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Old 09-13-2021, 06:06 PM   #21
JRaf
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Default Re: Batteries, charger, a long confessionary tale...

I don't know why I didn't think of that. If you flip the meter around and read from the other direction, the numbers match.
The USBatteries stuff is voluminous and filled with info. It will take me a while to get through it. And yeah, they apparently no longer recommend single stage charging. They also recommend testing often with a hydrometer. I've never done that. (These are new batteries, the electrolyte is fine! Right? Right?) But USBatteries talks about the significant link between that measurement and SOC.
I definitely need to replace the old TCIII, as much as I like it.
That said, my last experiment, giving extended (and repeated) charges with the board relay shorted out, seems to be working. The cart doesn't climb vigorously up the hill, (not that it ever did), but it does climb successfully. During charging, the amperage drops quickly, delivering 2 amps or less in just minutes, but the charging voltage went up quite a lot... almost a full volt, usually a little less. I haven't yet measured resting voltage. And I'm not going to leave the cart on the charger more than a few hours anyway.
On another note, I'm not entirely sure Centennial batteries are made or designed by USB. It's what I've seen reported on the internet and the guy in the battery warehouse where I bought them seemed convinced of it. (This place had pallets of USB batteries right next to the Centennials. So....) Centennial hasn't yet responded to a pair of emails which concerns me.
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Old 09-14-2021, 09:47 AM   #22
JohnnieB
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Default Re: Batteries, charger, a long confessionary tale...

I've ran into similar issues with various types of digital meters. Slightly different readings when you swap the test leads between the same two points. Theoretically, you should get the same value except for the + or - sign, but with some meters one way is slightly higher than the other. It wasn't an issue with analog meters since the needle would only move up-scale when the test probes were connected with a specific polarity. So when I need precise or critical Volt, Amp or Ohm measurements using digital meters, I try to keep the relative direction of electron flow the same.

-------------
Voltmeters tell me just about everything I need to know about my batteries, so my hydrometers collect dust most of the time. I checked the SG when they were new (after a few charges) to establish a baseline and once a year or so after that.

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If possible, check something for me.

With the relay bypassed so the charger is on whenever plugged into AC power. Measure the DC voltage output at the D-plug when it isn't connected to the cart. That will give us the highest on-charge voltage your TC-III is capable of raising the battery pack to. (Actually, the on-charge won't go quite that high due the transformer loading of about 2A or so, but it'll be a ballpark figure.)
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Old 09-14-2021, 11:50 AM   #23
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Default Re: Batteries, charger, a long confessionary tale...

With the relay unconnected and the charging plug unconnected I get a reading of 40.87 volts. Roughly 41 volts.
But the charger will never bring the batteries that high. They go up to 45.7 or so with the charger connected but the pack voltage drops like a rock as soon as I disconnect.
That brings up something I keep thinking about. There are still a of of these single stage chargers out there and in daily use. And there are a lot of different brands of batteries in various condition and in various chemistries... and there are a lot of simple series carts like this one and they mostly work pretty well. Some of them might not meet challenging circumstances every day (like hills) but they work better than my cart does. I'm pretty sure the TCIII is working as designed (it comes on when the battery voltage is too low and it brings the pack up to 44+ volts at high amperage, properly bubbling up the electrolytes, etc., then finishes the charge at low amperage and shuts off just before the pack gets to 45 volts. Twelve hours of rest leaves me with 38.8 volts (or so) of stored energy.
Then why does this cart not quite work right? Is it the age of the motor or the controller (even though they work well when the batteries seem to be at optimum charge)? Is it cumulative resistance in the cables and wires many of which are old? (No wires get very warm, but cumulatively when does very warm become hot?)
I really haven't figured this out have I?
That said, I do understand that a multi-stage charger will do more including deliver a higher finishing voltage and it measures SOC with a more sophisticated metric... but people have been using ferroresonant transformers for decades. Golf carts were developed in the fifties? Earlier?
Is it just the batteries that are sagging? Or the whole system?
Or am I talking (and thinking) in circles?
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Old 09-14-2021, 12:20 PM   #24
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Default Re: Batteries, charger, a long confessionary tale...

Something triggered my memory. Currently the big capacitor in the TCIII is the old rusty one. But I bought a replacement of the same value. I swapped the two after I wrote the last post. And it gives me a reading of 41.15 volts (with the relay bypassed, unconnected to the pack). So a little higher voltage. Enough to matter?
As another experiment I plugged in another capacitor I have (it's 50mfd (instead of 20mfd) but also 370 vac. So I plugged it in (briefly). 43.8 volts.
Huh. I'm not going to plug it into the pack. Just an interesting experiment.
I am trying to borrow a multi-stage charger before I buy one so I'm not in a mood to blow stuff up today.
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Old 09-14-2021, 01:01 PM   #25
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Default Re: Batteries, charger, a long confessionary tale...

Quote:
Originally Posted by JRaf View Post
With the relay unconnected and the charging plug unconnected I get a reading of 40.87 volts. Roughly 41 volts.
But the charger will never bring the batteries that high. They go up to 45.7 or so with the charger connected but the pack voltage drops like a rock as soon as I disconnect.

That brings up something I keep thinking about. There are still a of of these single stage chargers out there and in daily use. And there are a lot of different brands of batteries in various condition and in various chemistries... and there are a lot of simple series carts like this one and they mostly work pretty well. Some of them might not meet challenging circumstances every day (like hills) but they work better than my cart does. I'm pretty sure the TCIII is working as designed (it comes on when the battery voltage is too low and it brings the pack up to 44+ volts at high amperage, properly bubbling up the electrolytes, etc., then finishes the charge at low amperage and shuts off just before the pack gets to 45 volts. Twelve hours of rest leaves me with 38.8 volts (or so) of stored energy.
Then why does this cart not quite work right? Is it the age of the motor or the controller (even though they work well when the batteries seem to be at optimum charge)? Is it cumulative resistance in the cables and wires many of which are old? (No wires get very warm, but cumulatively when does very warm become hot?)
I really haven't figured this out have I?
That said, I do understand that a multi-stage charger will do more including deliver a higher finishing voltage and it measures SOC with a more sophisticated metric... but people have been using ferroresonant transformers for decades. Golf carts were developed in the fifties? Earlier?
Is it just the batteries that are sagging? Or the whole system?
Or am I talking (and thinking) in circles?
Please verify you typed the numbers in correctly. The statements conflict with themselves.

--------------
The issue isn't with single stage chargers, it is with the control board shutting off the charger at a pre-selected voltage that will almost fully charge new batteries without being too high for old batteries. Also, the charge profile is designed around Trojan brand batteries, which was what EZGO installed in their carts at the time.

Your batteries having 38.8V after 12 hours rest indicates they are being fully charged by the TC-III. (Was the relay bypassed? Or was the control board in use?)

-----------
There are three sets of battery voltages.
On-Charge, At-Rest and Under-Load (or In-Use). The first and last are pretty much self explanatory. At-Rest is roughly 12 hours after charging stops or about an hour after being used.

During charging, the electrolyte in intimate contact with and in the immediate area surrounding the plates acquires a higher SG then the electrolyte further away from the plates. This gives an artificially high voltage reading at the terminals, called a surface charge. When the charging current ceases to flow, the SG of electrolyte equalizes throughout its volume and in about 12 hours the terminal voltage accurately reflects the SoC.

During discharge the same thing happens in the opposite direction, the SG of the electrolyte in close proximity to the plates is lower than the SG of the more distant electrolyte, so the terminal voltage is artificially low while amps are being drawn from the cell. However, the SG equalizes faster from under load to At-Rest and it only takes about an hour. (Or at least hat is as long as I monitored it. - see attached chart)

------------
Why is cart not working as good as it should. The list could be endless.
Brakes dragging.
Oil in differential has turned into molasses.
Wheel (and other) bearings stiff.
Excessive resistance in high amp cables or connections, but not enough to get any of them hot.
Pitted and burnt solenoid contacts.
Pitted and burnt F/R switch contacts
Tires taller than stock (18").
Low tire pressure.
Thick layer of carbon dust inside motor.
Worn brushes in motor.
Carbon dust fouled commutator in motor.

I believe we've already proved Controller was going to 100% open, so it and the throttle are good.

If you can, use your clamp-on ammeter on either the B+ or B- cable from the battery pack to see what the amp draw is when climbing the hill.
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Old 09-14-2021, 02:07 PM   #26
JRaf
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Default Re: Batteries, charger, a long confessionary tale...

I don't think my numbers conflict.
With the relay disconnected and the pack disconnected, the charger plugged in to AC and humming, the voltage at the plug is 41 volts. A little more with one cap, a little less with the other.
When the charger is hooked to the batteries, plugged in, and humming, and I measure the voltage being delivered to the pack it goes up as high as 46 volts. It takes a while to get there and that voltage is achieved only at low amperage.
When I disconnect the charger (or turn it off), the voltage drops to normal levels. At twelve hours the voltage measures 38.6 or thereabouts.

"Why is cart not working as good as it should. The list could be endless." MY RESPONSES IN CAPS, CAPS ARE NOT FOR EMPHASIS.
"Brakes dragging." I PULLED THE WHEELS AND DRUMS AND BACKED OFF THEM OFF. DEFINITELY NOT DRAGGING.
"Oil in differential has turned into molasses." MAYBE. MAYBE IT HEATS UP AND LET'S CART GO UP HILL? HMMM. BUT CART WENT UP HILL WHEN BATTERIES WERE FRESH AND CART WAS COLD. I'LL CHANGE IT.
"Wheel (and other) bearings stiff." SAME RESPONSE AS ABOVE. BUT WHEEL BEARINGS ARE GOOD. WHEELS SPIN FREELY. IT FLIES GOING DOWNHILL.
"Excessive resistance in high amp cables or connections, but not enough to get any of them hot." MAYBE THIS. MAYBE I SHOULD REPLACE ALL CABLES. I'LL COUNT THEM, MEASURE THEM, COLLECT WIRE AND LUGS AND MAKE NEW ONES.
"Pitted and burnt solenoid contacts." NEW SOLENOID. TWICE.
"Pitted and burnt F/R switch contacts" ? I'LL RE-INVESTIGATE.
"Tires taller than stock (18")." "18" TIRES.
"Low tire pressure." NOPE.
"Thick layer of carbon dust inside motor." OKAY. I DID SEARCH FOR CONTINUITY FROM MOTOR POLES TO CASE AND FOUND NONE. I DID NOT MEASURE RESISTANCE. BUT I CAN OPEN MOTOR UP AND LOOK AROUND.
"Worn brushes in motor." MAYBE. THIS MIGHT ACTUALLY MAKE SENSE. NOT ENTIRELY BUT MAYBE.
"Carbon dust fouled commutator in motor." I GUESS THAT'S THE SAME THING BUT WOULDN'T THAT BE A PERMANENT CHANGE?

First thing today I will try and measure amperage going B+ or B- cable.

Then if life cooperates, I'm going to put the cart on jackstands, drain the diff and open up the motor. I'll try and remember to take pictures.

BTW, JohnnieB, thank you so much for your patience and time. Really.
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Old 09-14-2021, 02:18 PM   #27
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Default Re: Batteries, charger, a long confessionary tale...

BTW, five minutes, maybe ten after I disconnected the pack the voltage was sitting a little over 40 volts. That's got to be a full charge right?
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Old 09-14-2021, 02:32 PM   #28
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Default Re: Batteries, charger, a long confessionary tale...

Using the max/min feature i got high of 95.7 amps going up hill. It drooped to 0 when i stalled. Is that telling?
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Old 09-14-2021, 07:16 PM   #29
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Default Re: Batteries, charger, a long confessionary tale...

Quote:
Originally Posted by JRaf View Post
1. Using the max/min feature i got high of 95.7 amps going up hill.

2. It drooped to 0 when i stalled. Is that telling?
1. Might be a little on the low side. Try measuring it starting from a standstill on the incline.
That should show the max amps your motor can draw with existing batteries, controller, cables, solenoid and F/R switch.
2. That is abnormal. Amps ought to increase as motor slows down and peak when it stalls.

Now the question is, why does is go to 0A when stalling. Conversely, is going to 0A the reason the motor stalls.

IIRC the voltage between the controller's M- and B+ terminals never went down to 0V when cart wouldn't make it up the incline. If so, you've got a motor issue.

------------
If your controller has an A2 terminal, 14 high Amp cables are needed. All 14 should be 4Ga or thicker.

------------
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Old 09-14-2021, 10:04 PM   #30
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Default Re: Batteries, charger, a long confessionary tale...

Hmm. I had the meter on the B- cable. Maybe I measured backwards. Or maybe I screwed up the min/max. I'll do it again several different ways.
I pulled the F/R switch. The contacts are clean. I just can't see a problem here.
I traced every wire against the schematic. There aren't that many wires in the cart, it took ten minutes.
I jacked the cart up, spun the wheels, listened to the bearings. I believe the wheels are spinning freely. No issues with the bearings.
I detached all four wires to the motor. I measure absolutely no continuity between any of the four lugs to the motor case.
I do think all the wires to the motor are a little puny. I'm surprised how lightweight they are. Might be eight gauge. All the B+ and B- wires are much thicker. It's also curious that the main B- wire has about 20" of slack. Why is it so long?
I think it would be best to replace every wire. I'll make that my next chore.
I did take off the motor (I dreaded this, but it was three bolts. Motor's heavy but it came off easily.) The spindle looks good and I can turn the differential easily by hand. The bearing on that side has no grind, no issue.
(Because of this I didn't drain the differential, but I also have to look up and acquire the correct gear oil).
I opened the motor case and I found some dust from the brushes and maybe the brushes should be replaced but the springs are good and they make good contact with the commutator. (I'll attach pics.) The bearing on that end also looks good. I cleaned out the dust but it really wasn't excessive.
I buttoned everything back up and rode the cart and there was no improvement. Stalled on the hill.
I'll either build or buy new wires as soon as I can.
I'll take pics of the wiring as I reassemble. Maybe I'm missing something. I should have done it today but I didn't think of it.
Again thanks for your help.
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