Does charge rate effect run time lipo?

[Reaxion911]

Just as it says ive got some lipo packs that are getting on in there lifespan and starting to dump early. i was wondering if charging at a lower amperage lik 1a vs my regular 4a will improve runtime? Any other tricks for improving runtime on lipo packs?

[Noll11]

Shouldn't do, no. You're just making the charger push more slowly, essentially. If you don't balance charge, I'd advise picking up a cheap balancer as well.

I'm sure others will chime in as well .

[Calderwood]

It depends on the charger. One of my flying buddies uses the same packs that I do. If he charges at 2c with his china charger it finishes quickly and and doesn't quite fill the pack. When I charge the same packs at 2c with my Hyperion the algorithm slows down the charge rate so much near the end of the charge that it fills it up like you started on 1c. At the end of the charge that started at 5amps the Hyperion is charging at .15amps. I don't think his china charger slows down any where near that much at the end and it finishes more abruptly.

[Johnnysplits]

Yeah, you're not gonna get the same results when using a high quality charger compared to a cheap piece of crap.

[Reaxion911]

I have both cheap dual and quality chargers. I Always balance charge

[Reaxion911]

So no tricks for gaining runtime on experienced packs?

[Johnnysplits]

Are you not getting full charges? Does your charger show capacity as a percentage? If not, do you have a lipo meter?

[Solitaire]

Originally Posted by Reaxion911

So no tricks for gaining runtime on experienced packs?

If you're charging at the suggested C rate and each cell is 4.2v, then there is nothing else you can do. Packs don't last forever.

[road_rascal]

I charge most of my packs at 1C, although some of my larger lipos I'll charge at 1.5C (I'm talking about 5 cells or bigger 5000+ mAh lipos, even though they're rated for 5C charging). Always balance charge and never run them down past 3.7V per cell. I have had lipos last 4+ years with heavy usage for some of my smaller airplanes. Most of time I'll 'retire' a battery due to the balancing wires pulling out of the battery. My current batch of 2s5000 packs for some of my trucks are around 3 years old and still going strong. Having a decent charger is a must, and I know a lot of people balk at spending $200 for a charger and/ or power supply but it's a worthwhile investment for RC hobbies.

[Johnnysplits]

Originally Posted by road_rascal

Having a decent charger is a must, and I know a lot of people balk at spending $200 for a charger and/ or power supply but it's a worthwhile investment for RC hobbies.

[Madmax1]

Originally Posted by road_rascal

I charge most of my packs at 1C, although some of my larger lipos I'll charge at 1.5C (I'm talking about 5 cells or bigger 5000+ mAh lipos, even though they're rated for 5C charging). Always balance charge and never run them down past 3.7V per cell. I have had lipos last 4+ years with heavy usage for some of my smaller airplanes. Most of time I'll 'retire' a battery due to the balancing wires pulling out of the battery. My current batch of 2s5000 packs for some of my trucks are around 3 years old and still going strong. Having a decent charger is a must, and I know a lot of people balk at spending $200 for a charger and/ or power supply but it's a worthwhile investment for RC hobbies.

Road rascal which charger you talking about. I need to get one. I have 3s 850 lipo.
Thanks

[STANG KILLA SS]

in my old NiCad racing days it did. a fast high C charge would discharge harder but not last as long.
a slow trickle charge would last a bit longer but not have as much punch.
no clue if true or not, but that was the consensous.

[Olle P]

Originally Posted by STANG KILLA SS

in my old NiCad racing days it did. a fast high C charge would discharge harder but not last as long.
a slow trickle charge would last a bit longer but not have as much punch.
no clue if true or not, but that was the consensous.

A slow charge is better because it spreads the charge more evenly over the entire inner surface.
This maximize the capacity and I see no reason why it shouldn't also be able to deliver at least as high current as if fast charged.

Another aspect to consider is the number of cycles.
Higher charge rates "eat" permanent capacity faster from the battery, so after 200 recharges a battery that's always been charged at 1.5C will have notably less capacity than one of same make/model/batch that's always been charged at 0.5C.

[WHITE-TRASH]

Originally Posted by Olle P

A slow charge is better because it spreads the charge more evenly over the entire inner surface.
This maximize the capacity and I see no reason why it shouldn't also be able to deliver at least as high current as if fast charged.

Another aspect to consider is the number of cycles.
Higher charge rates "eat" permanent capacity faster from the battery, so after 200 recharges a battery that's always been charged at 1.5C will have notably less capacity than one of same make/model/batch that's always been charged at 0.5C.

You're correct as far as lips are concerned but he's referencing NiCd/Nihm betteries.


As far as older battery types the charge rate absolutely made a difference. We would charge our 1700 scr packs at 2 amps till they peaked then right before lining them up crank it up to 10 amps fore initial hit off the line. That higher peak would last about half a lap.

[Calderwood]

Originally Posted by WHITE-TRASH

You're correct as far as lips are concerned but he's referencing NiCd/Nihm betteries.


As far as older battery types the charge rate absolutely made a difference. We would charge our 1700 scr packs at 2 amps till they peaked then right before lining them up crank it up to 10 amps fore initial hit off the line. That higher peak would last about half a lap.

I don't miss nicad racing one bit. Having the pack dump on the last lap sucked.

[WHITE-TRASH]

Originally Posted by Calderwood

I don't miss nicad racing one bit. Having the pack dump on the last lap sucked.

That's a fact! I stepped away from everything rc for years because battery technology was crap.

[Olle P]

Originally Posted by WHITE-TRASH

As far as older battery types the charge rate absolutely made a difference.
... crank it up to 10 amps fore initial hit off the line. That higher peak would last about half a lap.

That's a completely different story. What you did was to overcharge the battery, giving it a slightly higher initial voltage that, as noted, lasted a short while.
What you also did was to permanently reduce the total capacity by ~10% (according to a study performed at a Swedish college a couple of years back), so I suppose the packs weren't useful for that many runs.

It would also be interesting to know the difference in top speed at lap 20 between a "supercharged" battery compared to a slowly charged one...

[WHITE-TRASH]

Originally Posted by Olle P

That's a completely different story. What you did was to overcharge the battery, giving it a slightly higher initial voltage that, as noted, lasted a short while.
What you also did was to permanently reduce the total capacity by ~10% (according to a study performed at a Swedish college a couple of years back), so I suppose the packs weren't useful for that many runs.

It would also be interesting to know the difference in top speed at lap 20 between a "supercharged" battery compared to a slowly charged one...

So every time we cranked up the amperage we reduced the capacity by 10%... That study may have said that but our real world experience says different. Did our technique shorten over all cell life? Certainly but the capacity remained pretty close to advertised.


Nicad and nihm batteries acted far different depending on charge rate. A slow 1 amp charge would last a long time but top speed was reduced. A higher charge rate made the top speed at the expense of run time.

i haven't noticed that effect in lipo batteries.

[EddieO]

10% my ass..........we used to nuke our packs daily and there certainly was no 10% drop in runtime....we would see a drop over time sure, but nothing like a 10% rate, I doubt it was even 1%.

But to answer the OP question, regardless of battery type....higher charge rates will over time shorten cell life, not only reducing runtime but increase resistance and within time lower voltage curves.

Don't buy into the no memory crap either.....NICADs were by far the worst, but anyone who raced when NIMH hit the scene can recall the whole "they have no memory" crap we were told. NIMH had memory as well, just not as bad as NICADs....Lithium packs have it as well, its just greatly reduced...

Later EddieO

[Johnnysplits]

There's nothing wrong with high charge rates on a lipo as long as the battery is designed for it. Most of mine are charged at 3C except for the few that the mfr. states 1C charge rate max.