Combine Ebike Batteries for Motorcycle

[Briansterling]

Out of curiosity has anyone tried or thought about putting a few of those E-Bike battery cases together for use on a EV Motorcycle?

Here's what I've been finding:
http://www.ebay.com/itm/Aluminum-CASE-for-bar-type-36V-48V-e-bike-EB-electric-bike-bicycle-battery-/121618916563?pt=LH_DefaultDomain_0&hash=item1c510d64d3
OR
http://www.ebay.com/itm/Aluminum-Al-CASE-for-36V-48V-e-bike-EB-electric-bike-bicycle-battery-DIY-pack-/111421990446?pt=LH_DefaultDomain_0&hash=item19f144a62e


Versions of these builds have a built in fuse, temp saftey shutoffs, BMS balancing, and even a key ignition. They house 18650s which can come in mAh up to 6000. This would put a single 36V unit at around 25ah. They say that they can handle high amp loads and isolators would prevent one pack from charging another. They come with rails for mounting and just seem very convenient. Maybe 4 of these 2 in parallel and those two sets in series? Any thoughts?


Motor: Etek-RT 72v
Controller: Alltrax 7245

 

[Nobuo]

I think that would be unnecessary expensive. Would be much cheaper if just make the whole battery at one pack, and then a custom aluminium/wood/plastic case.

You can buy several different BMS with temp shut-off function

 

[amberwolf]

They house 18650s which can come in mAh up to 6000.

If they say that single 18650's are up to 6Ah in capacity, then you should never look at that vendor again, because that's about double what the best of the best of that size cell does.

So whatever else they are telling you is probably wrong or lies, too.

 

[Briansterling]

Yeah, you are probably right about the amp hour battery capacity. My focus was really more on the functionality of the battery enclosure and it's benefits/drawbacks. If i went this route I'd probably order test cells from several different vendors to test them myself.

Building my own pack is definitely a benefit in being taylored to my needs. I don't think it'd be more expensive to go this route (assuming it's feasible) especially considering the time and effort saved by the inherent BMS features, safety, and ease of installation. That being said there would still be a good bit of external battery management but i think the pros are worth investigating.

 

[dnmun]

there is no BMS. it is only a metal case they are selling. you should learn more before you decide to build your own battery from scratch.

 

[spinningmagnets]

They house 18650s which can come in mAh up to 6000

There is a common problem with EV component advertisements where...the retailer either grossly under-labels their power rating (A country that has a 250W power limit, will have systems that can easily survive double that), or...in the majority of cases, components are grossly over-rated.

There are still a lot of new customers who are unfamiliar, so they are still excited when they see an advert where a tiny, light, and inexpensive motor can put out 2,000W. You buy it and when you apply 2,000W, it fries from too much heat, or parts of it break.

Someone buys a turn-key electric bike, specifically because the advert claims it provides 50 miles of range. But somewhere the fine print says that the 50-mile range is only on flat ground, with no wind, and with a 100-lb rider pedaling 95% of the time. This is why forums are vital to the electric bike community, we can share actual real-world data. And sometimes, a company that is blatantly lying in their ads will still be making a good product, it's just good to know what to actually expect.

There are no 18650's that provide 6000-mAh per cell. There is a Panasonic rated for 2900-mAh that is well-known and well-proven (29E). Even so...it is a "medium current" cell (as I rate them). I have read what I consider to be reliable reports about the Panasonic 34B cell (3400-mAh, NCR prefix, Li-NCA chemistry).

As far as the using the empty shells to house whatever cells you end up buying, that might be an interesting experiment. Either way, you might plan on buying your own spot-welder, here are some links (thanks to Nobuo)

"18650 spot welding -how to- ULTIMATE REPOSITORY" (Nobuo, 2 pages)
http://endless-sphere.com/forums/viewtopic.php?f=14&t=68005

The next problem is the amount of current that any battery pack can provide. This year, my favorite cell for providing high current is the well-known Samsung 25R cell (2500-mAh, NCA chemistry), which is well-proven, well-known, and readily available. I believe next year, the cell to get will be the Samsung 30Q (3,000-mAh, not as much current as the 25R, but still very good current when configured for 15-Ah or more).

 

[Briansterling]

dnmun - Some of these cases do in fact come with a BMS. I've tried to do my research and there's very little reviews and real world reports of these and how they function. What little information I've found points to these cases having rigid internal mounting lattices (and leads) for 18650 batteries. They're usually in a 4S/13P within these cases. Even if no BMS was included the ease of installation and access is worth $50. That's of course assuming the math works out with the batteries in the first place.

spinningmagnets - Thank you for the in depth post. I wasn't really hanging my hat on that specific model of 18650. I realize the 6000mah was most likely not accurate. I was really just pointing that (on paper) these 18650s pack a lot a bang for the buck and one of the reasons I've bypassed them before is because of the hassle of basically building a battery pack from scratch, which this method could presumably alleviate. I have a 4000mah "go-to" vendor to which I"ve tested the cells and have been satisfied with. I'm really just trying to find someone who has physically worked with these cases to get an insight on how they work. If all else fails I'll just order one to check it out.

 

[fellow]

If you are looking for distance, but not cycle life:
Samsung INR18650-35E, 3500mAh, 8A cont, 48 gram, 8€/piece.

http://www.akkuteile.de

Panasonic NCR18650G, 3600mAh, 4.87A cont, 48 gram, price unknown.

http://www.keeppower.com.cn/products_detail.php?id=500

If you want an afordable, idiot-proof cell with excellent cycle life and up to 18A peak:
Panasonic NCR18650PF, 2900maH, 10A cont, 46 gram. 3€ to 6€/piece.

http://www.akkuteile.de