Guide to rebuilding/upgrading Ford Escort EV's originally converted by Solar Electric Co., Santa Rosa, CA


In 2002, I finished upgrading/rebuilding a 1986 Solar Electric Ford Escort EV. There are a number of items that owners of these EV's may have to deal with, and some of them are safety related. In particular, the isolation and ground faulting aspects of the original design were changed. Also, severe corrosion at the forward battery rack connections to the car required some rework. I'm discussing my changes on this web page for the benefit of other owners.

The original vehicle as I received it was a 108V system, using 18 Trojan T-125 batteries. The original charger had been replaced by a K & W BC-20. Other than that, it was original. 9" GE motor, Curtis 1221B controller, Curtis Contactor, Heinemann circuit breaker, and a hair dryer as the heater (seriously, it was a real hair dryer). Solar Electric put a voltmeter and ammeter in a "pod" under the dash. This pod also contained the heater controls and controls for their transformer-based charger.

Since mine had a K & W charger, the original charger controls were inoperative. So was the ammeter. As I understand it, they just used a length of wire for a shunt, and weren't that accurate anyway. The shunt had been removed. The voltmeter was an SOC meter, and only indicated % charge. It was useless for driving, and without knowing what voltages the various marks corresponded to, it wasn't very useful for at rest measurements, either.

Soon after I received the vehicle, I replaced the hair dryer with a real EV heater core. In the process, I discovered that the wiring to the hair dryer heater (which used pack voltage) was pretty risky. It ran pack voltage into the passenger compartment, and I think the switch used, though heavy duty, was only AC rated. I mounted the control relay on an auxiliary board made from plywood. I mounted the board over the front batteries in the radiator area. I used wiring virtually identical to what Jerry Halstead used, as the Ford fan system is the same as he pictures. There is just enough room on the ventilation control panel to mount a 1" rocker switch, DPST, for this purpose. Replacing the heater core itself is super easy. Flip down the glove compartment by pressing in at the two stops in the back. It will flip completely out of the way. You will see an air duct behind it with an access cover. Remove the access cover screws. There is plenty of room to remove the hair dryer and mount a reasonable EV core, although undoing the screws is kind of tricky, and screwing in the new core is also difficult. If you have a lot of different lengths of screwdrivers, and a magnetic pickup for the inevitable dropped screw, it will be a lot easier. I'm not sure exactly what Solar Electric did with the wiring to the fan. I ran my own wires. The hot-cold control slider usually controls a flapper door inside the ducting. The door directs a portion or all of the incoming air over the heater core. Solar Electric had removed the door, so there is no way to bypass the heater core. Therefore, the airflow seems restricted since it has to pass through the core whether it is in use or not.

I replaced the auxiliary battery with a small wheelchair battery (30 AH, deep cycle, AGM construction). The premature death of the Solar Electric "truck" starting battery was due to the vacuum switch being failed in the "on" position, and the battery being the wrong type. It was a starting battery, and a deep cycle is required. The pump running continuously quickly killed it. Fortunately, the failure mode for the switch is for it to stick on, so at least you can continue to stop the car.

The vacuum switch was replaced with a small one from evparts. (After the rebuild, I noticed that this relay, too, was stuck on. Careful reading indicated that it was only rated for 0.4 amps. Therefore, I replaced it, but only used it to switch the coil of a Bosch automotive relay that I purchased from Waytek Wire. The Bosch relay is rated for 20 amps NO, and 10 amps NC, which is the setting I will use.)

Later, I also added a shunt (to B+, there wasn't room to mount it to B-), removed the OEM fuel gage and mounted a 2" round ammeter. Again, there is barely room. Be warned that the escort instrument panel uses a plastic sheet with circuit traces on it to distribute power from a central connector to the indicator lights, etc. You must cut through this sheet, while being careful not to damage the traces that lead to the indicators that you still use. It is possible, but difficult. I mounted mine so that the ammeter is flush to the face of the panel, along with the speedometer, etc. The ammeter looks like it was built in at the factory. You will have more room if you make it stick out from the front. I also tried to cover up the old E-1/2-F markings with black magic marker. This didn't look as good, though, and didn't last long.

The only size of goodyear Invicta LRR tires that were available for the standard Escort's 13" rims were P155/70R13's with a max. pressure rating of 35 psi, and a max. load rating of 853 lb. Just UNDER what the weight on each one was in the rear. This car is very tail heavy, with 10 batteries in the back, and would "tail-wag" after going around a corner, due to the sidewalls flexing. The tiny tires were simply being mashed flat by the excessive weight.

I replaced the old tires and rims with Escort GT 15" rims and Bridgestone Potenza RE910 P195/60R15 tires rated at 44 psi and 1190 lb. load each. This completely eliminated the sidewall flex problem, and put me under the max. load rating. Performance GREATLY improved. I am sure I suffered a small penalty in range, due to the greater footprint of these tires, but it was worth it to be able to drive safely, and have control and good traction in the wet and around corners. With the help of a very knowledgeable tire dealer, I selected the lowest rolling resistance tire available that would meet my needs. The similar Potenza RE92 is standard equipment on the honda insight, and is one of the lowest resistance tires available today.

The battery pack I received with the car gave me 2 years of good service, which was good, considering its checkered past. When the battery pack finally gave up the ghost, I decided I needed to correct a few other problems when I installed a new pack.

  1. The isolation ranged in quality from bad to nonexistent.
  2. The interconnect wires suffered from cracking of the heat shrink at the ends, exposing the wires. Some of the terminals had extensive corrosion damage, and the tin plating was missing from areas of others. Apparently, the heat shrink used was too small, and continued to shrink over the life of the car. This was especially prevalent on high resistance connections, which generated a lot of heat.
  3. The controller mounting plate is mounted between the RH engine mount and the transmission. This lets it rotate during high torque periods. Since the potbox is mounted on the plate, but above the axis of rotation, these torque events resonated if you kept your foot in a fixed position. This resulted in a repetitive jerkiness that in some conditions could build in intensity.
  4. The potbox couldn't travel through the complete range of motion
  5. There were no boots around the battery terminals. The danger of accidental shock when reaching inside was high.
  6. The solar electric "pod" under the dash was ergonomically dangerous. To look at the SOC gauge, you must take your eyes off of the road.
  7. The SOC gauge is inadequate for proper battery care.
  8. The only insulation was aluminized bubble wrap around the batteries. This caused ground faults and afforded no protection to the rear pack in the event of a rock or debris being flung that way from the tires.
  9. The controller mounting plate looked heavy.
  10. The 108V voltage was far too low for the 9" GE motor
  11. The Curtis controllers were prone to capacitor failure
  12. The vacuum pump isolator mounts were failing, and it cycled every time I touched the pedal.

To solve all of these problems basically meant that a complete rebuild was neccessary. Here's what I did:

The disassembly process went smoothly. I removed my auxilliary board, the heater power and control leads, then all of the interconnects and then the batteries, circuit breaker, and potbox. I labeled all the wires as I removed them. Some Solar Electric wires were not labeled, because I never knew what they did. If I ever get an original schematic, maybe I can remove some of them.

To remove the batteries, I made a jig which consisted of a beam long enough to reach across the car (a 2 X 6 works good. I laminated two scrap 1 X 6's), a handle on one end, and a vertical support on the other end, with a foot assembly to keep it from tipping over. To use, just lay the beam across the car, tie a piece of cord to the place you attach the battery's handle, loop it over the beam, and tie to the other side. You may now stand out of harm's way, and keep from breaking your back while removing the batteries. This jig gives you enough leverage to muscle them out, move them away from the car, and set them down with minimal strain.

I removed the aluminized bubble wrap and cleaned the angle iron frames that supported the batteries as best I could. I removed the plexiglas bottoms from the racks. The controller and mounting plate was barely removable due to the use of bolts and nuts. However, I eventually got it off. I was still convinced that it was too heavy, even though it was aluminum, not steel as I had thought. After considering several options for remedying the low voltage, I finally decided to just add 1 battery for 114V. I considered rewinding the motor, but that would have led to other problems. This EV motor is really designed for high voltages and high amperages. The rest of the system is designed for sustained low amperages, and low to moderate voltage. This motor really needs a T-Rex controller and at least 192V of AGM batteries to get good performance.

I did remove the motor and had it serviced. The auxiliary battery location was the perfect size for adding another pack battery. I would have to relocate the auxiliary battery to the RH fenderwell, but that was OK, because the charger was being moved from that spot to the hatchback area.

The vacuum pump was removed and inspected. It was in excellent condition, despite some surface corrosion on the outside of the case. I did lightly sand the comm. and brushes in the pump motor to remove oxidation, and thoroughly cleaned the whole thing out. The mounting was really odd. New holes had been drilled in the side of the case for the Solar Electric mount. The existing mounts were removed, and mounts with a captive design were added to the bottom of the pump. (I found out later that this raised the pump far enough that I had to relieve the bottom of the hood by cutting away the metal ribs in order to close the hood. This wouldn't have been too bad, but the extra battery I added was also just a bit too tall, so I had to manufacture a replacement fiberglass hood sooner than I had expected.) A reservoir was plumbed in and placed behind the windshield washer tank. I ran the pump from a 12V battery and measured the current. Only 4 amps with no restriction on the outlet. The amount of noise is directly proportional to the restriction of the outlet, however, and when muffled it tends to raise the back pressure and thus the current. Never got above 8 amps, though, even with complete blockage of the outlet. I will work out some sort of "quiet kit" for it.

The Solar Electric design lends itself to ingesting and keeping a lot of debris and grime. Getting the motor cleaned was the most beneficial part of having it serviced. I also had the brushes and bearings replaced. After I got it back, I wrapped up all the openings with duct tape to keep it clean while I did the rest of the work. I replaced the clutch too, although the old one was still in good shape.

To remove the motor, I had to remove the front battery racks. The motor can then be easily lifted out of the car with the aid of a hoist. It is also possible to remove it from the bottom, but that requires disassembling most of the drivetrain.

The battery rack by the firewall is removed from the forward-aft tubing braces by disconnecting three bolts. It has to come off first. The lower rack and the forward-aft tubing braces are welded together into one piece. They unbolt at two places in the back and two under the frame cross member in the front. The lower mounts were each 1/4" all-thread welded onto the forward-aft tubing braces. They had the problem of sticking down about 2" past the bottom of the car. When I removed the nut from the RH one, the entire assembly torqued off. The placement of these connections exposed them to road spray, and corrosion quickly set in. Overall, however, it is generally a good design. The front rack is restrained in the forward direction by the car structure, and in the aft direction by the motor, so the forward two attachments really only have to carry the load of the three firewall batteries in a crash. I really like the bolt-in and easy removal feature.

On inspection, the front battery racks had severe corrosion, and two broken welds. The original welds are on the tops of the angle iron frames. The appropriate places to weld are actually on the bottom, on either side of the square tubing. This area has space for twice the length of weld, and it does not have to be ground down. I had the frames rewelded, and had pieces of 1/2" all thread welded on. I then enlarged the holes in the cross piece to match the new all thread size. The racks were sandblasted and powder coated to remove and prevent corrosion. The front was reattached using stainless steel locknuts and fender washers. Some grinding of the washers to fit the available space was required. After sanding/grinding off all the surface corrosion on the vehicle itself, I primed it and reassembled the racks.

The back racks were not in as bad a shape, but they were completely exposed on the sides. Luckily there was room to wrap them with lightweight, rigid honeycomb material. It is not an airtight seal, but it provides some protection and insulation.

The charger was relocated to the hatch area. With the new higher voltage, it required a booster transformer. When I received the car, I had to have the charger rebuilt by the factory due to corrosion. It is vulnerable to moisture, so relocating it to the interior was a good idea anyway. In the process, I cleaned the AC male flanged plug. It really needs to be replaced by something that can handle higher currents.

AC wiring is now run in bright yellow wiring loom. DC high voltage wiring is now run in bright red wire loom, for easy ID. Some crossovers exist, but in general, you can tell quickly in an emergency what to avoid. (I have to get some in a nice soothing blue or green for the 12V wires.)

The new battery box bottoms are made from 1/8" thick fiberglass honeycomb material (non-conductive). KTA services heater pads were bonded to this material using ordinary silicone caulk (GE silicone II), then 0.020" thick aluminum sheet was placed on top of that using heatsink compound. More heatsink compound was used between the batteries and the aluminum. Make no mistake, this takes a LOT of heatsink grease. Temperature sensors and heater controllers from McShane, Inc. will be added later.

The honeycomb material was also used to make a new main mounting plate (this time 3/8" thick). Since the controller had lost its "heatsink", I installed one from KTA services. The entire assembly is mounted on standoffs. The plate has room (barely) for the shunt, main fuse, precharge circuit, and controller. (I had to mount the circuit breaker to the heatsink. This worked out pretty good, but I no longer have the ability to reset it from inside the vehicle because I had to extend the leads using cable. This could be good depending on how you look at it.)

I fabricated a new auxiliary board from the same material, and mounted an electrocraft DC/DC converter and my heater relay to it. Due to the new heatsink taking up a lot of room, this board mounts in 2 places to the front forward beam using aluminum clips, as before, and rests on the heatsink in the back.

To guard against controller failure, I replaced the old single contactor arrangement with a dual contactor precharge circuit, using Lee Hart's design as a basis. This is much gentler on the capacitors, and will extend the life of the controller. (Funny story, I goofed when sizing the coil resistor for the relay that pulls in the second contactor. That last stripe on the resistor was X1K, not X100. So the second contactor did not pull in, as expected. I replaced the resistor with a 0-10K pot, let the charge voltage come up, then turned down the pot until the second contactor pulled in. Pretty slick!)

I mounted the potbox to the firewall. No more jerky starts, no more oscillation.

A 50-150 VDC gage was purchased from Evparts and added to the dash. With this change, I was able to completely remove the Solar Electric "pod" and associated wiring.

With a new battery pack, I built and ran new interconnects. I purchased premade 4/0 gage cables to run between the motor and controller (with the controller mounted on standoffs, the existing cables were too short), and rebuilt all the connections I had using new terminals. The cables were still good, just the terminals and heat shrink covers were bad. I needed to get some new cables, as some of the cable lengths I had would have been too short after cutting off the existing crimped terminals. I added battery boots over the terminals. The heat shrink I used was so thick, the boot ends couldn't fit over it, so I wound up cutting the boot ends so they can slip over the cables. I used heat shrink tube that shrunk to just the OD of the cables at its minimum size, so there would be no problems with it cracking later.

To guard against corrosion, I implemented the recommendations of the EV list. This is a three step process. Starting with clean batteries, seal around each post at the base using RTV silicon. Then add the felt washers impregnated with the corrosion preventive compound. Finally, spray the assembled connections with the commercially available battery terminal corrosion preventive spray.

I cannot believe how cramped the installation was. Every time I needed to fix, rebuild, or improve something (and everything needed it), I didn't quite have enough space. I had to move the hood prop rod because with the 12V battery in the new location, it would short the 12V battery. The vacuum pump location was a bit higher, which required removing the hood stiffener right over it. The extra battery required that as well (and the hood still wouldn't close!). On the other hand, I have not intruded on the passenger space.

It took some effort to "tune" the precharge circuit. At first, the resistors I put in series with the coil of the 120VAC relay kept the current from flowing enough that the relay wouldn't pull in. Rather than go by trial and error, I replaced the resistors with a 0-10K ohm potentiometer, precharged with the pot set to max, then lowered it until the relay pulled in, which closed the 12VDC circuit for the coil of the second contactor. I lowered it a bit more to be sure that sagging voltage would not make the contactor drop out.

I wound up with a very well done vehicle. In the upgrade process, I tried to clean everything I could, and to remove any unnecessary structure. These vehicles are very heavy (for EV's), and I tried to combat that any way I could. I figure that it lost at least 2 lb. of dirt and grime. I am working on fabricating a composite fiberglass hood that will save at least 30 lb. (Have to hurry, so I can actually *close* the hood!)

Good design practices and sealing things well allowed me to greatly improve the isolation. With the boots on, the vehicle may now be more safely displayed, and stays a lot cleaner. Interestingly, I'm using the US battery "speedcaps" which most people on the list agreed leaked too much, compared to individual caps. I haven't had any problem.

In summary, these are the changes I made to the Escort EV:

  1. Changeg to Escort GT rims and Bridgestone Potenza RE910 tires (P195/60R15)
  2. Remove the original fuel evaporation system charcoal canister (located INSIDE the LH fenderwell!)
  3. Remove unnecessary structure
  4. Remove old batteries and interconnects
  5. Relocate potbox to firewall
  6. Remove front battery racks
  7. Remove motor and clutch
  8. Have motor serviced
  9. Install new clutch
  10. Reinstall motor
  11. Replace front battery rack lower mounting threads with larger ones - have welded on
  12. Sandblast front racks to remove corrosion
  13. Powder coat front racks
  14. Remove corrosion at battery rack mounting points and prime
  15. Enlarge holes for lower mounting threads and prime exposed metal
  16. Replace front battery racks
  17. Clean and prime rear battery racks
  18. Line rear battery racks using honeycomb panels
  19. Use honeycomb panel as the battery box bottoms instead of Plexiglas.
  20. Add battery heater pads to battery box bottoms
  21. Change charger ranging resistor to charge 114V pack
  22. Add booster transformer for charger
  23. Remove angle mount for charger that was made from "tread plate" aluminum.
  24. Remount charger and booster in hatchback area.
  25. Reroute AC lines to supply AC distribution to all the points that the heater controllers will be located.
  26. Add aluminum heat distribution sheets to battery box bottoms using heatsink grease
  27. Add 1 battery for 114V.
  28. Add additional insulation to prevent shorting 114V to frame/hood
  29. Install batteries using heatsink grease
  30. Remove metal from underside of hood to accommodate extra battery
  31. Relocate accessory battery
  32. Add additional insulation to prevent 12V shorts to hood
  33. Remove the old (inoperative) vacuum switch (replaced last year with Wilde Evolution's switch)
  34. Remove sheet metal "flap" hanging behind back of rear battery box
  35. Replumb vacuum system adding reservoir
  36. Replace shock mounts on vacuum pump
  37. Remove metal on hood underside to allow for higher vacuum pump orientation
  38. Bumpers are attached to bumper mounts using 8 bolts per bumper. Replace using 4.
  39. Rear bumper rubber seal was attached using 6 panel fasteners. Reattach using only 4.
  40. Remove Solar electric "pod" under dash.
  41. Install new voltmeter in dash.
  42. Add precharge circuit with second contactor.
  43. Mount controller and precharge circuit, heater relay, misc. control electronics on honeycomb panel
  44. Relocate circuit breaker
  45. Replace motor cables with longer ones to reach new controller location
  46. Fabricate new rear battery box lid from honeycomb panel.
  47. Remove degraded plastic trim in the hatchback area and build new interior structure (with charger access) using honeycomb panels. (incomplete)
  48. Add partial rear wheel fairings made from honeycomb panels (not installed yet, but fabricated)
  49. Add Belly Pan made from 1/8" honeycomb panel (incomplete)
  50. New interconnects with battery boots
  51. 3-layer corrosion prevention implementation
  52. Add AC fan for booster transformer (incomplete)
  53. Get front end aligned (incomplete)
  54. Mount heater controllers (incomplete)
  55. Add AC power switch/timer for heaters (incomplete)
  56. Route switched/timed AC power to heater controllers (incomplete)
  57. Mount temperature sensors (incomplete)
  58. Wire temperature controllers to temperature sensors (incomplete)
  59. Wire battery heater pads to temperature controllers (incomplete)
  60. Wire in leads for individual battery monitoring (incomplete)
  61. Add voltage monitoring system (incomplete)
  62. Replace hood with fiberglass copy (incomplete, gotta get done soon so I can close the hood!)
  63. Replace bumpers with composite copies (incomplete)
  64. Rewire relay system for vacuum pump.

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