Electric Vehicle Project
Replacing the pack with Universal batteries
April 2009
One of the biggest things I learned with the 2004 pack was the value of having regulators on every battery. That means building 50 of the Lee Hart Zener regulators and putting them in. I cannot overstate the value of these things. Most people get one year out of a pack before it dies. I got 5 years on a set of used old batteries. Can't top that. Check out the site, google on Lee Zener regulators, there are even videos on how to build. It's utter simplicity.
But the pack was losing range quickly. Would only go 10-15 miles, and I need the car to go 20 in order to make it to Columbia mall and Arundel Mills mall. So down came the pack and out came the batteries.
Turns out most of the batteries are *still* fine. A few had dropped to 10 volts with no load, dropping to 8 volts under a 100a load tester. But one of them dropped to zero volts, this was the problem battery. Because it was dropping to zero I was running on only one string. Now I could have replaced about 6 batteries total and brought the pack back to a nice 20 mile range, but I decided it was time to take the plunge and try replacing all 50 with a cheaper battery.
The Hawker vs. the Universal Battery
Universal battery is a company in China that makes a clone-ish of the Hawker GP26. It costs a lot less ($40 vs. $120) is about the same size (1/16th of an inch taller) and is about 2 pounds lighter. The last is important: It does not have the same capacity or performance as the Hawkers. But since I don't have a million dollars, I really needed something that was a bit more reasonable. $2,000 would be a good price. Also there is the issue of blazing a trail; someone needs to test this stuff and it might as well be me.
So down the pack came, and out came the Hawkers. I had to make new interconnects for the UB batteries, I did this using braided flat cable, and 3/8 inch copper pipe cut to lengths and flattened onto the braided cable. Result was a really nice solution, although making so many of them was tough.
The UBs use a flag style terminal instead of a bolt-down one, and this is a pain. Unfortunately the other batteries I have seen (the power sonic ones) with top screw terminals wind up having the top of the bolt above the top of the battery. This will not work, not enough space up there for the bolt. Don't do this, you will wreck your car.
To make the right angle connections to the main cables I used right angle adapters from some old APC Matrix UPS battery boxes. They work perfectly for the job.
I also built 50 new regulators and attached them to all the batteries. Once again I feel this is critical as without the regulators, the batteries will drift out of sync.
Lastly I installed two complete sets of PakTrakrs to watch every battery. This was expensive (almost $1,000 for two units and 6 more remotes) but man it is worth it. I can now see the voltage on every battery in the pack, and I can do it *SAFELY*. It's amazing to watch the batteries as I drive, and now I will know if one is dropping too low or getting creamed on charge.
I'll attach pictures of all this in a bit, but once the pack was up I had a car with the 20 mile range restored. It's a bit less peppy, but still more than enough for the highway. And the lower weight of the pack (about 100 pounds less) helps to bring the speed back to normal.