Li-ion pack suitable for BMS+?

Hi all, been out of the loop for a while but might be finally getting closer to my PHEV conversion. Doing our home solar now, and when the incentive payment comes in hope to put it toward the PHEV upgrade.

I had been considering Enginer, but gather they are still having issues. Its probably not the best fit for my commute anyway, as its ~10 miles each way mostly surface streets (~40mph stop and go) with a few short stretches of 55mph. It also sounds like they have some temperature issues, which could be a major concern here in Phoenix. I spent a lot of time working with the cal cars prius plus folks back in the day, and always like that approach but couldn't afford to actually do one at the time. It sounds like that has evolved in a pretty interesting direction with Norm's BMS+ approach.

From what I've read it seems like using Li-ion packs with the BMS+ is the direction things are going but still very much a work in progress with a lot of experimenting going on. Anyone have any thoughts on using something like these kits for this purpose?
Elite Power Solutions
6 of these in series would give you 72 cells with balancer's and chargers already setup for these specific batteries and a 1 year limited warranty. They also happen to be local which is appealing. Assuming the charger outputs are isolated it should be possible to charge them all in tandem while still series connected (have to check with the manufacturer on that). Cost would be about $3300 for the batteries, chargers, and balancers, might be a little better with a volume discount for 6. Should yield about 3.7kWh usable at 80% DOD spec'd for >2000 cycles. Beyond that I assume I'd need something like the CellLogs to keep from discharging any one cell beyond that point.

Interestingly I had been looking into a similar charging approach way back in the day when I was looking at a PbA pure EV conversion before I decided to just get the Prius, but thats a whole nother story Stacking multiple low voltage chargers like this seemed to have some nice advantages for protecting the pack and maintaining balance. There were also potential temperature/reliability improvements to not having one high power charger, although you now have more possible points of failure I suppose.

Rob

 

Thanks big, nice to see some old familiar faces around along with lots of new ones

 

Robb's PIS system looks quite impressive. Anyone know what they are asking for the DIY 4kW system?

 

FWIW I appreciate what Enginer is trying to do. They came up with a pretty innovative approach to radically lower PHEV costs. At the time they entered the market at $2-4k the options were pretty much calcars DIY for $4-5k or $10k+ for a commercial kit. In many ways they achieved what calcars was really trying to do with the Prius+ project, coming up with the cheapest possible effective PHEV conversion strategy. If nothing else they have really driven the industry to get more cost competitive, which seems key to more mainstream acceptance. Unfortunately I think they have discovered first hand the challenges of dealing direct with Chinese OEMs in regards to spec and quality control. Working in the tech industry I know that this is a major challenge even for big companies, let alone a small operation like this. I think they were pretty upfront about the maturity of the product when they essentially started beta (alpha?) testing it on the public, though maybe it was not clear enough. Part of that is just the reality of a small company without the resources to do large scale internal testing without significantly increasing the cost of the end product. If it was a better fit to my driving needs I would still consider Enginer despite its issues, more out of a desire to help them continue to refine their product than anything. But as it is I really need a solution that is more full power capable for mostly EV driving.

From that perspective what Robb seems to have achieved with PIS is all the more impressive in terms of offering a mature, turnkey product at a reasonable price. Its too bad he seems to have run into so many problems with his distribution partners. Everyone (including me) is always tempted to think they can do it better for cheaper (or at higher margin) and undervalues the experience, testing and quality control that goes into offering a mature product.

Being an EE who's into this kind of stuff anyway I am still tempted to custom build something, but I have to say the PIS solution looks excellent and getting to a price where it might be hard to justify the custom approach financially.

Thanks all for your thoughts and comments.

Rob

 

Thanks, $4500 is not too shabby!

 

I like the look of the 20Ah GBS, but am concerned about the the charge/discharge rate. At 40Ah it should be under 3C, but for the 20Ah we're pushing 5-6C. Not sure they are up to it. This seems to be where the A123 pouch cells really shine for smaller cells. Pretty sure they're good for up to 10C, which is pretty phenomenal. Wish we had a more direct/reputable source for them at a reasonable price. The back channel is a heck of a deal, but it might be worth paying more to get known good cells with guaranteed specs.