Considering the time, effort, and expense associated with the planes we fly, I'm curious about what "rules of thumb" people follow for determining when it's time to replace battery packs. I check my receiver and transmitter packs before every flight and cycle them all a couple times a year. Several of my packs are coming in at 90-95% of capacity. At what point should they be replaced? 85% of capacity, 80%, ....? What guidelines do you follow?

Flight pack Nicads- 2 years or 90% whichever comes first.

Flight pack Li Ions/Lipos - 2 years

Transmitter Nicads - 3 to 5 yrs or 85% whichever comes first.


I then keep the Nicad packs for shop use (plane setup etc) for a couple more years and maybe for sport plane use until they reach 85%. Li Ions I keep around for shop use only.

Then again, I usually don't keep a competition plane more than two years<g>
I have always used new batteries in a new competition plane.


And then again, I was told many, many years ago 80% for Nicads.

It all adds up to what risk you are willing to take. I think the biggest thing to worry about, is damaged wires. I caught one just in time last season that had been chaffed through to the wire in one place. Inspecting your plane on a regular basis is a must.

You are correct. We have too many $$$ in these planes. Probably 80% will work. My suggestion is to use 80% and maximum 2 years whatever comes first. Probably it will be even safer to do 1.5 years but I believe 2 years works. I am sure that other expert in batteries could tell us that depends of the battery type, etc...

Vicente "Vince" Bortone

As a rule, I replace the RX battery switch when replacing the RX battery pack. Large displacement YS 4C motors vibrate......alot!.... and all the switches I've seen are HARD mounted.
Steve

I second the switch harness replacement. I replace mine at the end of the season on my primary plane unless I am using a fail safe/regulator combo.

On my higher dollar planes I run 2 switches and packs. I end up using my packs a little longer than I otherwise would if they were single packs.

Do these times assume regular use? I have a couple of li-ions that were purchased new about 1.5 years ago and haven't been used. Would these still be good after 2 years?

Thanks

I've found (possibly due to the climate and geography of where I live, most of my packs fail from black wire. I replace the pigtails on my battery packs and replace switch harnesess every two years.

THe battery packs are usually (I use NiMH) good for about 3 years of abuse. After that I tend to break the pack and use the batteries for "round the house" use.

Never again, shall they find their way into an aircraft lest they cost me it.

My experience says no. They seem to go if you use them or not. I've got two planes that haven't flown much in the last two years and the packs don't look good. The message is only buy the packs you need at any given time and move them from plane to plane if you have to.

Jim o

I hope for your sake you're not cycling Li-Ion batteries... not good for them.

No, I don't cycle my Li-ions. I just work alot and some years I get to fly alot and others, not nearly as much. Last year was pitiful. I have all these nice Duralite and Fromeco batteries and 2 nice 50cc planes and a 100cc plane and they practically never saw air. I've checked the batteries several times this year getting ready for the season and they seem to peak to the norm and the couple of times I've used them sofar this year they preformed seemingly normal. I just don't want any supprises and have a plane going in over something as simple as changing a battery due to age.

Thanks for the advise