How long will a lipo retain its charge

[12stepRC]

I'm new to the crawling and trailing section of rc but not rc itself. After I finish my exo kit I'm getting a wraith for crawling and trailing. I don't live really close to any place that's worth spending your time on but there is a REALLY good area about a hour away. When I get my wraith and I take it out there, is it possible to charge two or three lipos, throw them in a day pack and once im out there on the trail and a battery dies replace it with a charged one in the pack and so on?

long question short
how long would a fully charged lipo retain its charge on the trail while not in use and not plugged in to a charger.

And I'm guessing based on my pass semi knowledge of lipos , that given a lipo will last about 45mins to an hour or longer, correct me if I'm wrong, would the 3rd lipo be charged at all by the time I got to it?

Hope I didn't blather on too much

Thanks, much appreciated

[M1tch]

They will last for sometime. I regularly go out with 2 4000mah 3s batteries and they will give me over 2 hours of driving. Lipo's dont lose charge all that quickly once disconnected. I have used lipo's that I charged the evening before and they have been fine

Best bet is to get a small lipo checker. Not only will it let you know what the cells are at before you use them, you can check you esc cut off is working at the right voltage.

I have one like this. It's very small and compared with an expensive shop one it is as accurate.

http://www.ebay.com/itm/DYN4071-Dyna...item53fe515d25

[12stepRC]

Thanks for the reply, Wow that's a lot longer than I expected. what brand of lipos do you use, or does it matter, for the run time that is, because I'm looking at either gens ace or max amps, also would you mind me asking what setup your running as far as truck and motor ?

[12stepRC]

Oh that's not a bad price at all and nice and small.

[M1tch]

I use turnigy nano tech batteries most of the time. The ones I have are 40 to 90c, but I also use them in other faster trucks, so it makes sense to have the high power ones for both. You could get away with lower C rated batteries if you are just crawling with them.

I'm running a castle MMP with a Tekin 35 turn HD motor.

These are the batteries I use. They fit perfectly in the scale truck I have and also into a Vaterra Glamis Uno.

http://www.hobbyking.com/hobbyking/s...Lipo_Pack.html

[M1tch]

I'm not sure what size battery will fit the wraith. Obviously the run time will be different depending on battery size. If I want the truck to be lighter I have some 2250Mah batteries I could try. They weigh 7.4 oz against 12.6 for the 4000mah

[12stepRC]

Thanks for all your help that's all I needed to know

[12stepRC]

I take that back one more question have you ever had any trouble with those lipos ? And what charger would you recommend ? Thanks again

[M1tch]

No problem with the batteries. As for charger everyone has their own favorite. If you can buy from a local shop, then do that as any problems can usually be sorted quickly compared to buying online.

[hotwheels000]

A lipo's voltage loss due to storage is minimal. You could use a batt charged a month earlier and it would perform almost the same as one charged that day. With that said, it is not a good idea to store your lipos charged for a long periods of time.

I gleaned this info from a heli site:

"A LiPo naturally loses 2%-4% of its capacity per year even when left at "storage voltage" in room temperature. Cooling a partially-charged LiPo below 32F reduces that capacity loss to near zero. Cooling a fully-charged LiPo below 32F reduces its capacity loss per year to around 2-4%. Just don't charge a cold LiPo above 4.0v/cell! Note the actual battery chemistry itself does not freeze until around -20F (no water inside)..."

[Charlie-III]

Originally Posted by 12stepRC

I'm new to the crawling and trailing section of RC but not RC itself. After I finish my exo kit I'm getting a wraith for crawling and trailing. I don't live really close to any place that's worth spending your time on but there is a REALLY good area about a hour away. When I get my wraith and I take it out there, is it possible to charge two or three LiPO's, throw them in a day pack and once I'm out there on the trail and a battery dies replace it with a charged one in the pack and so on?

long question short
how long would a fully charged LiPO retain its charge on the trail while not in use and not plugged in to a charger.

And I'm guessing based on my pass semi knowledge of LiPO's , that given a LiPO will last about 45mins to an hour or longer, correct me if I'm wrong, would the 3rd LiPO be charged at all by the time I got to it?

Hope I didn't blather on too much

Thanks, much appreciated

Any type of battery will self discharge over time, depends on the battery chemistry & temperature of the battery.
Some chemistries discharge faster than others, none (that we tend to use in RC) self discharge as fast as you're concerned about.

When you get a charger, you can look for a dual input power version like a Venom ProCharger. The basic charger can be powered off a car battery/DC power supply. It also comes with a small power supply that can be plugged into a wall outlet.

Originally Posted by hotwheels000

A LiPO's voltage loss due to storage is minimal. You could use a batt charged a month earlier and it would perform almost the same as one charged that day. With that said, it is not a good idea to store your LiPO's charged for a long periods of time.

I gleaned this info from a heli site:

"A LiPO naturally loses 2%-4% of its capacity per year even when left at "storage voltage" in room temperature. Cooling a partially-charged LiPO below 32*F reduces that capacity loss to near zero. Cooling a fully-charged LiPO below 32*F reduces its capacity loss per year to around 2-4%. Just don't charge a cold LiPO above 4.0v/cell! Note the actual battery chemistry itself does not freeze until around -20*F (no water inside)..."

I think the 1st time you say "2%-4%" it should be "per month". But yes, it's a low discharge rate.

For most batteries (especially NiCD & NiMH), we used to charge them up the day before a race, then re-peak them a few times just before a race to top them off and get them warm. They lose a bit of voltage quickly when you do that, but then level out to a slower self discharge.

[12stepRC]

Well since you brought up nimh battery's I have a question, this happened to me yesterday I just charged a battery for my slash 2wd, unplugged it from the charger plugged it in to my slash, long story short my slash is broken yet again , got about 8 mins of run time and had no choice but to unplug and let it sit there, couldn't use it in any of my other cars, my question, will it hurt the nimh batt to sit there without use for another day or two maybe three ?

[ZippoMan]

I wonder how this li-po checker would work? Dirt cheap....
1 8S LED LiPo Voltage Indicator Checker Tester Low Voltage Buzzer Alarm T1K | eBay

[12stepRC]

I like to be able to see a name brand I can trust, I always prefer to spend money on something that you will probably never have to replace, at max once, and spend a little more as apposed to buying 30 pos's over a 2 year timespan

[rcmedic]

Originally Posted by ZippoMan

I wonder how this li-po checker would work? Dirt cheap....
1 8S LED LiPo Voltage Indicator Checker Tester Low Voltage Buzzer Alarm T1K | eBay

Works very well, it's really loud

[M1tch]

Originally Posted by 12stepRC

Well since you brought up nimh battery's I have a question, this happened to me yesterday I just charged a battery for my slash 2wd, unplugged it from the charger plugged it in to my slash, long story short my slash is broken yet again , got about 8 mins of run time and had no choice but to unplug and let it sit there, couldn't use it in any of my other cars, my question, will it hurt the nimh batt to sit there without use for another day or two maybe three ?

It won't hurt. It's long term leaving it discharged which will cause problems.

Originally Posted by 12stepRC

I like to be able to see a name brand I can trust, I always prefer to spend money on something that you will probably never have to replace, at max once, and spend a little more as apposed to buying 30 pos's over a 2 year timespan

My "pos" has lasted fine for 3 years. Also with it being cheap I don't worry about losing it.. A good investment I guess. I (or you) could always go to the lhs and ask them to check the battery if you feel the need.

[Johnnysplits]

Originally Posted by 12stepRC

I always prefer to spend money on something that you will probably never have to replace, at max once

You in fantasyland?

[Johnnysplits]

Originally Posted by ZippoMan

I wonder how this li-po checker would work? Dirt cheap....
1 8S LED LiPo Voltage Indicator Checker Tester Low Voltage Buzzer Alarm T1K | eBay

You're better off with this: Hyperion EOS Sentry Battery Checker | eBay

[6sharky9]

GensAce batteries for years..not a single issue and all still charge above advertised capacity and still perform..30 dollars or less except for my latest set..40 shipped,.

I get about 1 hr or slightly more with a 4000 2s 25c

[Olle P]

Originally Posted by Charlie-III

I think the 1st time you say "2%-4%" it should be "per month". But yes, it's a low discharge rate.

You're mixing up stored energy and capacity.

The capacity loss means that a nominal 1000 mAh battery will permanently lose 20-40 mAh of storage capacity per year, if stored under normal circumstances.
The charge will meanwhile drop from some 50% to 40% of that capacity.

That said, having a battery fully charged and then not used for a day or two is no problems. It's not like it will lose quite a bit of "bite" as a NiMH battery.
You can even have the battery at storage charge (to 50% capacity) and just plug it in for a run (with shorter run time).