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HomeRC & Power✈️Aircraft🚁Helicoptere-Electric Battery-Charger-pSupply › Why do Some Lipos take so DANG LONG to Top Off???
03-31-2012 04:56 PM  7 years ago
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flustercluck

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Newnan Ga (Just S. of ATL)

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Why do Some Lipos take so DANG LONG to Top Off???
Fellas maybe you can explain some lipo mysteries to me here.

Ok, I have four (long story) of the Hobbypartz AC6 ac/dc chargers. Love em, work great, no probs (knock wood).

I also have about two doz of their Sky Lipos, in all sizes & cells. Love em, work great, no probs (knock wood).

But here's the thing: some lipos take forever to top off; ie, complete the charge cycle wherein the charger displays FULL and it's done.

Here's the behavior:
Regardless of my initial charge rate, from .1 to 5A (the charger's max), the unit always varies the charge from high at startup (ie, 4A) to low (ie, .1A) when it's almost done.

In other words, you can start with a 4 or 5A charge, but none of the units will maintain that 5A throughout the cycle (I suppose that's normal, so as not to overcharge?)...the amps trickle down as the batts charge.

On some of my 3S & 4S batts, they never seem to tell the chargers they're done...so the chargers (all of them) trickle down to .1A, and then add like a single mah or a few mah (visible on the total mah display) for what seems like forever- or until they time out and stop.

Eg, long after nominal voltage has been reached (3S 12.6 or 4S 16.8) I can stop & restart the chargers; and after like 30 sec or a minute, it will have added only 1 or 2 mah. Or maybe 5 min will pass and it's only added like 10mah.

So I never really know if the packs are "fully" charged. They're showing the correct topped-off voltage, based on 4.2V per cell, but I can't tell if I've put enough "fuel back in the tank", mah-wise.

Just a handful of my batts do this but it drives me nutz, since I never know if or when they're done.

Any ideas???

thx
Jeff

(Battery care note: I baby all my batts, never running below 20% of rated mah and I always balance-charge. No packs are puffed.)
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03-31-2012 06:24 PM  7 years ago
flyride

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Salt Lake City UT

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It usually happens when the cells are out of balance and it is slowly balancing them at the end. Some packs just start to wear abit after time and take longer to balance out. If you can check the voltage of each cell with the charger and all are at full charge then you are ok to take off the charger as the few extra mah it will put in at the end when it takes forever wont really matter. I have batteries that if I don't use them for a week or two it takes forever for them to balance but if I fly them and charge soon after they charge up fast.and the blonde said "RECTUM, Hell damn near killed em!!"
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03-31-2012 09:34 PM  7 years ago
A&J

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Hudson FL 34667

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wrong charger

I chareg two 6s packs @ 20amps in 20 mins all charge and balance

love that FMA charger
Lets do the time warp againnn !
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03-31-2012 10:16 PM  7 years ago
Shortman

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Portland, Oregon

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The chargers also "ramp" down when getting close to the finish of a pack. If you really want to charge fast, you can take the packs off when they are at 4.15v per cell, the last 5% of charge can take 20 minutes where the first 95% only took 20 minutes to charge.Team JR
Team ThunderPower RC
Boca Bearings
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03-31-2012 10:19 PM  7 years ago
A&J

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Hudson FL 34667

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my packs charger 100% in 20Lets do the time warp againnn !
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03-31-2012 10:27 PM  7 years ago
TheWoodCrafter

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Costa Mesa, Ca.

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High output chargers will do wonders.
Makes thoughs little 50watts chargers look like toys.
Thanks, TheWoodCrafter
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04-01-2012 10:37 PM  7 years ago
pyroM!KE

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Poteau,Oklahoma

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When you use your pack and then put it on the charger, what do each individual cell voltages look like? say if its a 3 cell, and you put it on your charger, and it says 3.90 3.91 3.75 then your pack has seen better days(dying)..Even when they are discharged all cells should be pretty close..At least within +or- .05v or closer..
I always charge my packs at no more than 1c and stick to the 80% rule..My packs seem to last longer than most of my buddies..
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04-04-2012 02:33 PM  7 years ago
CoronaL

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Winnebago IL

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depends on BOTH the packs and the charger.

if packs are slightly out of balance, the charger is trying to re-Align the balance at the end of the charge. Cheaper chargers have a smaller balancing capacity, so many MAH capacity that is. Like sucking a Wendys frosty through a cocktail straw. The FMA charger as a 1amp(I believe) balancer. That's why I like the FMA charger as it not only charges great, but the balancer is generally working well through the charge cycle with higher capacity so that the tail end of the charge is not left to try to balance cells that have been out of balance the rest of the charge. And if they were still out of balance by chance, they will come in line quicker with the FMA charger(PL8)
Randy!!! I am the liquor
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04-05-2012 03:54 AM  7 years ago
Egroeg

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Cyprus

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I charge 6 4000Mah packs in parallel in 26 minutes.
The charge is there at 15 minutes...the next 11 minutes is where the trickle charge goes on.
No Pitch...No Fun!
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04-05-2012 03:55 AM  7 years ago
VKGT

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Sanford, NC

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Which charger? I like my Hitec x4 but now that I have all these plans for 12s helis, I need to upgrade
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04-05-2012 04:05 AM  7 years ago
Egroeg

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Cyprus

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PL8 parallel charging and a meanwell 1500 W PSU.
You will NEVER look back.
Trust my word
No Pitch...No Fun!
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04-05-2012 04:19 AM  7 years ago
Stephen Born

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USA

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But here's the thing: some lipos take forever to top off
My question: Do you ever balance charge? How often?
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04-05-2012 05:16 PM  7 years ago
flustercluck

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Newnan Ga (Just S. of ATL)

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When you use your pack and then put it on the charger, what do each individual cell voltages look like?
Pyromike, for both my 3S & 4S, they are all within .01V of each other the moment they go on the charger... eg 3.96, 3.95, 3.96, etc ...so from what I can see they are discharging & charging in a balanced manner
I always charge my packs at no more than 1c and stick to the 80% rule..My packs seem to last longer than most of my buddies..
Regardless of where I set the initial charge amps, the AC6 always seems to vary that figure based on what the specific batt will accept (??).

I fly hard and charge often, & so far so good. But some of my batts never seem to tell the charger "stop- I'm done!"
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04-05-2012 05:18 PM  7 years ago
flustercluck

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Newnan Ga (Just S. of ATL)

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My question: Do you ever balance charge? How often?
Every batt, every time, w/o fail.

But for whatever reason, some batts will go to the charger timeout (currently set at 120min) and STILL not be done.

This is what drives me nutz.
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04-05-2012 05:59 PM  7 years ago
pyroM!KE

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Poteau,Oklahoma

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You might want to look into a new charger..Ive owned cheaper chargers before and had good luck with them..But recently I have purchased a new Team Orion Twin spek charger and its pretty sweet! Its like 2 chargers in 1..I can charge 2 packs at 10a each.. Just break down and get a quality charger..Youll be happy you did..
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04-05-2012 11:04 PM  7 years ago
Stephen Born

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USA

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Every batt, every time, w/o fail.

But for whatever reason, some batts will go to the charger timeout (currently set at 120min) and STILL not be done.

This is what drives me nutz.
Go to the field and ask a pilot kindly if you could use his charger. See what kind of results you get. I would be interested in hearing the results.
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