lipos questions

[coactjet]

So i just goty first set of 6s lipos, so this is my first time charging them. They are 60c 6000mah hoovo brand. Set the charger up at 6amps, and the one side read 6.0amps the other was 2.0. so i stopped the charge to make sure the other battery was good. Checked out ok started the charge again. This time the readings were flip flopped. I am assuming i have reached the max output on ac , but i just want to confirm

 

[WickedFog]

Yup. You topped out the capability of your charger.

 

[bill_delong]

Can you provide a link to the charger you are using?

The most important feature to me is having an IR meter on the charger to know the health of your battery, more info here:

• Which charger is the best?

 

[tntpoof]

You have reached maximum watts of charger... That 2 amp charge wont hurt the battery .. maybe only charge 1 battery at a time to reach desired amps on charging...
Purchased a very expensive meter years ago when we in rc got the ir bug(maybe 2004 ish).it sits on a shelf collecting dust..I find ir useless to most bashers ,good for wanna be racers but .you can tell when a battery has reached its usable time

 

[bill_delong]

...I find ir useless to most bashers ....you can tell when a battery has reached its usable time...

To elaborate on this, I used to believe that visible appearance was sufficient where I would wait for signs of pack swelling to be my indicator of when I felt it was time to replace an older pack. It wasn't until I experienced a LiPo fire in my house while charging a pack that had no visible signs of swelling that I learned the importance of checking the IR. Fortunately I was able to get the pack outside before the pack burst into flames, but enough smoke had filled our home where it took SEVERAL WEEKS for the stank to clear out of the house... my wife was not impressed to say the least.

There are too many variables which effect the longevity of our batteries to provide any certainty, but knowing the IR of your batteries is a measurable safety feature that is by far the best feature that everyone should take very serious. If you don't know what your IR's are, then you've got ticking time bombs.

Of the dozen or so LiPo fires I've witnessed first hand over the years, not a single fire had any data collected on the IR for the pack before it burst into flames.

Since IR checking has become standard practice, I rarely see LiPo fires nowadays.

 

[Grizz03]

Agreed that charger output is reached.

You could try setting the charge to 4amps if you want to try having both batteries finish around the same time.

 

[tntpoof]

Bill you can say what you want ir testing has not decreased lipo fires its the technology that is put into them. unlike when rcers had fires..I saw a tv show a few years back where this scientist in Michigan invented this lipo he could cut pieces off with steel scissors and have no fire.I remember the 1st chargers dint have lipo balance options on them and would charge at 1 amp max..If I see a packs performance start to lessen its time to retire that pack it dont see my home again.
Bill invest in Ozone machine so next lipo fire you have the Ozone machine will get rid of that smell.A carpet installer told me about those machine 30 years ago I bought one with tubes then upgraded my internals to new plates and transformer and fan...Ozone will eliminate cat urine other smalls like fish.dead animals that die under your home.kids milk spilled in back seat so many more
the technology from when we 1st used lipos to today .I be leave the formula has been tweaked to help prevent accidents its not IR readings of cells alone...I have a common sence lipo 2 cell pack 3 of them had 4 but one grew legs at a race.. there IR are really high. 27 mohms.they will outperform any 2 cell 5000mah 110c pack...all 3 are in same fire proof box with built in smoke alarm ...so ir readings for safety are not correct.its the anti spark battery connectors..and much more

 

[bill_delong]

Side note... when a battery is new the IR of the cells are matched and you can use this as a baseline to measure how long it takes to charge the pack. If you don't have an IR meter, then I guarantee the IR of cells are no longer matched once the pack takes twice the amount of time to charge than when it was new. While the IR may still be acceptable, I would consider discarding the pack as you now have evidence that the IR has faded and the pack is no longer operating at it's peak performance when new.

 

[J’sCrawler]

You don’t have to charge the batteries with that many amps……

 

[tntpoof]

very very few cells have a perfect matching numbers in ir on new cells they might be close but match Id say almost never unless you pay for matched cell lipos.like back in the sub C days

 

[DavidB1126]

You don’t have to charge the batteries with that many amps……

True, but takes a very long time.
If you know me, I'm very impatient. Right @Lukedavis ?
well, coming from a racers perspective, a good charger with IR meter is needed. Higher charge rate means faster it can charge up for the next race, and from what Ryan Harris said, it can get a bit more heat in the battery and lower IRs, but, for a basher type of pack, not really needed.

 

[tntpoof]

its really funny how a guy thinks he made a spark when he vented a puffy lipo. heck he could have used a wooden stick and he would have gotten the same result a smoke show with fire in the end...
and when your in a sanctioned race it has rules one is temperature of the lipo you are going to race along with over voltage of the lipo...still think its 4.20 volts a cell

 

[bill_delong]

very very few cells have a perfect matching numbers in ir on new cells they might be close but match Id say almost never unless you pay for matched cell lipos.like back in the sub C days

I'm going to quote the following notes from the link I posted above, and perhaps you may begin to see the value of understanding the IR readings:

• Internal Resistance (IR) Meter - this is probably the single most important feature to me, this gives you the ability to check the overall health of your packs(take the reading immediately after a full charge). For example, a brand new pack might measure both cells below 1 mΩ, and then as the pack ages/degrades you will slowly see the IR increase over time... anything below 3 mΩ is still considered "low IR" but I start to notice pack swelling and degradation of performance (fade, etc) as soon as any individual cell goes past 7 mΩ... it's a very subtle difference and is hard to tell if you use the same pack and that's where having an IR Meter helps you decide when to retire a pack. I might still keep an aged pack for practice up until any cell hits 15mΩ but at that point I typically toss them out or give them away. I have also found that when any cell is farther than 1-2 mΩ apart, then the pack tends to take longer to balance and that's when I may consider selling the pack provided the cells are still below 7mΩ... I make sure to post IR readings of any packs that I sell and I would refuse to buy any used pack without IR readings so you understand the current condition of the pack!

The following pic was taken on a battery that was about 6 months old, I would consider the IR on these cells to be "fairly matched" where they're only 0.2mΩ apart. I personally feel that anything over 1.0 mΩ is when I'd say the cells are no longer matched:

 

[ahr43]

So i just goty first set of 6s lipos, so this is my first time charging them. They are 60c 6000mah hoovo brand. Set the charger up at 6amps, and the one side read 6.0amps the other was 2.0. so i stopped the charge to make sure the other battery was good. Checked out ok started the charge again. This time the readings were flip flopped. I am assuming i have reached the max output on ac , but i just want to confirm

OP, Try charging one battery at a time. Start at 6A, then drop the charge rate if you have to get a charge.

Regarding LiPo's in general: Personally I do not think LiPo technology should have ever been approved for release to the using public. But here we are and it's what we've got. So, we have to muddle through dealing with them and reading all the disparate opinions on what to do or not what to do.

Regarding IR: Bought a charger that was supposed to measure IR. It didn't. Shrugged it off and anymore if a pack puffs, discharge and dispose of it. At 36mo's age, discharge and dispose of it. Charge all at 1C. So far, so good.

 

[J’sCrawler]

True, but takes a very long time.
If you know me, I'm very impatient. Right @Lukedavis ?
well, coming from a racers perspective, a good charger with IR meter is needed. Higher charge rate means faster it can charge up for the next race, and from what Ryan Harris said, it can get a bit more heat in the battery and lower IRs, but, for a basher type of pack, not really needed.

Patience….. that’s what your extra batteries are for. Besides you race, you should know throwing a hot pack on a charge further expedites the degradation process. How’s that for big words?

 

[bill_delong]

... throwing a hot pack on a charge further expedites the degradation process....

I'd like to see this claim published somewhere with some sample testing explaining what temp limits can potentially degrade the longevity of the battery.

While I agree that any amount of heat causes batteries to degrade faster, I am not convinced that the pack needs to cool down to room temp because I often get better IR readings after a pack has been cycled and is warm which suggests there is a sweet spot where some amount of heat is acceptable.

I am suggesting that the high discharge rate causes more harm than the lower charge rate and temp of battery at charge may not be as critical as some might believe.

The following article provides key temp range conditions to limit when charging as temps increase but doesn't say anything about charging an already warm battery:
https://batteryuniversity.com/article/bu-409-charging-lithium-ion

*** UPDATE***

There are some more specifics on temp limits here:
https://batteryuniversity.com/article/bu-410-charging-at-high-and-low-temperatures

The way I'm reading this article, the "moderate temperature range" is defined as 41°F - 113°F... so long as the battery temp is below 113°F then we're golden

 

[J’sCrawler]

I'd like to see this claim published somewhere with some sample testing explaining what temp limits can potentially degrade the longevity of the battery.

While I agree that any amount of heat causes batteries to degrade faster, I am not convinced that the pack needs to cool down to room temp because I often get better IR readings after a pack has been cycled and is warm which suggests there is a sweet spot where some amount of heat is acceptable.

I am suggesting that the high discharge rate causes more harm than the lower charge rate and temp of battery at charge may not be as critical as some might believe.

The following article provides key temp range conditions to limit when charging as temps increase but doesn't say anything about charging an already warm battery:
https://batteryuniversity.com/article/bu-409-charging-lithium-ion

View attachment 182955

View attachment 182956


*** UPDATE***

There are some more specifics on temp limits here:
https://batteryuniversity.com/article/bu-410-charging-at-high-and-low-temperatures

View attachment 182957

View attachment 182958


The way I'm reading this article, the "moderate temperature range" is defined as 41°F - 113°F... so long as the battery temp is below 113°F then we're golden

Huh…. I stand corrected! I guess I always assumed after I ran the crap out of a pack I should let it sit for a while then charge it back up.

 

[bill_delong]

Huh…. I stand corrected! I guess I always assumed after I ran the crap out of a pack I should let it sit for a while then charge it back up.

not necessarily, because there are many times where I have a pack read close to 120°F after a race and that's 7° above the "moderate" temp range so you helped me seek out the information I needed to learn to look for that acceptable temp range, thanks for that!

 

[J’sCrawler]

not necessarily, because there are many times where I have a pack read close to 120°F after a race and that's 7° above the "moderate" temp range so you helped me seek out the information I needed to learn to look for that acceptable temp range, thanks for that!

Right on I won’t worry about letting them rest then!