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eCigarette Forum => Battery => Topic started by: Claviger on June 13, 2014, 07:53:03 PM

Title: This is doing my head in
Post by: Claviger on June 13, 2014, 07:53:03 PM
For some reason data sheets, circuit diagrams, and doing math is all easier for me than sorting this crap out. Go figure. cant_believe:

I have 2 cells that are 2s1p Li Poly cells, so 7.4 volts nominal with both the 7.4v output wires and 3 wire balance plugs on each.  I want to connect them in parallel both on the balance and main output wires. Basically, make a 2s2p battery with a single balance plug.

If I do this, can I use a small 1amp balance charger to recharge while they are still inside the mod and connected to pos/neg on the main output wires? Something like this:

All the diagrams for parallel charging I see online have the main output connected to a positive and negative on a charger, and the balance plug also plugged in. From what I understand and my brain (kinda) is digesting, batteries in series should not be simultaneously connected in parallel as it creates a short circuit (boom  scared:).  So is this safe or is going to create a short?
Title: Re: This is doing my head in
Post by: CraigHB on June 14, 2014, 06:49:41 AM
I know what you mean, sometimes I get stuck on things I shouldn't too.

Treat cells hooked up in parallel like a single cell.  Maybe tape them together or something to help you visually.  Just remember to check they have matched charge when you connect the parallel cells initially. 

After you group them in parallel sets, hook them up to the charger like a regular 2S cell, one wire from the charger plug on negative for the first group, another wire on the positive-negative connection between the groups, and one wire on the positive connection of the second group.

The point of a balance charger is charge each cell as if it stands alone so there's a channel dedicated to each cell in the series set.  The first channel shares the high side connection with the low side connection of the second channel.

You'll have to check the pinout on the charger.  The pinout is standard on those JST-XH connectors that come with the LiPo packs since the intent is to plug the cells right into the charger.  Wire colors will depend on the extension cables you're using or if you're making cables yourself.

In terms of loading the pack while it's being charged with a balance charger, it's not an issue.  Just like a USB charger, each channel is not adversely affected by the change in load.  It simply goes to max rate when the battery is loaded then resumes normal charging when the load is no longer present.

I hope I answered your question, I'm kind of tired right now, pretty late, off to bed.
Title: Re: This is doing my head in
Post by: Claviger on June 14, 2014, 06:54:43 AM
Yes you did answer it thanks. The wiring insanity of the different setups I am working concurrently were making my brain spin Lol.

Great little tid bit about loaded balance charging.