Thread Tools
Jul 09, 2016, 02:18 AM
Registered User
Thread OP
Discussion

Mixing old and new lipos in same pack


I have now about 50 cycles used lipo pack which has 6 x 5s 5000 mah 25c turnigys. I use them 10s 15ah configuration (3 packs parallel and two of these pack in series)

I would now buy 2 new exactly same lipos and but each on those separate parallel pack so my configuration would be: 10s 20ah.

I am using these on my kids electric trial bike and we aren't even close of that c-rating. We pull maximum of 60 amps from batteries. Is it okay to add new lipos to our pack?
Sign up now
to remove ads between posts
Jul 09, 2016, 03:37 AM
Registered User
Since you're adding them in parallel it's fine.

Problems only tend to arise when putting mismatched (potentially stronger and weaker) cells/packs in series.

Steve
Jul 09, 2016, 04:54 PM
I think I just want to fly
Rhea's Avatar
New wine in old wine skins. .
Jul 09, 2016, 05:48 PM
Registered User
Quote:
Originally Posted by Rhea
New wine in old wine skins. .
I put new wine inside my old skin all the time. No problems yet .

Steve
Jul 10, 2016, 03:18 AM
Registered User
Quote:
Originally Posted by slipstick
Since you're adding them in parallel it's fine.

Problems only tend to arise when putting mismatched (potentially stronger and weaker) cells/packs in series.

Steve
How bad am I and why:
12s:
9cells 90c 4.5ah, and the 3cells 35c 5ah connected in series.
Jul 10, 2016, 03:59 AM
Registered User
Quote:
Originally Posted by Hummina
How bad am I and why:
12s:
9cells 90c 4.5ah, and the 3cells 35c 5ah connected in series.
Can't say I believe that 90C for any cells...but in theory you have 9 cells capable of 405A and 3 that are only capable of 175A. And the full current you're drawing goes through all of them. So at a certain current level you have the obvious potential for damage. And the 9 cells are smaller so will get depleted sooner. And you can't rely on LVC because the 3 cells will drop more voltage than the higher C-rated cells. Basically it all gets a bit messy .

OTOH if you're drawing relatively small currents probably little or no problem.

Steve
Jul 10, 2016, 12:30 PM
Registered User
Ok. The 90c cells(think it's 90) are a-spec nanotec and they're the smaller 4.5ah. The bigger 5ah are 35c. I never have seen higher than 50amps pulled from the batteries.
I was worried that the while a parallel connection of different packs will balance each other the series connection would maybe suck the "weaker" cells harder. How does the battery higher resistance of the lower c effect?
The voltages of the pack stays pretty balanced


Quick Reply
Message:

Thread Tools