3s batteries wired in series quick question.

Batteries, Chargers, and Battery Management Systems.
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alex jones   100 mW

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e longboard charging problem

Post by alex jones » Jul 19 2016 7:47am

Hello, I've made an electric longboard. I'm having problems with smoke coming from the battery charger - even before the charger is pluged into the mains.

On the outside of my board I have a 3-way DPDT switch, a 6s balance input socket, an XT60 socket and a voltage display.
The 3 way switch is On/OFF/Charge.
Image

(I haven't glued the ports in place yet hence the wonky looking XT60)

I use 2 x 3s batteries wired in series. I use a twin pack balance charge lead to convert the two 3s balance leads to a 6s balance lead.

The battery is connected to the "O" on the switch. The VESC is connected to the "I" on the switch. The XT60 socket is connected to the "II" on the switch. The voltage display is also connected the "II" on the switch.

So when the switch is set to "O" nothing in theroy should work.

Today for the first time, I connected the battery charger to the XT60 port and connected the 6s balance charge lead from the battery charger to the port on the longboard....before I even managed to plug the charger into the mains there was smoke coming from the charger near the fan area. (I use a turnigy accucell 6 80w charger).

What I can't work out is why when the DPDT switch was switched to OFF there must have been power going to the output socket of the the battery charger. How can a switch that is set to the off centre position divert power through the charge cables connected to the "II" terminal?

Any help or ideas would be gratly appreciated. I really want to get this sorted before I connect my very first VESC. I DO NOT want that smoking!!!

Cheers.
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alex jones   100 mW

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Posts: 35
Joined: May 16 2016 7:42pm

smoking charger using 2 x 3s batteries

Post by alex jones » Jul 19 2016 1:07pm

So with two 3s Lipos wired in series. Do I NEED to connect the 3s balance lead coming from battery with the main charge negative cable to the 6s balance port with the negative wire and connect the other battery 3s balance lead (with the main charge cable which would be positive), to the twin pack charge lead port with the red positive wire? I ask because I had smoke coming from my Turigy 80w Accucell 6 battery charger before pulling all the connections apart. The charger was not even plugged into the mains.
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mccloed   100 W

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Re: smoking charger using 2 x 3s batteries

Post by mccloed » Jul 19 2016 6:37pm

Did you leave the batteries plugged in series?

alex jones   100 mW

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Re: smoking charger using 2 x 3s batteries

Post by alex jones » Jul 19 2016 7:05pm

Thanks for the response. Yes the batteries are connected in series.
battery diag.JPG
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Image

I can't work out where I'm going wrong. I have used this set up on two previous boards with no problems at all...!!!
I've bought new twin pack connection leads today just to be safe.

I did read somewhere that you have to insert the 3s balance leads in a correct order...so the battery with the main negative charge cable the ballance lead would be next to the negative of the 6s connection JST-XH and the battery with the main positive cable you would plug that batteries 3s balance lead next to the positive wire on the 6s JST-XH.

...but I still don't understand how the power from the batteries can cause my charger to smoke when you consider that the 3-way switch was in the center position (OFF) and the charger was not even plugged into the mains. How does the power jump????

What would have happened if I had connected the charger connected to the mains to the board? Power coming out/power going in...any ideas?

alex jones   100 mW

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Joined: May 16 2016 7:42pm

3s batteries wired in series quick question.

Post by alex jones » Jul 20 2016 5:48am

Hi can anyone confirm that if I use a Twin Pack Balance Charge lead to balance charge 2 x 3s lipo batteries wired in series then I have to insert the 3s balance charge leads into the 6s connector in a certain way in order to avod shorting out the battery.
6s charge1.jpg
6s charge1.jpg (170.19 KiB) Viewed 499 times
So the battery with the main negative lead I would plug its 3s JST-XH connector opposit the negative wire on the 6s charge lead input socket...and with the battery with the main positive cable I would plug the 3s connector into the large 6s connector with the tiny red positive wire coming from it. Sorry if that makes no sense.

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dogman dan   100 GW

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Re: 3s batteries wired in series quick question.

Post by dogman dan » Jul 20 2016 6:13am

It would, I think, be impossible to plug in the JST upside down. But if one pack is first, its jst needs to be first as well. Not crossing over the leads .

alex jones   100 mW

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Re: 3s batteries wired in series quick question.

Post by alex jones » Jul 20 2016 6:31am

Thanks for that dogman dan ...I think I found a clearer example of what I was trying to ask.
pos&neg side.JPG
pos&neg side.JPG (53.09 KiB) Viewed 489 times
The twin pack charge lead is basically made up of two 3s JST-XH ports soldered into place ...so the possibility of inserting the positive side 3s balance lead into the negative side (and vice versa) of the 6s balance port is easily done.

dventu   100 W

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Re: smoking charger using 2 x 3s batteries

Post by dventu » Jul 20 2016 9:58pm

Reverse polarity???

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