Battery protection - Road dust

[Mark Brems]

Hey All,

Is anybody running their LifePO cells with BMS modules and without any covering?
Has there been any issue with road dust accumulating and creating problems?
Has anybody attempted to clean the road dust from the cells and BMS modules?
If so, how did it go?

Thanks,
McB

(Just got all of my front end parts sorted out, and I'll be putting my new suspension in tonight.)

[Ben A]

Yes, yes, and yes, but I have a custom BMS so I'm not sure how applicable it is.

Mine uses the LTC6802 cell balancing IC, which has very fine pitch pins.  Despite my (thin) conformal coating, the right combination of road dust & moisture seems to have caused one of the balancing resistors to stick ON.  Luckily, I managed to catch it in time to save the cell.  I took the board out, blasted it with compressed air, cleaned between the pins with a dental pick, made sure I'd fixed the problem, then poured potting compound over all the circuitry.  Two other boards still remain unpotted (I haven't had time) and haven't given me any trouble.  But they did, as I mentioned, have conformal coat.  I'm assuming I just didn't do a good enough job applying it to the one board. The car's been running since March and has ~1500 EV miles.

My advice would be to do everything you can to keep moisture and dirt out, then you don't have to worry as much about the board itself.  It also reduce the chance of inadvertent leakage paths from the pack to chassis, which poses a safety hazard and can impede charging by tripping your GFI.

If you come up with a good method for cleaning the batteries so they look nice, I'd love to know.  My car isn't as spectator-worthy as it used to be.

-Ben

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