Project Miatabusa Part 11 – Shorai Lithium Iron Battery (and Lots of Plumbing)

The battery is split into two 6-volt cells for shipping, and you have to connect them with this bar before the battery works. This seems to be some regulatory thing for shipping batteries, but I’m not entirely sure of the logic. The two 6-volt cells are still charged and could still be shorted during shipping (very unlikely given all that foam in the box), but maybe there’s some 12-volt threshold in the regulation.

Since you can’t get inside the battery and actually see how the thing is built (and since it’s all chemistry and electrons anyway), it’s really hard to judge the quality of something like a battery. Somehow the perfect fit of this cover really gave me warm fuzzies about the quality of the stuff inside. It looked like it wasn’t even going to fit, and then it just snapped in place and fit perfectly flush.

Who cares? That’s exactly my point. If something as inconsequential as a cover over the shipping posts gets this attention to detail, odds are good the meaningful stuff on the inside got a similar treatment.

The Shorai batteries don’t have automotive-style terminals, but converting the stock Miata negative terminal to the simple, 6mm bolt mount was a simple matter of a few seconds with a hack saw.

The Miata ground cable has a short section from the battery to the car, then a longer section from the car down to the drivetrain. I clipped off the longer part, leaving a super-light, short cable. The body-to-engine case cable is closer to the firewall where the cable can be shorter. The positive cable is the factory Hayabusa cable that goes to the Hayabusa starter solenoid/main fuse. (The Miata’s factory battery cables weigh about three pounds, nearly as much as this Shorai battery!)

I don’t have a solution to tie down the battery just yet, but with the cozy fit between the gussets, it only needs to be held in one direction.

Shorai says their batteries can be charged with some conventional battery chargers (as long as there are no desulfating features, and as long as there is no trickle charge mode that will relentlessly keep shoving electrons into the battery after it’s full), but I bought their charger just to be safe.

The Shorai charger connects through this balance port that lets the charger monitor the charge of each cell individually and balance charge them for best performance.

OK, it’s gonna take a lot more than a battery to get this car running, so let’s look at some of the other things we’ve been working on.