[roach374]

Always loved the look of those mid-70s Datsuns, and I've seen this done before, but I'm a complete newbie to EV conversions, and car mechanics/electrics in general (mostly worked on motorcycles before this). Lots of reading to do!

• Your skill level with auto mechanics and fabrication - Decently good at fab (drilling / cutting / welding, but no machining).
• The range you are hoping to get (how many miles/charge) - 60+ miles.
• What level of performance you are hoping to get - Decent highway speeds (60-100 mph)
• How much money you are willing to put into your project - Basically trying to keep it under 100K, including the price of the rolling chassis.
• What parts you've already considered, if any:
  • Curtis 1239e-8521 HPEVS Dual AC-35 Brushless Motor Kit - 144 Volt
  • 48s1p configuration of CALB 180 Ah CA LifePO4 cells
  • Elcon PFC5000 Charger
  • 5x basic radiators and fans
  • Motor / ignition coupler
  • Curtis 1239 Chill Plate kit

 

[brian_]

While the component choices all look like a historical snapshot of several years ago, it looks like they would likely work.

The peak power output of the dual AC-35 motor is comparable to that of the original engine, the peak torque is comparable to the engine's peak torque, the transmission would presumably be retained to keep the motor in an effective speed range (and hopefully it's a manual), the battery configuration would provide a suitable voltage, and the set of 48 of those cells would hold about 27 kWh (nominal) of energy which would be enough for the target range.

Despite the claim of 1800 amp (10C) peak discharge rate, I'm not sure that those cells could handle the demands. CALB USA do not list both continuous and peak discharge rates - they only list 2C (360 amps for these cells) as the "maximum discharge current". 360 amps at 154 volts is 55 kW, which is much more than needed to maintain even highway speed, but much less than will be used at full power (which will require about 1000 amps).

 

[roach374]

While the component choices all look like a historical snapshot of several years ago, it looks like they would likely work.

Like I said, I'm VERY new to this, so I'm trying to pick up info from a lot of sources, and some of those might be quite old. What would you recommend as more modern components? Super open to feedback and suggestions!

Despite the claim of 1800 amp (10C) peak discharge rate, I'm not sure that those cells could handle the demands. CALB USA do not list both continuous and peak discharge rates - they only list 2C (360 amps for these cells) as the "maximum discharge current". 360 amps at 154 volts is 55 kW, which is much more than needed to maintain even highway speed, but much less than will be used at full power (which will require about 1000 amps).

Any recommendations for a more appropriate LiFePO4 cell? I'm skipping the LiIon / BMS route in favor of keeping things safe and simple, but maybe I'm being naive about that.

Thanks!

 

[DansEVhobby]

Like I said, I'm VERY new to this, so I'm trying to pick up info from a lot of sources, and some of those might be quite old. What would you recommend as more modern components? Super open to feedback and suggestions!



Any recommendations for a more appropriate LiFePO4 cell? I'm skipping the LiIon / BMS route in favor of keeping things safe and simple, but maybe I'm being naive about that.

Thanks!

I'm brand new to this too, but up until ur post I thought the BMS route was the safe and simple route...so much to learn still I guess.

 

[brian_]

Like I said, I'm VERY new to this, so I'm trying to pick up info from a lot of sources, and some of those might be quite old. What would you recommend as more modern components?

This isn't a recommendation, but the recent trend has been to salvage parts from wrecked production EVs, because they have better components at lower prices than these aftermarket products. Unfortunately, they're harder to work with in some ways, because they're designed to work in a specific production vehicle.

Any recommendations for a more appropriate LiFePO4 cell?

If you insist on using LiFePO4 cells, I don't think that there will be a lot of difference between them. Generally, production EVs don't use LiFePO4 cells, although there have been and continue to be notable exceptions.

I'm skipping the LiIon / BMS route in favor of keeping things safe and simple, but maybe I'm being naive about that.

"Li-ion" means any lithium-ion battery, and that includes LiFePO4 (also called LFP), but many people refuse to accept that.

I assume that you mean that you are avoiding the lithium-ion electrode chemistries - all around 3.7 V per cell (nominal) and including those commonly used in EVs such as NMC and NCA - on the basis that it is "safer" and does not need a battery management system (BMS). While many DIY builders have used LiFePO4 without a BMS, I think it is a bit naive to assume that there are no consequences to going without a BMS. No commercial product (automotive or not) uses lithium-ion cells of any type without some sort of BMS, cars with LiFePO4 cells use a fully-featured BMS, and even the drop-in replacement for 12-volt lead acid batteries that people buy to upgrade their travel trailers include a BMS (with overvoltage isolation, low voltage shutdown, high current cutoff, and cell balancing features). You could be okay without a conventional BMS if you set conservative limits on the controller and charger and manually monitor the state and health of the battery, as some others have done.

 

[brian_]

I'm brand new to this too, but up until ur post I thought the BMS route was the safe and simple route...so much to learn still I guess.

Using a BMS is the safe route in some ways - it avoids cell damage. It is also simpler in operation, since the BMS does automatically the monitoring and protective shutdowns you would need to manually without a BMS. A BMS does involve installation complexity.

 

[roach374]

This isn't a recommendation, but the recent trend has been to salvage parts from wrecked production EVs, because they have better components at lower prices than these aftermarket products. Unfortunately, they're harder to work with in some ways, because they're designed to work in a specific production vehicle.


If you insist on using LiFePO4 cells, I don't think that there will be a lot of difference between them. Generally, production EVs don't use LiFePO4 cells, although there have been and continue to be notable exceptions.

Well I wouldn't say I INSIST. I have very little dogma, since I'm just getting into it. I would like to avoid the aspects of "Tricking" the battery into thinking it's in a (e.g.) Tesla or something, but I'm open to 3rd-party options, like a CALB or a Samsung pack or something. Integrating a BMS is a whole other thing to learn though. Thanks for the feedback!