Ebikes.ca compares all of their batteries
- Thread starter Russell
- Start date
dogman dan
1 PW
Very interesting to see how much less flat the lipoly curves are. And the nicad curve is not as bad as I would have thought, but it sure does drop off fast in the beginning. I would have expected more slope on the nicad line. The way I use my nicads, I bet there is a lot more slope! But this graph really shows how moderate discharges like 10 a continuous are no problem for these batteries. At 20 mph, just a tiny bit of pedaling gets you into the 10 amps area.
VERY COOL JUSTIN!
VERY COOL JUSTIN!
Russell
1 MW
I was actually surprised by the amount of sag from the NiCads considering that they are rated '5C'. The premium high-rate LiFePO4 battery is of course the best of the lot but the price tag is premium too.
The average voltage over the discharge curve is what's important and the stock eZee LiMn battery did very well in that respect. The LiPo's eZee is using however must be a basic grade though becasue they don't appear to perform well at all.
Now what would be nice to see are competing batteries on the same chart!
-R
The average voltage over the discharge curve is what's important and the stock eZee LiMn battery did very well in that respect. The LiPo's eZee is using however must be a basic grade though becasue they don't appear to perform well at all.
Now what would be nice to see are competing batteries on the same chart!
-R
snowranger
10 kW
Yes, throw a couple 20 C Zippy Lipos on there.
vanilla ice
1 MW
Thats great seeing all the different chems lined up on the same graph, mad props.
liveforphysics
100 TW
Here is some good RC LiPo for a compare:
Notice they start it out at 7C, where these other discharge graphs are 2-2.5C.
A 2C discharge graph for good hobby LiPo has roughly no detectable voltage drop at all. lol
Notice they start it out at 7C, where these other discharge graphs are 2-2.5C.
A 2C discharge graph for good hobby LiPo has roughly no detectable voltage drop at all. lol
gotta keep in mind that the HK graph is a single cell test vs the ebikes.ca full pack + BMS voltage curve !! ( still no comparison to high end lipo.. but yet. )
liveforphysics
100 TW
Ypedal said:
Keep in mind for a 36v pack (10s), you just multiply everything in the voltage side by 10, and if you want to see it as a 10Ah pack, just multiply the current and Ah by 2x.
dogman dan
1 PW
Maybe those nicads can put out 5c, for about 10 cycles :lol: I consider them 2.5c at best, after using them at that rate and being a bit dissapointed.
A good part of the appeal of the lipo is that when you cut thier practical use c rate in half, you still have 10-15 c left! Do that with a ping, and you have 1c left.
A good part of the appeal of the lipo is that when you cut thier practical use c rate in half, you still have 10-15 c left! Do that with a ping, and you have 1c left.
Zoot Katz
100 kW
If you look at Justin's graphs for the individual packs you'll find discharge tests that were done at different current draws according to the specs of the pack.liveforphysics said:Here is some good RC LiPo for a compare:
Notice they start it out at 7C, where these other discharge graphs are 2-2.5C.
A 2C discharge graph for good hobby LiPo has roughly no detectable voltage drop at all. lol
For example my pack is rated 5C and he shows the curve for 25.0 Amps
http://www.ebikes.ca/images/B3610LiF-EL_Graph.gif
Zoot Katz
100 kW
dogman said:
Justin discharged the 8Ah NiCd packs at 22.1 Amps
http://www.ebikes.ca/images/B3608Cd-EL_Graph.gif
Russell
1 MW
liveforphysics said:Here is some good RC LiPo for a compare:
Notice they start it out at 7C, where these other discharge graphs are 2-2.5C.
A 2C discharge graph for good hobby LiPo has roughly no detectable voltage drop at all. lol
Here they are with about the same scaling for direct comparison.
-R
dogman dan
1 PW
Well, mine (5c nicads) have not lasted so good discharged at 22 amps with an aotema controller. Using a 5304, and 48v 8 ah, the constant draw at 22 amps trashed em pretty quick, like 100 cycles or so. So that was close to a 3c discharge rate, and lots of the use was climbing steep hills. I'd get 30 amp spikes, and then the controller would ramp it down to about 22-25 amps. Just for the record, I was told this would happen, and I needed 16 ah for the clyte. Deep discharges are also part of the problem, had I kept dod lighter, I would have gotten better results.
Just trying to make the point that a 10 ah 5c rated cell pack does not mean it will last when used at 50 amps till all 10 ah is gone, but you see guys calculating that way all the time.
Just trying to make the point that a 10 ah 5c rated cell pack does not mean it will last when used at 50 amps till all 10 ah is gone, but you see guys calculating that way all the time.
mrzed
100 W
Similar experience to Dogman on my 8ah NiCd pack with a 9C at 20 amps. Running to average 80% DOD, I got through 100 cycles, then the next 100 cycles steadily saw the capacity drop.
Part of the reason I went over capacity when I got a LiFePO4 replacement was the suspicion that regularly using that much of the capacity was a factor in the early demise.
Part of the reason I went over capacity when I got a LiFePO4 replacement was the suspicion that regularly using that much of the capacity was a factor in the early demise.
Zoot Katz
100 kW
What I've noticed with my 48V, 10Ah, 5C rated LiFePo packs is that after eight and change the BMS trips when I turn up the wick.dogman said:
I always have to make sure I can coast home after about 7.7 Ah are spent.
Two in parallel gets close to 16 Ah before fizzling out.
