New Batteries and losing electrons

[cmalberto]

So I bought new batteries this week. The old ones had trouble charging to a full charge. So I made my second charge this yesterday....after the batteries cooled down, I was reading 51.4 volts which was what I remember being about right...however, I checked them again today - almost 24 hours after charging and I noticed I am down to 50.3 volts. That seems excessive amount of discharge. The cart is obviously turned off or I wouldn't be asking what else could be drawing down on the batteries. Radio is off so that shouldn't be it other than the milli-amps it would draw to keep its memory.

Any ideas to check what is drawing some juice and by how much?

Thanks in advance.

[jjance]

How about the voltage reducer if it doesn't have the trigger wire enabled/disabled through the key switch.

[cmalberto]

Originally Posted by jjance

How about the voltage reducer if it doesn't have the trigger wire enabled/disabled through the key switch.

Maybe - dang - I can't remember how I wired that thing. Is there a way to measure the draw? Like with a meter?

[jjance]

Easy to check. Do the light turn on and off with the key sw? Next to check and see there is any load on the batteries. Connect your voltmeter across the pack. Then disconnect the main neg battery lead. If the voltage increases you have a load on your batteries.

[cmar143]

Has the voltage dropped below 50.3 since?

[kernal]

I'll through out a couple of possibilities.

1- New batteries require multiple charge cycles to achieve their rated capacity. Trojan says 50-100 cycles. It would be similar for other brands.

2- Temperature has a noticeable affect on battery capacity. Trojan says their battery provides 100% of rated capacity at 80°F. At 60° it has lost about 15% of rated capacity. Also at temps above 80° the batteries actually perform above rated capacity but it is hard on them. Can shorten life span.

Soooo, the only way I have of determining (guessing) the state of charge of my batteries on a daily convenient way is a digital meter. I'm suggesting that this change in battery capacity due to temp manifests itself in the open circuit voltage.

I observe this: The charts say 50.9 is 100% charge(capacity) for a 48v pack. In the hot summers in Atlanta, the resting voltage stabilizes above 50.1 for a couple of days before it starts to decline due to parasitic draw and self discharge. Now with declining temps here the resting voltage stabilizes at 50.9 and starts to decline within 24 hours of charger shut off. I'm concluding this is due to the decline in battery capacity due to temp.

I suggest you don't have a problem or at least don't panic and further observation is required.

Note: My batteries are 6 mo old T-875's with 83 cycles on them.

Link: http://www.trojanbattery.com/pdf/Tro...UsersGuide.pdf Look at page 25 specifically.

[cmalberto]

Originally Posted by cmar143

Has the voltage dropped below 50.3 since?

It was still at 50.3 this morning...won't be able to check until Saturday evening. I will be curious to see what / how much has changed.

I have also confirmed that the Power Reducer is NOT switched...I remembered choosing to install that way so i can play music without having the key switched on.