Alright, WTF am I doing wrong?
 

I seem to be a serial lipo killer.
It seems like every single lipo I touch begins to swell within 3 or 4 charges.
My charger is a Hitec RDX2 Mini
Lipos are Gens Ace Redline 4000, shorty packs.
​​​I don't race. I barely run. When I do, it's generally out front of the house for about 10 minutes. This barely seems to discharge the batteries beyond 3.8-3.9v.
I'm running RC10s with the proper gearing and very mild motors. (21.5, 17.5, and 13.5 for my 74.1)
I charge them when they've returned to room temp, and only charge at 4.0A.
What am I doing wrong?
When not in use, I'm religious about balancing them at 3.8v and then keep them inside the house, in a steel ammo can that sits directly on the tile floor. (So it stays cool) (I keep them inside bcuz I'm in San Antonio, TX so in the summer, my garage gets up to about 110deg)

I don't get it.
I just recharged the "worst" battery and ran the resistance meter on the charger. One cell is showing 10.4ohm, while the other is showing 10.1.
My other lipos are already creeping past 5ohms/ cell.
Like I said, I'm killing these things and I'm barely using them.
Help?

When you say 3.8-3.9V, are you talking for the whole pack or for each cell? If it's for the whole pack, you are over discharging them. That would explain why you are destroying them.

Martin Paradis

That's, pee cell. Sorry. I think the lowest I've ever gone per cell is 3.7....

Are you charging the batteries inside with cool air and then storing them outside in the heat for any substantial amount of time?


Heat will cause voltage to spike and that can damage the cells.


TheJANG from URC shared a story where he charged a handful of brand new LiPos inside in house, then packed his gear into the trunk of his car and drove 2 hours to the beach only to discover every battery was swollen with cracks on the seams of each battery where they were never used a single time!


Generally, you want to charge them at the ambient temp where they will be used if you want to minimize risk of damaging the cells.

It sounds like you’re doing everything right with storage, charging rates, and even ambient temps, so it’s weird you’re still seeing swelling and high internal resistance so fast.

One thing that stands out is the charge rate,4.0A on a 4000mAh pack is technically 1C and should be safe, but some shorty packs, especially lightweight race packs like the Redlines, prefer a slower charge like 0.5C (around 2A) to preserve longevity. It might be worth trying slower charges and seeing if that helps.

Even though you’re not discharging them much during runs, lipos can still be sensitive to slight over-discharge spikes under load if there’s a sudden voltage sag, especially with older cells or if the ESC isn’t perfectly tuned. You might want to try monitoring real-time voltage during a run just to rule that out. You’re doing a lot right, a few small tweaks could make a big difference!

Redlines easily handle 10A+. They won't fail within a few cycles just because they're charged at 4A.

What voltage are you charging them to?