Tamiya LF battery - balancing plug

[taliesin 259]

So I've got a couple of Tamiya 6.6 volt LF2200 mah LF batteries that have an unusual balancing plug. The instructions say to use the balancing lead every 5 charges (as opposed to every time for a Lipo) but the connector plug is something unique. It won't mate to the Electrifly adapter or to any fitting on either of my chargers (i.e. the normal 2 cell balancing port used for Lipos). The chargers (Onyx 235 and a Racer's Edge) will charge LiFE, A123 and Lion batteries and both seem to charge it just fine - just without any balancing.

Does anyone know of an adapter or connector that will work in the standard ports for most chargers? Seems like it needs to go from the proprietary Tamiya LF connector to the standard 2 cell Lipo / Electrifly type of plug.

Does such a thing exist? Tamiya makes the charger for this battery, it just costs a bunch and my two existing chargers are fully capable of charging this type of battery according to the instructions (and use). Seems like there should be an adapter out there somewhere....

[Backlash 478]

Can you please post a photo of the balance plug?

I have been searching the web trying to find a photo of the Tamiya LiFe balance plug, and couldn't find one..

I did however find a company in the USA selling a universal balance board, that will do Tamiya Life batteries?.. Scroll down to the universal adaptor..

http://www.radicalrc.com/category/Balance-Adapter-Boards-541

[taliesin 259]

I wonder if that universal might work.

I tried to get a decent photo but my wretched camera just won't zoom enough to get a decent image. The plug itself is similar to the standard one you would see on a Lipo battery, just a bit smaller (narrower in width, slightly taller in height, same number of pins).

I would like to see a different brand of LF battery but I suspect Tamiya might have made their packs proprietary.

[Backlash 478]

Well, the only other option that I can see that you have is to cut the Tamiya balance plug off the LiFe battery, and fit something more common, such as the JST-XH3 plug..

[taliesin 259]

Here is a pretty good image showing the plug. At a glance it looks much like the standard balancing connector - but it isn't.

http://www.rceasy.com/wp-content/uploads/2009/01/55102.jpg

[pl212 4]

I have these LiFE batteries and the accompanying charger:

I'd bet that $15 universal balance adaptor would do the trick, if they explicitly claim Tamiya LiFE compatibility. Pity the photo is so low-rez:

[alfagta 126]

not sure if this will help , http://www.eflightwiki.com/eflightwiki/index.php?title=LiPo_Balance_Plugs , might help you id it so you can make up a simple adaptor lead ,

[taliesin 259]

That is the creature PL212, cheers! My camera just won't get that level of quality (yes, I need to update - badly). It is not only that odd little clip on top - which could be nipped off - but the narrow width that keeps it from working with my adapter board.

Nice one, alfagta!! That is a great chart, thanks. I don't see this exact style on that chart, so now I really think it might be proprietary. Anyone else see something I don't or can put a name/style number to the Tamiya plug?

Think I'll order that adapter and see if it works. $15 is not a big risk.

[taliesin 259]

Success! Thanks for the help gentlemen, the universal board does the trick nicely.

Hadn't ever seen one quite like it, but it works a treat.

[Jamlot 1]

I, too, have the Tamiya LF Battery charger and a few LF1100 and LF2200 batteries.

Do I risk damaging the batteries if I plug in the balancing connector with every charge?

-- Jeff

[Backlash 478]

Jamlot...(Jeff) .

All that balance charging does is keeps the voltage of the individual cells that make up the battery the same.. Typically, the charger does this by slightly discharging any cell that is higher or exceeds the voltage of the others in the battery to keep all of the cells at the same voltage, thus balanced.. Because the balancing process does discharge the cells slightly, it does however take a little longer to perform a balance charge than it does to do a normal charge..

When you balance charge, you connect the small balance plug to the charger, and that plug allows the charger to read the voltage of the individual cells within the battery, and also put a load on any cell (typically up to 200mA) that's voltage is greater than the others in the battery pack to balance it..

If you don't connect that balance plug to the charger, (for a normal or non balanced charge) then the only voltage feedback that the charger will receive from the battery during the charging process is the overall voltage of the entire battery.. What can then happen is that the voltage of cells in the battery could become out of balance (different), and the voltage of one cell could be higher than the other to the point that the voltage could exceed the cell maximum voltage even though the fully charged voltage of the battery is still correct..

Using LiPo as an example..

The fully charged voltage of a single LiPo cell is 4.2 Volts.. So the fully charged voltage of a 2S LiPo is 8.4 volts, with each individual cells voltage @ 4.2 Volts if the battery is balanced... (4.2 + 4.2Volts = 8.4Volts)

BUT, if you didn't connect balance lead to the charger, and then did a normal, non-balanced charge, the charger would still charge the 2S battery to 8.4 Volts, but the voltage of the individual cells could be quite different, to the point where one cell could be 4.1 Volts, and the other cell 4.3 Volts (4.1 + 4.3Volts is still = 8.4 Volts), but the cell that charged to 4.3 volts is over the maximum voltage for a LiPo cell, and that cell then could be irreparably damaged as a result..

In my opinion you would have a greater risk of damaging the cells, by not balancing the battery, and allowing the cells in the battery to become out of balance....

[taliesin 259]

I agree and never really understood the recommendation on the Tamiya LF packaging that you balance the pack every five charges.

[Jamlot 1]

BACKLASH: Thank you so much for the wonderfully in-depth description. That is some very valuable information. Thanks again.

-- Jeff