What cell, max current, watt-hours for 48V Stoke Monkey?

[Syncromesh]

Hello. I'm a total newb.

I just bought a Classic Stoke Monkey from Grin for my Surly Big Dummy. I want to run the motor at 48v. I'm not sure which cells to get. And what to set for max amp via the controller. In general, I strongly prefer a battery that I can remove when not riding the bike. And, I want to by something reputable and that will last more than 200-300 cycles. I prefer range to top speed. Bike has a 8 speed Alfine IGH. Happy to max out at 22-24 mph max speed when bike is used as a commuter. Yes, I am having a shop whose owner has a stoke monkey do the install.

Crystalyte 400-Series SAW is the motor currently used in the stoke monkey. Not sure how to interpret the specs on it. And to choose a cell, max current setting, and Watt-hours based on our most rigorous intended usage which is...

We want to go 45-50 miles loaded, with about 2500 elevation gain. We'd like to carry our 18 mo daughter on long bike-based adventures on Mt Tam and to Point Reyes and to Stinson Beach, etc. Weight would be me approx 300lbs loaded up: me (160) + 25-50 (as daughter grows) + 70 (bike/motor/battery) + 20-30 lbs of stuff. I'm happy to pedal. I rode 3000 miles last year. I can put out 150W for 3-5 hours without strain, and can do 220-250W for an hour when climbing . My wife could prob add 100W when she rides it. We will use the IGH 8 gears to try to use the most at peak efficiency.

Cells in the batteries I'm considering are Panasonic PF, Panasonic GA, and Panasonic NCRB. Which would be best for my use?

Dolphin Packs are appealing for many reasons, but have limited capacity compared to triangle packs. To make a 48v 17.5 ah battery work for this application, I need to average no more than 13 Wh/mile. Is that reasonable? Triangle packs would offer more range, but it seems like a pain to constantly unplug them when I run to the grocery store. Are they more fragile? A 48v 24ah triangle battery would allow me to use about 18.5 Wh/mile to get a 50 mile range. That seems quite doable. The shop suggested I buy 2 of the same dolphin packs and plan to swap, but alas, that would be $800 in batteries and money is not infinite. I'd prefer to spend $500 if that will get the job done.

I have read some concerns on es that the Panasonic GA cells don't have the best life span under some circumstances. I can't for the life of me find that thread... Still that concerns me, but is it relevant to my application? I would probably discharge the cells to 20%, 30-40 times a year if I got the 48v 17.5 ah battery.

Planning to charge at 3 amps for longevity. Probably will charge to 80% when commuting and for normal use, and up to 100% maybe once or twice a week when we do a long trip.

Any help thinking this through would be appreciated. Please excuse my ignorance. I no longer have time I once did to research things in a thorough manner. Thank you

 

[Syncromesh]

Found that thread where user youyoung21147 states the the Panasonic GA cycle life is very limited if you use them hard: https://endless-sphere.com/forums/viewtopic.php?t=85383

thoughts?

 

[flat tire]

Would you buy a scooter, and then decide to limit the fuel capacity to 1/4 gallon?

That's what you're doing by cheaping out on the battery. DO NOT CHEAP OUT ON THE BATTERY!

 

[Syncromesh]

IF you were trying to be helpful, perhaps you could make a suggestion. Do you have any relevant information or data to help me make a decision?

 

[flat tire]

I recommend a 1.5KWh battery. That will let you meet you meet your goal at 25 Wh / mile, which is probably a more reasonable power target since you have climbing even if you're going slow.

With a battery of that capacity, and your low power requirements, you can use the non high discharge cells and still get decent performance since you'll have a bunch in parallel.

 

[Matador]

And please do not choose the NCRB. Yes they have capacity, but they have very low discharge current rating, so unless you build an absolutely huge pack, you risk damaging them prematurely. Between your 3 choices, I'd choose the PF cell.
Personally I'd go for 25R, 30Q, HG2 or VTC4...
What others have said is right. You should always plan to invest more in the battery than the eBike motor or accessories.
Cheap out on the battery and you will create a money pit for an all too frequent battery replacement need, ending up costing way more and not being as enjoyable.

You have a lot of hills. You need lots of power, thus taxing your range capability a lot.

Here is a mapping of my needs for comparison, you could inspire yourself of it. But keep in mind, I have a mid-drive (which does better efficiency in hills than hub motor). It's a 1000W nominal output BBSHD.
I expect 31-36 km from a 1.017 kilowatt-hour pack because I dont want to put so much stain on the cells (not charging to 100% nor dischargind to 0%). I also account for the 3.1V LVC of my setup and voltage drop under load...
Capacity on paper is not capacity in real life.

50 miles in hills.... Thats 80 km. I agree with the above. At least 1.5 kWh pack. But if you want to run the pack conservatively for great life span, go for 2 kWh you'll have a lot more flexibility, especially when you're bored of pedalling along all the time.
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[Syncromesh]

Good responses, thank you.

Should I get one big battery or two small ones? Seems to have +/- for both. The bigger battery seems like it would be better, but, if just one cell fails in it, I now have a pretty useless bike.

If I'm willing to compromise on range I could get a Luna 48v24ah.... Otherwise, I may bite the bullet and get 2x 48v17.5aH dolphin packs.

Anyone recommend a vendor that sells pre-built 48v30ah triangle battery packs?

I searched es for a battery locking system, any ideas? Seems like with some custom fab I could do use a seatpost lock, see : https://www.electricbike.com/duty-cycle-awd/. Some people like ammo cases. Anyone know of any injection-molded plastic cases?