Volt Blocher

Well, it's been a long time between posts but here we is again.
Updates: There's been battery failures, the battery balancing system actually got recalled by the manufacturer...the vehicle still tries to dart into the oncoming lane, attracts valdalous whackos, won't steer straight, and bounces up and down enough so you can hear the seats creak. Despite all that we've put on over a thousand miles in the last six weeks. What can I say, we're kinda stupid that way.
As mentioned earlier I've been working with a guy in California to 'morph' his existing battery charge management system into something that will work with the AGM Lead Acid batteries in this type of car. His name is Brian Blocher, so since the board progressively bypasses current to 'block' the voltage from getting too high the product is called Volt Blocher. Clever, huh?

Here's the first functioning prototype I've built.

The big white things are resistors the dissipate the excess heat (current) to keep the peak voltage under control during the charging cycle. Even a couple tenths of a volt too high can shorten the battery life considerably. The switch is so you can set an appropriate voltage for a given temperature range: Under 50F, 45-80F and above 75F respectively. There is one board for each battery so I've built seven of them. Three worked correctly right from the beginning, one is real close and three others are off by a bit more. Troubleshooting is ongoing.

I'm very glad I got three done since we had two batteries that really needed them and one that wouldn't mind a little help. Both got 'swapped in' from the other car when we had two of the originals fail (both still awaiting warranty replacement) and since they have a little less capacity (mainly from being older) they would charge up sooner than the others and begin to vent off gas as the voltage gets too high. The electrolyte lost that way cannot be replaced. So, the battery would loose capacity, charge up even quicker, vent more, lose capacity...you get the idea. The road to ruin (kinda like the US economy...)

More to come on this topic as the rest of the boards get put in place.
In the mean time, it's driving to work and school and everywhere local.