Quantifying Battery condition

[JohnnieB]

Originally Posted by birmingham

Ok, So finally got all of the stuff together and made my new high amp wires for the cart, this made a difference (guessing that means that one or more of my cables were toast) Also the charging wires looked terrible, cant believe this was working.

My findings, Ill skip right to what i think is wrong, after about 2 miles on mostly flat ground i was still going along well, so i did some uphill, found my voltage to be dropping drastically under load, Using volt meter. So i hooked up to each battery individually This is what i found:
At Rest Under Load
Bat 1 6.1v 4.9v
Bat 2 6.09v 5.08v
Bat 3 6.07v 5.1v
Bat 4 6.07V 5.57v
Bat 5 6.03v 2.3v
Bat 6 6.2v 5.71v

Winner winner #5. Next question
1 im recharging them all now, is this safe to recharge with a "bad Battery"?
2 is it ok to replace just that battery with a cheaper new one?

i know this isnt best but i really dont want to replace them all now because i wanted to stage in my upgrades and go 48V so i want to replace the bad one get it running again then around xmas do the controller and solenoid, then when the batteries really die do 48v and the charger. At some point I want to make this thing look better to.

See if you can find a used battery about the same age and AH capacity as the rest of the batteries.

If you can't, get an inexpensive one. Anything close to 200AH or above should work okay considering the condition of the rest of the batteries.

Just remember, it is a sacrificial battery. It will have to be replaced at the same time the others are replaced.

As for charging, none of the batteries are being fully charged, so you may also have some charger issues. (Should read about 6.37V)

Charging the pack with the "bad" battery in it won't hurt the other batteries any more than they have already been hurt.

[birmingham]

I should have stated, that was after about 24 hours or more rest off the charger, maybe the bad battery is pulling them down? Dont know if that is possible. Getting on the phone now to look for another battery.

[JohnnieB]

Originally Posted by birmingham

Sort of off subject but im assuming that the 4 wires hooked to the motor,

2 big ones feed it juice
2 smaller ones work with the "regen?"

Is this correct?

No, it is incorrect.

The two big ones feed the armature and the two small ones feed the field windings.

All four wires are used when motor is propelling cart and when regen brakes are slowing cart down.

Due to the nature of the beast, field current maxes out at about 1/10 the armature current, so smaller gauge wires can be used for them.

[JohnnieB]

Originally Posted by birmingham

I should have stated, that was after about 24 hours or more rest off the charger, maybe the bad battery is pulling them down? Dont know if that is possible. Getting on the phone now to look for another battery.

From 12 to 24 hours is the typical rest time for measuring battery voltage, so it probably should be a bit closer to 6.37V.

What charger are you using?

[birmingham]

I replaced all of the wires in the battery section and the 2 from the batteries to the controller/solenoid The wires from the controller/solenoid to the motor looked brand new, and were already as large as the 4 gauge i was replacing the battery cables with. Should i have replaced them anyway? I can get the torch back out if i should. Still got plenty of cable.

[birmingham]

After some phone calls, my most viable option was the new battery. Quick trip to sams club where the worker proceeded to poor battery acid all down his front (picked up the battery by leaning it on his chest) got it back, replaced, recharged. Power is probably up 40% she is killing it compared to where it was. did a little more testing and its looking like the front 3 or batteries 1-3 are about the same strength, then the back 3 (includes the new battery) seem to be about the same strength (stronger) less sag under load.

Will this level out? Charging over night, i will have more numbers in the morning.

[cgtech]

Throw that uniform in the trash.....
Since the batteries are connected in series, your pack is limited to the strength of the weakest battery. They should even out after several charge cycles, now that the junker is gone. The weakest battery will usually overcharge first too, preventing the others from getting a true full-charge.

[birmingham]

Originally Posted by cgtech

Throw that uniform in the trash.....
Since the batteries are connected in series, your pack is limited to the strength of the weakest battery. They should even out after several charge cycles, now that the junker is gone. The weakest battery will usually overcharge first too, preventing the others from getting a true full-charge.

This is about what i was thinking.

[birmingham]

Not sure if i should start a new post or continue here. If no responses ill make a new one.

Did some range testing today, used the ipad for the gps system and a free app, seemed to work. I made 4 laps, of the same lap in my neighborhood, Its almost all hills. My elevation change on each lap was 170 feet X 4(laps)=680feet. I have no concept of elevation change, not sure anyone does so idk if this seems reasonable. Results

39.17V 30 min off charger start
27min
5.31miles
12.7 average speed
20.6 MPH max (chip in freedom mode) 18 Max on flat ground probably could have gone faster but that wasn't the goal
returned home after the 4th lap, light bar showing 1/2 battery pack.
let rest 20 min bat voltage 37.38V
Bat1 6.24V
Bat2 6.23V
Bat3 6.19V
Bat4 6.18V
Bat5 6.27V (this is the new one)
Bat6 6.30V

Thinking after the charger cuts off of putting the 12v charger on 3&4. I have been using my 6Volt charger for 1 hour periods and think i have the batteries better.

What do you think my range is? What do you think the condition of my battery pack is currently? Is range Liner on the chart? If I go into mild Hills mode from freedom what is the expected % impact on my range? I need some more testing. I think i have been bitten by the Bug.

[remac]

Ya - you got the bug - keep playing and keep reading...

Remember with elevation changes, what goes up must come down.
The Freedom chip gives you more speed but less range.
The other chips actually use the downhill part of the ride
for something called regenerative braking.

It uses the motor as a brake which puts juice back into the batteries.
This recharges them a little bit and increases range.
Like anything with carts - you decide what trade offs you want to make.
More speed or more range, more speed or more torque, etc.

When you are done riding put your cart on the charger.
Don't take your cart past 50% SOC and don't trust the bar gauge.
Even if you ride a little bit, say 80%, recharge when you are done.

I like to charge my cart up until the charger quits
and then unplug the charger and plug it back in again.
That resets the charger and it starts a new cycle putting more juice in.
Depends on what type of charger you have but it works for me.

You might also see the low batteries start to come back a little
the more you use them and charge them.

There is a chart that gets posted here often showing SOC;
oops, I think it just showed up again

Charge your batteries completely, but wait at least 12 hours after
to measure the voltage and get your 'at rest' starting point.
Look on the chart and see where you are starting.
The go drive your 5.3 miles or whatever distance you want
and park the cart, wait at least one hour and check voltage.
This is your 'at rest' end point.

If you start at 95% SOC and end at 75% SOC after 5.3 miles,
then you can go another 5.3 miles and should end at 55% SOC.
This would be a conservative range for your older batteries.
You don't want to take any batteries below 50% SOC
because it will start irreversible damage and shorten their life.