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u/lemlurker

▲ 3 r/EVConversion

Thoughts on over-volting motor and controller by 8%

I have a motor/controller combo rated to 328v on the way (88s battery design). I also have a battery from a Renault Zoe. in a completely unrelated vein BMSs are expensive!

my battery, theoretically, has a fully functional BMS it is possible to hook into and control via canbus (they have been used as monoliths for solar storage) I would still need to repack the battery to fit the conversion vehicle, and I need to check that a monolithic battery even fits but in the hypothetical that it does do you think a small over voltage (88s to 96s, 32v nominal difference) is liable to be problematic? I can't find -any- results for the motor controller and very few for the motor and as such user experience isn't available for this specific part.

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u/lemlurker — 1 day ago
▲ 2 r/EVConversion

Low cost BMS options/design for 400v Zoe pack

I'm working with Renault Zoe battery modules and I'm trying to work out the best way to structure a BMS. each Zoe module is 16 cells spot welded in pairs, (module config 8p 2s, pack 96s 2p). I'm looking for the cheapest option to BMS from a purely cell balance/protection standpoint, happy to eat some capacity/peak voltage if it makes it simpler. I'm weighing up options for different pack configurations, I haven't offered up the volume yet but I'm theorising two config options-

opt one: one big monolithic pack in the engine bay, should be approximately like for like on engine and gearbox removal weight, this could allow for using the integrated Zoe BMS if it's possible to interface with it but has some packing and space limitations- not sure if the engine bay will be big enough,

opt 2: a distributed pack, 4 modules under rest where fuel tank was, two under rear seats, 6 in engine bay- it is my understanding that the standard BMS won't work for this as you need fairly matched BMS cable lengths, what budget options are there for satellite BMS designs?

as a side question to the opt 2 and with the cost of high cell count BMS options could you utilise a module level BMS to keep each cell in a module balanced then a parent BMS to keep each module in balance (so 12 8s BMS linked with one 12s BMS in control of the whole pack)

looking for cheap options as it feels crazy to spend as much as the pack on basic BMS functions

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u/lemlurker — 5 days ago
▲ 19 r/EVConversion

Minimum viable product ancillaries

I've decided to break in to ev conversion with a project car, an MGB GT in a bit of a state but all parts there (just not on car) I'm going with a Zoe battery pack and a random eBay find 40kw peak motor, controller & diff combo. I'm looking to do a minimum viable product conversion. minimum smarts. minimum automation. if I can get away with manually triggering contactors I will.

the Zoe packs are 96s 2p I think with the parallelism happening at the minute level (each sub module is 2 3.7v cells stuck together) I will have a split battery pack with 4 or 6 modules in the rear, 6 in the front.

I want to start speccing up the ancillary components, chargers, dc-dc converters, contactors, BMS ect to work out a final cost excluding restoration and repair. what options are there? I want a BMS that just keeps cells in balance and MAYBE reports SOC.

one bonus question is regarding chargers. as stock the early Zoe came with a 43kw 3 Phase charger and id REALLY like to use one. it would make the end car actually road tripable. 150 odd miles, 40 or 50kwh and an hour AC charge time (albeit at limited stations) has anyone worked with a Zoe charger module before?

u/lemlurker — 7 days ago