Problem: Charger? Batteries? What

[Silverstreak]

Thanks AzPete,
While I have you here...........this is what happens. When I plug in the charger, the analog state of charge meter almost immediately goes up into the red charging zone. Within about 15 minutes, the meter on the charger starts dropping fast. Within an hour, it is down to almost zero. At first, I thought that meant I was trying to charge full batteries. But the state-of-charge meter points to a much lower voltage than when it is well charged.
Is the charger acting like something is wrong with it?
Maybe I shouldn't say much more until I check the batteries. I will do that shortly.
I'm just trying to understand how to interpret things.
Thanks!

[JohnnieB]

I'm not sure if you have an analog or a bar graph style SoC meter, but if it is the bar graph type, I wouldn't trust it as far as I could throw it.
If it is an analog meter (Mechanical pointer that moves over a scale with multiple colored sections), I'm more inclined to believe what it says, but for troubleshooting you need a meter that gives an actual voltage readout.

Here is a drawing showing where to attach Negative test lead (Black) and Positive (Red) is attached to the positive terminal on the right-front battery.
Also, here is a chart that correlates State of Charge to the voltage you read.
(Note: The voltages listed are after the batteries have rested 12 hours after charger cuts off automatically)

Set your DMM to "DC"

I'm guessing, but you probably have a Powerwise, Lester or Total Charge automatic charger (case about 8-10 inches on a side and weighs 20-30 pounds).
If so, what you described in your first post was that type charger, charging a close to fully charged battery.


Monitor the battery pack voltage while on charge.
When you plug charger into cart, there should be a few seconds delay before it turns on.
When it turns on , the ammeter should jump to about 18 Amps (may be lower if battery is near full charge) and the battery pack voltage should start to climb.
At about 42-43 Volts, the ammeter should start tapering off to about 8 Amps and stay there for a while as the pack voltage continues to rise.
As the voltage approaches the 44-46 Volt cut-off range, the ammeter
might taper of to 1-2 Amps.
The charger should cut off around 45 Volts.

Everything is based on voltage, so charge time varies with the SoC of the battery pack when it was put on charge and the age/condition of the batteries.

If the batteries charge up normally, the charger and batteries are good and your SoC meter is flacky.
Do yourself a favor and get a DVM type SoC meter from ScottyB.
http://www.cartsunlimited.net/Digita...ry_Meters.html

[JohnnieB]

Originally Posted by Silverstreak

Thanks AzPete,
While I have you here...........this is what happens. When I plug in the charger, the analog state of charge meter almost immediately goes up into the red charging zone. Within about 15 minutes, the meter on the charger starts dropping fast. Within an hour, it is down to almost zero. At first, I thought that meant I was trying to charge full batteries. But the state-of-charge meter points to a much lower voltage than when it is well charged.
Is the charger acting like something is wrong with it?
Maybe I shouldn't say much more until I check the batteries. I will do that shortly.
I'm just trying to understand how to interpret things.
Thanks!

Got Shanghaied by SWMBO while I was typing and a couple posts got in before I posted.

Your charger is acting like you are charging batteries that are already fully charged, or close to fully charged.

The fact your analog SoC meter is reading lower than it has been, could mean battery issues or it could be a SoC meter issue.
Getting the actual voltage reading will tell which is the case.

[Silverstreak]

Thanks for that great info JohnnieB! I really appreciate it.

Good news! Each of my batteries tested at 6.5v. I was so excited I forgot to test the charger. haha
What threw me off was that I used it alot on Sunday, but I didn't charge it at all Sunday night, because there was supposed to be a thunderstorm. Then I charged it in the afternoon and it shut off after 2 hours, and the analog meter was lower than usual.
So..........if I'm understanding this right........From the voltage numbers of the batteries, I was trying to charge a full battery, and that's why the charger was acting the way it was........right?

I think it is time to buy a digital charge meter. My analog soc meter is definitely reading lower than usual........but I think I should ignore it and just check the actual voltage of the batteries, until I buy a digital meter. The wiring of it is scaring me a bit, which has made me put off buying it.

Let me know if my thinking is wrong about the batteries and charger. I really appreciate the help!!

[JohnnieB]

At 6.5V, you are reading a "surface charge" on the batteries.
Let them rest for at least 6 hours or drive it for about a half mile to disipate it.
Then you can get an idea about the SoC from the chart I posted.
38.2V is fully charged for the pack and 6.37V each for the individual batteries.
Also, the individual voltages should be within about 0.1V between highest and lowest.

From what you are saying, it sounds like your batteries and charger are doing okay, but need to know the actual voltages after the surface charge is depleted to be sure.

Wiring the DVM SoC meter will be easy since you've already got an Analog one installed.
Just pull the two wires off it and put them on the new DVM SoC meter.

One thing I would do while installing it is measure the voltage at the meter end of the wires and compare it to the pack voltage. Should be identical.
The reason for doing this is because the reading on the analog meter changed and while analog meters aren't super accurate, they are repeatable and don't often change in reading for the same applied voltage.
(I'm thinking a connection might have gone bad.)

[Silverstreak]

Actually, I hadn't charged it since yesterday afternoon. So I imagine the readings I got today are correct.

Its funny, but the analog soc meter is actually acting more reasonable now. I got used to it staying in the "charging" white zone until the batteries got low, and then it would go into the green area. Even when I had really bad batteries (before I got new ones), and had hardly any power, the arrow would stay in the mid-green section. So maybe its finally being more accurate.
But I agree with you........something has changed and I should figure out what.
But at least now I know how to test the batteries.
Thanks so much JohnnieB!

[JohnnieB]

Originally Posted by Silverstreak

Actually, I hadn't charged it since yesterday afternoon. So I imagine the readings I got today are correct............

Considering the batteries are only about 9 months old and you are taking very good care of them, 6.5V is probably about right.
Newer batteries have a higher "Fully Charged" terminal voltage than older ones, so whatever you are doing to your batteries, keep doing it because you're doing it right.....

Personally, I believe analog Soc meters make good "Fuel" gauges for the less technically inclined.
Just add a line at the 75% SoC voltage (based on a DVM voltage reading) and tell the wife/kids/whoever to head for home when that mark is reached.
That way, the batteries shouldn't get discharged below 50%

[Silverstreak]

Thanks Johnnie B....I'll do that.
Oh....by the way........I'm the wife. :)

[JohnnieB]

Mea maxima culpa.

It should have read: Spouse/Kids/whoever.

Must have forgotten to take my PC pill.