LyonNightroad
100 W
- Joined
- Feb 13, 2014
- Messages
- 105
You need to test with another watt meter. There is no way you are getting 50% efficiency out of a 10c Lipo at 3c discharge.
Multistar lipo questions / issues / solutions
- Thread starter amund7
- Start date
amund7
1 W
LyonNightroad said:
I'm on the second one now, it shows the same.
So the conclusion is then, both my lipos have a leak?
My friend had the batteries for just a couple of weeks, on storage charge.
amund7
1 W
Recent measurements turn out more confusing.
My friend bought 4 batteries in the same batch. When testing the last 2 (cycled once or twice) on the bike, one battery is off the cliff at 3.1 Ah. Several cells were down to 2.9 volts at that point, before I managed to stop.
Graph shows said battery discharging on the charger at max, which is around 2.8 A. Battery then willingly delivers just over 10 Ah, as labeled. I have tested 3 out of 4 batteries up till now, and they all deliver.
What is going on here? The batteries are labeled 10C. Can they not even handle 3C which I am trying to pull from them (30A)? Or am I misunderstanding the C rating? 10 000mAh battery * 10C = 100 A, right?
Watt meter wise, I'm on the 3rd one (same brand, GT power). They all show the same. And the last day, when bike lasted 3.1 Ah, I only got 8 km! Usually I will get at least twice that. My 48v13Ah bottle battery gives me
Maybe the solution is to always use 2s2p, so I will pull 15A per battery instead. If they can manage even that.
Simonvtr
100 W
Icecube57 has those battery in his setup but he said they are not 10c like the label say. They are more like 1/4 of 10c.
https://endless-sphere.com/forums/viewtopic.php?f=6&t=66305
https://endless-sphere.com/forums/viewtopic.php?f=6&t=66305
skoleskibe
100 mW
- Joined
- Aug 22, 2015
- Messages
- 35
Im using 3 4's 10000mAh multistars for my xiongda XD powered bike. When in assist level 2 just about 200w i get about 55-60km on one charge. Max assist speed is 25kmh. I currently use lvc alarms, the batteries are quite equal in voltage until ive lifted about 8ah out of them, after that one of the batteries loose voltage rapidly. In practice i charge once it shows under 44v at load (5-10amp's) eg between 1/2 and 1c discharge rate. If i use assist level 4-5 thats upwards of 15amp's and assist speed of 35 Kmh the battery get sligthly warm just enough to be able to notice it. And my range drops to 30-35 km. Normally i charge to 4.1v per cell, thus not utilising the total potential of the battery.
999zip999
100 TW
It's easier to follow if we can see pack voltages like.
1. 4.23v
2. 3.99v
3. 3.98v
12. xxx volt
These way we don't have to guess which cell, I like it on paper ez reading.
How old are cells ? Give back to friend let him deal with dud cells. You can't return cells you did not buy , it's on his H.K. account so if dud's he must return. Don't be to nice of a Norwegian if to old to return to H.K. return to friend as dud's.
My brother is coming today from Harstad and went to school in Oslo.
1. 4.23v
2. 3.99v
3. 3.98v
12. xxx volt
These way we don't have to guess which cell, I like it on paper ez reading.
How old are cells ? Give back to friend let him deal with dud cells. You can't return cells you did not buy , it's on his H.K. account so if dud's he must return. Don't be to nice of a Norwegian if to old to return to H.K. return to friend as dud's.
My brother is coming today from Harstad and went to school in Oslo.
amund7
1 W
Simonvtr said:
Spot on. I have done several tests as I'm trying to collect proof that these batteries are not doing what they're 'sposed to. But the hardest I can discharge with any of the chargers I've had my hands on is 20A, and they still give the full 10 000 mAh. It got pretty hot at 20A though, like 45-50 celsius.
The bike pulls 31A, and that kills the batteries after just 3100 mAh. It's surprising to me that they suddenly cave in completely when pulling 30A vs 20A. I suppose this is what happens when you exceed the C-rating?
I will put 2s2p with these, which will load each battery 15A, that should give me an honest 20 000 mAh. Will test during the weekend.
amund7
1 W
amund7 said:
Did the test. First cells hit 3.3v after 8.3 Ah. That should have delivered 20 Ah!
And now I only pulled 15A per battery, theoretically, meaning I'm pulling less than I did with the charger, a test that resulted in the batteries delivering the full 10 Ah.
Is this my watt meter being absolutely off (GT Power)? If it is, that must mean my cheap bottle battery is delivering twice it's label, because I measured 9 Ah out of it. But maybe it gives utterly random results. Also, the range in kilometers I am getting seems to match the wattmeter numbers from the other battery.
It seems to me then, that whatever I do and however I measure, bench tests show the batteries are delivering 100% what they should. And on the bike they deliver less than half.
What about temperature? We've had around 10 C here this weekend. Is that too cold, and could it result in getting 1/2 capacity?
I could use suggestions for proper tests.
How about, drive the same course for as long as it can handle, with both batteries, then note distance + wattmeter readings? If I bring all my batteries I can do this and still get back home.
