Hi. I am planning a Defender conversion.
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Yes and no.
Ideally yes.
Or, you can connect balance wires to both packs, but, microscopic differences in battery chemistry, under massive load, can perhaps overload those balance wires. Also, there's a lot of high potential running amok on those fragile wires. If one were to ever short, it could have the full voltage of the pack across it and whatever it shorts to. It's probably fine unless you're drag racing.
It's almost impossible. You'd really have to fabricate a situation in which it becomes a problem.
Basically this is long-distance parallel. It's fine, unless something causes a large voltage difference between a cell on one pack and its mate in the other pack, and then causes current to flow, which is more current than the wire can handle. I can't really think of a situation that could cause that, but, it could. A solution could be to just use beefier wires to do your long distance parallel, then they can handle it better. Bit of a goofy setup though.
Ideally yes.
Or, you can connect balance wires to both packs, but, microscopic differences in battery chemistry, under massive load, can perhaps overload those balance wires. Also, there's a lot of high potential running amok on those fragile wires. If one were to ever short, it could have the full voltage of the pack across it and whatever it shorts to. It's probably fine unless you're drag racing.
It's almost impossible. You'd really have to fabricate a situation in which it becomes a problem.
Basically this is long-distance parallel. It's fine, unless something causes a large voltage difference between a cell on one pack and its mate in the other pack, and then causes current to flow, which is more current than the wire can handle. I can't really think of a situation that could cause that, but, it could. A solution could be to just use beefier wires to do your long distance parallel, then they can handle it better. Bit of a goofy setup though.
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189 Posts
a battery pack split into 2 boxes? the battery will act as "one" when running (drive mode or charge mode) there are a few different distributed bms's available to use. such as thunderstruck.
depends on the type of battery you use. tesla modules for example have the bms boards in each module, so you just need a master that talks via canbus, like the simpBMS
depends on the type of battery you use. tesla modules for example have the bms boards in each module, so you just need a master that talks via canbus, like the simpBMS
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Yes.
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.
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.
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189 Posts
this 1000%
iv been censored when calling out conversion shops on social media for doing this, running their bms leads outside of the battery case. some just through cable glands even.
only thing that should be coming out of the battery box on the smaller lines is CANbus. or what ever the comms are.
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And that CANbus is galvanically isolated...no, 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.
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.
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Defender conversion! Fantastic! One of my favorites! FYI, Electric Classic Cars from England makes a Defender EV conversion kit using Tesla motor and batteries. You may want to check them out as they have considerable experience. They also have a very informative youtube channel.
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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.
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