December 2008

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.

Isn’t debug fun? It sure separates the boys from the men, or me from my sanity Wink

I’ll be on vacation starting Monday. That excuse one for not having my BMS installed. #2 is that the second truck has taken all of my time to get corrections made to it’s various electrical systems. It’s basically done. Just needs a new pack. So the #1 truck is the tough vehicle to get a shielded cable from the pack to the interior of the truck. Once the cable is mounted through the wall of the pack, then adding the BMS is easy. Now I have Thundersky’s that I have been testing as well as 3 new 50ah Hi Power cells to test.

To look for noise it’s helpful to determine if it’s conducted or radiated noise. Steps that I use.

Conducted Emissions

1) I like to use clip on ferrite beads for initial debug. Easier and faster than adding components. The kind you see attached to a wall wart power supply or your pc monitor cable. 25-30mm long. 15-20mm in diameter. When picking them up from surplus locations, get a few different versions as you don’t know which RF material they are made from. Clip them onto both ends of the master bus cable. One at the master board and one at the first slave. Check for changes. Does the system work better? Verify with a scope, always.

2) Now repeat step one with the Slave bus, with all of the master bus ferrites removed. The slave bus could easily carry EMI/RFI and cause issues.

3) Repeat step one with ferrites on Master and Slave bus.

4) The shotgun approach is to just do both Master and Slave bus at the same time. But you won’t know the sources of noise as well.

If 1-4 improve function then it’s the noise is mostly conducted emissions. Although radiated emissions from the vehicle could turn into conducted emissions due to the huge amount of wiring we have to use.

5) Always twist pairs of cables to 4 turns per 25.4mm(1 inch) between slaves. Cordless drill works great for twisting wires together.

6) Use shielded cables with twisted pairs for Master to first slave cables.

Radiated Emissions

Here is a fantastic article on how to make a home made probe for sniffing EMI/RFI with your scope from a piece of coax a tiny ferrite bead, and some sandpaper. When I showed the crew at work this article, everyone had me making these probes for them.

Here is the probe I made from the article.

Above is the probe I made from the article.

Here is the probe I made from the article.

Above is the probe diagram from the article.

Below are scope shots using my probe on a project that has so much EMI that it smoked the processor and other drivers badly enough that my head with a full face helmet, hit the ground hard and made me unconscious. Had a concussion for a year. So EMI and I have become great friends!

There are EMI and RFI (aka E field) probes. An E field probe is just the ground of your scope probe tied to the probe tip. It shorts it in a dc sense. But for RFI, it’s a path to joy and harmony. If you make your probe ground lead a bit longer and coil it, the probe becomes much more sensitive to weak signals.

HBoth EMI and RFI probing examples of my concussion making machine (a home made self balancing scooter) are shown here.

Both EMI and RFI probing examples of my concussion making machine (a home made self balancing scooter) are shown here.

These scope shots showed me clearly at the time where the emissions were coming from. Each output from the processor got a 1k resistor to isolate it from the drivers. A 1k resistor was put on the output of the driver chips. These two steps did not reduce EMI, but did reduce it from getting into the sensitive parts. The next step was to reduce the EMI itself. I had used 250mm long ribbon cables for connecting the master board to two slaves (control board to 2 H-bridge boards). Normally the ribbon cables are about 50mm long. Reinstalling the 50mm cables did the trick. The EMI probe showed me the way. As you can see from the scope shots I also found EMI from the power supply inductor as well that I could follow with my handy EMI probe along a ground trace. That’s right. EMI was following the ground!!

So assume nothing, and measure everything!!

I put an ad on Craigslist for the rear bumper, class 3 trailer hitch, and a bed mounted tool box. These are the parts I took off of both USE trucks to they could have perfectly functioning tilt beds. I wanted only $40 for all 3. But the only fellow that showed interest, did not need the other stuff. So I cut the price to $20 and he took all of it. It was all stored in the wagon. This stuff took up all of the room in the wagon. Now it’s nice and cleared out. Still there is a USE motor back there. I was just glad to get rid of it all.

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.

Blog is

I’m down 38 lbs.

Here is Lanny’s work on putting Hi Power Lithium modules into Ford Ranger EV’s .

He’s really moved the Rangers ahead and out of the hands
of a terrible fate. I’ve exchanged a lot of email with him as I’ve
worked on Rangers. I’m hoping he has a good BMS picked out or on the
design board.

I’ve had the Thundersky equivalents of those Hi Power cells that Lanny
is using. The Hi Power’s that he is using I have ordered and will
arrive next week for testing.

The issue for us is how will lithium function in a real EV. Bench
testing has major limitations compared to real world. Real world
driving beats on batteries like no bench testing ever could.

I’m also in a group that has a working Lithium BMS that is being
majorly tweaked at the moment. It has no street time yet, but will
soon. I was suppose to have some street time already but this second
truck has taken all of my energy.

The good news for us is that a small or medium pack will fit our
trucks fairly easily. My nicad pack is about 1400 lbs lighter than the
bone stock Hawker pack. The Lithiums would be 1800 lbs lighter than a
bone stock Hawker pack. But each of the 100 cells has to have a BMS
module. All of those 100 cell modules have to talk to a master to keep
the driver informed.

The good news about using around 100 cells is that our chargers can be
tweaked to handle lithium. I’ve done it. The max voltage output of our
chargers is 400vdc. 100 cells could only charge to 4.0v each. 3.6v to
3.8v has been suggested. The 400v limit will help keep from
overcharging the cells. But they still have a mandatory requirement
for a BMS.

108 40ah cells would fit easily. 100 60ah cells will fit nicely. About
100 90ah cells with a second batt box will fit. The range due to the
light weight would be great. The lifespan in an EV has only been
tested to 25k miles. Then they were accidentally discharged overnight
and ruined in the blink of an eye.

40ah pack = $6.9k. 60ah pack = $9.6k. 90ah pack = $14.4k. All of these
prices are without a BMS. Right now a BMS looks to be $1.5k+ if you
assemble it your self.

There may be cold weather issues as was reported by a lithium user
some time ago. So testing is everything because toasting these babies
is vastly more expensive than buying the truck in the first place.

You’d think this format of Lithium would fit in the Prizm’s nicely.
But I have never heard of anyone trying.

A fellow EV’er commented about using 40 foot long greenhouse soil heaters
to warm his battery packs. Liking his idea, here is what I wrote back.

The ACP cars use battery heaters. It only draws a few hundred
watts when it’s running. It takes a day or two to heat up a cold pack,
but holds it there nicely after it does. The lead packs I’ve worked on
in ACP cars put off heat for a whole day once they are in the 30-40C
range. When we pull a pack out to replace a weak battery you can feel
the heat in a big way.

The pack heaters are also one of two reasons the ACP vehicles get 30k
miles from a lead pack. Heating up a battery to 30-40C also increases
it’s capacity, making it less likely to reverse a cell. The second
reason for such great longevity is having a BMS.

The ACP battery heaters are powered from the pack itself I just
remembered. That’s why they don’t have to worry about what voltage
they are charging from. They do have a simple IGBT circuit that turns
on, off, or pulses the heaters to keep them at the same temp with a
thermal sensor.

A little math shows that the ACP heaters total about 450 watts. So on a
336v system that’s about 1.34 amps. So our packs would supply a little
less as our nominal voltage is 312v. So it’s not a huge drain when
it’s running.

It sure looks like the schematic for the precharge board is done. I see something that does not make sense yet it matches the original board perfectly. It was a fair amount of work. But I’ve noticed that the #2 truck has a hard time booting up sometimes. I think the 24k miles on it has worn out the precharge relay. The #1 truck is on it’s second precharge relay. Commuting with the #1 truck will surely wear out it’s second precharge relay, quickly too.

At some point I need to get a board made and start testing it before the precharge relay goes out completely on the #2 truck. I may also make a 2nd board layout that is exactly the same as the original board. Right now the components are in the same place but the traces are routed differently. At least I did find all of the data sheets for the parts. The capacitors were the toughest to find by far. I do need to open a Dolphin and look at those two tapped holes on the Dolphin floor to see if they match up to the holes in the original precharge board. That would be nice if all Dolphins were tapped to mount a precharge board!!

Last night I finally got the blower to stop running when the selector switch was in the off position. It turns out that USE wired it in such a way that it grabbed power from an always on source. Although it appeared that I also added to the issue. The blower was tied to a 3 amp circuit for power. So when I turned the blower up to high, it popped the 3 amp fuse. Now it’s rewired straight to the heater/ac fuse and gets all the juice it needs. The 3 amp circuit is now independent and works fine. All of this also made me update my heater/ac schematic yet again. I have not looked at an air conditioned truck before so I am not sure if my wiring will match. I made this system work the way that is the most useful and makes the most sense. This truck was an early version and their ac wiring was not tested enough to find any bugs. The big thing is that the heater and ac never worked from day one according to the original owner. So I think now the system is wired correctly. Buying the factory S10 manuals used from Ebay made a huge difference in diagnosing the electrical and vacuum issues with the #2 truck!

I also bumped the regen in first gear to the maximum. The first time I tried it the truck shuddered like mad, but without faulting. The pack voltage jumped from about 330v to 380v. There is a limit to the voltage and I exceeded it. This really points out how high the pack impedance really is. This pack is shot.

When the dash gets taken apart the orange heater switch has to get pulled out. So the small panel that it is mounted to clips into the dash bezel. One of the molded in tabs snapped off. I used my standard repair of CA (CyanoAcrylate) and Kelvar strands to fix it. It may make the tabs too stiff which would require them to be shaved down a bit so they can be installed/removed easily.

I also added 2 12v batteries to the #2 truck’s pack. The pack is showing such low voltage output as the seasonal temperatures get down into the 30’s. Then the charge curve had to be increase up to 400v since there are now 27 batteries in the pack. That should get the truck around the block over the next few months. I did notice that the 592AE processor would not accept a full download of the .set file. I think it might be because the file was for a 5B5AA processor. The only real difference is in the checksums being different. So I went through manually and changed the several settings to match the nicad settings so the truck will charge higher and run on a lower pack voltage if needed.

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