What 20AH battery pack to build?
- Thread starter agniusm
- Start date
agniusm
1 MW
thanx alot guys. well, if i could get 25m range with cargo i would be pretty happy. sweet spot is 30km range with cargo and if it is few miles extra, all talhat is great. maybe it will be posible to go 50 60 without cargo. as i see it most important thing i battery pack because everything else is changeable with 10 times smaller amout of money: motor, controller, bms, chassis parts etc. i am planing on 2kw constant with peaks maybe 4kw and need a pack to cope with that.
o00scorpion00o
100 kW
agniusm said:
2kw is around 30 amps at 72 volts, If you go ping, you would need at least a 30 ah pack and that would probably give you the range you want too!
I think any more than 72 volt 30 ah, then the cargo becomes the battery!
Pure
10 kW
o00scorpion00o said:
LiPo wouldn't be too bad. But yeah, that's a whole lota battery!
o00scorpion00o
100 kW
Pure said:o00scorpion00o said:
LiPo wouldn't be too bad. But yeah, that's a whole lota battery!
LiPo is great, only 1 thing is, it has about half the cycle life of LiFeP04 and LiFeP04 has a bms for ease of use.
Also you loose a bit of capacity with LiPo if charging to 4.15 volts and discharging to 3.5 ish, where LiFeP04 you can discharge all the way if you need the range. So it slightly narrows the weight gap, but it is smaller in size!
agniusm
1 MW
Thanks. Now cellman states that he is selling A grade cells but they are a lot cheaper than you could get from mazive buying more than 1000, there fore are they realy a grade ? 
Does not matter at the end if they are matching cells and he has good feedback from a customer.
Does not matter at the end if they are matching cells and he has good feedback from a customer.o00scorpion00o
100 kW
cell-man is great!
Ping is great too!
just make sure you know what you want before you order!
Ping is great too!
just make sure you know what you want before you order!
dogman dan
1 PW
Again, forget the lower c rate stuff if you are going to pull 2000w continous. You'd have to carry a lot of ah. I'd say 40 ah mimimum. That would give you lots of range, but leave you carrying a huge battery all the time.
Cellman has so far provided a very good product. Something you might consider is two batteries. One 72v 15 ah A123 pack for use on the shorter trips. For longer trips, paralell a 72v 15 ah or 20 ah of a 2c battery such as the ping or the ones at the top of the thread.
Cellman has so far provided a very good product. Something you might consider is two batteries. One 72v 15 ah A123 pack for use on the shorter trips. For longer trips, paralell a 72v 15 ah or 20 ah of a 2c battery such as the ping or the ones at the top of the thread.
1000w
1 kW
I have dealt with Cellman on many occasions and can not recommend anyone higher.
His service and products are second to none.
Cheers,
Matt.P.
His service and products are second to none.
Cheers,
Matt.P.
o00scorpion00o
100 kW
The only thing is if agniusm wants 50+ kms range and 60-70 km/hr speed he is going to need a lot of ah, and 30ah doesn't sound unreasonable for the weight of a cargo bike, the cost of that is going to be a lot!
4 x 36 volt 15ah pings would give him the range at the speed. He is going to use at least 60 wh/mi that divide by 2160 w/hrs is a range of 36 miles.
6 x cell-man's 39 volt 11.5ah A123 for 78 volts and 34 ah is 2550 U.S.D
4 x Ping's 36 volt 15ah for 72 volts 30 ah would cost 1550 U.S.D
Add another 150 maybe more for shipping, that's a lot of extra money to buy cell-man's batteries.
1C from the ping = 30amps and that's still fairly decent acceleration, 1.5C would be 45 amp and a lot better acceleration and the pings could handle that burst for acceleration no problem.
If agniusm decides to only go 30 mph or less his need for ah will go down a lot, and might get away with 72 volt 20ah, in that case cell-man's batteries are top dog, because the 20ah ping at that stage would get a hammering!
20S 4P zippy LiPo would cost 1504 U.S.D for 74 volts 32ah, but half the cycle life maybe less ?
SO the ping works out better value of any and would probably be cheaper and smaller than the headways ? +the LiPo would have no bms and that's a shit load of bricks to balance, too much hassle!
The 30ah ping would be good enough and cell man's would be the best if he chooses to go with 20ah!
4 x 36 volt 15ah pings would give him the range at the speed. He is going to use at least 60 wh/mi that divide by 2160 w/hrs is a range of 36 miles.
6 x cell-man's 39 volt 11.5ah A123 for 78 volts and 34 ah is 2550 U.S.D
4 x Ping's 36 volt 15ah for 72 volts 30 ah would cost 1550 U.S.D
Add another 150 maybe more for shipping, that's a lot of extra money to buy cell-man's batteries.
1C from the ping = 30amps and that's still fairly decent acceleration, 1.5C would be 45 amp and a lot better acceleration and the pings could handle that burst for acceleration no problem.
If agniusm decides to only go 30 mph or less his need for ah will go down a lot, and might get away with 72 volt 20ah, in that case cell-man's batteries are top dog, because the 20ah ping at that stage would get a hammering!
20S 4P zippy LiPo would cost 1504 U.S.D for 74 volts 32ah, but half the cycle life maybe less ?
SO the ping works out better value of any and would probably be cheaper and smaller than the headways ? +the LiPo would have no bms and that's a shit load of bricks to balance, too much hassle!
The 30ah ping would be good enough and cell man's would be the best if he chooses to go with 20ah!
Pure
10 kW
o00scorpion00o said:
Agreed. The cellman packs only make sense if you are using a smaller pack. The larger the pack, the price just gets out of control. I would recommend going with 2 15Ah pings to help spread the load of that much bat on a bicycle. They can still be wired as one pack and charged as such. And really a 30Ah Ping could safely pull 60 amps during acceleration. One thing we really need is a smart CA, one that will limit acceleration amps then limit "at speed" amps.
agniusm
1 MW
Ok, good to know, but i really dont want to balance on the limit. I would like to have some reserve just in case. Better for me. better for battery pack i guess. There is no rush, i am talking with http://www.fe123battery.com asking them some samples of their 10ah 20ah and 30ah prismatic cells to test them. By the time they will arrive i will possibly buy some sort of PSU to do some basic tests and maybe bring them to mates lab to kill them while testing and see how they really perform.
o00scorpion00o
100 kW
agniusm said:
Does that mean you can build your own pack ?
agniusm
1 MW
Why not? Have some skills
o00scorpion00o
100 kW
agniusm said:Why not? Have some skills
Pity you didn't say that in the beginning!
Then use the headways, That's what I would do. They are more than good enough for your needs!
Ask around E.S for reliable sources of headway cells, I would trust them more than some unknown Chinese supplier or unknown cells!
You will also be able to design the packs to the design of the bike.
The headways are good because you don't have to weld tabs, so they are perfect for diy!
Pure
10 kW
Agreed.
Not to mention they have a high enough C rate to provide pretty decent performance/acceleration.
Not to mention they have a high enough C rate to provide pretty decent performance/acceleration.
agniusm
1 MW
o00scorpion00o said:agniusm said:Why not? Have some skills
Pity you didn't say that in the beginning!
Just noticed that myself, but look at the topic
o00scorpion00o
100 kW
agniusm said:o00scorpion00o said:agniusm said:Why not? Have some skills
Pity you didn't say that in the beginning!
Just noticed that myself, but look at the topic
Haha yeah I see that, so how the hell did we get talking about ready built packs?
I'm after looking up a few headway cells and from what I can see is they will give 1500 cycles at 1c Even though they are rated at 10 c. So god only knows the cycle life at 3 c+ ?
miro13car
100 kW
agniusm,
I have been following your story closely.
It was your bad experience with A123 but if I were you I would try to get A123 20Ah cells for my project.
A123 RC offers them right now, webfoot member bought from them, look up his posts
, maybe they are grade B but not in an way damaged or something.
I am very close to making decision to by 12 15Ah cells from them.
I am almost sure they are rejects B grade but even A123 rejects beats for sure any China brand 2C weak cells.
I would choose such rejects anyday over weak 2 C cells.
Others can say all day if you need just 2C for your application and so on...
Truly you want to carry pack made of high C cells if not only for longevity
I have been following your story closely.
It was your bad experience with A123 but if I were you I would try to get A123 20Ah cells for my project.
A123 RC offers them right now, webfoot member bought from them, look up his posts
, maybe they are grade B but not in an way damaged or something.
I am very close to making decision to by 12 15Ah cells from them.
I am almost sure they are rejects B grade but even A123 rejects beats for sure any China brand 2C weak cells.
I would choose such rejects anyday over weak 2 C cells.
Others can say all day if you need just 2C for your application and so on...
Truly you want to carry pack made of high C cells if not only for longevity
agniusm
1 MW
Have decided to leave headways behind. I will go for the A123, be them b grade, rejects. If their capacity is in 19.5Ah market i think they will last long enough till new science batteries becomes available. Prismatic cells will be good to place in my project, as i had decided earlier to get them stacked in 4 piles, 6 cells each. I hope i will not get burned again as this time going for more reliable source with mates for quantity discount. I was told that they were tested at 150A constant draw few hundred cycles with no significant capacity change so i bet it will be ok for couple thousand cycles @ 5C draw no problem. There will be also BMS hopefully in spring for these cells.
o00scorpion00o
100 kW
The A 123 would be great if you can find a good source!
The headways would be good really for people that can't weld the tabs, the headways are probably cheaper too!
Good luck and keep us updated with your build!
Mark
The headways would be good really for people that can't weld the tabs, the headways are probably cheaper too!
Good luck and keep us updated with your build!
Mark
