Justflying1

Does anybody know when a LIFE battery is reaching its end of life. I run dual batteries in most of my planes and have noticed that on one of my planes which is just 3 years old when I charge one of the batteries it's taking a very long time to charge than the other battery. However when I check them with a battery checker the two of them are showing 99% charge. This to me seems acceptable however what do you battery experts think. Should I be replacing my batteries every certain amount of time to be sure or am I just waisting good batteries. I'm not a tight arse in spending money on maintenance but don't want to spend money on nothing either.

josecilurzo

Jets are expensive, batteries are cheap, for safe reasons, we change ours ( lion, lipo and lige ), after 300 cycles or 2 years.
jose

gunradd

My Feedback: (9)

I have had 2 go bad on me. They started loosing capacity so I replaced them. You need to drain them low but do not drain them dead Probably around 3.0 volts per cell. Then recharge and see how many MAHs you put back into them.

bri6672

My Feedback: (6)

That a exactly the way to do it! I retire them after they have lost 20% of there totally capacity.

Len Todd

I use LiPo receiver packs. They come out of the planes for each charge. So, for me, there is a lot of battery handling, etc. --- I just recently had one that the + wire looked like it was flexing more at the battery connection than normal. The battery seemed to work and charge fine, until I load tested it. The voltage drop was more significant than normal. After close examination, the foil that the + wire was connected to was hanging by less than 20% of its original thickness/width. Point being don't count out wear and tear that may not be visible. This looming failure was under the protective cover. The battery can seem to work fine, look good and still be ready to fail. Consequently, I recently decided to replace all my Rxer batteries that are 2 years old or OLDER. Also, I am glad I have battery redundancy built into every large plane. Battery failures are one of our largest risks and are frequently encountered. Yet, that risk is easily and relatively cheap to minimize. So now, ... replacement is every two years for me also. And the newest ones will go into the Jet, once they too are load tested.

Justflying1

Thank you for the advise. However just a few things I don't understand 100%
when discharging to 3 volt per cell how are you supposed to know how many MAHs the battery is going to take. Is it all done with a battery checker to verify the capacity.
So as an example. I have a 1000 MAH battery which I discharge to 3v per cell. I recharge it and it takes 700 MAHs. How do I know that there was 300MAHs left in the battery to give it a 100% charge. I have been told to throw away batteries which no longer charge to 80% or take longer than usual to charge. I will be replacing the batteries in this particular plane but would like a little extra explanation with knowing if the battery is receiving the full charge or not. I have also been told that battery checkers don't work well with LIFE batteries, but than again this is questionable. .

bri6672

My Feedback: (6)

3v is pretty much 0 capacity. I run dual 1100mah A123 packs in my smaller jets, once every few months I cycle them and once they go bellow 800 mah I retire them. Obviously running 2 packs means if one dies in a flight the second gets me home, I put a voltage meter with a load on them before each flight ( not for capacity but to confirm the pack is working right)

thepamster

The only way to tell the true capacity of a battery is to discharge a fully charged battery to a predetermined level. 3.0 volts per cell really is not quite low enough. I discharge mine down to 2.5v per cell.
Hangtimes.com has the most info reguarding batteries.
http://www.hangtimes.com/a123_batter...iants_faq.html

I copied this from a section reguarding discharge.

Justflying1

Thank you

afterburner

My Feedback: (18)

+1 Every two years

Then I save the old packs to use in my fueler and on the bench to test equipment.

jhicks112562

buy one of the battery checkers that shows you mah left as a percentage. They are relatively cheap (under $30.00) and easy to use. Additionally, they have a button on them that ask for type of battery. When a LifE battery is plugged in to the battery checker, it shows a low percentage until you change the type of battery to LifE, then it shows the true percentage of mah left over.
And as always, if you ever have doubts about a battery, replace it!

bri6672

My Feedback: (6)

How does that work???? Most of those gauges base capacity on voltage which does not work for a LiFe battery, they hold their voltage till the end and fall off..

gunradd

My Feedback: (9)

My cell pro chargers have the percentage and I have found for LIFE batteries its very inaccurate and I don't trust it. MAHs back into the battery is the only true way of knowing your full capacity.

CraigG

My Feedback: (40)

I have been using these batteries for several years now on both my receivers and ECU's and never had one go bad. They are rated at 1000 cycles and loose very little charge even when they sit for months. Because of their flat discharge curve there is the misconception that safe-to-fly voltage is difficult to measure. Electrodynamics sells a handy little checker that measures voltage within +/- 0.005v under load. As long as the voltage is 3.3v or better you are good to go.

I don't cycle my A123's but I have a very good idea how much Mah they discharge per/flight and by closely monitoring their voltage I know they still have good capacity.,,,even my older ones. It's also nice that they re-charge quickly and safely.

Here's a link to the Electrodynamics tester: http://electrodynam.com/rc/EDR-207/index.shtml

Craig

azalner

My Feedback: (8)

Totally agree! The percentage meters seem to be fairly accurate with LiPo chemistry but definitely not with LiFe chemistry. Discharge to 3 volts and measure total mAh put back in to determine true capacity.

S_Ellzey

Checking how much you put in while charging can be misleading. As the cells age their resistance goes up, so more of the power put into them gets turned into waste heat, not capacity. The real test is how much you can pull out of them. One way to test that is to fully charge the battery and then put a fixed load on it till it reaches a set voltage, and check how long it takes. The device that Craig pointed to does this very nicely, but you have to do the timing. If the time gets much shorter, the capacity has gone down. You do not have to take them down all the way, just to a reasonable value, for LIFE 3.3 is a good point.

VF84sluggo

My Feedback: (55)

Good info, Craig! I think I'll put one of these on order today.

Calil

If the battery behavior seens strange to me, I throw it away and buy a new one. 3 years is a lot, and if you fly a lot you should buy new batteries NOW!

lxfly

Like Graig, I switched to Life for receiver in 2009 and from now 15 packs I still use 3 of the first A123/2300mAh packs in a helicopter(single) and a 50cc Yak (dual). Helicopter has more than 300 flights, Yak about 200.
With the helicopter I make 5 flights, with the Yak 10-12 flights, discharged at about 25-30% before charging at 1C.
Once or twice a year I discharge completely and check capacity, always control capacity charged, when recharging.Just do balancing sometimes. So the single pack is charged just over 60 times, the other about 20 times far away from the possible 1000 ?.
Just to say, as long as the Lifes do not show any anomalies they are working fine over years.
Nevertheless, should replace the packs perhaps next spring.

Stick 40

I just put one on order, did not know I could get one. I have been using A123 2 cell packs for inflight for some time. I just fly about 6 flights and recharge, never takes even half of the 2300 cap.

One more thing , from what I have read . I don't think we can go by the stated Capacity of a batter, as all are not make equal. If we get a new A123 2 cell 2300 Mah and test it, I drought we will get 2300Mah.

But do we take the 80% of stated capacity or the tested capacity???

thanks

sticks

Eddie P

My Feedback: (4)

On my packs - LiFe of Lipo - after the first 10 cycles I make a label and stick it on the side of the pack. It shows the max cell voltage of each cell after a full charge to within .01 volts for record keeping, the capacity of the pack on a capacity check discharge and also the date of service entry. That way I never have to fumble for records and always know what the pack condition is compared to the base line when they were new and broken-in. (Lipos have a chemical when new in order to increase their shelf storage life before sale. It will dissipate after the first 5 or so cycles but before those cycles they aren't really preforming at their base line performance yet). The first few cycles I put them on my Powerlab charger and cycle them several times at 1C to get them conditioned for their first use.