72v Battery Recommendation - HK Li Ion vs LiFePo4

[walmslpj]

My pack went a year or two ago. My previous battery was an 11ah custom trangular LiFePo4 pack. I loved the weight distribution but I wished it was larger. My 12ah pack barely got me 13 miles (hilly around here). It was a 52 volt pack and slowed to 17mph up hills. My sister borrowed the bike, dumped it, and left it "on" in the cold for 3 months. I was unable to repair it due to its welded nature.

I'm buying a chunk of land about 15 miles from work and near some trails so i've decided it's time to fix my ebike! I want my next battery to be larger, easier to repair, and if possible not heavier. I plan on taking the new bike trail riding so it must be durable. I want/need to have ~30 miles range. I'd like to upgrade to 72+ volts for safety. So 30+ ah @~77v without load.

My nine continent motor used to get fairly warm on hills - unbearable after 5 seconds of contact. I'm thinking about upgrading it or buying a second motor and putting this on the front wheel (attached to aluminum forks). Am I crazy for wanting more than 72v? Should I consider a geared setup?

I'm leaning towards getting whatever i can for my charger and buying an ebikes.ca adjustable charger (cycle analyst was a godsend). Does anyone know if i can modify my charger for 72v? I'm debating between screw in place round screw cell LiFePo4, prismatic cell Li Ion (gets expensive), or an array of Hobby king Li Ion batteries. I work about the screws coming loose with cells. The size/weight and cost is also off-putting. The HK batteries look appealing - plus their cheap. Does anyone have BMS recommendations? I may be able to have a friend 3d print a mount for the cells/packs. Also considering upgrading to something full suspension with disc brakes for this new build.

On another note, does anyone know of a good way to limit power with the flip of a switch to meet legal regulations - is this just something i need to create and can't buy? :/

I'm envisioning a bike i can plug in for a fast charge then ride to work or on a trail with a 40 mile range.

 

[999zip999]

40 miles @ 20 ~ 25mph. Three speed switch. Where are you located ? You may have a local battery builder near you.

 

[walmslpj]

Yea, long range at slower speeds would work.

Ideally target speed would be closer to 40 slowing to 30/35 on hills. I can recharge at work, just not where the bike is parked. So if the battery were light it could even be a 15ah battery. But 30+ miles at 20-40mph would be ideal as that would allow me to get to town, ride to a few places sorta manually, and get home.

A multi speed switch sounds right! Is it typically a difference in wiring or an electronic cap imposed by the controller?

I'm near Concord/Manchester NH. It would be great to get something quality/US made. Cruddy Chinese chargers put a real damper on my first season - finally got a Battery Space charger which was well built and a great warranty department.

This pack also caught my attention as a possibility: https://www.allcelltech.com/index.php/products/battery-packs/summit Two of these would work.

 

[bionx 1954]

I have a 72V 9C 2807 set up. I have 2 separate batteries each are 36V@10AH (lithium magenese). I have two 36V@4A chargers. So I can charge both packs at the same time. I made a harness which series the 36v to 72V then plugs into the controller. I have about 700 W capacity which gives me 25-30 miles range. I use about 24W/mile (mild pedaling) To get 30+miles you would have to pedal A LOT or LIMIT you speed . Yes a 3 speed switch would be needed.to help max your range

 

[999zip999]

40 mph will kill range.

 

[walmslpj]

Been a busy week, sorry for my slow response.

Cheaper the better; buying some land and a trailer so i'm pretty strapped for cash but i figure if the bike can pay for itself it will be worth it. So cheaper is better so long as there solid enough. It isn't my only transportation but I don't want a fire or to get stranded.

The target speed would be around 30mph. It would just be nice to have the extra oomf in the city, around traffic, and on hills (idk if more voltage will help here). Got into a really nasty accident on my last bike because someone felt weird passing me and there wasn't anywhere safe to pull off. In hindsight I should have gotten a slow wind motor; the hills are really the killer.

Good to know about the allcell's. There only 2c. :/ 40amps is the max current at 24ah (48v $1500 battery)... I guess I won't go that route.

I LOVED not having voltage sag. From my understanding LiPo and LiFePo4 cells have no sag but others do?

I like the idea of a hybrid pack! It would be nice to be able to buy a pack and charge it at work then down the road buy more batteries to improve speed or ideally range. Sound like the idea would be to have a reliable pack and a 'play' pack that boosts my range/power. It would suck to not charge the packs at work and 'break down' somewhere. On a side note I also kinda like the idea of a backpack battery so something square and large but like would be alright i guess...

A123's are appealing (i enjoyed them) - but I don't want to loose a $700 pack after just a few hundred rides again. Bummer there welded together. :/ Any idea if there is someone in the US who will back or at least repair these packs? I was unable to find someone to repair my last pack - I'm on the east coast (Manchester, NH - hr from Boston).

I've always kinda dug those modular skrew down LiFePo4 cells and i can get them from battery space. But prismatic cells seem cheaper and more compact/simple in a way. What do people think about the Nano-tech HK packs? Are they safe? 6 to obtain 66v (so 60ish with sag) would be pretty cool. Also, any input on the larger LiFePo4 cells.

@ - You mention switching hubs; what do you mean by this? Were they limited by the controller? Or a slower wind? Or rated for a lower wattage? Or are there literally low power hubs? I'd be targeting 30mph. I wan't to move to a mid drive after i upgrade the battery to improve performance on hills and possibly do some trail riding. Idk though; most of the available e-bike frames kinda suck imo. Dream bike would be a 72v 40amp trek fuel or remedy with mid drive - better geometry imo.

@e-trike - Would you advise opening the motor to add the oil? Is it necessary to de-lace it? Do you think it can handle 72 volts (i can stick with 48 or maybe 60v or sell it)? "make sure your phases are upgraded a few inches outside the axle for reliability." - huh? I have a lot to learn

So I guess my options are:
- Prismatic LiFePo4 cells - seems popular and cheap
- Round modular LiFePo4 cells - always been appealing
- HK prismatic packs - was the original plan for my next build
- A123 pack - eh, had a bad experience. but there not out of the question

 

[walmslpj]

Thank you guys BWT

 

[walmslpj]

How about this: http://www.a123rc.com/goods-1634-A123+7S3P+magic+block+module+for+electric+vehicles.html

...3 in series or reconfigure to be a 20ah 66v battery.