Birty Dastards Jeep Club
Tech Forum => Workshop => Topic started by: suppersready on May 20, 2015, 12:37:58 PM
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I have a 78 amp battery and I do not know the amp output rate of my charger when set on Normal ... Can anyone advise what would be a safe charge time from the battery being flat ? As I'm worried about cooking the cell !
Cheers ..
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the battery will only take what it requires in regard to charging, hence when you have an old charger with an amp meter display you will see the amp draw decrease as the battery charges
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Thanks ...
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If you have a "HI/LO" charge rate switch on your battery charger and the battery is well and truly flat, start if off on the "LO" setting for a few hours until it starts drawing some current (assuming you have an ammeter on your charger) and then switch it onto "HI". Be prepared to switch it back quickly though as the extra voltage from the charger may then push the charge rate off the limit of the charger.
Once it's had a few hours on the higher rate, switch it back to "LO" to give it an "equalising" charge, preferably overnight.
A rough rule of thumb if you're using a constant current charger would be about 4A on that battery. The approximate formula is battery capacity in A/h divided by 20 which gives about a 20 hour charge. In your case, 78 A/h divided by 20 is a gnats whisker under 4A.
Hope that's helpful for you.
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or get a battery monitor charger type