Charging in parallel questions

[davethepitch]

Hello all

If i have got this right and i want to charge two 3s lipo';s 1 x 1500 mAh and 1 x 1800 mAh lipo that is a combined mAh of 3300 at 11.1 volts.

My questions are would 1C charging be 3.3 amps x 11.1 volts at 3S and would i be pushing my Imax B6 charger which has a maximum charge of 5 amps although 3.3 is only over half the available power it delivers.

Thanks Dave

[dougc]

I think it';s best to use matched ampage batterys but someone my know more

[davethepitch]

I think it';s best to use matched ampage batterys but someone my know more

That is another concern I have although I have read somewhere that if the amps are combined it is seen as one capacity lipo.

[guest325]

First off you need a parallel charging board (HK do them), second  don';t try charging batteries of different capacity in parallel,  it doesn';t work  - it';s also better if they are both discharged similarly  - if you don';t things could get interesting  ::)

[davethepitch]

First off you need a parallel charging board (HK do them), second  don';t try charging batteries of different capacity in parallel,  it doesn';t work  - it';s also better if they are both discharged similarly  - if you don';t things could get interesting  ::)

That advice will do for me then. 

Dave

[Ynot6]

i plan to parallel charge the pcks that i use in pairs on my Y6, others will only be charged singly. much simpler, and safer,IMHO.

[davethepitch]

I saw the below image on a search engine which led me to believe that different mAh lipo';s could be charged in parallel but i will take the DarrellW advice.

Dave

[guest325]

Here you go, this is the HK parallel charging board:
http://www.hobbyking.co.uk/hobbyking/store/uh_viewItem.asp?idProduct=31843
Look at all of the text!
The problem with charging different capacities is that the smallest one will fully charge first - so what happens next???

[davethepitch]

The problem with charging different capacities is that the smallest one will fully charge first - so what happens next???

If I had two lipo';s with the same mAh I would have purchased one of those boards but being as i have not i will take your advice.

Dave

[Edders]

I know this is my First post but I wanted to put a few point across

Firstly I always parallel charge my packs this allows me to charge up to 6 batteries at a time

The batteries must be the same voltage 2s/3s/4s/5s......

Capacity of the batteries doesn't matter it's all about the voltage

The rule of thumb I use is the packs must be within 20% useable battery of each other
So a 3s 1800 with 30% usable battery left can be charged with a 3s 5000 with 50% capacity left
Remember it's all about the volts

when you connect the batteries to a parallel charging board the batteries will level themselves of with each other so the higher charged batteries will "Charge" the lower charged batteries, so this is the reason the gap between the batteries should be no more than 20% as the parallel charge board you use will have to handle this "levelling" which you can't control the speed of and risk it over heating, my board has self-healing  fuses on each to stop any damage and at 20% I've never triggered the fuse.
O also use the cheap hobby King Version of parallel board and I have never had any issues charging mine and others quad packs
For info the most packs I have charge at the same time is 6 x 6s 5000
Also add up all the capacities to work out the "C" rating for charging

Mike

[bazzerh]

i agree with edders, same cell count, same discharge state (measure pack voltage and within 0.5v  is my yardstick) but the capacities and C rating doesn';t matter, unless you';re pushing the charge to the limits which is not the done thing anyway.

only thing i dont agree with is using a hobbyking parallel board. the things are terrible. ive had the ';safe'; one with fuses give up the ghost on one side, bought the cheap version to replace and that went up in unmagic smoke on one of the balance tracks. bought another (yes i am that gullible) and that one was bridged with solder underneath from the main + and - rails. obviously i should have checked it with a meter for connections before attaching a 4S pack to it, it would have saved me a right scare and a battery. sparks, smoke, puffed lipo.

I';ve built myself a 3 way split cable affair now and bought a 10 pack of the balance lead extenders and made a 3 way splice affair for balancing. works a treat and no more fire risk, bonus.

[Nige8021]

Have a look at this http://www.rchelicopterfun.com/parallel-lipo-charging.html   

[guest325]

Have a look at this http://www.rchelicopterfun.com/parallel-lipo-charging.html   

Very interesting, seems I was wrong BUT he still says if you are not comfortable with it don';t do it and that for it to work well for you a high capacity charger is needed.
I chose the option of getting a couple of chargers and a decent power supply that had enough power to easily power them.

[Ynot6]

rapid electronics have the jst pcb sockets, so you can make up your own boards with vero board.