Recommendations for two DIY builds for low usage? (re: BBS02, batteries, etc)

[sofakng]

I use my bike (Specialized Expedition) for recreation and only a few times every couple of weeks. I ride in my development (with lots of hills) and on rails-to-trails up to about 10 miles at a time. My current conversion kit (Swytch EBike w/250W front hub motor) works OK but it's not great on the hills and I want to move it to one of my kids bicycles.

So ... I'm looking for two more kits. One to upgrade my bike (something more powerful) and one for my other kid.

I'd like to keep each kit (with battery) under $600 if possible?

I've been looking at the BBS02 mid-drive motor (UART) for my bike and it's $400 which is fine, but I can't find a reputable/safe battery for under $400 (even with lower amp-hours) so that makes the total cost much too expensive. I am considering using my EGO 56V (52V) batteries but I'm not really sure about that yet.

I'm also looking at the BAFANG 500W or 750W rear hub motor for my kids bike, and it's cheaper ($250 or so?) but again it needs an expensive (?) battery.

Can anybody give me any advice?

I do have electronics experience but not with battery building. I've considered buying a K-weld system and making my own batteries but that is extremely expensive and not worth it...

 

[docw009]

Batteries are the most expensive part of the ebike, but we do want quality packs for peace of mind. Until last Fall, I thought Rad Ebikes were one of the more responsible players. Always advertised quality cells. Went after UL certifications on newer product, Still had fires on the old stuff. enough that the Consumer Product Safety Commission went after them.

Luna and EM3EB wire bond their batteries which gives you fusible links. Expensive batteries. Grin (ebike.ca) has UL certified packs. Also expensive,

It's going to be expensive to have safe batteries unless you can use existing tool packs like the EGO, or configure lightly used commercial scooter and ebike batteries from defunct ride-share-rental programs. The latter often requires addibg a BMS. You also mght conside LiFePO4 technology. Ford/Tesla did. More weight but less fire risk,

 

[docw009]

Setting aside the battery question, I did a BBS02B conversion 10 years ago, Still have it. A very strong motor. Mine will pull 25A. I think the later UART versions are set at 18A, as that's all I saw on a second conversion I did for someone two years ago,

A 500W hubmotor with a 20A controller is also a nice bike but I don;t live in a hilly area. I've been to Pittsburgh. That's hilly,. Have no idea how my ebikes would fare, but if a Swytch can almost make it, then a 48V motor should be OK.

.

 

[sofakng]

Thanks so much for the reply.

I’m located in the United States (and I think this forum is more dedicated to Canada?), but do you have any definitive recommendations for batteries?

I’d think that even a smaller better (48V, 10 Ah) would be sufficient but I don’t think they really make any that small.

I’m definitely concerned about safety so that‘s my biggest concern and I want to make sure I’m purchasing (or building?) something safe.

I would still consider building my own battery because at least I would know the quality of the parts but then there are other risks…

 

[2old]

I've purchased three batteries over the past seven or eight years from bicyclemotorworks and all have been functional (still, I store them in a safe place). They're not cheap but have offered good service. I wouldn't consider buying "out of country" because a strange tariff could balloon the cost.

 

[E-HP]

I use my bike (Specialized Expedition) for recreation and only a few times every couple of weeks. I ride in my development (with lots of hills) and on rails-to-trails up to about 10 miles at a time. My current conversion kit (Swytch EBike w/250W front hub motor) works OK but it's not great on the hills and I want to move it to one of my kids bicycles.

So ... I'm looking for two more kits. One to upgrade my bike (something more powerful) and one for my other kid.

I'd like to keep each kit (with battery) under $600 if possible?

I've been looking at the BBS02 mid-drive motor (UART) for my bike and it's $400 which is fine, but I can't find a reputable/safe battery for under $400 (even with lower amp-hours) so that makes the total cost much too expensive. I am considering using my EGO 56V (52V) batteries but I'm not really sure about that yet.

I'm also looking at the BAFANG 500W or 750W rear hub motor for my kids bike, and it's cheaper ($250 or so?) but again it needs an expensive (?) battery.

Can anybody give me any advice?

I do have electronics experience but not with battery building. I've considered buying a K-weld system and making my own batteries but that is extremely expensive and not worth it...

Since your Swytch works OK, but not great on hills, it sounds like it at least provides some assistance on the hills (probably not extreme grades).

My recommendation is to buy a complete kit and battery from an established vendor/retailer. This will limit or eliminate any issues with installing the kit, since all parts and connections will be compatible. Most retailers don't build their own batteries, but if you buy it all together, at least you know they'll still be around if you have any issues.

On the battery itself, relative to your build, I'd generally recommend spending about half your budget on the battery. Being disciplined about this will avoid overspending on the rest of the build and just using the leftover money on a battery (frequently people go for the super cheap, totally fake, blue batteries from Amazon, eBay, or Aliexpress, etc.). You can't guaranty the quality, but if you are able to select the type of cells being used, and use brand name cells rather than cheap generic Chinese no name batteries, you're in a lot better shape. Good packs will never use generic cells for obvious reasons, and ensuring that the cells are brand name gets you most of the way there when it comes to safety (things like matching of cell capacities, etc. are time consuming parts of building quality packs, but brand name cells will be better matched than a box of unbranded generic cells).

For $600, I'd get something like the kit below, and select the 48V20Ah battery, since it's built with LG M50LT cells, which are decent, and have a high cycle life. The Samsung options aren't as good due to low charge cycle life (battery degrades more quickly over time).
I'd get the cheapest display unless you want something specific
I'd get the magnetic brake cutoff sensors if you like the feel of your existing brake levers. The kit ones are usually pretty cheesy.
$546

Varstrom 48V 1000W Front Hub | Hub Motor Conversion Kit | E-Bike Conversion

VARSTROM 48V 1000W gearless front hub kits. OLD (mm): 135 (±1) [not include anti-rotation washer]. 55Max Torque (N.m): 66. Certifications: IP X5/ROHS/CE

varstrom.com

It doesn't seem like the hills are steep enough to warrant a mid drive. Seems like a front hub with a little more power would be easiest to install and more pleasant to ride. It's more battery than you think you want, but you have tons of space in your frame, and it's not much more weight. I'm sure your kid won't object to more riding/throttle time.

 

[docw009]

I cannot recommend any batteries. I would not buy any battery that didn't use name brand cells,

Five years ago, I acquired a cheap spot welder and started building my own, Do a search on supercap spot welders. Some members here are doing OK with them and spent around $100-150. You can do without it, but you can spend another $200 on testing gear specific to batteries, not to mention supplies. It's a money losing hobby. If you only need two packs, better to buy them,

I recall Pittsburgh being especially hilly when I visited years ago, My wife refused to drive, and we had a stick shift anyway,

 

[sofakng]

For $600, I'd get something like the kit below, and select the 48V20Ah battery, since it's built with LG M50LT cells, which are decent, and have a high cycle life. The Samsung options aren't as good due to low charge cycle life (battery degrades more quickly over time).
I'd get the cheapest display unless you want something specific
I'd get the magnetic brake cutoff sensors if you like the feel of your existing brake levers. The kit ones are usually pretty cheesy.
$546

Varstrom 48V 1000W Front Hub | Hub Motor Conversion Kit | E-Bike Conversion

VARSTROM 48V 1000W gearless front hub kits. OLD (mm): 135 (±1) [not include anti-rotation washer]. 55Max Torque (N.m): 66. Certifications: IP X5/ROHS/CE

varstrom.com

How is that company with their batteries? It’s only around $260 for an LG 48V/20A battery and that price I’m wondering if it’s worth me buying the BBS02 ($400) + battery ($260) which is only $660 and right around my price range?

Also, they are selling a 52V/20Ah SAMSUNG INR21700-50E pack for $297 shipped.

That should be a 14S4P pack with 56 cells. Assuming they buy in the largest quantity from 18650batteries.com (just for example), that’s $3.50/each. 56 * $3.50 = $196 plus the BMS, housing, FREE charger, and shipping. That still seems like it might be too good to be true?

Also - I’ve heard I need a different chain ring? Are there any budget friendly options for that if I decided to go the mid-drive route?

 

[2old]

For what it's worth, BMW identifies the cells for each of their packs and AFAIK all of the batteries are manufactured in the US by one individual, the company owner (his wife handles the other facets). I have no vested interest in the company, just have received three good batteries from them.

 

[Matt Gruber]

I would try the EGO battery since you have the charger too, zero cost, probably top quality.
check the final charge voltage per cell. (it might be set low to extend cycle life)
I've been using tool packs since 2013

 

[E-HP]

How is that company with their batteries? It’s only around $260 for an LG 48V/20A battery and that price I’m wondering if it’s worth me buying the BBS02 ($400) + battery ($260) which is only $660 and right around my price range? The battery price (with free shipping) seems a little too good to be true?

Also - I’ve heard I need a different chain ring? Are there any budget friendly options for that if I decided to go the mid-drive route?

Don't know. I just chose that as an example, since I see folks mentioning getting their stuff from them. I bought a TSDZ8 from Amazon, and it turned out they were seller. PSPower is also mentioned often, and they have very similar batteries, probably all sourced from the same place. My main two points, buy everything from the same retailer to ensure compatibility and don't buy a battery unless you know what's in it. You can ask the forum about their experience with vendors.

Electric Bicycle Battery Pack KT-E27 48V 20Ah Powerful ebike Lithium Battery for bafang tsdz2b tongsheng motor

Electric Bicycle Battery Pack KT-E27 48V 20Ah Powerful ebike Lithium Battery for bafang tsdz2b tongsheng motor

www.pswpower.com

I agree that the bicycle motorworks battery are high quality. The price reflects the additional time and effort required to make sure the components are matched and stay that way. They won’t fit into your budget though.

 

[2old]

FME, the chainring in a BBS02 kit is steel and "offset", so functions adequately. I'd be interested to know whether anybody in the US has purchased the PSP battery from Germany; considering the cost of shipping, this is an amazing deal.

 

[docw009]

"Also - I’ve heard I need a different chain ring? Are there any budget friendly options for that if I decided to go the mid-drive route?"

Unless you want a small chain ring or have a rear axle a lot wider than the old 135mm standard, I think the chain offset on the stock bafang bbs02b should work. Try it first, and if the chain keeps falling off, spend the money later.

"I'd be interested to know whether anybody in the US has purchased the PSP battery from Germany"

The pswpower website has good prices until you try to buy something that is not truly stocked in the USA. You find that shipping anything from Germany to the USA is several hundred dollars. In other words, they don't want to ship from there to here.

 

[2old]

That was my point about the battery. The OP is US-based so the battery recommendation isn't viable. My wife has a BBS02 with the stock 46t chainring on her full suspension MTB and it functions perfectly. I may switch to a smaller chainring ($50+ unless purchased from China) in the future in order to lower the gearing.