IS LOWER AMPS WHILE CHARGING BETTER FOR LIPO LONGETIVITY?

[two0sicc]

FOR EXMPLE- CHARGING A 4S BATTERY 6000MAH AT 3 AMPS INSTEAD OF 6 AMPS? THANKS!

 

[MrWolfIsInnocent]

By my understanding 6amps would be optimal, I know charging a 5200mah at .8a took forever and it lasted 2 charges then puffed (used in a trail rig so not stressed). I was too impatient to wait for the better charger to arrive. But obviously while I think that was the likely cause, I can’t back it up with science.. if that’s any help.

 

[RedondoBeachRC]

LiPo manufactures have a suggested charge rate which is typically between 1C-5C. As you charge at a higher C rating the less mAh you’re putting in to the battery.

Charging under or over that can cause degradation issues and decrease the life span of your LiPo.

 

[dure16]

FOR LONGEVITY, MAYBE, BUT PROBABLY NOT A BIG DIFFERENCE.

HOWEVER, CHARGING AT A LOWER RATE WILL PUT MORE CAPACITY INTO THE PACK AND THEN IT WILL LAST LONGER DURING YOUR NEXT RUN.

 

[Jon NC RC]

FOR EXMPLE- CHARGING A 4S BATTERY 6000MAH AT 3 AMPS INSTEAD OF 6 AMPS? THANKS!

Not sure..... I have followed the 1-1 principle , ( 6000 mah at 6 amps for example) without problems

I do know that exceeding manufacturers recommended rate will not help longevity....

 

[RCbuzz]

Yes, typically charging at a lower C rate is best for the battery and will extend its life among other things (reducing the depth of discharge, and reducing discharge C rate). I typically charge between .5 and 1C and never outside the allowance of the MFR

I read some good literature on this a while back, I will try to find it.

EDIT (Check out "TOP TIP 4"): https://www.saftbatteries.com/energ...m-ion-batteries-5-expert-tips-longer-lifespan

EDIT: Another good read here, check it out!
https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries

I also set max charge voltage to 4.15V/cell to 1, reduce stress on the battery and 2, allow for voltage tolerance (% error) on different chargers.

 

[#ARRMArcfanboy4life]

It probably will make you battery last longer, but at some point you have to deicide, "Do I want to have fun in an hour, or tomorrow?".
Even if the battery lasts longer, if it is a basher or speed running car, the battery might have a reduced life due to other "factors"...

 

[jkflow]

Yes, it will prolong life, maybe by 5-10% in a nice clean world with controlled charge/discharge. Instead of 7 years, you could get maybe 8 years out of it.
The RC world is not anything like that, you will lose your lipos for other reasons within 2-3 yeas, if you are bashing.

In other words, there is no practical value, in the RC world, to 'slow charge'.

 

[RCbuzz]

Yes, it will prolong life, maybe by 5-10% in a nice clean world with controlled charge/discharge. Instead of 7 years, you could get maybe 8 years out of it.
The RC world is not anything like that, you will lose your lipos for other reasons within 2-3 yeas, if you are bashing.

In other words, there is no practical value, in the RC world, to 'slow charge'.

Speak for yourself @jkflow my drive style should handle me for 10 years.

 

[SrC]

Yes, typically charging at a lower C rate is best for the battery and will extend its life among other things (reducing the depth of discharge, and reducing discharge C rate). I typically charge between .5 and 1C and never outside the allowance of the MFG.

I read some good literature on this a while back, I will try to find it.

EDIT (Check out "TOP TIP 4"): https://www.saftbatteries.com/energ...m-ion-batteries-5-expert-tips-longer-lifespan

The above regarding "reducing depth of discharge" and "reducing discharge rate", would only apply to Battery chemistries other than Lipo. Like Nim and Nicad packs.
A slower charge rate, below 1C, does not reduce performance with a Lipo. Just takes longer to charge. A slight benefit to longevity only if you do this every single time over it's lifespan. So in reality it is not worth it if doing this on just occasions here and there. And some chargers simply cannot supply a 1 C rate. Depends on the lipos you are using. Charger may not be able to keep up with a 1c rate. Like with very high Mah capacities. With 4-6-8s packs.
Just charge at a 1C rate if your charger can provide it. Lipo mfr's typically rate their packs specs based on a 1 C rate. Despite some of them claiming higher charge rate capable.
I find that most of my lipos in general are only good for 50+ cycles give or take before the get tired. Yet it is claimed they can charge over 200 cycles.
RC lipo's go through a lot of abuse to begin with.

 

[dure16]

I find that most of my lipos in general are only good for 50+ cycles give or take before the get tired. Yet it is claimed they can charge over 200 cycles.
RC lipo's go through a lot of abuse to begin with.

How do you know when a lipo is ready for retirement?

 

[Diem Turner]

How do you know when a lipo is ready for retirement?

It kind of depends on what you use them for (bashing v. high performance). But generally speaking, a lipo has a good bit of wear when the IR of each cell reaches around 10mΩ and are ready to be relegated to the back burner when they reach 20mΩ. At 30mΩ it's probably time for the great battery park in the sky.

 

[RCbuzz]

I retire mine when they struggle to balance, the cells are way off from each other after a run, the capacity drops too low, or physical damage is present.

My charger does read internal resistance but it is not always accurate, regardless, I like to document initial readings. Different brands have slightly different values, I had a pack start at over 10mΩ new, ideally you are looking for the rate of change over time.

 

[Diem Turner]

I retire mine when they struggle to balance, the cells are way off from each other after a run, the capacity drops too low, or physical damage is present.

My charger does read internal resistance but it is not always accurate, regardless, I like to document initial readings. Different brands have slightly different values, I had a pack start at over 10mΩ new, ideally you are looking for the rate of change over time.

When measuring IR it's important that the packs are at as close to the same temperature as you can manage every time you do it. Every degree counts and will make a difference in what you measure as IR is very sensitive to temperature.

 

[RCbuzz]

When measuring IR it's important that the packs are at as close to the same temperature as you can manage every time you do it. Every degree counts and will make a difference in what you measure as IR is very sensitive to temperature.

That is a good point.

I just chalked it up to the difficulty in reading crazy low values. If I jiggle the balance lead I get different values everytime.

Or maybe it's just the Hobbymate D6 Duo struggles with the reading. Not sure, but I have heard from others the same issues (inconsistent readings).

What charging are you using?

 

[Diem Turner]

That is a good point.

I just chalked it up to the difficulty in reading crazy low values. If I jiggle the balance lead I get different values everytime.

Or maybe it's just the Hobbymate D6 Duo struggles with the reading. Not sure, but I have heard from others the same issues (inconsistent readings).

What charging are you using?

I'm using an ISDT P20.

 

[SrC]

How do you know when a lipo is ready for retirement?

Resting voltage when fully charged will fall off more quickly , after a full charge.
Internal resistance of all the cells will spread out, increase and not be matched from cell to cell.
The pack will take very long to Balance at the end of the charge cycle.
Good to have Lipo testor around for this. Some chargers will also provide internal resistance readings.

Performance will degarde.... LVC cutting will start to happen early on. Meaning you have a cell that cannot keep up with the rest. This is a tired pack. Swelling is also a sign. (Puffed cells) Tired packs will keep going. Just that they won't be your best packs. Watch your tired packs more closely. They are the ones that can cause a fire.

 

[two0sicc]

thanks 2 all 4 input- your comments/knowledge/opinions are valuable!

 

[21STalion]

Read a paper recently on lipo battery longevity and a huge factor regarding number of charges you got was related to the max charge voltage.

Blah blah blah charge to less than 4.2v and they will last much longer. 4.15v is nice. 4.1v is probably the lowest I'd bother going to.

Sorry I don't have a link to share.

 

[jkflow]

@21STalion you are correct, but look at applications and where it makes sense. I have yet to own a lipo that lasted 3 years in bashing. My flight packs lasted 7 years, and they degraded by age more than abuse from bashing.
The life expectancy is fairly flat with respect to charge rate going from 0.5-1.5C charge rate but is exponential on both ends.

Where this makes perfect sense is in Solar or other long term power solutions.