December 2008

This morning I headed over to the hardware store to see if they had any 3/8″ fuel line to help adapt the 5/8″ heater hose to the 3/8″ barb. The fuel line was difficult to push onto the barb even with lubrication. In fact I had to use the coolant bottle from my spares that had the barb cut off. This allows the fuel line to barely fit over the barbless inlet. At least it worked. Then with some lube the 5/8″ heater hose fit snugly over the fuel line. A hose clamp made the whole thing water tight. This is what prevented the truck from being finished last night.

The heater element pulls about 8.5 amps at 321vdc. That’s over 2700 watts! The air sure gets warm quickly. On the drive to work I watched the thermometer that I stuck into the vent. It peaked at 130F or so, and then the over temp sensor would shut off the heating element. The temp at the vent would drop to about 105F, then the element would come back on. It was so nice to have a real heater for a change!!!! The bad news is that the heater uses 2.7kwh. So it’s a bit of a load for my small pack.

The original heater hoses were fairly brittle. When I clamped them with long nose vice grips they cracked and leaked. So the heater got all new hoses. I’m a little concerned about using 100% coolant and no water. I may siphon some coolant out and add water. Ethylene Glycol is not as efficient at 100% concentration. I used silica free coolant. A large syringe really helped when I had to prime the pump or remove coolant without any spilling. I used a Dremel tool and fiberglass cutoff wheel to shorten the inboard mounting tab on the Hotstart heater housing. It was a lot faster than using the mill because I didn’t have to figure out a jig. Cut off enough of the tab to just remove the 2 inboard mounting holes and no more. Otherwise there won’t be enough material to keep the seal in compression.

BTW, the heater core tubes coming through the firewall were aluminum. Be careful when adding or removing hoses!

This heater upgrade could really be polished off with a variable temperature control. I thought about it today. The control circuit could be placed with the heater relay in the battery box, or if it fit, into the heater box. The heater box is a bit cramped. I suspect the circuit will need a source of metal around to thermally sink the fets to. The heater box might be too warm, but it would be the most convenient. Maybe the engine compartment is a decent mounting place for at least initial testing. This circuit would also lighten the load on the battery pack by allowing the heater to run at settings less than full current.

The temperature control knob would mount next to the heater button the dash. I think it will fit onto that small cover. An LED would be good to indicate if temperature control is on or not, and at what rate it’s pulsing. Maybe zero to 100hz would do it. The schematic is in pieces but has enough info that I could start on circuit testing in the future.

A lesson learned from an ACP failure that I witnessed, will give the circuit an indicator signal that is actually enabled when there is high voltage present at the output of the fets. This makes sure that if there is a fet failure, that there will be an indicator to tell me that.

I used a Dremel tool and fiberglass cutoff wheel to shorten the inboard mounting tab of the Kim Hotstart heater housing. It was much faster than using the mill because I didn’t have to jig up the heater to machine it.

Don’t forget to prime the pump!! It’s a pain in the butt!! You will smoke your heater if you don’t!!! You can shine a flashlight behind the coolant bottle to make the coolant glow. When you look inside the bottle or through the wall of the inlet, you can see both huge bubbles or microscopic bubbles. Both of them should be moving to show that the coolant is flowing. I used my aux battery to spin the pump without running the heater. A 50/50 mix of coolant and water will help with the priming as coolant is way too thick.

I worked all afternoon and evening putting in a Kim Hotstart heater in the #1 truck. It’s going to be a cold week. I need a better heater. I was nearly done tonight with the swap and found that there is a 5/8″ heater hose that has to fit on a 3/8″ barb. There was a smaller piece of hose adapting the two together, but I nicked it with the knife as I was removing it. The stores were closed by the time I figured this out. So the truck is not going to drive me to work in the morning.

The coolant bottle also had to be rotated 180 degrees because it would be in the way of the air conditioning hose that goes around the firewall, when I add the AC that is. So a couple more holes had to be drilled.

Hopefully the Kim Hotstart heater will have decent longevity. It’s a 240vac 1500w heater running at 300-400vdc. That’s about 2700w. At least the plastic body helps get rid of ground fault potential.

Here is the Hotstart heater before it has one of the mounting tabs shortened. Next to it is the wiring that I add to make it easy to test and remove if needed. The small connectors at the end of each of the wires are from the Hotstart. The high voltage connector with the green and blue 10ga wires, has 4 positions with two of them empty between the pins to help prevent arc-over. The 3 position connector with the 2 yellow wires is for the temperature sensor. The pump motor shown in other images, has a 2 pin connector. This keeps connectors from being confused during reassembly.Hotstart Heater.

This #1 truck was built very late in the program. 1996. So it has some improvements. Tonight I found that the hoses attached to the pump and the heater had a large diameter stainless spring inside to keep the hoses from collapsing. This could be helpful.[/caption]

The Z shaped hose that connects the pump to the heater, tends to kink at both ends. These stainless springs took care of that. I should retrofit the #2 truck with the same hose springs.

As soon as I can adapt the 5/8″ hose to the 3/8″ barb, the truck will be ready. I also pre-primed the pump by adding coolant to the heater and the pump with a syringe, then spinning the pump before it will be put back into the truck.

I was not able to test the original heater output before the swap, to generate a temperature versus time plot.


– Made a schematic for the heating and air conditioning systems.
– Scanned and imported 3 different drawings to make the schematic.
– Used it to repair the AC and heater systems.
– The AC and heater never worked per the original owner.
– Air conditioning now working!!
– Heater has upgraded element and gets hot very fast.
– #1 truck will be getting an upgraded heater asap.
– AC had corrosion on the black box control connectors.
– Bad crimp too.
– AC works but connector is still intermittent.
– May have to solder crimped wires.
– AC increases output by the compressor running faster based on positon of temperature knob.
– The blower was on all of the time.
– Found wiring issue and rewired to correct blower issue.
– Factory had made some bad choices for wiring the heater and ac.

Heater works now as it was a pot that was trying to supply current to two relays at the same time.
– Only one relay would energize at a time and cause the heater element to smoke before the water pump was running.
– Now it turns on with a button.

The precharge board schematic looks to be finished.
– This will take the place of the precharge relay that does not last that long.

Heater temperature controller idea.
– Can use part of the precharge circuit to control heater temperature!
– Could run with any voltage EV heater up to 500 volts.
– PWM to the heater from zero to about 5 khz or so.
– Led and temp would be mounted on the dash.
– Opto isolated from dash.

The lithium cells were removed as I overcharged them and they now have a reduced capacity of 10%.
– When I can get a data cable fished from the box to the cabin, I will reinstall the lithium cells.
– 3 New 50ah Hi Power Lithium cells are due to arrive next week for evaluation.
– The good news is that the cells went many hundreds of miles without issue.

Lanny is putting some Lithium cells into one of his Rangers as we speak.
– NIMH Ranger hardware used for the BMS.
– Only monitors every 4th cell.
– 100ah pack of what looks like Hi Power cells (from Thunderstruck Motors).

Had some cells that appeared to be low on electrolyte only to discover they were just very undercharged.
– They spewed KOH and had to be removed and cleaned up with vinegar.

Pack was ground faulting during the last rain.
– 3 sides of the lid had new weather stripping. The 4th side that leaked had a different and softer material.
– The 4th side now has the better material like the other 3 sides.
– Also cheated by tweaking the software so the truck is not so sensitive to ground faults, until I get the battery box water tight.
– With 500 terminals, 5 times more than a lead acid pack, it’s easy to get a ground fault.

Nicad pack now has 12k miles on it as of this week.

The tilt bed on both trucks now has two gas struts per side.
– Makes lifting the bed easier.
– Holds bed up without a prop rod.
– Sometimes in the garage the bed needs to be held down. Prop cable?
– Can demonstrate outside.

The #2 truck has an unpainted roll pan that needs to be finished and installed.

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I’m down 38 lbs.

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