Featured New (?) Chinese Lithium Prius Battery Conversion

Are you guys kidding right? this is NCM lithium chemistry, it is literally a disaster waiting to happen on a Prius...

 

Yeah, the subject of changing out NiMH modules for lithium in a car that still thinks it is managing NiMH has generated discussion here before.

 

This topic first appeared on the PriusChat forum 4 days ago. Take a look at this thread, https://priuschat.com/index.php?posts/3535943

 

I think some of the finer points of this discussion rarely get enough attention... As in each battery chemistry has its own specific types of safety risks.

For example high density cells like Lithium-Ion require the highest level of safety with every cell needing to be monitored and the whole system shutting down when a cell starts giving bad readings because if a Lithium-Ion cell catches fire the odds of putting that fire out before the whole car burns to the ground are slim to none unless it happens in front of a fire department or you can push your car into a swimming pool.

On the other end of the safety spectrum are Nickel Metal Hydride (NiMH) batteries that Toyota uses in most of their hybrid cars. These are low enough density that if they fail you'll get smoke, blown covers and melting plastic, but your car won't turn into a raging inferno. This is why Prius' battery system doesn't monitor every single cell in the pack but block of 12 cells because it reduces costs, complexity and is safe enough. Another thing that's great about NiMH is they can handle being overcharged much better than Lithium which will fail if they are overcharged.

Somewhere between the two extremes is Sodium-Ion (closer to NiMH) and Lithium Iron Phosphate (closer to Lithium-Ion). Both of these chemistries are also considered low density so a pack could fail and smoke and melt plastic, but no risk of a catastrophic fire unless maybe if you're a gasoline smuggler.

In a perfect world we'd simply design a BMS that is specific to needs of each chemistry. But in the proprietary corporate world we live in where we can't re-write Toyota BMS code and most types of hacking with a different battery monitoring system will trigger warning lights and system shut down, makers of these types of after market packs have had to do lots design changes to keep all the sensors and computers happy in a Prius.

All that being said, in a decade or so the aftermarket hybrid and EV battery business is going to advance enough that the safety risks we face today won't be as challenging, nor will the pricing.

 

hard pass

 

First time seeing this but I must say I like the build quality, looks as if the whole case is a heatsink.

Just change the chemistry to sodium and all should be good.

 

Yes, the whole case is a heatsink. Unfortunately, I do NOT recommend this product for several reasons. I can film a video if people are interested.

 

only if it's organized and succinct

 

No promises, but I'll try. We'll see where my mind takes me.

 

I'm not as disappointed as I thought I'd be. Based on your capacity/load test, the cells seem decent enough. The housing is nice, and the overall construction seems at least halfway decent. With a few mechanical/electrical refinements like those you outlined in your video, they might be onto something... If you pair it with a proper BECM replacement for obvious reasons.

$1,400 for a full set of modules ($1,200 in a couple of places I've seen), realistically even lower if/when they swap to cheaper injection molding for the main body, is quite appealing. I'd still consider it cost-effective even adding at least a few hundred for a BECM replacement if/when someone designs one.