Battery pack weight. 72V a123

[andla]

I have 2 36 volt battery packs and they are very heavy. It feels like the weight are about 15-20 kg. I use AHR32157-M1 type and have 12 cell in each pack. How do you handle so much weight?

 

[Doctorbass]

I have 2 36 volt battery packs and they are very heavy. It feels like the weight are about 15-20 kg. I use AHR32157-M1 type and have 12 cell in each pack. How do you handle so much weight?

Well.. it depend on the battery location on your ebike!... but on my mongoose i have 55 pounds of battery and the handling is still really well. The ebike weight 132 pounds.

Btw.. WHERE DID YOU GET THESE CELLS? AHR32157-M1??

Doc

 

[skeetab5780]

so you only have 24 cells an you think thats heavy? i got 150 cells built into the triangle on my frame and i find it fairly light and easy to handle

if you want an ebike you have to sacrifice a few things so you dont have to pedal your little heart out.

1 being the weight of the batteries.

so the short answer is you just have to put up with it.

 

[julesa]

so you only have 24 cells an you think thats heavy? i got 150 cells built into the triangle on my frame and i find it fairly light and easy to handle

Number of cells doesn't mean anything. These are big cylindrical EV prototype cells, of similar size to Headways. 15-20kg seems like an awful lot though, it's hard to believe they're really that heavy.

 

[skeetab5780]

no the number off cells means something...not nothing. i was just pointing out that i clearly have more weight than he is talking about regardless of the cell type or quantity. i do know the type of cells he is talking about, and yes they are larger than the cells i am using, but he is talking about weight.

Number of cells doesn't mean anything. These are big cylindrical EV prototype cells, of similar size to Headways. 15-20kg seems like an awful lot though, it's hard to believe they're really that heavy.

so 6000 cells weight the same as 1 cell apparently (since the number of cells mean nothing when calculating pack weight)

 

[julesa]

no the number off cells means something...not nothing. i was just pointing out that i clearly have more weight than he is talking about regardless of the cell type or quantity. i do know the type of cells he is talking about, and yes they are larger than the cells i am using, but he is talking about weight.

Number of cells doesn't mean anything. These are big cylindrical EV prototype cells, of similar size to Headways. 15-20kg seems like an awful lot though, it's hard to believe they're really that heavy.

so 6000 cells weight the same as 1 cell apparently (since the number of cells mean nothing when calculating pack weight)

Sorry, I didn't mean to offend you. All I meant is that cell count is an orthogonal measure. It doesn't mean anything at all until you specify how much each cell weighs. Once you know the weight of each cell, then of course the number of cells becomes meaningful.

You didn't say what kind of cells you have. Regular 26650 A123 cells are about 75 grams each, so if that's what you have, your 150 cell pack is probably about 25 pounds? If so, that would be a lucky guess on my part since I don't know what kind of cells you have. Definitely less than the 15-20Kgs the original poster claimed, though I am skeptical about that number.

EDIT: I see in your sig something about a 10Ah V-power pack. I haven't seen what's under the duct tape on those, but I'm pretty sure they're quite a bit smaller than A123 26650s. So if that's the pack you're talking about, it probably weighs less than 24 A123 AHR32157-M1 cells. I'd guess maybe 15 pounds?

In any case, to address the original question, as both skeetab and DocBass said, the best place to carry all that battery weight is low and center on the bike, preferably in the triangle of the frame, where it doesn't make the bike feel awkward and tail-heavy.

 

[skeetab5780]

lol, no you didnt offend me at all, and Vpowers use 18650's but thats not what im using anymore. I just had to comment on the fact that you say quantity means nothing(obviously this is relative) i didnt specify cell type but im using Makitas like doctorbass, and my packs plus wires/balance leads and heatshrink and mounting hardware adds up to around 44pounds. I should have specified this. but when you install them nicely into a center triangle that weight really doesnt bother me. It does seem odd that those new a123 cells weigh that much but they are much larger Ah cells maybee they are worth it.

 

[andla]

I bought the AHR32157-M1 from FalconEV. I have not actually measured the weight and I suppose that AHR32157-M1 only have a certain weight unless you mean that this type comes in different sizes.
I expected my battery pack to only be a couple of kg.

I'm planning to put them in side bags so it can be easily attached and detached. When I want to leave the bike don't want to fish around. I have thought off adding 2 small wheels to the side bags so I can use it as wheel bag. I don't think you can buy that anywhere yet.

 

[julesa]

Btw.. WHERE DID YOU GET THESE CELLS? AHR32157-M1??
Doc

From here:
http://www.falconev.com/batteries.html

 

[skeetab5780]

its weird those cells say "automotive class lithium-ion" on them arent they Lifepo4?

and they are 8ah hmm whats the price per cell? i didnt see it on the site

 

[julesa]

I don't know. Good luck finding out.
DocBass probably remembers the falconev guy from here:
http://endless-sphere.com/forums/viewtopic.php?f=14&t=2498&p=43916#p43862
http://endless-sphere.com/forums/viewtopic.php?f=14&t=3716&p=54773&#p54773

I wouldn't buy from FalconEV.

If I was in the market for big A123 cells I would probably buy from Cell_man:
http://www.emissions-free.com/catalog/c1_p1.html

Or maybe from one of these, though I don't have any personal experience with them:
http://www.mavizen.com/contact.html
http://www.a123rc.com/goods-471-High+Power+Automotive+AHR32113M1Ultra.html
http://www.a123rc.com/goods-473-Excitingly+Powerful+A+123+15ah+PRISMATIC+CELLS.html

 

[andla]

For me Andy has been very helpful. Very quick e-mail responses. When I was talking to him he said there were some new a123 flat cells type but they were more expensive. Don't know much about them.

I had a flat tire today. I normally are prepared that all kind of shit happens to me so I have brought along both a pump and a repairing kit. So I have fixed 3-4 flats in 2 weeks. Now I'm planning to change the entire inner tube because the repair things you put on blows up and leaks. And of course my bike brand Pilen doesn't seam to support standard tools when changing the back wheel. Its very frustrating.

 

[oatnet]

I bought a whole bunch of the flat a123 prisimatics from cell_man, and a 16ah24v block (8s1p) weighs @7.5 pounds including wiring, so a 72v16ah
pack would weigh @22-23lbs, and give a pretty good range with a kw of capacity. I missed how many AH your pack has, which would have a lot to do with how much it weighs.

I last bought batteries from FalconEV in 2007, including I think the first LiMn cells on E:S. They were encased in metal boxes that could probably take a bullet but weighed almost as much as the cells did. That is probably not your situation, but what sort of packaging do your packs have, do it look heavy?

I did a few transactions with Andy, and he replaced a pack that was killed in transit by a defective BMS. All of my interactions with him were good, and I didn't get a sense of underlying rage from him... But he was fairly outspoken here on the board, and burned bridges with a lot of folks here. I hope he is still my friend, but from his actions I can see how a lot of other people here have a different opinion. Over the years I have developed contacts for getting cells cheaper, but if you don't have that access, Andy will hook you up with stuff you would not be able to get otherwise.

-JD

 

[Starson]

Andla,
In a thread from a month ago, Racer_X asked you "Did you get atleast one torque arm for your kit? Going to need one with the kind of torque your going to put those forks through.." In response you said "The stuff in the video was pretty much all I got from them. I guess I have to go easy"

Then you asked "How many of you had problem with front wheel drive regarding the stress the fork need to handle?." As far as I can tell, no one answered your question.

Sorry to temporarily hijack the thread, but I just wanted to make sure you do get a torque arm and install it properly. With your setup, you could have a very bad accident and end up dead or badly hurt if you don't use one. At the very least, the axle can end up spinning and pull all the wires out of your motor ruining it. The very worst would be your front forks crumpling at high speed, sending you flying like an arrow into cars or other solid objects. There is a lot of documentation on Endless Sphere regarding this issue. True, a few people with a lot of experience know how to properly install a front motor without torque arms, but not in a high power setup like yours. Hope for your sake (and others) that you get a torque arm and properly install it as soon as possible!

Gary

 

[andla]

Hi Gary.

Racer_X helped me with an installation of the e-bike including a torque arm that he provided. When we mounted the hub motor with the torque arm we made sure it was really secured. I only wish I had two torque arms.
With a high speed motor the torque shouldn't be so high as in a high torque motor. But I'm about to see what it is I'm actually running. I guess it is an angry bull

I found out when I opened a pack that it has 24 cells. So 48 in total. Not 12 as I said before.


BTW a question.
Comparing a 36v controller with a 72v. If running the same distance with the same speed who will have most power left in the batteries?
That is will I save more power if I run the 36v?
Does it consume less?