Charging batteries in series

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Sportball
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Joined: Mon Sep 23, 2013 7:29 pm

Charging batteries in series

Post by Sportball »

I have just bought a Sky Rc charger

http://www.nitroplanes.com/26p-e4-charger.html

and 2 x Lipo batteries that I will connect in series to create a 2 cell 7.4v battery.

Can someone tell me how to connect these to the charger; should I charge them individually or leave them connected in series? If I charge them when in series where do I connect the balance lead? Where can I buy the PH JST connectors to plug into the batteries and what about the ones on the charger (xh I believe)?

Any help is appreciated....
Sportball
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Re: Charging batteries in series

Post by Sportball »

razerdave
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Re: Charging batteries in series

Post by razerdave »

If you put 2 new cells together as a 7.4v lipo pack, you charge it as such. The charger will not know any different. Wire the 2 cells together as a permanent pack.

Then you can get whatever lead you want, solder it to the pack and use the opposite one with Banana plugs on the end that will plug into the charger you linked to.
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BeligerAnt
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Re: Charging batteries in series

Post by BeligerAnt »

It's not essential to balance charge small battery packs. You can, and it may improve lifetime, but many smaller packs come without a balance connector and are just fine.

If you don't want to balance charge you can just connect the red and black 4mm outputs from the charger to the positive and negative terminals of the battery pack. Most people use the JST RCY connectors (known as "BEC" connectors in R/C circles) for antweight battery packs. They are available from most model shops.
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Gary, Team BeligerAnt
Sportball
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Re: Charging batteries in series

Post by Sportball »

razerdave wrote:If you put 2 new cells together as a 7.4v lipo pack, you charge it as such. The charger will not know any different. Wire the 2 cells together as a permanent pack.

Then you can get whatever lead you want, solder it to the pack and use the opposite one with Banana plugs on the end that will plug into the charger you linked to.
That's what I thought but where do I wire the balance lead?
Sportball
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Re: Charging batteries in series

Post by Sportball »

BeligerAnt wrote:It's not essential to balance charge small battery packs. You can, and it may improve lifetime, but many smaller packs come without a balance connector and are just fine.

If you don't want to balance charge you can just connect the red and black 4mm outputs from the charger to the positive and negative terminals of the battery pack. Most people use the JST RCY connectors (known as "BEC" connectors in R/C circles) for antweight battery packs. They are available from most model shops.
Image

My batteries are single cell and have a JST pH connector, I believe my best bet is to charge in parallel and forget about balancing. Thanks
razerdave
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Re: Charging batteries in series

Post by razerdave »

2 cell batteries don't really require balancing. I would advise making the 2 cells a permanent 2-cell pack and charge it as such, because then it means you don't need 2 chargers on the go.
Sportball
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Re: Charging batteries in series

Post by Sportball »

razerdave wrote:2 cell batteries don't really require balancing. I would advise making the 2 cells a permanent 2-cell pack and charge it as such, because then it means you don't need 2 chargers on the go.
My charger comes with a socket to balance 2 cell packs? If I make up a lead to charge in parallel on one charger they will charge in half the time apparently....
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BeligerAnt
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Re: Charging batteries in series

Post by BeligerAnt »

You can't charge cells in parallel!

If you want to charge both cells at the same time there are two options. Both will involve making some sort of adapter, but then you will have to wire your 2 cells together anyway...

First you can wire your cells up as a pack with a single 2-pin connector to connect to your robot.
You can charge a pack like this by connecting it to the red & black 4mm sockets on the charger.

Second, you can balance charge the two cells. Balance charging is essentially the same as charging a series pack (above) but with the addition of a sense connection at the junction of the cells.
In this case you need some kind of adapter from the 3-pin balance charge socket to the two cells. The cells must be connected in series with the common connection to the middle pin of the balance charger. Positive and negative connect as usual.

Personally, I would wire the two cells in series and forget about balance charging.

Don't try to charge cells in parallel, you will probably destroy them (possibly with flames!)
Gary, Team BeligerAnt
danjr1
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Re: Charging batteries in series

Post by danjr1 »

is balance charging really not worth it on a 2s antweight scale lipo?!
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