RC Car batteries for e bikes

R

Richard1174

100 mW
Joined
Jun 10, 2008
Messages
35
Location
UK
I have been looking around at different batteries to increase the voltage on my bike,at the moment it is just a standard 36v lipo kit with a 250w bafang motor. I have read on here that these little bafang motors can handle alot more power so I was looking for a relatively in expensive way to go up in volts and also get the batteries mounted in the diamond of the frame. I only have an 8 mile commute to work and I can recharge at work so I thought these might do the job.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=320254843209&ih=011&category=34063

My plan was to go for 5 of them 60v but start of with 48v to see if my controller handles it and if it proves to be reliable connect up the other pack and go for 60v.
Its a Santroll speed controller 36v 18amp brushless don't know if any of you guys have had much experience with these controllers and what they can handle.

Thought it was a practical way to go up in 12v steps for a short range bike.
 
they don't have a lot of capacity, but do seem to have a decent output if it is actually 30 amps. I am using a similar 10,000 MAH LIPO pack as a booster on an ebike, and it works fine. I wonder if you string 3 or 4 of those and run them together how they will stay in balance. the other pain is you have to charge them all individually.
 
I have been using the same cells but the 3700mah versions for the last 3+ years. I have done over 10,000 miles on them and just yesterday - that very same pack took me 18 miles on my new ride........... These are good uns:)
 
They do look pretty good. Energy density isn't far short of some of the LiFePo4 cells. Power density is pretty respectable, too, but with a higher penalty...
 
I thought they looked pretty good for short journeys and testing. I am still pretty new the the e bike scene but I have always had plenty of kit in other hobbies for testing, like when used to race rc cars I always had lots of batteries and lots of motors for trying different setups. They looked really good for getting the batteries off the rack and into the diamond of the frame aswell. Think I might go for it and get a good charger for them and give them a try.
 
Richard,

When they were much newer than they are now I tested some individual cells to 5C and my 3700 cells returned (from memory) 3300mah.... at 1C they were doing nearly 3800mah.

Definately good for 300+ cycles - I have long ago passed 500 and they still deliver the goods. To be fair - the bikes pulled a max of 20A and 7A most of the time which meant each pack was having to deliver a max of 10A (2.7C) and normally only 3.5A (.9C) so they were hardly thrashed as the designers intended!

Miles - quite right - I don't know about the 4300 cells since they are incredibly expensive to begin with but the 3700's can be got at quite a bit less than the asking. I can't divulge my latest quote for obvious reasons!

That lets the cat out of the bag! Yes - I am looking at equipping the new bike with the 3700mah 12V packs - identical to what I use now. Its hard to justify 3X the cost on questionable performance - or 6x the cost for A123.........

Scott
 
Yeah 3700 ma are £10.00 unit cheaper which brings down the cost quite a bit you can get a peak detection 5000mah charger from the online shop

http://www.vapextech.co.uk/acatalog/High_Power_Model_Control_Batteries.html

for £69.00 it also does lipo aswell but its not on the ebay shop.

I know you can run these cells pretty hard from my rc car days I used to flatten 7.2v 1800maH packs in a five minute race with a car running 40mph.
 
Richard - for less money you could pick up what I use - a 'pro peak supernove' it has a 120W circuit - I am currently charging my 24V 15AH pack at 4.3A - with that other charger you will only hit 2A or so with a 24v pack.................. You will need a power supply for it though - a 12 or 13.6V one - capable of at least 10A.

Supernova doesn't do lithium................... have to pick one up used on ebay.

Scott
 
At large volumes (say 10+ I guess) it works out cheaper on a WH basis to go 3700's..... I guess it applies to retail too - £22 for 3.7 vs £29 for 4.3 - whats that - 5.9 vs 6.7 - yep its less per KWH there too
 
I will have a look round for that charger sounds good to me do you know what sort of money they go for. I am now thinking the same as miles and asking how much I could get 10 3700ma packs for that way I can either run a lightweight 60v pack or 7400mah pack for longer rides.

Its good to know some out there has been using them for a while with success and I'm not barking up the wrong tree.
 
scottclarke said:
At large volumes (say 10+ I guess) it works out cheaper on a WH basis to go 3700's..... I guess it applies to retail too - £22 for 3.7 vs £29 for 4.3 - whats that - 5.9 vs 6.7 - yep its less per KWH there too
Click to expand...

You lose a bit of energy density, though.... The 4300s are almost as light as LiFePo4
 
Miles said:
You lose a bit of energy density, though.... The 4300s are almost as light as LiFePo4
Click to expand...

Exactly! Ok so the 3700's are not quite as good - but unless headway agree to sell in the volume I want I have no real urge to go with them - I know the vapex cells do 300+ cycles at 1-3C, I can't say the same for headway. If those lifepo's don't offer anything other than possible longer life and a tiny weight saving - what do they offer? I know they can't do 10C which will be handy for me - for starters!
 
2C for doubled up 3700s @ 48V is 700 Watts, which is all I need.

I think this seems a reasonable way to go. They would probably last until the LiFePo4 supply sorts itself out.
 
I am sure its a reasonable way to go!

FWIW I have been charging these 8 packs (48V 7.4AH) in a parallel config (24V 15AH) for the last few years with zero balancing troubles. To begin with I would check them religiously every few cycles but that declined when I saw no changes.

My charging profile was basically to pump 5AH in at 4.3A(1/3rd cap) then discharge .5AH at .5A

repeat 3 times if empty.

Terminate charge at 28.8V on the charger which results in a resting around 27.9V.

Cells do get just a little warm. (+10C rise)

My charger has no temp cutout - its delta v only and it doesn't really work very well with paralleled cells............. so its NOT plug and forget but I have used a wattmeter for a while so program the chargers last cycle for the capacity I know it will take - less a little bit.

I know everyone says you can't parallel charge - I don't have proof it works other than these are the same cells I was using on day 1 of ebiking! I am sure not pushing the last stage of charge helps - maybe that has been the key?

Scott
 
Miles - nope its new to me.

TBH it matters little - they don't appear to offer anything I have not been getting from the nimh cells other than a slight reduction in weight and I have doubt about their suitability when it comes to 10C or so peak requirements...........

Scott
 
You can buy 3 cell 4500mAh or 5000mAh lipos for $30 or so on ebay. Much cheaper than the NiMH linked to in this thread.

Cheaper, lighter, less voltage sag.

Why wouldn't you just use them instead? Charge them individually with $15 E-sky chargers and you just need a mulitmeter or CA for LVC.

You can also get 10000mAh 3 cell lipos, but they cost about $100 (lower volumes).
 
Hi Scott

I found a pro peak constellation charger in my local model shop. It will do up to 25 nimh cells at 5000maH Looks like a nice bit of kit but they want £80 for it plus £24 for a 240 to 12v 10amp p.s.u to run it.
http://www.galaxymodels.co.uk/results.asp?subt=Battery+Chargers&offset=10
Why does anything to do with batteries end up expensive.
 
Mark,

I have a stack of lipo's - been using them since us modellers had to rip them out of phones since you couldn't buy them! Problems I have are twofold.... 1, In the UK they cost 50% more than the nimh I currently use 2,I have only ever seen more than 300 cycles on the bench at less than 1C. Any higher currents and you are looking at far less than 300 cycles before you are down 20% or more.

You see, my requirements are very specific and lipo generally don't fit very well. I am looking for a 2C+ continuous discharge every ride since my ride is short and I want to do it fast.

I am aiming for a 30V (25 cell) 26AH pack and I need to be able to drain it in less than 30 minutes and for it to return 90% of cap at that rate AND it must deliver at least 300 cycles, finally it must be price competitive with the nimh over the full life. Here in the UK I could buy lipo but I would need a 30V 50AH pack (which weighs more than nimh) which would cost - with UK pricing - £1000+ - and then I might - just might get 300 cyles out of them! Of course - I could go twice as far - but I don't need that ability!

Richard - the constellation charger has basically the same insides as the supernova but I think it might have a slightly higher discharge rate........ IMHO the supernova is the choice pick if you are doing nicad/nimh - especially when you can pick them up for £40 on ebay :D
 
I have 200 cycles on my lipo booster pack and they don't seem to have dropped any capacity.

I don't understand why they are expensive in the UK - just go to Hong Kong Ebay. I nearly fell over when I read the price for those NiMH. Lithium is cheaper than Nickel these days.
 
Mark_A_W said:
I have 200 cycles on my lipo booster pack and they don't seem to have dropped any capacity.
Click to expand...

Do you always drain them in 20-25 minutes though?

Scott
 
Thats ive gone for ordered 5 12v 3700maH packs off ebay that will do me for the time being I also got a deal on the charger from my local model shop so I didn't do bad ( its also a better charger than the one I have for my rc helis so thats good, kill two birds with one stone so to speak) hopefully it will all turn up tomorow and I can start playing and find out how much these speed controllers can take I have two of them so if I have an accident its not a total loss.

Scottclarke

I have been looking at your build in the testing and photos section thats one sweet ride. I was at a model engineering show a couple of weeks back and I should have bought one of those brushless outrunners and a speed controller but I refrained. You can get so much power out of Rc kit, I used to rig my cars up to pull me down the road on a skateboard ( great fun).
 
Richard,

Keep an eye on these motors: http://www.micronradiocontrol.co.uk/scorpion_about.html they're good value and the magnets are rated for a maximum of 200 deg. C. I'm waiting for the 55mm series to come out...
 
You must log in or register to reply here.

Similar threads

E
Finding the "SUV" of Bikes
2
Replies
25
Views
1,832
EarthlyTulip
E
S
Multiple Built Bikes For Sale
Replies
1
Views
721
A-DamW
A-DamW
victorhooi
Good analysis-type battery charger for 52V eBike batteries?
Replies
8
Views
1,989
67RS427
6
CoCat
Chinese e-scooter - identifying mystery parts
Replies
1
Views
1,368
Dui ni shuo de dui
Dui ni shuo de dui
E
Help understanding / replacing controller please!
Replies
14
Views
3,859
encore-moi
E
Back
Top