10.02.12

The 50 CAL Bottom Balancing Machine

Posted in Batteries, High Voltage System, Lets All Plug In, Tuning at 12:17 pm by Administrator

After frying my Revolectrix Cellpro PL6 twice, trying to bottom balance my 42 cell 180Ah pack (one battery at a time on the second go round) I have come to the conclusion that there is a need for a heavy duty bottom balancer. The first time I Fried it Revoelectrix sent me an RA (return authorization) and I paid the shipping to send it back for repair, they paid the shipping to return it to me. the second time Revoelectix quit answering my emails and won’t return my calls. So I am stuck with another piece of $250.00 junk which I have to replace some MOSFET’s on someday. That being the case and me not being one to give up easily, I seem to be in the unique place of having to come up with a tool which will bottom balance higher Ah LiFePo4 cells, and since no tool seems to be available, I am also in the precarious place of having to build one, which I have done and am testing it as I write this. So far it works quite well discharging one 180Ah cell (CALB SE) at a time. I am starting at 3.28Volts and it takes about 4 hours per cell. If the batteries were discharged down to 3 Volts ea it would only take about 45min per cell. I plan to make this bullet proof and send it to the master of product testing, Jack Rickard at EVTV (if he’ll have it) to see if he can fry it. If it passes the test and gets the EVTV stamp of approval, I will build and sell these. But not until the prototypes have been thoroughly tested. Who knows, I may even get these confounded batteries fully bottom balanced. I know I have been living on the razors edge and taking a real chance with my pack by not having the whole thing bottom balanced. I bottom balanced some and top balanced the rest to make the charges equal right before Laguna Seca. This is the wrong way to go about it. Fortunately these batteries are amazingly resilient and I have not observed that any damage was done. But now that I have a proper heavy duty bottom balancer I am confident that this pack will be balanced well.

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