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| Recharging flattish battery http://taxi-driver.co.uk/phpBB2/viewtopic.php?f=9&t=5753 |
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| Author: | Fae Fife [ Wed Mar 14, 2007 5:05 am ] |
| Post subject: | Recharging flattish battery |
I have a one year old Passat, and a few nights ago the battery seemed a bit flat, but since I'd had the side lights, roofsign, interior lights meter etc on for two or three hours while hardly moving this was hardly surprising. However, someone said to me that with new-style batteries if they go quite flat then they won't charge refully again on the alternator and they have to be recharged with a proper trickle charger. Now I'm a bit paranoid about sitting more than a few minutes with my lights etc on. Is there any truth in what I've been told? |
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| Author: | stu [ Wed Apr 04, 2007 7:19 am ] |
| Post subject: | |
Yes, but thats always been the case anyway, when you say new style battery has it got the calcium one? Anyway the rule of thumb when charging a battery is that the charging current in amps should not be more than 1/10th of the battery's rated capacity in ampere hours, so if the battery was a 60 Ah job it should not be charged at a rate of more than 6 amps. If it is fully discharged I think it may be 1/20th of the rated capacity, it could take the best part of a day to charge it up, maybe 18 hours or so. I think if you try to charge it at the higher rate the resistance turns the charge into heat and there is a risk of damaging the battery. |
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| Author: | MR T [ Wed Apr 04, 2007 6:07 pm ] |
| Post subject: | |
stu wrote: Yes, but thats always been the case anyway, when you say new style battery has it got the calcium one?
Anyway the rule of thumb when charging a battery is that the charging current in amps should not be more than 1/10th of the battery's rated capacity in ampere hours, so if the battery was a 60 Ah job it should not be charged at a rate of more than 6 amps. If it is fully discharged I think it may be 1/20th of the rated capacity, it could take the best part of a day to charge it up, maybe 18 hours or so. I think if you try to charge it at the higher rate the resistance turns the charge into heat and there is a risk of damaging the battery. Give the man a Gold clock, spot on Stu |
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| Author: | Fae Fife [ Wed Apr 04, 2007 6:25 pm ] |
| Post subject: | |
stu wrote: Yes, but thats always been the case anyway, when you say new style battery has it got the calcium one? What I meant was maybe the normal jump start or bump start scenario when the car would probably have no problem recharging on the alternator. What I was told was that the latest batteries won't even recharge from this kind of situation. Sorry, I don't know whether its a calcium job or not. Quote: Anyway the rule of thumb when charging a battery is that the charging current in amps should not be more than 1/10th of the battery's rated capacity in ampere hours, so if the battery was a 60 Ah job it should not be charged at a rate of more than 6 amps.
If it is fully discharged I think it may be 1/20th of the rated capacity, it could take the best part of a day to charge it up, maybe 18 hours or so. I think if you try to charge it at the higher rate the resistance turns the charge into heat and there is a risk of damaging the battery Thanks for the info stu. Fortunately there's been no sign of any further problems so it looks as if I won't have to put it on the charger, so fingers crossed. |
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