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Old May 15, 2015, 08:51 PM
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Adam Stallcup
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Life charging question

I am new to this type of battery. I am using the hitec x4 ac/dc charger. I went in through "user program" and told it I had a LIFE battery. While balance charging it says it is charging a LIFE battery, but when I click over to the individual cell voltages, they do not add up to the value in the total voltage on the main screen. With lipo's, I have seen at most that it is off by 0.02 for this, but this is off by 0.35 volts. Since I have never used this type of battery before, I was curious if I should be worried. It is brand new out of the package; just got it in the mail today in fact.

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Old May 16, 2015, 02:23 AM
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There's no reason why LiFe batteries should be any different from LiPos in that respect. If the values don't add up it suggests that perhaps there's a bad connection in one of the balance lead connectors. I'm surprised you charger doesn't sound an alarm because of the mismatch -- it presumably doesn't think it's enough to be concerned about.

When you've read the voltages, is that at the beginning or the end of the charge? Have you checked with a DVM to see what the cell voltages are?

I would unplug the balance connector plugs, and then plug them in again a couple of times to see if it improves. A quick spray of switch cleaner might also be good.
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Old May 16, 2015, 08:06 AM
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Adam Stallcup
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I thought about connections later on after the charge was through; Thing is that I have never seen this before with other lipo batts. I have another new one I purchased. I will try it today and see what I get. I will also charge a lipo and see what I get.

on another note, lipo's start to loose power and voltage very quickly around 3.6 volts per cell. What value can I expect with the LIFE batts. Is the low voltage alarm on the radio at the right voltage to take care of this? Or should I charge it before the alarm?
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Old May 16, 2015, 08:30 AM
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Life are pretty much drained once they hit 3 volts per cell resting voltage. I set my alarms at 2.7 volts. Also even though life and lipos should show similar on your voltage checker the life packs I've always noticed are almost never showing perfectly balanšed like one cell may show 3.31 and the other 3.30 and when I put mine on total voltage sometimes it does not add up.
This seems to happen most when fully charged. The thing about life is they charge to 3.6 volts per cell and when you take them off the charger they settle to as low as 3.3 per cell within five or so minutes. This is normal and if your checking voltages at this time your definitly going to see differences. Try waiting about a half hour after a full charge and check you voltages.
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Old May 16, 2015, 09:55 AM
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Adam Stallcup
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interesting info. The first pack was fully charged last night and this morning it is around 10.4 total for a 3 cell. last night it was 10.8... When I first plugged it in, I always go straight to the cell voltages screen on my charger to make sure the cells are all close, and both of them the #1 cell was almost half a volt less than the other two. The second one is charging now at a 1 C rating. is this ok?
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Old May 16, 2015, 10:03 AM
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Quote:
Originally Posted by chyorn View Post
interesting info. The first pack was fully charged last night and this morning it is around 10.4 total for a 3 cell. last night it was 10.8... When I first plugged it in, I always go straight to the cell voltages screen on my charger to make sure the cells are all close, and both of them the #1 cell was almost half a volt less than the other two. The second one is charging now at a 1 C rating. is this ok?
LIFE's are fully charged once they hit 3.60 volts per cell while being charged. They hold 95% of their charge after sitting on the shelf for months.

As for me, I top them off after a days flying and they are ready to go, next day, or next month. If desired, you can always top them off after sitting for a month, but it won't take much.

If you are worried about your pack, put a 20 ohm 5 watt resistor across it for five or ten minutes. After that all cells should be close to the same voltage.

About 3.3 Volts per cell while the load is on. For a few days after full charge with no load the cell voltage will be all over the place, from 3.6 to 3.3 Volts on each cell. That is normal.

Caution though. Don't forget about it and run your LIFE flat. That WILL damage them!
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Old May 16, 2015, 11:49 AM
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Adam Stallcup
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So when the transmitter says 9 to 9.2 volts on it then go charge it then?
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Old May 16, 2015, 12:02 PM
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So when the transmitter says 9 to 9.2 volts on it then go charge it then?
Nope. The under load voltage discharge curve of a LIFE is nearly flat. Their voltage drops off fast when they are nearly discharged. Just top it off after every day of flying and you are ready to go the next time you go flying.

These LIFE's can be stored at full charge, half charged, don't matter much.
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Old May 16, 2015, 02:23 PM
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then that totally defeats the purpose of having a LIFE battery; if I wanted to charge it everytime I use it, then I would have kept my NiCad battery.

I have been use a lipo for years in my 9503 as a lot of guys do, but I heard someone say that it is really hard on the transmitter with that extra volt at 12.6 vs a fully charged NiCad pack at 11.6. So I went with the LIFE so I could have a safe voltage.

The lipo gets me about 7.5 hours of transmitter on time, which means I charge it about once or twice a year for my radio. It is nice not having to charge it all the time. Yes I realize it is not a big deal to charge it every time, but it is just one more thing to have to remember and do before I can go play.
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Old May 16, 2015, 05:31 PM
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Set your voltage alarm for 9.3 volts and see how long you can use it.
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Old May 16, 2015, 06:23 PM
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Originally Posted by chyorn View Post
then that totally defeats the purpose of having a LIFE battery; if I wanted to charge it everytime I use it, then I would have kept my NiCad battery.

I have been use a lipo for years in my 9503 as a lot of guys do, but I heard someone say that it is really hard on the transmitter with that extra volt at 12.6 vs a fully charged NiCad pack at 11.6. So I went with the LIFE so I could have a safe voltage.

The lipo gets me about 7.5 hours of transmitter on time, which means I charge it about once or twice a year for my radio. It is nice not having to charge it all the time. Yes I realize it is not a big deal to charge it every time, but it is just one more thing to have to remember and do before I can go play.
IMHO there is nothing wrong with Nih batteries for the transmitters and their low level currents.

Where LiFe and A123's really work well is for receiver servo power for the larger models and their high powered high current servos.
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Old May 16, 2015, 08:11 PM
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how do I do this:

Quote:
Set your voltage alarm for 9.3 volts and see how long you can use it.
I tried this but did not work.

http://rc.runryder.com/helicopter/t572728p1/
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Old May 16, 2015, 08:20 PM
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What TX are you using? If it is a computer/programmable type then there should be an option in a menu someplace to set a voltage warning. Your comment in post #3 sounded like you knew how to set the alarm.

My TX also shows the voltage and even though I'm using a Lipo in it I usually charge it before I hit my alarm setting. The amount of time you get between charges is going to depend on the mAh capacity of the battery.
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Old May 16, 2015, 08:58 PM
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X9503; In post 3 I was asking if the default alarm value would be ok to use for the LIFE batt's. I have no idea how to change it. I tried the directions in the link above 4 times and nada. I have never used throttle hold as I am not a heli guy; I assume that T.HOLD is the switch I need? If the radio is on its back, I have tried the directions with the T.HOLD switch up and down; nothing gets me to the menu the link talks about. Any other ideas? I think the default value is alarm is at 8.5volts, but I am not for sure. My screen also shows voltage and with the lipo batt (the batt I am replacing with the life batt) I would charge it got to 10.2 volts as it seams to drop off fast after this.

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Old May 17, 2015, 08:28 PM
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I'm not familiar with the menus on that radio. You might try in the Radio forum for specifics on how to set it up.
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