New Trojan 1275 set. How long to charge

[teckersley]

I just bought a new set of 4 Trojan 1275s and I wanted to get some opinions on how long it should take for the initial charge. The charger is a Power Drive Club Car charger and it seems to work but I for some reason, my gut doesn't have the best confidence in it automatically shutting off and want to get some estimates from you folks so I can keep an eye on it so I do not over charge them. I have no reason to believe it doesn't work other than I can not figure out why all of a sudden my batteries went bad but maybe I am being paranoid since they were 2007 afterall.

Anyway, once I installed them, I used a a voltmeter and the pack measured 50.7v (90%+ according to the battery charging guide). I recall reading somewhere that folks were saying it could take overnight to charge. However, when I asked the guy at the cart shop where I bought them, he said it would probably take 3-4 hours. I am on hour #4 and the needle on the charger is measuring 4 amperes and it was initially all the way at 12-13v or so. I want to make sure I do this right and not mess up a set of $800 freaking batteries.

1) How long would you guys estimate it should take?
2) is there a way to cure my paranoia and test the auto shut off feature of the charger?
3) Even and 50.7v does it just take longer on initial charge to "soak" or "condition" them?

Thanks

[teckersley]

Update:

After exactly 4 hours of charging, the amperes needle on the charger is still at 4. Without unplugging the charger or turning it off, i hooked up the voltmeter again and the pack is reading 64.1v. Also, I hear the water "boling or gurgleing" in the batteries.

Does all of this appear "normal"?

[rib33024]

sounds like your doing good,, it can get to 67 volts before it turns off on it's own, and the charge time is longer on new batteries,,, just make sure there is nothing getting hot, batteries , charger, or the wires, and watch, the volts every once and a while, but it should turn off anytime now, if nothing is hot let it charge.

QUOTE: JohnnieB

"when your cart is fully charged the battery pack will get up to 60 - 65 volts",
In fact, the charger may have to take a 48V battery pack up to 67V, or above, to fully charge it.
On the other hand, 59V may fully charge a 48V battery pack.
The voltage it takes to fully charge a 48V battery pack depends on who manufactured the batteries in the pack as well as their age and condition.

By definition, a lead-acid wet cell is fully charged when the specific gravity of the electrolyte ceases to increase while a charging current is passing through it. Since open-circuit voltage increases/decreases as the electrolyte's specific gravity increases/decreases, open-circuit voltage is an indirect or secondary means of monitoring the electrolyte's specific gravity and is often used to do so.

An ideal charger would monitor pack voltage and when it ceased to rise over a predetermined period of time, it would stop the regular charging mode and go into a float charge mode, however few, if any, chargers typically used by golf cart owners are ideal. Most of them simply shut off at a predetermined voltage that is high enough to almost fully charge most battery packs without being so high that repeated use would significantly harm battery packs that are fully charged at the lower end of the typical voltage spectrum needed to fully charge a battery as determined by empirical data.

Here is Trojan's recommended charge curve for a single (2V) deep cycle wet cell. There are 24 cells in a 48V battery pack, so do the math and you get 58.80V to 66.96V. However, Trojan uses an electrolyte that is 27.7% sulfuric acid by weight (SG = 1.277) and other battery manufacturers use different concentrations, so the on-charge voltage that is typically reached when their batteries are fully charged, will be higher or lower.