Charging Cut-Off Voltage

[JimInMiami]

So, here's one for the experts. My Venom Pro 3 has a default voltage cut-off of 8.40 volts for my 2 cell lipos. I was wondering, would there be any benefit from bring that down a bit, say to 8.30 volts to lessen the strain on the battery?

What percentage of normal run time would I lose if I did that?? My thinking is that my 5200 mah lipos provide WAY more run time than I ever need on my crawlers, so wouldn't it be smart to do something to try to increase the battery's lifespan??

[HumboldtEF]

In theory it should extend the life of the battery. As for run times why not just test it for yourself. Run times vary based on driving style and conditions already so the best way to find out is an actual test.

[durok]

A while back I searched for life-lengthening tips on LiPos, ran into these statements from people that knew what they were talking about (At least the second paragraph of this is from JohnRobHolmes of Holmes Hobbies).

My packs have all benefited from using them - and I have several brands, cell counts, mAh and C ratings - all used in crawlers:

"For the longest life of the batteries, LiPos should be stored at room temperature at 3.8V per cell

If you want to extend life more and have a smart charger, terminate charge at 4.19 or 4.18v per cell and set your ESC cutoff at 3.3v or higher per cell. Narrowing the voltage range of the cell like this will easily double the useful battery life."

[Kingmeow]

I adjust my cutoff voltage to 3.17V per cell and not use the standard 3.20V per cell. Having said that, I don't have my own scientific data to back to up other than a lot of people have recommended that in the airplane world. I fly mostly airplanes so that's what I set all my packs to terminate at and I do the same for crawling.

[JimInMiami]

Originally Posted by HumboldtEF

In theory it should extend the life of the battery. As for run times why not just test it for yourself. Run times vary based on driving style and conditions already so the best way to find out is an actual test.

Hi Casey, hard to test in the real world (especially for a crawler). I think you'd have to run the same course at a constant speed and measure the duration. Your suggestion did give me an idea tho, I charged a 5200 mah pack till 8.3v and then plugged it into my CellMeter 8. FWIW, it's showing 88% charge.

[JimInMiami]

Originally Posted by durok

A while back I searched for life-lengthening tips on LiPos, ran into these statements from people that knew what they were talking about (At least the second paragraph of this is from JohnRobHolmes of Holmes Hobbies).

My packs have all benefited from using them - and I have several brands, cell counts, mAh and C ratings - all used in crawlers:

"For the longest life of the batteries, LiPos should be stored at room temperature at 3.8V per cell

If you want to extend life more and have a smart charger, terminate charge at 4.19 or 4.18v per cell and set your ESC cutoff at 3.3v or higher per cell. Narrowing the voltage range of the cell like this will easily double the useful battery life."

That's good info, I hadn't thought of upping the voltage cutoff on the discharge - thanks!

[JimInMiami]

Originally Posted by Kingmeow

I adjust my cutoff voltage to 3.17V per cell and not use the standard 3.20V per cell. Having said that, I don't have my own scientific data to back to up other than a lot of people have recommended that in the airplane world. I fly mostly airplanes so that's what I set all my packs to terminate at and I do the same for crawling.

Cool, methinks I'll start doing the same or even lower for crawlers.

[HumboldtEF]

Originally Posted by JimInMiami

Hi Casey, hard to test in the real world (especially for a crawler). I think you'd have to run the same course at a constant speed and measure the duration. Your suggestion did give me an idea tho, I charged a 5200 mah pack till 8.3v and then plugged it into my CellMeter 8. FWIW, it's showing 88% charge.

Hey Jim, I didn't mean you have to do scientific test to get exact measurements, I just meant why not just run it and see whats what. If you have two batteries you could use one (thats fully charged) as a control to compare against the slightly undercharged pack.

[JimInMiami]

So I got me one of those battery tester thingies https://www.amazon.com/Cellmeter-Dig...28735034&psc=1 and ran a simple test: Charged two different 2-cell packs with an 8.30 v cutoff (4.15 per cell) and plugged the suckers into the gadget after leaving them rest for half an hour. FWIW it's showing both of them at 94% charged, which I think is good enuf for my purposes.

[Kingmeow]

Yep, that should be fine.