fault. i should have said that the voltage was indeed considerably above 12.6 volts by the time the automatic cut-out on the charger told me the battery was full (can't remember exactly what but i think it was about 14.5V). An hour or two later it had come down to about 12.8V and when i checked the battery this morning after it had been resting without any charging for 36 hours it was reassuringly at exactly 12.60 volts. so fingers crossed... i'll be putting it back in the car tomorrow.

[seatkid]

In that case you got away with it. :( The best way to make sure its fully charged is a loooong journey as other have said.

[Guest Turbo]

Just out of interest I have just fitted a new battery to my Tdi as the one on the car was huge, not even sitting on the battery tray properly. While it was removed I repainted the tray then waxoyld it before fitting the new correct battery.