Trouble with LiPo connection to charger

[Kobur]

I bought my first LiPo batteries, 1/18th scale Duratrax 1800 maH batteries. They each came with three connectors, a pair of 3.5 mm maie connectors and a 2 mm male connector. I understand the 3.5s, they are for positive an negative leads from the ESC to connect to the battery. I don't get the 2mm. The instruction sheet says it is for the "center tap" which I located on the battery easily enough, but what is the center tap for? Is it for the connection to the balance board? If so, there is nothing for it to connect to. This battery does not come with a balance connector and I don't have special leads for that. My chargers (Traxxas peak detection and an Imax) each have a balance board, so I thought I was ready.

So, 1) what's the purpose of the center tap? 2) How do I connect to the charger? 3) what kind of lead do I need and where do I find it?

[Stumpy]

Yes, the 2mm bullet connector is for when you are balance charging.. Basically, when balance charging the charger needs to monitor the voltage of each cell in the battery in order to keep the two cells (in a 2S battery) at the same voltage..

If you were to use a multimeter to measure between the positive 3.5mm terminal and the centre 2mm terminal you would see the voltage of one cell, and if you measured between the 2mm terminal and the negative 3.5mm terminal you would measure the voltage of the second/other cell..

What you need to buy or make is a charging adaptor such as the one pictured below, but using plugs that will suit the charger that you have, and 3.5mm bullet connectors (instead of 4mm) to suit your battery.. This one has a Deans main battery connector, and a JST XH3 balance plug..


Goodluck
Mark..

[Kobur]

What you need to buy or make is a charging adaptor such as the one pictured below, but using plugs that will suit the charger that you have, and 3.5mm bullet connectors (instead of 4mm) to suit your battery.. This one has a Deans main battery connector, and a JST XH3 balance plug

Mark, thanks for the explanation. It was both clear and helpful.

Is the XH3 balance plug pretty much universal for 2S batteries? I notice the balance board on my charger has multiple size connectors depending on the number of cells. Will a 6S battery have 8 leads and connectors then? If I buy/make a charging lead for the type battery I have will I end up having to buy/make a separate lead for every brand and type of battery I get?

[LTO_Dave]

A-Main sells several pre-made adapters that should work for you, depending on the plugs on your balance board. I got one from them to charge my TrakPower 2s saddle LiPo's and it works great.

I was confused about balance plugs when I first got into LiPo's because there are several different plug types. It seems like JST is becoming more common.

http://www.amainhobbies.com/advanced_search_result.php?keywords=ProTek+adapter&x=-172&y=-169

[Stumpy]

Hi Kobur,

If you already have a charger, then you will need to buy the balance plug that suits that charger... (or buy a balance adaptor to suit your charger and balance connector you use..)

I'm not 100% sure, but I think that the Imax chargers use JST balance connectors.. (JST is the connector brand, XH3 is the type and size)

The adaptors are not that difficult, or expensive to make.. Buy a JST-XH3 plug with leads, some 14ga silicone wire, and whatever battery connector you use, and solder them up..

JST-XH3 extension leads (just cutoff the female plug).. http://www.ebay.com.au/itm/1-JST-JST-XH-2S-Balance-Wire-Extension-Adapter-20CM-/230476270104?pt=US_Radio_Control_Control_Line&hash=item35a974ca18

If you want or need to get a JST balance adaptor for your Imax charger, try this.. http://www.ebay.com.au/itm/JST-XH-2S-6S-Balance-Board-iMax-b6-Charger-Adapter-/150667947231?pt=US_Radio_Control_Control_Line&hash=item2314826cdf

As you can see, neither option is that expensive..

Personally I use JST-XH3 connectors, as that is what came on the first LiPo batteries I bought (Reedy 5000mAh 20C).. The JST connector plugged straight into my Hot Power charger (Chinese IMAX copy), so it was an obvious choice...

Later when I bought some IP5000 50C LiPo's that had 4mm banana plugs, I just made up an adaptor lead (like the picture in my first post), for each of my batteries, and just left them plugged in all the time so they were just like my Reedy's.. When the battery was on charge, I used both the Deans* connector and the JST balance plug, and when in the car, I used only the larger Deans* connector...

Mark..

[Kobur]

If you already have a charger, then you will need to buy the balance plug that suits that charger... (or buy a balance adaptor to suit your charger and balance connector you use..)

I'm not 100% sure, but I think that the Imax chargers use JST balance connectors.. (JST is the connector brand, XH3 is the type and size)

The Traxxas charger I have comes with a plug in balance board. The Imax is a B6 and it has the balance board built in with several connectors on the side. The Traxxas has JST XH plugs for 2S-6S. The connectors on the Traxxas board and on the side of the Imax both look the same to me.

The adaptors are not that difficult, or expensive to make.. Buy a JST-XH3 plug with leads, some 14ga silicone wire, and whatever battery connector you use, and solder them up..

JST-XH3 extension leads (just cutoff the female plug)

So the positive and negative battery connectors (whatever type) need to have an extra wire soldered to each which is in turn soldered to the correct position on the XH plug and the the connector for the center tap is soldered only to the XH plug, right?

I guess then that for 3S-6S the connection is more complicated and will likely come with a built in balance connector from the manufacturer?

And thanks for all the help!