test a battery charger

[JohnnieB]

Don't be bummed, we caught the fact your new batteries aren't being fully charged and now we are doing something to find out why.

In general, the initial current flow is from about 16A to 25A, but it varies with age/condition of batteries and state of charge, so with new batteries at 80% charge, I guesstimated on the high side.
Initial rate of 17-18A is probably okay, but charger might not be working at full efficiency.
(Capacitor value changed due to aging, diodes weak/marginal, or something minor like that)

What charger do you have? (Model name/number or picture of faceplate)

Here is a drawing showing where to attach DVM.

Go ahead and have someone connect the charger to cart.
When you get home from work, the on-charge voltage ought to be above 42V and the batteries ought to be gassing (bubbling).
If not, we need to troubleshoot the charger and/or connections in cart's charger receptacle and wiring to battery pack fro receptacle.

[lithoman]

I had someone take a pic of the charger. As you can see it is close to shutting off.
Yesterday it took 5 hours before it shut down.

So with the charger plugged in I should check voltage and it should be 42v?
Then after resting 10 hours it should be down to 37.2?

[JohnnieB]

Originally Posted by lithoman

1. So with the charger plugged in I should check voltage and it should be 42v?
2. Then after resting 10 hours it should be down to 37.2?

1. No. It should be at least 42V.
The instant the charger turns on, the output voltage will be whatever the battery pack voltage was prior to the charger turning on.
Then it will climb fairly rapidly until it gets above about 42V and then it will continue to climb at a slower pace until it gets somewhere in the 44-46V range and the charger turns off.

2. No. Maybe 37.2? was a typo, but after 10 hours rest, the voltage ought to be equal to or greater than 38.2V.
At the instant the charger clicks off, the battery pack voltage will read somewhere in the 44-46V range, but that is a "Surface Charge" and isn't an accurate measure of the batteries State of Charge.
Flooded Lead-Acid batteries (Wet Cells) self discharge and it take about 12 hours (or a short drive) to deplete the more or less meaningless surface charge to get a relatively accurate estimate of the battery packs SoC.

With new batteries, after 12 hours the voltage may be 38.5V or higher, but there are a lot of variables.

If the new batteries have been fully charged a few times and weren't discharged too much, a 5 hour sounds reasonable, but only if the voltage is up where it is supposed to be.

Here is Trojan's recommended charge curve, and the Powerwise charger you have was designed to match it closely.
The volts and Amp data is for a single cell, a 36V pack has 18 cells and a T-105 is a 225AH battery, so you have to do some math.

BTW: Your charger is an excellent one. It is built like a tank and is 100% repairable.
(The transformer is replaceable, but costs as much as the charger, so that might be considered by some as an exception to the 100%)

[lithoman]

Good news...I got home and checked voltage and got 38.68v.. the charger was off.

I will check in the morning and post results.

Thanks again for taking time answering/troubleshooting Questions

-litho

[lithoman]

Ok ..after resting over 12 hours the pack voltage reads 38.58V.
Looks like I can move on to the next mod...I ordered Scottys digital meter last week ..still waiting on it to arrive..(where is it Scotty?) after that i will install lights.


Thanks again for the help.