FWIW, I have early PakTrakrs in each of my two Corbin Sparrows which have a string of thirteen 12v Optima (AGM) batteries. I've noted individual battery PakTrakr voltages as much as 0.3v off from measurements made with a precision DVM, and thus I've made a calibration table for each PakTrakr showing how many tenths of volts I need to add or subtract from each displayed reading. Since I have mixtures of new/old batteries, I no longer worry about differences of even 0.2v-0.3v amongst batteries when under load. The PakTrakr does a great job of flagging ("Alert") a problem battery (which, incidentally, may not necessarily be a battery with a lower initial voltage when under load).
Since I use the EVs daily, the tiny current draw from the PakTrakr I consider negligible.
During bulk charging I monitor the batteries and shut down when any one of them gets to 15v (to make my life simpler, I've made an automatic shutdown circuit which does this).
For Balancing (which I do every night), I then finish charging using a string of 13 very small and inexpensive individual smart chargers (each one attached directly to a battery) which put out up to 0.8A at a controlled voltage and automatically pop down into a lower float voltage when the current gets below 200ma. Batteries seem happy.
On the boat if I had this electric drive system and recognizing it could be weeks in-between usage I'd simply put the small chargers on a timer to periodically activate them for a few hours. If the boat is on a mooring, a solar-powered scheme doing the same thing could be implemented.
JoeS.
No comments:
Post a Comment