Lipo questions - again !

[MichaelC]

Okay bear with me guys........ HobbyKing for some strange reason takes a long time to ship to me, so just got the first of three orders and this one is a 500mAh 3S 20C I planned on using on the Devo FPV camera and transmitter. I know last time I posted lipo questions a bar fight broke out, so please behave.

Questions:

1. I realized that I might have gotten the wrong battery. I think I want a lower discharge for the camera/transmitter (like a 1C or 5C ?). Is this a problem or the battery just drains out faster ?

2. I have been reading up on care and maintenance of lipo and I am doing most of them anyway even with NiCd and NiMH. I always charge them when I am around, never run them down etc etc. My question here is, do I have to worry about leaving them in tanks/radios if I don't use them that often ? I am planning on taking them out anyway when I am not using it but just to make sure.

3. One of my charger said that it won't charge if the battery drops below certain voltage, so does that mean I have to charge the battery once a while just to make sure it doesn't drop below that voltage ? I know that you are not suppose to drain them while you are using them, but what about it is just sitting there by itself for a long time ? Would it become useless ?

4. Taps. What is it ? Do I have to worry about it if I am already using a balancing charger to charge the battery ?

5. Is 20C a good discharge rate for running tanks ? Do I need more ?

6. I don't need a lipo low voltage monitor if my radios have telemetry to tell me the battery level. Is this correct ?

That's all and if you can let me know your best practices or opinion on these questions it would be great !

MichaelC.

[tomhugill]

1. Higher c value just mean if required the battery is capable of providing more current.

2. Jury seems to be out on leaving lipos fully charged. Some chargers have a setting to put in a storage charge, I've never used it but might be worth reading up on.

3. I think lipos hhold their charge well so shouldn't be a problem. If you've run it right down to 3v might be worth giving it some charge if your going to leave them a while.

4. No idea what taps are

5. 20c should be fine max current is capacity x c value so in theory a 20c 5ah pack could manage 100a discharge.

6. Correct, as long as you can see when your falling below 3v/cell

[MichaelC]

Thanks Tom........ That answers most of my questions. Taps apparently is something you do to measure the voltage across the cells to make sure that they are matching before charging them ? Seems like something the charger should do and we should not have to worry about it.........

[ALPHA]

1. Should be ok Micheal... if you have any doubts ... that might be where you might want to incorporate a mosphet circuit ...as the most that will happen is you will burn the power conduit to the cam

2.well it's the general consensus that it is better that you leave a charge in the battery... I generally follow the mantra as it does seem to hold true

3.Not sure what charger you are using Micheal... my charger auto detects battery condition...if it's no good it's no good ....one trick is to charge it anyway... just for a short while... let it sit... this allows the current to run and transfer through all the cells... I usually let it sit for about three weeks.... plug it in to see if I get a "chargeable reading" if so ...I let it go through the process.... I've had a 50% success rate with this...as I only had two problematic lipos so far... one revitalized itself... the other did..but didn't hold the proper power ...so that one got trashed

4.never worried about Taps... subject really never came up ...my charger has auto detect ...plus you generally don't want to be cutting open a lipo pack like you would with NiMH or NICDs

5.15 to 20 c is usually the standard.... going higher puts some of your electronics at jeopardy ... too low and you just get less play time..perhaps overheating in the battery cells... causing them to bloat... but not really a big concern

6.yup .... though some like the gadgetry of having a meter there..is isn't really necessary


But it sounds like you have a good grasp on using lipos Micheal... If you take care of them they will take care of you and your tanks... no problem leaving them in...
so long there is an ON/OFF switch...so on the camera rig... make sure there is one


ALPHA

[MichaelC]

Thanks ALPHA....... Good point on the camera. I was planning on removing that one anyway but I guess I could also put in an on/off for that as well just in case.

Another related questiongood point........ How do you trash a lipo ? Can you bring it to the places where they accept used batteries or is it something special ?

MichaelC.

[ALPHA]

Thanks ALPHA....... Good point on the camera. I was planning on removing that one anyway but I guess I could also put in an on/off for that as well just in case.

Another related questiongood point........ How do you trash a lipo ? Can you bring it to the places where they accept used batteries or is it something special ?

MichaelC.

I know I should be more responsible with lipos....but basically I generally cut the leads off and toss them in the garbage... it isn't all that safe because of the instability of the polymer ... but at the moment there isn't really a place here that accepts them...not even the ones for cars...In Canada maybe there are places... Green cars are the future... sooner or later they will have to have a facility to accept them...not sure normal battery disposal places will take them...battery acid and this polymer don't get along well



ALPHA