21700 cases- any 56 cell options?

[electric_nz]

I like the hard plastic removable battery cases, they look tidy and can be easily removed to charge or service the bike etc. I can see on Ali express there are a few options for 21700 battery cases, but the main ones seem to have either 52 cell or a massive 70 cell capability.

I use 14s battery and don’t think I have space for the big 70 cell holder unfortunately.

Has anyone found a 14s 4p 21700 case or do I need to custom build a triangle battery.

Thanks

 

[Wattman]

I have a couple of 21700 builds 14s x 4p and trying to troubleshoot one right now in fact in my other post.
Both are in Reention Polly Dp-7 or similar. With a 14s X 4p 21700, you will need a case height of about 125mm so look for that.
Length and case width among different DP variants tends to be about the same, so it is the case height that really matters for no. of cells.
I really like the charging port and on off switch and Reention case architecture.

Here is a suggestion and only that. Consider a 18650 14s X 5p build for similar battery capacity aka amp-hrs depending on what cells you choose. More cells is better as a general rule. I have had pretty good luck with my 21700 builds with 4p but one has died a bit sooner than expected I may bring back to life.

Here is the case for a 18650 build 14s X 5p = 70 cells. I like this battery config.

https://www.aliexpress.us/item/3256803549795989.html?spm=a2g0o.detail.0.0.3875de72NNz7CI&gps-id=pcDetailBottomMoreThisSeller&scm=1007.13339.291025.0&scm_id=1007.13339.291025.0&scm-url=1007.13339.291025.0&pvid=df928153-c70a-4551-9524-2b364ac6f6ef&_t=gps-id%3ApcDetailBottomMoreThisSeller%2Cscm-url%3A1007.13339.291025.0%2Cpvid%3Adf928153-c70a-4551-9524-2b364ac6f6ef%2Ctpp_buckets%3A668%232846%238113%231998&isseo=y&pdp_ext_f=%7B%22sku_id%22%3A%2212000026981305215%22%2C%22sceneId%22%3A%223339%22%7D&pdp_npi=3%40dis%21USD%2126.88%2119.89%21%21%21%21%21%402101d1b816795327518761573efb4b%2112000026981305215%21rec%21US%21&gatewayAdapt=glo2usa&_randl_shipto=US

If wanting to build with a smart or bluetooth BMS you may be hamstrung on available volume inside the case so somthing else to consider.

Good luck.

 

[mudflap5]

This...

https://www.aliexpress.us/item/3256803661314117.html?gatewayAdapt=glo2usa4itemAdapt&_randl_shipto=US

 

[docw009]

I bought that above case in a 65 cell 18650 version, with the Bemuchsafer BMS. I like the way this particular Hailong wires up, with all the wiring in the base, so the top of the case has no wires attached. ALso like how the key and charge port are molded into the bottom, Their BMS appears to work well too. It does balance, and when the switch is flipped, the MOSFET's don't leak. Cost me about 90 bucks though,

I have the similar concerns about the 13S-3P 21700's pushing over 30 amps. I think it's hard on the cells and shortens life. I built two of them this winter, but have yet to run them on an ebike, only tested them on a load tester. Did one with Samsung 50E's and one with LG M50LT's. The latter seem better. I will be running them at 22A max though,

 

[Wattman]

This...

https://www.aliexpress.us/item/3256803661314117.html?gatewayAdapt=glo2usa4itemAdapt&_randl_shipto=US

He said, he didn't have space for qty=70 21700 cells. Case you reference is the jumbo shark aka big boy size that won't fit many ebikes...and its heavy of course with 70 cells.

 

[Wattman]

I bought that above case in a 65 cell 18650 version, with the Bemuchsafer BMS. I like the way this particular Hailong wires up, with all the wiring in the base, so the top of the case has no wires attached. ALso like how the key and charge port are molded into the bottom, Their BMS appears to work well too. It does balance, and when the switch is flipped, the MOSFET's don't leak. Cost me about 90 bucks though,

I have the similar concerns about the 13S-3P 21700's pushing over 30 amps. I think it's hard on the cells and shortens life. I built two of them this winter, but have yet to run them on an ebike, only tested them on a load tester. Did one with Samsung 50E's and one with LG M50LT's. The latter seem better. I will be running them at 22A max though,

Doc, can you explain how you load tested your two new batteries and why you may believe the LG M50LT build maybe stronger than the Samsung 50E's, both built with 13s X 3p? Is it each battery builds' response to load? Any theory why the difference as it pertains to cell type based upon what you know about cell chemistry difference?
Thanks
PS. reason I ask is because I was thinking of picking up some 50E's. If you think the LG M50LT is clearly a better choice, I may reconsider.
Believe the LG 50LT have less max. continuous discharge current of 1.5C(7,275mA) which is about 20% less than the 50E's, presuming higher internal resistance but perhaps this quality helps in other ways you may have uncovered by testing under load. Capacity diff isn't much different. Theory?

 

[docw009]

Atorch load tester. Just a big MOSFET with a CPU cooler. Around $35. Limited to 160W, so 3-4 amps on an ebike pack. You could pull 10A at 4.2V, etc, though. Never gone higher, as the circuitry is fragile. I blew up the first one on day 1, but aliexpress gave me a refund immediately. I bought a second one, and it's held up. On youtube, people attach water cooled CPU rigs and can dissipate up 500 watts or more. I like it because I can cycle a pack right after building it, and verify the BMS works, etc. It won't shake the battery like an ebike though,

Granted, I compared 50E's taken out of battery hookup packs to new M50LT. However both were over 5000 mah and came in at 11-13 millohms on a Liitokala 500S, On the tester below, at 13S-3P and 3A, the LG's were around 250mv in sag where the 50E's were around 350mv. I tested down to 40V and the tester gave 14AH for the LG, 13.6AH for the Samsung. Either way, that's still around 90% or rated AH, which is pretty good. I would choose LG's because they're advertised as 14.4A, althugh I will run them at 8A..

Those are Lishen 4.5AH cells in the photo, which came in at 3.9AH, about 87%.

 

[Wattman]

Thanks for sharing your considerable knowledge, Doc. Great info. Appreciate it. Will move LG M50LT to the top of the list for high capacity 21700 cells.
Do you have a source for these LG cells you have had good luck purchasing from?