Mix and Match LiPos
08-22-2010, 03:31 PM
#1
Mix and Match LiPos
I currently have one Zippy Flightmax 5000mAh 20C 2S LiPo hardcase pack that I use for my car, but I want to get another one because my new ESC (HK 100A) can take up to 4S. I've been using my Zippy for a few months and it probably has 20 or so charges on it, it still balances perfectly and has long runtime. I don't want to buy another pack from HK right now because of wait times/shipping costs, so I was looking to my new favorite site, HobbyPartz. Their car pack, specifically the 5000mAh 20C 2S hardcase pack, has the same specs and looks identical to the Zippy one besides the hardcase color, even down to the shrink wrap and printing on the wires (so I'm pretty sure it's the same battery since they both come from China as well. Is it a bad idea to mix LiPos if they are from "different manufacturers?" How much will the age of my current LiPo play into the equation?
08-22-2010, 04:50 PM
#2
Typically not a good idea, but if you keep your runtimes short you should not have a problem. If any of the cells are stronger than others and you run them to a low cutoff point, the stronger cells could show a total pack voltage high enough to keep running while "weaker" cells could fall below safe voltage. If you have the option to run a 3.6V or higher cutoff, that should keep all of them well above a safe voltage.
08-22-2010, 05:31 PM
#3
Typically not a good idea, but if you keep your runtimes short you should not have a problem. If any of the cells are stronger than others and you run them to a low cutoff point, the stronger cells could show a total pack voltage high enough to keep running while "weaker" cells could fall below safe voltage. If you have the option to run a 3.6V or higher cutoff, that should keep all of them well above a safe voltage.
08-22-2010, 05:41 PM
#4
I'd also check temps on the lipos - what I'd worry about is IR differences that would make one lipo get hotter than the other.
When I started running 2 pacs in my MTs they were always paired and charged as a single batt. That got old and I started just charging them separately - couldn't tell any diff. The I bought a 3S and paired it with a older 2S that had 100+ runs on it and I didn't see either lipo get any hotter than the other. These were both Neuenergys and 25Cs.
If the C ratings are realistic and not wildly optimistic (inflated) then as lomng as they are close, I would use them. Just check lipo temps, as long as they are same, its time to play!
All the cautions that get tossed around may be a bit overdone.
When I started running 2 pacs in my MTs they were always paired and charged as a single batt. That got old and I started just charging them separately - couldn't tell any diff. The I bought a 3S and paired it with a older 2S that had 100+ runs on it and I didn't see either lipo get any hotter than the other. These were both Neuenergys and 25Cs.
If the C ratings are realistic and not wildly optimistic (inflated) then as lomng as they are close, I would use them. Just check lipo temps, as long as they are same, its time to play!
All the cautions that get tossed around may be a bit overdone.
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