Lipo questions need answers!

[Bigmaxx]

I bought three of the same 4s lipos from hobbyking an two have been sittning for two months.

1st question is, is that ok for them to sit like they came from hobbyking?

2nd question is, how long can a balanced lipo sit before needing to do anything to it?

3rd question is, the one I have been using is alittle bigger than the ones I haven't even used, it's not that noticeable but I can tell when I put one I have used next to the new ones, the one i have used i charged , balanced it correctly so I knw that's not the problem . So is that normal?

 

[tmaxxfreek]

as long as they were Charged to Storage Voltage when they shipped them they will be fine.

I never let mine sit over a few days, i think they are fine sitting longer than that but i never take the chance.

The one you have been using could have "Puffed", this happens if the battery is over charged or the C rating isnt high enough for your motor/esc setup, overheating the battery can cause this too. I'm sure there are more experienced guys here that will answer your questions as well.

 

[trax de max]

the one thats used may be just normal swelling with use, sometimes it's easier to see when comparing it to a new lipo, but normally without checking it with an identical pack it could look like swelling, maybe 2mm top and bottom and 2mm on sides. If a pack starts to puff you can tell without comparing with an identical pack. It just feels different. But swelling and puffing are different. Take a pic if you can. But like above it could be from charging too high a current, draining the battery pretty low, even hitting the lvd often, causes puffing, or just smaller specs than the rc needed.
But remember pics speak 1000 words.

 

[Greywolf74]

If the lipo is storage charged it can set a couple months before needing to be checked. If its fully charged I typically try and not let them sit for more than 2-3 days before either using them or storage charging them again.

As for the slight swelling it can be caused by the factors above. Id keep an eye on those factors as much as possible (over charging, Over discharging, temps etc) and as long as you dont see those things happening then I probably wouldnt worry about it unless the pack actually puffs which will be noticeable without comparing it to another lipo.

you may want to invest in a charger that measures internal resistance of the cells too. That can help you determine if your cells are being damaged during charging or use as the IR will start going up considerable amounts if it is being damaged. Those types of chargers arent very cheap though.

 

[Bigmaxx]

I have only ran the lipo 6 times, I will try to get pictures up shortly. I do run the battery till esc Lvd kicks in, I think it's set on 3.6 , il have to recheck to make sure what it is. Is that not good to run them down till Lvd turns on?

 

[trax de max]

the lvd is there as a final barrier, 3.6 isn't low and should be ok if it was 3.3 and under then that normally stresses the battery and significantly shortens the battery life. It's ok on a charger as the load is much lighter than what the motor would pull.

 

[Bigmaxx]

Here is two pictures, hope you can see or tell, I tryed taking fifty plus times it just not noticeable in the picture

http://s1258.photobucket.com/albums...ction=view&current=1357946149_zps0b5dd976.jpg

http://s1258.photobucket.com/albums...ction=view&current=1357946212_zps1b5a7ae5.jpg

 

[trax de max]

the first pic looks like the wire is leaning the battery at an angle so it's hard to tell.
the second looks normal use.
soft cells can appear to show slight swelling, with hard case you can't tell until it's too late.
nano techs are quite decent for cheap packs, but the higher capacity packs aren't as good as the smaller packs. They are delicate at low voltage. Has it got wet, Whats the charger your using.

 

[Bigmaxx]

Its never got wet, the batteries is always cold after use. I have a IMAX b6ac charger

 

[trax de max]

If you have a volt meter check the voltage of the pack, If you have a lipo monitor that plugs iointo the balance plug check the cell voltages after the charge.
I'm sure i read a while back that charger was going over the charge limit, i think they had to change some resistors in the charger to make it more accurate.

 

[Bigmaxx]

I have noticed with the charger that when charging/balancing that the voltage is different in the balancing than the storage setting(not sure if that's what's it suppose to do)an when the charger says the 4s is charged at 16.8 the balancing cells menu the numbers don't add up, like for example will say the battery is 16.8 but when looking at the cells there like 4.0 not 4.2, is this how it's suppose to do?

 

[trax de max]

they should be 4.2. I think the charger is giving false readings. If there's a way to check the voltage of the cells with a meter,either at a hobby shop/electronics shop. or yourself but being careful not to short out the cells.

 

[Bigmaxx]

Yeah , I have to look into that, so this charger isn't anygood? Or just get a voltage checker an it would be fine?

 

[Greywolf74]

you have to be sure the device you are using to check the lipo voltage with other than your charger is accurate too. My first multimeter I had when I got into the hobby was old and cheap and as a result I eventually figured out that it was way off.

I've also owned actual voltage checkers that you plug into the balance plug of a pack and it gives you the overall voltage followed by the individual cell voltage that were not reading correctly too. the first run of the 6S Dynamite volt checkers had that problem.

Just a thought.

 

[Bigmaxx]

Can you point me in the right direction of one that would read accurate ?

 

[Greywolf74]

I would start by comparing yours to maybe a friends if you have a friend that has a good high quality multimeter. If you dont know anyone maybe take it down to your local hobby store and see if someone there has something you can compare yours to. If yours is close to theirs then its probably fine.

 

[usv568]

I have a thunder ac680 charger and I charge my packs after every race and check them with a voltage meter after every charge to make sure I'm.getting full charge and balance. So far what the charger is telling me what each cell is doing and the volt meter is saying there spot on. I know its not a top of the lime charger, but it works. I also don't run my packs down to the lvc either, I get back in the pits pull the battery and it goes on the charger, and I always balance. I paid $49 from hobbyparts and I'm very happy with it. I have four packs with me on race day at any given time, usually one on the charger and three ready to go. If I'm not going to use them in a couple days I put a storage charge on them. Doing this my packs have lasted are still in good condition after multiple.chargers and great output.

 

[trax de max]

from just what i've read in the past the chargery BM-6 voltage monitor is quite accurate.

 

[Bigmaxx]

Yeah I need a new charger this cheepo sucks