Battery Box


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.

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!

When using Dolcom for looking at ground fault info, the standard nominal reading is about +20 counts above the pack voltage.

In my experience when the ground fault reading taken with Dolcom is higher than nominal then the ground fault is between the negative most battery in the string and mid pack. When the ground fault reading is lower than nominal then the ground fault is between the positive most battery in the pack and mid pack.

So far with mild rain exposure the #1 truck had only had a ground fault reading swing about +30 to about -20 from nominal. It looks like the new gum rubber weather stripping is working.

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