Crash course in LIPO's required

[lgray88]

So I've got myself another heli a leccy one this time, so previously i have only been charging a few 3s packs for my nitro helis too run the electronics. So this one runs on two 5s packs, i know next too nothing about what charger or psu to get. I have also sort of neglected the 3s lipos i have at the moment as in not discharging them when not in use, as the last time i attempted to do a storage discharge the battery blew up, and i don't mean puff up i mean it in the sense that they were flames involved. Some pointers would be appreciated or if someone could send me in the right direction to videos on the net about lipo care.

Cheers

Liam

[LaurenceGough]

Hi Liam,

I hope no one was hurt with that incident!!

It sounds like you are in need of a decent charger, a quality lipo should never catch on fire unless it's mistreated, such as by a faulty charger, short or impact damage.

Lipos are very sensitive to the following in our use but I may have missed out things so not limited!

Overcharging (4.2v max per a cell).
Overdischarging (never discharge a pack below 20%, this works out at around 3.7v min per a cell after a flight, but this various slightly)
Impact damage (never touch the lipo with anything sharp and always store/transport in a padded container).
Under-rated packs for use (never use low quality low discharge packs on a fast heli in aggressive flight for instance)
Heat (if a lipo is too hot to touch it has been damaged... Ideally it shouldn't be very warm after a flight.)
Shorting (never let a lipo short out, such as by touching the leads together, this is the quickest way to damage a pack. Always use female connections on the lipo side, or a combination which prevents shorts or wrong connections to your model)

If a pack has puffed discontinue use as it is a fire risk.

Make sure your model is running the appropriate pack size and voltage if not you could cause too much pack stress.

It might be useful to add some notes on your charger to glance over.

Storing lipos at full charge longer than a week or two can cause faster degradation - it is recommended you use a charger's storage charge if you can't discharge the pack to around 30-80%.

A good charger should let you see how much mAh you put back into the pack, mAh is basically the energy which is stored in the pack. There is a 80% rule where you should never use more than 80%, so with a 3000mAh pack you would not want to put back in more than 2400mAh after a flight. To avoid this you can time your flights.


This may look like a lot of points but in reality it is very simple once you get used to them.



This is a bit of a copy and paste from a previous post of mine:


For charging I would recommend one of the following chargers:

There is the Cellpro PL6 charger found here: http://www.fast-lad.co.uk/store/cell...6-p-17908.html

And there is the Cellpro PL8 charger found here: http://www.fast-lad.co.uk/store/cell...2-p-13532.html

The main differences are one charges up to 6 cell and 8 cell respectively, there is also a difference in charging power but both chargers can charge VERY fast (and with top safety).

Most people will never need more than the Cellpro PL6 but I'll leave it to you, I have a Pl8 to future proof myself perhaps a bit better.

These chargers will charge pretty much any type of battery you throw at them.

The Cellpro chargers are always worth paying a bit more for the safety and charging accuracy, I have used them for many years without a problem as have many others.

You would also need a power supply which outputs 12V to 30V. - I'll let you take a look at them (just search for power or power supply at your favorite heli shop.)


Cheers,

Laurence

[lgray88]

Nah no one was hurt bar a few carpet tiles!

So does that mean when you do the storage discharge the balance lead should be attached too your charger?
As this is probably where i have gone wrong. I see someone selling a cell pro 10s charger on the for sale section here for £70 would this be a reasonable buy?

[LaurenceGough]

So does that mean when you do the storage discharge the balance lead should be attached too your charger?
As this is probably where i have gone wrong. I see someone selling a cell pro 10s charger on the for sale section here for £70 would this be a reasonable buy?

The 10S is a great charger but personally I would 100% pay a bit more for a Powerlab as it really has set the bar for chargers! If you think you are going to storage charge often the Powerlab would be a much better choice - it also has a fast regenerative discharge function if you have a lead acid battery it will discharge into that efficiently.



The Cellpro 10S does not have a discharge function, it will only perform storage charge when the pack is already quite low. Yes balance leads should be used as you always want to keep a cell in balance.

Although not using a balance lead should not cause a fire, balance leads are there to optimise your pack for long life and top performance. With the addition of balance leads your charger knows more about what is going on and this way I believe it's safer if one cell goes a bit crazy.

[lgray88]

Thanks for the help laurence, il try get one picked up sharpish!

[cjcj1949]

Without balance leads the charger will not be able to allow for a low cell. It will then overcharge all the others. It will also not allow for a high cell and will overcharge that. For example if you have one cell go short it will read 0v. My first Twister Storm Lipo did that. It was a 3S lipo and if I had used an unbalanced charge to 12.6V the 12.6 would have been shared between the other two cells. That's at least 6.3V each. That's the voltage that valves used in the heater circuit. Balance charging is there for a reason. It isn't needed for good lipos, it's for the bad ones. If you check the cell volts before charging you can probably charge unbalanced, providing all cells have the same capacity. Lower capacity cells will reach a higher voltage than the others if charged unbalanced.

Lipos are much better than they used to be and as people get more experienced they can tell a bad lipo before it becomes a problem. If in doubt don't try to charge it.

[PeteStewardson]

To help work out your 80% flight times I use a spreadsheet. I put it on my blog so anyone can use it Flight logging | RCHeliBlog.co.uk

You put the flight time for each flight plus the mA put back into the pack when charging into it and then it works out your max flight time on that flight. I log every flight on it ( well I've slacked recently so need to start doing it again ) and it really helps.

[scuba steve]

the better quality chargers also have a 'monitor' function....if your at all unsure about your battery before charging/discharging/storage you can plug it into your charger (balance lead must be attached) and select monitor mode....it will tell you all you need to know about the state of your battery so taking any guess work out which can only add to safety IMO.

scuba

[lgray88]

Thanks for spreadsheet Pete.

Well im going to buy my charger tonght. But im wondering if i have my 10s heli running on two 5s packs connected in series, does each battery need to be charged seperately or can both be charged together ?

[AcidDrink]

Thanks for spreadsheet Pete.

Well im going to buy my charger tonght. But im wondering if i have my 10s heli running on two 5s packs connected in series, does each battery need to be charged seperately or can both be charged together ?

Separately.

[PeteStewardson]

Thanks for spreadsheet Pete.

Well im going to buy my charger tonght. But im wondering if i have my 10s heli running on two 5s packs connected in series, does each battery need to be charged seperately or can both be charged together ?

Separately, but if you're using a PL8 or similar you can charge both in parallel.

[lgray88]

I was thinking to go for the PL6 will this be capable of doing the batterys in parallel also. Didnt want too spend too much as i have to get the Power supply also.

[LaurenceGough]

I was thinking to go for the PL6 will this be capable of doing the batterys in parallel also. Didnt want too spend too much as i have to get the Power supply also.

Yes it will . PL6 and PL8 share the same adapters.

[lgray88]

So other than the PSU , What else will i need too purchase alongside the pl6 charger?

[PeteStewardson]

The balance boards you need for your packs. That's it.