Oh yeah - that will make battery maintenance a heck of a lot simpler.
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We lifted / tilted the bed up last night to show the then state of the art array of lead acid batteries ā¦
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The metal flake candy purple vinyl accents in the cab are, well words elude me for the right adjective.
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Delectable maybe? The purple fur is what really puts it over the top for me.
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A LiFePO4 upgrade to this project would be a bit more work than simply swapping the PbA (lead-acid) batteries. While LiFePO4 doesnāt offer the energy density nor current-delivery capabilities of some other Li-ion chemistries, itās far safer and slots in well with motor controllers and chargers designed for PbA batteries since theyāre available as turnkey assemblies in similar form-factors.
The summary indicates that the batteries are Crown CR-225, which are 3-cell 6 volt group GC2 batteries. They have a a nominal faceplate capacity of 225 AH at a 20-hour discharge rate; 183 AH at a 5-hour rate; and looking at a similar competing modelās discharge chart, a little bit more than 100 AH at a 1-hour rate.
There are a few wrinkles when looking at LiFePO4 - besides their staggering cost.
- The few group GC2 models I can find are nominal 12V, 100AH. Simplistically, this means one can either use half as many batteries or run two parallel strings for markedly greater useful capacity; I donāt know what the complications of charging strings of LiFePO4 batteries are, to say nothing of charging parallel strings.
- The same GC2 models offer maximum 100A sustained current and 200A surge current (typically for ~30 seconds). PbA is known for its generous current capabilities, thus a single of LiFePO4 string might not provide enough juice upon acceleration; even two strings might choke. The controller might be configurable to limit current.
There are surely some other options based on the available volume of space, but I donāt have dimensions and this is already a bit involved for a back-of-the-napkin assessment.
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Use the weight reduction from the lighter Li batteries to accommodate a supercapacitor bank that picks up from the regen and allows for significantly higher instantaneous discharge for acceleration.
Another option would also be to buy a literal ton of 18650 cells and use those like a certain real world EV maker in their floor tray battery.
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Donāt know if this thing has regen. The design concept looks to be straight up 90s homebrew EV with DC motor and controller. Perhaps the project binders can confirm.
The issue with conventional 18650 cells - be they high-capacity / <3C discharge chemistry or high-current / >10C discharge - is that of safety, inconvenient voltages, and the need to perform markedly more engineering. The raw cells will surely be cheaper per watt-hour / peak amp than pre-packaged LiFePO4, but that will be eaten up with the need to manage charge/discharge protection, safety, and perhaps a different motor controller.
But to be fair, if we somehow have the resources to roll LiFePO4, why not just start over on the drivetrain and underlying architecture anyway?
- Hybrid pack : high-cap cells for most of the heavy lifting alongside a smaller high-current pack that manages acceleration and accepts regen
- AC motor and controls
- Integrated charge controller that handles current standards
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I mean, Iāve been advocating for tearing all the 90s junk out of it and redoing the electrotruck the whole time. Needs more AC motors so we can have AWD skids.
Call it Purple Lightning 2: Electric Boogaloo
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Indeed. Just a big heap of greenbacks for drivetrain upgrades no matter how we proceed.
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Always Sunny reference, well played sir.
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A bank of 45 new LiFePO4 100A CALB cells with connectors will be about $7100, shipped.
Cheaper LiFePO4 (and other Lithium chemistries) are available in used packs and modules. Iām looking at a few different battery options.
A drop in replacement AC motor/controller kit is about $5000, but would give regen capabilities. I donāt think that would be a prudent purchase. The current DC motor is fine, as long as travel time is kept under an hour. It will āheat soakā if run longer than that. With Lead Acid batteries that wonāt be an issue. 
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This guy sells a lot of lithium batteries. Got popular from a youtube channel "jehu garcia*
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Lead Acid replacement batteries, similar to the ones in it, are $80-90 each, for a pack cost of about $2000.
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I found a deal on an actual metric ton of 18650s for the low, low price of only $27,000!
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Iāve found a set of LiFePO4 cells (the MUCH safer type of Lithium) that cut the battery weight by 2/3rds. (1500 lbs Lead Acid vs 550 lbs LiFePO4) for $6,022 for an estimated range of 48 miles. If we want to kick the range up to 78 miles it will cost about $11,184.
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Due to parking issues - the purple truck may be for sale very soon
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If you mean sale to member, I might be interested in purchasing it. I need a project like that in my life.
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PM me your offer or post here - I know Frank is interested in it.
We at automotive (unlike all the other committees) have no project storage space - i.e. parking outside. This includes the purple truck - so it is for sale.
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While I find this prospect very interesting, unfortunately Iām not sure I need another involved project at this time.
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