Clouse wrote: ↑
Jan 23, 2018 11:39 pm
At my previous job I obtained about 30 lightly used 100A-hr LiFePO cells that were salvaged from a project.
If those are the blue or yellow (or whatever) plastic bricks with ridges, make sure you build them into a compression pack holder that places appropriate pressure evenly on all sides of the cells, or they may swell up in use, which causes damage between the layers inside.
I'm now searching for a suitable brushless dc motor (8-15kW) that I can fit in place of my alternator. I can then use the motor to assist the diesel engine and improve fuel economy.
Keep in mind that most of these small but high power RC motors can typically only be used at those high power levels while at very high RPM, since most of them are made to drive propellers. At lower RPMs, they'll burn up if used at those high power levels, because tehy're not generating enough BEMF to keep current down. They're also meant to be used with the high-velocity air cooling that comes with the propwash, so you generally need to create a cooling system for them, too, when not used in their original application.
The other problem is eRPM--the electrical RPM, or switching (commutation) speed, at very high RPMs, can be beyond what a controller can do, especially for "ebike" type controllers--the MCUs inside just don't have a high enough clock speed in many cases. Most of them were designed around hubmotors, which with DD versions are very low RPM, around wheelspeed, and even geared versions usually are only around 5x that.
You can get lower RPM motors to do the same power levels, but they are physically larger.
I'm hoping to use a controller with regen capability so I could charge the 48V pack up if needed on a long trip.
As long as the regen current doesn't exceed the normal charging current for the pack it would work. Sometimes regen can be so powerful that it's much higher than the pack's normal charging current, but since regen is usually used for braking, it's only momentary peaks, so it doesnt' make that much difference.
Also, there's something often called EABS that's different than regen, and actually uses up power from the battery to stop the motor--you don't want that mode.
Otherwise, that should be fairly simple, as long as you keep in mind the motor is going to run at a wide range of speeds depending on engine RPM, and the regen voltage (and thus current) you get out of it will vary with that speed. Some of the controllers with regen are adjustable for how much they provide, but not usually on the fly. Some might be, though, if they are adjustable via bluetooth, etc. Might still not be enough to compensate for the RPM range, so you'd have to figure out what that will be and what range of compensation you need to provide to charge the pack at the rate you want.
Unfortunately I've emailed PowerVelocity twice with questions and haven't gotten any response.
He's also a member here, so maybe posting in his sale thread or PMing him might get a response?