Battery Monitors

It has been a long time but EV's are in the news more now than ever. For many, building your own EV is still viable especially compared to the cost of a new Leaf or Volt. I did a quick search for battery monitor systems from http://evalbum.com and here are some numbers, which by the way are not scientific but do offer some insite into what others are using.

• Paktrakr 144


• Curtis Fuel Gauge 74


• Xantrex 30


• Westberg 29


• Evision 25


• TBS E-Xpert Pro 25


• Elite Power 22


• Elithion 19


• Trakr 16


• Mini BMS 9


• Victran 3

BMS end board

The MiniBMS has a simple single wire control for both HVC (high voltage cutoff) and LVC (low voltage cutoff). Basically, if the keyed input (12v) is off and any cell goes to too high (from charging) the end board cuts off the charger (through an AC relay). Then if the keyed input is on (driving) and any cell goes too low a buzzer sounds and ya gotta pull over. The end board can also be wired to cut the throttle in half. This is the BMS end board in a plastic box and the charger relay, not the neatest but pretty good considering all the things right there.

The tests for the buzzer and charger shut off went great. Now the only thing left on this EV is a vacuum pump, which really isn't needed because the disc brakes work really well. Here is the area with the lids on both the BMS and main control box.

MiniBMS Boards

The MiniBMS boards arrived and all of them are installed with a green led on. The boards went on pretty easy, except I had to remount the controller and the heat gauge sender to leave some room for the boards.

Notice, the one board could be pushed sideways to make room for a cable, nice.

Twenty boards on the trunk pack.

Heat gauge sender mounted on a copper tube strap.

Time to wrap things up

Well now that the weather is warming I'm making a move to get the del Sol finished up. I'm going to use Dimitri's MiniBMS and an Elcon PFC 2000+ Charger. The Elcon web site has the output for the PFC 1500 listed as 8A for 115V input but I was told that is for 230v input so the actual is half that, 3-4A. But, the PFC 2000+ has an output of 144v/10A at 115v AC input and is only $130 more.




I've also had to replace the PB-6. It was the cause of my jerky startup. Notice this is a genuine "Curtis" product from KTA. "Beware of imitations".