Can I build an EV bike battery using Prius HV modules?

Use a 5th cellmodule because 99% of the time they won't be completely full.

A 40v (nameplate) series battery with a motor load on it will drop a lot closer to 32v anyway. You'd also need to make certain everything was safe up to 48v so there's headroom for the charger.

 

Can't say I did exactly that, but...I did do 2 ebikes that were 36 volt. On one I used 2 Ryobi batteries (18 volt each), and the other one (a 3 wheeler with a basket on the back) using 3 17AH 12 volt SLA lawnmower batteries. On the Ryobi conversion, I used the Ryobi charger, on the other one, I bought a 36 volt small (20 amp) golf cart charger that would put out 42 volts. IF...BIG IF, you can wire them in series to produce around 40 volts, your ebike kit can handle that just fine. And...IF your charger will charge the Prius batteries (it should) to a total of 40 volts...you should be able to pull off a neat conversion. Hope this helps, but if not...have to say you are on track to have a cool ebike. I ended up selling both of mine and using the money to buy a factory produced ebike. But...building the kits was WAY MORE FUNNER!!

 

I don't know if there's a ready-made BMS you can use, but the radio controlled hobby world developed a lot of expertise with NiMH batteries before lithium became available. Consequently you can use chargers, meters and tools from that world.

I guess I don't see a downside of isolating the motor controller when you need to apply a charge. Heck, for some rides you want to pop the battery off and carry it in to a charger that isn't onboard for security and weight savings.

 

does the kit have a battery recommendation?

 

In general NiMH technology is 30 years older and way heavier than Lithium... Using a small number of Prius modules will discharge so quickly on your motor that your time and effort put into this will feel like wasted time once you're done.

The modules for Prius are not good at holding a sustained charge under load, especially in small numbers. But what they are good at is handling large amounts of amps going into or going out of the pack. But without a Prius engine, transmission and inverter connected to them it's gonna be disappointing how fast they drain down versus how long they take to charge.

I'd encourage you to use a lighter weight and more legit lithium based battery that's specific to what this device was designed for. One way to do it on the cheap is buy a box of old laptop batteries and take them apart and harvest the cells inside and test all of them and then use the best ones. There's other ways similar to this as well.

 

Another similar way I think, is harvesting one of the modules of any of lithium ion based vehicles. I currently have some modules from a Hyundai sonata hybrid, that I recently worked on.

I have a scooter with 2 12V blas(can't remember the amps now though). The batteries are wet cells, and dead. I intend to harvest some of those modules, and use them for a future ebike. I have tested one of the modules. They are 30V each. It ran so well on the scooter I tested it on. My concerns, is I have to be monitoring the charge, as the battery is being charged with an external, 48V 1.0A charger.
Motor on the scooter is a 24V one.

 

You also might want to follow Jehu Garcia on YouTube as he's constantly buying surplus battery power from electric bike & scooter companies so the electricity you need is already in a package that's easy to mount to a bicycle. Like his latest ones from his most recent uploads:

 

discretion is the better part of valor

 

Because saving gas costs a lot of Money.

 

He’s got great cold temperature cut off bms stuff so your lifepo4 batt didn’t charge below 32F and not deteriorate itself.