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Batteries & Chargers Discuss Li-P, Li-Ion, NiMh, Nicad battery technology and the chargers that juice 'em up!

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Old 11-21-2013, 01:19 PM   #1
dontrinko
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Default How do you charge/store your battery's?

I'm new at using lipo's. I have done a lot of reading and not sure how I want to charge/store my battery's.
I understand that storing fully charged shortens the life. (from what I read 20% loss at 20 degree c for one year storage)
If I don't keep them fully charged I will have to charge immediately before use. This is inconvenient; Many times I fly at half time of a ball game.
I also understand not to leave them discharged for long.
I have 70mah, 130mah,150mah, and 500 mah single cell battery's and 800 mah 2 cell battery's. I have several single port chargers; the ones that came with the helicopters ( .3 amp) a Celetra (.1 to .7 amp) and a 2 cell charger for the 800 mah battery's.
1. Can I use the celectra at .1 amp to charge the 70mah battery's?
2. What do you do? I'm thinking of leaving the small (cheap) battery's fully charged and replacing if/when they loose capacity and partially charging the 500 mah and 800 mah after use.
3. The chargers I have have a indication (flashing light) when the battery's are almost fully charged. What this be a good indicator of the proper charge level for storage? Thanks; Don
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Old 11-21-2013, 02:41 PM   #2
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I charge mine the night before I fly, or first thing in the morning.

if your always flying during halftime of a ball game, ill bet you have a pretty good idea of when you'll be flying .

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Old 11-21-2013, 04:50 PM   #3
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We like to warn of the potential danger, but I've been using LiPos heavily for years with no accidental fires.
(I'll stick a screwdriver through a pack that is bad and toss it out on the paved runway)

I just keep the charger and the packs being charged on some spare 1 ft square ceramic floor tiles and ensure there is nothing easily burned too close.

Charge the day before flight or at the field.

The single cell "packs" less than 200 mah are safe to charge at "3C" or a rate that fills them in 20 minutes. .1 amp for 70 ma pack is 100/70 C or about a 40 minute rate. You could go with the 200 ma rate. The 100 ma rate is safer, but not much.

Generally I store packs at the LVC shutoff voltage. For most of my planes this is between 3.6 and 3.8 V per cell.
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Old 11-21-2013, 05:44 PM   #4
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Originally Posted by fhhuber View Post
Generally I store packs at the LVC shutoff voltage. For most of my planes this is between 3.6 and 3.8 V per cell.
Yeah
I did some work with young members with an interest in the EAA last year. And after they put some flights on their model, they were left as is. One fully charged, one about 1/2 charged.

After six months, that fully charged LiPo still shows fully charged, but can't turn over the motor. It's shot. Don't know if its a dud, or if all LiPos do that.

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Old 11-21-2013, 05:50 PM   #5
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Thanks for the information. I have several digital voltmeters but I have to adapt to the tiny battery plugs. Is there an easier way? I see little crk boards on ebay. Are they any good? Don
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Old 11-21-2013, 05:53 PM   #6
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Originally Posted by dontrinko View Post
1. Can I use the celectra at .1 amp to charge the 70mah battery's?
2. What do you do? I'm thinking of leaving the small (cheap) battery's fully charged and replacing if/when they loose capacity and partially charging the 500 mah and 800 mah after use.
3. The chargers I have have a indication (flashing light) when the battery's are almost fully charged. What this be a good indicator of the proper charge level for storage? Thanks; Don
1. You can charge at 0.1A, It's a little over 1c charge rate but personally I'd not worry about it.
2. If you buy a halfway decent charger (even a cheap 50W charger) you will be able to charge those relatively small batteries in about half an hour, so no real need to buy 'extra' batteries just to leave them charged. Charge earlier in the day and fly when you want.
3. Unless you over discharge your batteries (which should always be avoided) you can just put them into storage with the charge that is left, so no special need to charge up to storage voltage. The main advantage of charging up to storage voltage is that it shortens the final charge time. if you buy the halfway decent charger referred to in the last reply then it will automatically do storage charge/discharge.
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Old 11-21-2013, 06:46 PM   #7
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Originally Posted by dontrinko View Post
Thanks for the information. I have several digital voltmeters but I have to adapt to the tiny battery plugs. Is there an easier way? I see little crk boards on ebay. Are they any good? Don
Yeah, I've also got a handful of digital meters from the cheap Harbor Freight units to $$$$ Fluke 87's.

But, seems to me that somewhere you can buy a LiPo battery meter that reads individual cells, just by plugging it into the battery balance cables.

Can someone locate one of these meters, and provide a web site for it?

Thanks.

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Old 11-21-2013, 06:56 PM   #8
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Originally Posted by kyleservicetech View Post
Yeah, I've also got a handful of digital meters from the cheap Harbor Freight units to $$$$ Fluke 87's.

But, seems to me that somewhere you can buy a LiPo battery meter that reads individual cells, just by plugging it into the battery balance cables.

Can someone locate one of these meters, and provide a web site for it?

Thanks.
commonsenserc.com
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Old 11-21-2013, 08:34 PM   #9
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Default LiPo Battery Care and Use experience

A great battery checker:
Hyperion EOS Sentry Battery Checker for about $25. Gives % Charge and individual Cell voltages thru Balance Connector. Also measures Receiver Batteries via Servo Connector. Great for distinguishing between depleted and fresh batteries!

Care and Feeding of LiPO's:
1. Look at 'Battery University Link' for some good advice and data:
http://batteryuniversity.com
2. If you must store Fully Charged batteries, do so at low temperatures (i.e. in 40F Refrigerator). Fully charged batteries tend to Gas over time which causes swelling and reduced life. Best to charge batteries just before use.
3. Store batteries at about 40% of Charge and Top them off every few months. I compromise and store mine at about 60% during the flying season so that I can charge them while I am driving to the flying field.
4. For maximum life, discharge to only about 50-60% Charge Remaining. Pushing the battery to only 20% Charge remaining will result in lower numbers of Charge/Discharge cycles. I can do 6minute runs on my T28 with 3Cell 2200mAH batteries with remaining charge levels of 60%.
5. For maximum life, charge to only 4.1V per cell (~90% of capacity)
6. Don't charge at high temperatures and at more than 1C rates (except for smaller batteries if manufacturer allows).
7. Use the Integy C23212 Lipo Voltage Checker/Warning Buzzer in flight for multi-cell park flyers to make sure that high throttle runs are not draining the battery to low levels. This ~$10 gizmo plugs into the Balance connector and has a LED Voltage readout and programmable warning buzzer which can be heard from the ground. I set mine for 3.7V/Cell on my Parkzone T28. If I am doing high throttle flying, it starts to buzz at full throttle when the battery is nearing the safe operating limit. It will also alarm if you have a bad cell that is dropping voltage prematurely. It is small and weighs <10gm so it usually will fit in battery compartment.
8. Do use a 'Balancing Charger' so that all cells are kept matched.
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Old 11-21-2013, 09:22 PM   #10
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Bear in mind that only charging up to 90% then only fly down to 60% means that you only use 30% of your battery capacity. That's only 660mAh from your 2200mAh battery

While i don't doubt that (in theory at least) this may optimise your battery cycle life it will also drastically reduce your flying time to less than half (nearly a third in fact) of what you would enjoy if you fully charged then flew to 20% remaining. I usually charge to 4.2v and fly to 3.7V (20% remaining). Many of my batteries are over 300 cycles and going strong. If I had only used 30% of my battery charge then I'd have done less than half the hours of flying, but would my batteries really last over twice as many cycles? To be honest even if they did last twice as many cycles I'd still rather have the flying time.

I'll draw an analogy to buying a Ferrari then pottering around at 30mph to maximise gas mileage... it's totally missing the point
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Old 11-21-2013, 09:51 PM   #11
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I am no expert on lipo's but I think battery's of all sorts tend to die after a few years no matter how you use them. So is it really worth jumping thru all sorts of hoops to keep a $5 battery going a few extra cycles? Don
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Old 11-21-2013, 10:23 PM   #12
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My 2c.....when I started this wonderful flying part of the RC experience (raced 12th scale carpet cars on Nicads back in the mid-80's) approx 5yrs ago I had no idea how to care for my lipo batteries. I kept every battery topped up just so I could fly at a moments notice (I live across the street from an accessible soccer field)......but after a few months none of my batteries had much punch or nearly the capacity they once did
I was told by a good friend that if I left them at storage or nominal (11.1v approx for 3s) until I was ready to charge them that they would last much longer. I tried it and was pleasantly surprised that even after sitting months at a time they would perform as new . I use this HK charger, has been good to me for a long while and will charge 1s to 6s. http://www.hobbyking.com/hobbyking/s...cessories.html
I use mostly low and middle of the road grade lipo's and don't run them hot or down to LVC ever so quality doesn't have much to do with how my batteries live. I discharge my packs after a day's use with tail light bulbs (2 for the smaller packs, 3 for the bigger....5 and 8amps respectively ) and a cell checker with adjustable alarm ( http://dx.com/p/1s-6s-lipo-battery-v...er-alarm-72381 ) to tell me when it's discharged enough.
It's up to you to know if keeping up with your batteries life and health is worth it......me, I just hate for things to go to waste if I can help it
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Old 11-22-2013, 12:55 AM   #13
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Originally Posted by dontrinko View Post
I am no expert on lipo's but I think battery's of all sorts tend to die after a few years no matter how you use them. So is it really worth jumping thru all sorts of hoops to keep a $5 battery going a few extra cycles? Don
Yeah
That's why I've been using those over weight, over sized, under voltage obsolete A123 cells in all of my models. They don't have the storage issues of the LiPos, no puffing, you can recharge them repeatedly with a 15 minute charge. And I've got 6 year old battery packs with 400 flights on them that still have 95% of the mah as when they were brand new, and still turn the same motor and same prop at the same RPM.

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Old 11-22-2013, 08:06 AM   #14
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In my experience, lipos have no issue as long as you leave them at a mid charge level of around 3.8V per cell. Leaving them near empty or at full puts strain on the batteries. I am new to rc flight, but have been in rc for many years. I am running an rc car that goes 75mph and have never had issues with puffing, and I run my stuff to the max, meaning the motor runs at near 200 degrees. I put my knowledge right into the planes I am getting into. You will never have puffing as long as storage is kept with what I stated above, and also that the batteries are never pushed passed what they can deliver, based upon their C rating and capacity. Now lipo care does get annoying, and I have a near dead battery now because of it. Getting into planes has caused me to have about 8 different packs of 4 different sizes and it is hard keeping up, but I simply try to remember that if I am putting the car or plane away for a bit, just slap all the batteries on a charger and put into storage mode. I have heard of some putting lipos in the fridge, but there is no need really, you aren't going to get that much more life. Also, don't charge too quickly. While lipos can be charged faster than nimh, the slower the charge the easier it will be on the battery. If you get too high on the charge rate, the battery can puff. Essentially don't do anything stupid with the batteries you have. It's okay to wait a bit for the charge to finish. Also, test the battery with your setup. Run the motor with prop on on full throttle for a minute. If there is any noticeable change in the temp, then if may pushing the battery. At no point should a lipo get hot, preferable change in temp much at all. Essentially, storage is nothing if you are not watching how the battery is doing during use. When storing, the charge you use should have a storage mode, and this is all your really need to keep the life of the battery long. Naturally, the battery won't live forever.
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Old 11-26-2013, 11:08 PM   #15
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I charge mine as fast as they can and use immediately. Then they set until next time. Only if something strange happened or the pack is suspect of being weak, out of balance or overdischarged will I do anything else to it. If they are over 3.5 then they set. I very rarely leave any full, and if so it is only a day because something strange happened that I didn't get to use it.
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Old 11-27-2013, 12:58 AM   #16
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I use a lipo bag from headsup its fireproof
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Old 11-27-2013, 02:03 AM   #17
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Originally Posted by zoltron55 View Post
I use a lipo bag from headsup its fireproof
I see no need for a fire proof bag. As long as you aren't rough on lipos and balance charge them regularly (I usually balance charge every couple of uses), storage charge them and don't run them over what they can handle, lipos aren't any more dangerous that other batteries. Some strap lipos to the bottom of planes and they can take a beating when landing and even more when crashing, that can lead to damaged cells which makes the pack unstable. With rc cars it's not much of an issue, but don't empty the pack. Eve without
A timer, you should be able to figure out how long a pack will last. I don't use a timer, but know when I should take the plane down. Usually I am left with a third charge left. Have multiple packs so you aren't trying to get the most out of one. Having driven rc cars for many years and quite a few years with lipo
I have learnt how to take care of electronics, find limits of batteries, amp pulls from motors, and so on. I just apply the same to planes. In fact batteries should be in better shape in planes than rc cars, simply because you aren't giving the batteries any shock until landing or crashing. More or less, storing is the easy part, it's learning to use the pack properly that will keep it stable and functional.
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Old 11-27-2013, 06:24 AM   #18
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I only fly once a week,so the batteries i use are storage charged when i get home.I then charge them the day before i next go out flying.
However,I do have several packs that i haven't used for some time.
Perhaps I should run them down,and then storage charge.
Btw.,I use a cheap little beeper alarm connected to the balance plug.Even with several planes in the air,I can clearly hear the beeper when the battery is at it's lowest safe voltage,e.g. around 3.3v per cell.
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Old 11-27-2013, 06:33 AM   #19
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Originally Posted by DHC Beaver View Post
I only fly once a week,so the batteries i use are storage charged when i get home.I then charge them the day before i next go out flying.
However,I do have several packs that i haven't used for some time.
Perhaps I should run them down,and then storage charge.
Btw.,I use a cheap little beeper alarm connected to the balance plug.Even with several planes in the air,I can clearly hear the beeper when the battery is at it's lowest safe voltage,e.g. around 3.3v per cell.
Actually a very good idea, especially for planes, as you can leave out the timer essentially. If your plane has a really powerful motor, I would set that to 3.6v per cell or so, as there is a degree of voltage sag that will take the battery down to 3.3 or less under heavier throttle use. For a more of a trainer or a plane that isn't meant to go fast, 3.3v is great. I head of these beepers for escs that don't have cutoff, and as far as I know, most brushless esc for any form of rc have cutoff, or a half power drop, but the beeper can really help if you set it above what the esc will cut power at. Very good idea.
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Old 11-27-2013, 06:59 AM   #20
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Originally Posted by thepiper92 View Post
Actually a very good idea, especially for planes, as you can leave out the timer essentially. If your plane has a really powerful motor, I would set that to 3.6v per cell or so, as there is a degree of voltage sag that will take the battery down to 3.3 or less under heavier throttle use. For a more of a trainer or a plane that isn't meant to go fast, 3.3v is great. I head of these beepers for escs that don't have cutoff, and as far as I know, most brushless esc for any form of rc have cutoff, or a half power drop, but the beeper can really help if you set it above what the esc will cut power at. Very good idea.
I think you have your Voltages the wrong way round .....

On a HIGH draw motor - you want 3.3v ... on a LOW draw motor you may get away with 3.6v

Personally I advise all LVA's to be set at about 3.4v ... as long as battery bounces back to over 3.5v there should not be any harm done ... the recc'd storage voltage ranges from 3.7 to 3.85v depending on which site you read.

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Old 11-27-2013, 07:03 AM   #21
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Originally Posted by solentlife View Post
I think you have your Voltages the wrong way round .....

On a HIGH draw motor - you want 3.3v ... on a LOW draw motor you may get away with 3.6v

Personally I advise all LVA's to be set at about 3.4v ... as long as battery bounces back to over 3.5v there should not be any harm done ... the recc'd storage voltage ranges from 3.7 to 3.85v depending on which site you read.

Nigel
I'm confused by what you mean. A higher draw motor would put more stress on the battery, and cause it to voltage sag more. I think I must have written something wrong in the last post
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Old 11-27-2013, 07:10 AM   #22
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Originally Posted by thepiper92 View Post
I'm confused by what you mean. A higher draw motor would put more stress on the battery, and cause it to voltage sag more.
.... because what you said before would have the LVA sounding too early on the HIGH draw ... and the low draw would literally be wasted effort.

If your plane has a really powerful motor, I would set that to 3.6v per cell or so, as there is a degree of voltage sag that will take the battery down to 3.3 or less under heavier throttle use. For a more of a trainer or a plane that isn't meant to go fast, 3.3v is great.
It sounds daft - I see where your logic comes from ... to prevent HIGH throttle pulling battery down too low in DEMAND .. but short throttle bursts actually unless sustained do not do the damage you may imagine .. yes of course if you insist on really pulling one down - it will.

The low power draw model can afford to have its LVA set higher ... with the HIGH draw model lower setting.

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Old 11-27-2013, 07:22 AM   #23
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Originally Posted by solentlife View Post
.... because what you said before would have the LVA sounding too early on the HIGH draw ... and the low draw would literally be wasted effort.



It sounds daft - I see where your logic comes from ... to prevent HIGH throttle pulling battery down too low in DEMAND .. but short throttle bursts actually unless sustained do not do the damage you may imagine .. yes of course if you insist on really pulling one down - it will.

The low power draw model can afford to have its LVA set higher ... with the HIGH draw model lower setting.

Nigel
I think I understand where you are coming from. I too would set my LVC at 3.4V. If a motor is taking a lot out of the battery, once the battery gets low enough, it will have voltage sag, and a higher draw motor will put more stress and thus more sag on the battery. In terms of the beeper, I was thinking that it should be set to 3.6 or so, simply because if the motor is more demanding, it will reach the limit faster (the 3.3 or 3.4), so I would make the beeper go off earlier. If the plane is a slow flier, if the beeper is at 3.4v per se, it will probably get to 3.3v around the same time as a fast plane will get to 3.3 from 3.6, if that makes sense. My train of thought is that I would put the beeper on a more powerful plane at an earlier cut off, as it sucks the battery faster anyway, especially a plane that needs speed to fly at all, like an EDF, and you really have no option to deadstick at any point.
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Old 11-27-2013, 07:31 AM   #24
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Originally Posted by thepiper92 View Post
I think I understand where you are coming from. I too would set my LVC at 3.4V. If a motor is taking a lot out of the battery, once the battery gets low enough, it will have voltage sag, and a higher draw motor will put more stress and thus more sag on the battery. In terms of the beeper, I was thinking that it should be set to 3.6 or so, simply because if the motor is more demanding, it will reach the limit faster (the 3.3 or 3.4), so I would make the beeper go off earlier. If the plane is a slow flier, if the beeper is at 3.4v per se, it will probably get to 3.3v around the same time as a fast plane will get to 3.3 from 3.6, if that makes sense. My train of thought is that I would put the beeper on a more powerful plane at an earlier cut off, as it sucks the battery faster anyway, especially a plane that needs speed to fly at all, like an EDF, and you really have no option to deadstick at any point.
??

You've wiped me out with that ... trying to figure out what you want !

Simply - if I put my LVA to 3.6 on any of my EDF's - I'd literally launch and land. The LVA would be screaming at me shortly after launch.

One of the best uses of LVA's is actually on Heli's ... they don't dead-stick very well and auto-rotate needs height.

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Old 11-27-2013, 07:43 AM   #25
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Originally Posted by thepiper92 View Post
I was thinking that it should be set to 3.6 or so, simply because if the motor is more demanding, it will reach the limit faster (the 3.3 or 3.4), so I would make the beeper go off earlier. .
Yes, you are right the beeper will go off earlier, but that's the problem. If you set the alarm high in a high demand application it will go off well before the battery is even half drained, so either you have unnecasarily short flights landing with more than half the charge still in the battery, or you ignore the alarm (in which case what's the point?).

The alarm value should be:

Alarm value = Target resting voltage (say 3.7v) + Allowance for landing and go-arounds (say 0.1v) - voltage sag under load.

Note that it's 'minus' volatage sag, not plus.

Voltage sag under load can vary quite widely depending on load and battery condition/performance, anything between 0.1v and 0.6v is perfectly possible, some experimatation may be required to arrive at the optimum alarm value.
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