GGoodrum
1 MW
Actually, if you are talking about the LiFeBatt VMS boards, they do not use FETs for LVC. All they do is turn on a TTL-level signal (and an orange LED...) if any one cell goes too low. In a larger EV application, all of the VMS boards, in all the HPS packs, are daisy-chained together, and then connected to a vehicle computer system. I notice now that Dave, at Electricrider.com is now going to start offering LiFeBatt-provided 3620 and 4820 HPS packs, to replace the Eonyx packs they were trying to do using various Chinese offerings. PSI/Lifebatt is providing a small module that they will integrate in with their Crystalyte controllers, which inverts the TTL LVC signal, so it can be used to connect to the same ebrake signal line in the controller that we use with our LVC/BMS boards.
I have two 12-cell LiFeBatt/PSI-based packs that I use in a 72V/10Ah configuration on my wife's Townie, which routinely gets run down to LVC cutoff, and these cells seem to be as strong today as they ever were. They don't yet have more than a few hundred cycles on them, but I've seen no ill effects of using them this way. Basically, if we stop right when the first LVC "hit" happens, which is usually while under full throttle, going up a hill, the cells will still have about 10% left, and will take about 9.0-9.1A back in. If you back off the throttle, to about half, you can get another couple miles before the cutouts happen even with the slightest throttle. At that point, the cells will usually take 9.9-10.1Ah back in. I've only drained them down this far about 10-12 times. Most of the time we stop right after the first hit, or just before it hits. Anyway, like I said, they still appear to be going strong.
-- Gary
I have two 12-cell LiFeBatt/PSI-based packs that I use in a 72V/10Ah configuration on my wife's Townie, which routinely gets run down to LVC cutoff, and these cells seem to be as strong today as they ever were. They don't yet have more than a few hundred cycles on them, but I've seen no ill effects of using them this way. Basically, if we stop right when the first LVC "hit" happens, which is usually while under full throttle, going up a hill, the cells will still have about 10% left, and will take about 9.0-9.1A back in. If you back off the throttle, to about half, you can get another couple miles before the cutouts happen even with the slightest throttle. At that point, the cells will usually take 9.9-10.1Ah back in. I've only drained them down this far about 10-12 times. Most of the time we stop right after the first hit, or just before it hits. Anyway, like I said, they still appear to be going strong.
-- Gary
Seriously, this will make assembling packs for these a "snap". It looks like they would go together like Anderson PowerPoles, so you can make pretty much any size configuration you need.
