The used lead acid batteries finally after two years were beging to not be able to carry their own weight so I started to look for a Lithium replacement. They were good batteries for the development and testing but clearly it was time to get into some lighter weight batteries.

I managewd to find some used Calib 180 amp hour 3.4 volt litium cells. These cells required a rebuild of the engine compartment battery mounting system and a slight reconfiguration of the rear battery storage area.

front cells    


This configuration has been working fine up to 2020. The Van is still running but time to replace these cells as I have run out of spares. I might upgrade it to Tesla 24 volt packs or Nissan Leaf cells configured accordingly or sell the Van now that I have the EV II project and teh Rav4 EV up and running. This Van is surlus to my needs.


Although Grumman Olson designed and built the Kurbwatt prior to building the Kubvan with a Volkswagen diesel engine which ultimately secured the contract for Grumman to build the LLV for the postal service and the success of the Kurbwatt, Grumman Olson was unable to attract a market due to changes in the energy crisis it is speculated. The history of Electric vehicles from that time is well documented and so no need to go into it here. The rugged light weight aluminum construction of the Grumman Olson truck body is the perfect design for an electric vehicle and a great starting point for an EV conversion.

Motor mount

Motor getting ready to go in.


I based this conversion on second generation electric vehicle design as all the parts were available on the used market at significant lower cost than building a current generation electric vehicle. This is a 96 volt configuration usig 16, six volt lead acisd batteries.

The charging configuration used 8 individual 12 volt DC chargers to charge the batteris in pairs. They were of course all connected togeather to charge the entire pack at once.


EV1 engine compartmnet arduino Battery Comnpartment Controller

I had major failure of the Curtis Controller for unknown reasons possibly running with very low batteries one day which may have caused excessive current load.

Curtis 1232 controller

The effects of a semiconductor failing while passing 200+ amps. What you see in the picture is the large Mosfets which have had the pin on the right side of the ring terminal vaporized and sprayed enough heat and molten material to melt away the tab of the adjacent smaller diode which outside of physical damage are still OK. This effect is repeated at each pair of Mosfet & Diode which make up a parallel circuit that passes some 500 amps to the traction motor. Pretty impressive! Would have made a cool video.

None the less searching for information on repairing the controller found this reverse engineered schematic of a Curtis 1221 controller which is very similar to my Curtis 1231. You can find this schematic here : Curtis 1221 schematic

In the end I found a replacement controller on Ebay and the one above. Although I now have the parts it is still waiting repair as the replacement has been working fine since. Life goes on..............


Total investment for the originla conversion not including the Van and used lead acid batteries was around $3000.00 cdn. in 2015.