1994 US Electricar Repair Blog by Mike

This past Saturday I went to the EAA meeting expecting to plug in and charge.
Didn’t happen. The GFCI had tripped on the Dolphin. Different outlets and a few
resets were fruitless. Vehicle still ran fine, but the GFCI would fail.

Here are the steps I took:

-Plugging in at home. GFCI still failed.
-Swapped the GFCI out with another unit. GFCI still failed.
-Visually inspected inside Dolphin. Nothing unusual.
-Isolated ground on AC line with 2 prong outlet adapter. GFCI did not fail.
Charger still works.
-Removed J2, the largest connector on the Dolphin. GFCI did not fail!
-Reconnected J2. GFCI failed again.
-Started truck. Measured ISO in Dolcom. Was -130 points below pack voltage. Not
good. Oh look, the pack has all of 4 bolts holding the lid on and it rained for
2 weeks….
-Took the lid off. No puddles of water found. But had a high humidity feel/smell
to the pack. This backs up the -130 count found on ISO in Dolcom.
-Hung the 12″ fan from the bed and let it blow on the cells all night.
-Next morning GFCI stopped failing. Charges fine on 120vac and 240vac.
-ISO at -100 counts below pack voltage, but pack much dryer feeling/smelling.

Time to go ground fault hunting in the pack again.

Tonight’s test drive showed that the pack has improved. It held it’s voltage with all 251 cells in circuit, up above 310v for about 3 miles. And then declined from there. Much better, but not as good as a complete pack deep discharge. The 14 cells have not had the benefit of a major overcharge. So I’ll try to get to that this weekend.

So the next morning the pack was still soft. The voltage sagged right away. So I electrically removed about 14 cells from the pack so the charger could keep the current level up around 1-1.5 amps even at full voltage. This will overcharge the nicads and help equalize them. Flooded cells are the only ones you can get away with this. So the charger was programmed to stay on an extra 5 hours after full pack voltage, 400v, was reached. The pack was charged like this all week.

A couple of days ago, I noticed that the resting pack voltage after the charger shut off during the night, was very low. About 306 volts. This concerned me. The first day the resting pack voltage in the morning was 325v. But today it occurred to me that I may have finally gotten what I was trying to achieve. The pack’s cells are now all at the same state of charge. So the cell to cell voltage is closer. With 237 cells in circuit (14 removed), at 306 volts, that’s 1.29v each cell. That’s a bit low. Usually the cells are about 1.35v to 1.4v after sitting for hours. I am guessing that the cells hit the knee in the curve as a group, and the voltage starts to go down as the cells are overcharged. This is some fairly serious overcharging. But it shows that the cells now are more equalized.

Midweek I reduced the overcharge time from 5 hours to 2 hours.

This weekend I’ll reattach the 14 cells that were taken out of circuit and see how the whole pack is acting. Although the 14 cells did not get the huge overcharge, the pack should show improvement. I could add some overcharge to the 14 cells before closing the pack up just to try and bring them into the same state as the rest of the pack. I’ll actually make sure I do that.

The bottom line is that with 3 different versions of the same cell, they are getting worn out as exhibited by their impedance being high. This allows the pack voltage to rise artificially high and make the charger think the pack is full when in fact many of the cells are not fully charged, resulting in a sagging pack.

So after the last deep discharge of the nicad pack a month ago, the pack has been very soft lately. The voltage drops quickly long before I get to work. It is winter, but tonight I found out something new. I pulled the lid off of the pack and was wondering if the 24 redtops were way over charged compared to the rest of the pack, due to their higher capacity. This would allow the pack voltage to rise quickly and not fully charge the rest of the pack. So much for that theory. I took my discharge equipment and applied a 55 amp load for 12 minutes. That discharge took out exactly 11ah out of those 24 redtops. When they were almost finished, I checked them with a DVM only to find that many of them were nearly at zero volts! No good. So I put the constant current power supply on that group of redtops at 10 amps for 3 hours. So they took on 30ah worth of charge. Some cells were venting liquid which means they were over filled. I had refilled them a while ago, not knowing they were actually low on charge, which makes them low on fluid as well. Hmmm. So I’ll look forward to a stiff pack tomorrow morning on the way to work.

This past Tuesday the truck got another deep discharge on the nicad pack. The range was low, but it had also been cold lately. The pack went from -4kwh to +5.3kwh or -17ah to +29ah. This is encouraging. On the 5.7 mile drive to work, the pack voltage never went below 310 volts. This is also a good sign.

I’ve also been working hard on an analog Lithium BMS for 160ah cells. Later, it will be adapted to 40-90ah cells. The board has been iterated a couple of times. Each time better ideas were added for the layout. This last version needs to be built yet as it had some serious changes. The first version is built on a breadboard and works fine.

This deep discharge should be done at least one more time. The nicad manual states that sometimes up to 3 deep cycles are required to completely erase any memory issues. I will check the entire pack for water levels this weekend. A spot check showed that most levels are ok, but were checked while the pack was fully discharged. It has to be checked when fully charged.

This past weekend I jacked the #1 truck up to determine if I could get another water tight connector mounted into the front of the battery box. It looks like my only option is to remove the 1/2″ connector that is there for the Emeter cable and install a larger one. This would still be a tight fit to install. I may consider just adding lithium to the #2 truck, but it does not have a good pack in it yet. I have seen other trucks with a hole drilled and filled with silicone. Not an appealing solution.

Yesterday the #2 truck got most of the body clayed using the Groit’s Garage system. Eddie clayed, polished, and sealed my #1 truck using this same system and it came out fantastic. So now I have a much better clue as to how much work it is. I still need to get the body lines clayed, but I just ran out of steam. This was exhausting work. The paint already looks far better and it’s not even polished or sealed yet.

I’ve tried to use 3M General Purpose Cleaner for removing marks on the paint. It’s helped, but not as much as using Goof Off in a spray can. Good Off is stronger solvent but does not damage the paint.

I’ve also purchased a chip filling kit to help fill in the chips this truck has. The paint code is 5111. The name of this shade of white changes depending on the vendor. So I won’t report it here.

I spent a lot of time watching Youtube videos showing how to fill chips. Some are fast and easy. But most are geared toward average, or less, results. So I may have to invent my own process using steps from the various vendors that I watched. Deep chips need to be filled with a bit of primer if the steel was exposed. Some may even require some fine filler due to the dept of the chip.

Tom and his son bought the spare USE S10 battery box from me some time ago and installed it in their ’84 S10. At Saturday’s SJEAA meeting, I asked for input on how to get a BMS data cable into the #1 trucks’ battery box while keeping it water tight. Tom knew the answer because he knew the battery box better than I did. By removing the drive shaft, the wall of the box that holds the watertight connectors, is exposed clearly from under the truck. That way I can see if how hard it would be to drill a hole and add another watertight connector. The hole would need to be something like 5/8″ to 3/4″ in diameter. Someone talked me into using the water tight connectors that don’t need a threaded hole to be mounted. That translates into less work in a tight space under the truck. Thanks Tom!

– Looked at Coulomb chargers in downtown SJ.
One 208vac SPI and one 208vac Avcon charger were replaced with 120vac Coulomb units.
-Arguing about loss of 208v chargers in the 4th st garage with Tom Dowling.

Tom Dowling claims they will put in 208v Coulomb chargers when the connector standard is turned into a real product.

Coulomb rates:
$10 setup fee.
$15/mon for 10 night time charging sessions.
$30/mon for unlimited night time charging sessions.
$20/mon for ‘grid-friendly’ charging sessions.
$40/mon for unlimited ‘grid-friendly’ charging sessions.
$50/mon for unlimited chariging anytime.

– Titled, registered #2 truck.
Also ordered HOV lane sticker and San Jose parking sticker.
Ordered orbital buffer and supplies for polishing the paint.
Looking at Gel Cell batteries as they last a long time in the Solectria’s.

– Range on #1 truck was 12 miles.
Nicad pack needed to be shorted to zero volts.
Range and voltage is greatly improved.
May need to deep cycle a couple more times.
New 240v variac helped make recharging very fast.
This can only be done with flooded Nicads.

-The heater on the #1 truck works great!!

– SJEAA website updates
Added 3 links to DMV for the various EV stickers required for parking, charging and commute lane riding.
Will add more manufacturer and other links via the SFEAA website.

– Got rid of both S10 bumpers and the bed toolbox via Craigslist.

-My official weight loss for 2008 was 44 lbs.
Celebrated by having my first ice cream in many months.

Last night I took a drive on the highway. It was obvious the nicad pack was doing much better. So I drove at about 72mph which is the max the truck will go. Same thing driving back. About 11.7 miles round trip and the pack was above 300v 98% of the time. I burned over 4kwr and there was probably 1-2 kwh left. I’ll do a range test to see how much the capacity improvement really is.

On the way to work this morning the pack was over 315v the whole drive.

I will do the discharge maintenance again just to ring out any extra capacity that is held back by the memory effect. The manual says sometimes up to 3 complete discharges are required to restore the pack from deep memory effect.