DIY Electric Car Forums banner

Hi. I am planning a Defender conversion.

1247 Views 7 Replies 5 Participants Last post by  remy_martian
As I was thinking of having two separate battery packs. Do I need two separate BMS’s ?
1 - 3 of 8 Posts

And galvanically isolated connections outside the box.

No BMS sense wires can go to a "central BMS", since voltages above 60V are prohibited after a crash.

Lots of DIYers in the past have ignorantly run sense wires out of the battery box to an external BMS, including famous Irish EV hackers. Many of those wires have hundred(s) of volts on them - all the time, even when the key is off.

That DIY legacy needs to be stopped in its tracks, since there may be people risking their lives to save yours and you're building a contraption that will electrocute them for trying.

Nothing goes outside the battery box that cannot be fully disconnected if it exceeds 60V.

So, no Matt, it's not "no". All you need is one short to chassis of one wire, cell connection, or busbar due to the crash and all that tiny-wired shit's live.

Nothing goes outside the battery box unless it's galvanically isolated or on a relay/contactor.
See less See more
  • Like
Reactions: 4
And that CANbus is galvanically, you can't willy nilly connect a non-isolated Arduino CAN interface from inside the HV battery box.

Just because it's a conversion shop, it doesn't mean they are doing roadworthy conversions.

Call them out , make them correct the deficiency - this practice needs to stop or we'll all get regulated out of existence for not policing ourselves because a responder got killed.
  • Like
Reactions: 2
ECC don't deal with retail sales of their conversion kits last time I looked. So a dead end for sourcing unless you want a turnkey conversion.
1 - 3 of 8 Posts