electricsmooth

I bought this little adapter thing for my charger so I can charge 2 batteries together instead of just one.

So, I plug the adapter into the 4s balance port of the charger and also the positive negative dean connector into the adapter. The adapter charges via 2 separate 2S ports.

The batteries I'm charging are lipo 2s 4200 maH. What are the settings I need to make this work?

I set the charger to 4s and 14.8v but left it at 4200 maH. Should I also be doubling this as well (8400 mah)? I tried this once (just at 4200maH) and noticed it charges really quick but the battery life seemed a little lower than usual. It could have been that I was checking out top speeds at a park.

tacx

My Feedback: (1)

Your adapter should connect your batts in parallel.

When connected in parallel the voltage stays the same. ( A 2cell = 7.4 volts nominal and 8.4 volts fully charged. )

Only the mah doubles. In your case to 8400 mah.

The charger sees it as one 2cell battery with 8400 mah capacity.

You need to set your charger for a 2s battery.

So, without knowing your chargers capabilities you should set the amp charge to 8.4 amps, which is a 1c charge rate. Your batts may have a higher charge rating but we don't know that.

electricsmooth

Ok guy at hobby shop told me the exact opposite. Everything doubles except the voltage.

Are you absolutely certain that this is set at 2s 7.4 even though the adapter plugs into 4s balance port?

trax de max

is it a serial adapter or parallel adapter. Pic would help. But i think traxxas are the only company to make a serial adapter.
Serial add voltage only but capacity must be the same on the packs. ie 2s 4200mah and 2s 4200mah = 4s 4200mah
Parallel add capacity only, ie 2s 4200mah and 2s 4200mah = 2s 8400mah

electricsmooth

Here is the link to the same one.http://m.ebay.com/itm/RC-LIPO-batter...-/231166785347

electricsmooth

here are some pics

tacx

My Feedback: (1)

That's not the opposite. It's the same thing that I told you. The voltage stays the same and the mah doubles.

electricsmooth

What I'm saying is that the store owner told me the exact opposite. He said that the mah stays the same and the voltage goes to 14.8 and I select battery type as 4S.

So, what I will do is keep the setting as 2S, 7.4v and change amp to 8.4 (for 2 x 4200maH batteries), correct?

You would think an owner of a rc store would know his stuff but I guess that's not always the case. Good thing I didn't cause an explosion.

trax de max

It is indeed a serial adapter,Cell count goes up mah stays the same. Not one i would use, I'd throw it in the bin. Your putting the power through the balance connectors which can only handle 3A max. If you get the serial main wires There's a very good change you'll fry something if you connect the balance wires to the wrong battery with a seperate main wire adapter.
If your after a serial adaptor the traxxas one is much better. http://www.ebay.com/itm/Traxxas-Dual...item233f932b60

electricsmooth

I'm just after an adapter that will charge 2 batteries at a time. I don't care if it is series or parallel. Anything you suggest that has dean connectors? I actually have 4 batteries that are all the same. 2s 4200mah and 7.4v. If I buy a parallel board that can do up to 6, would it work for my Thunder AC6 charger (50w)? I would like to do all 4.

tacx

My Feedback: (1)

Your charger is not big enough to charge two 4800 batts at once.

It only has a max charge rate of 5 amps. 50 watts. If you charge at the normal rate of 1c you would set your charge amps to 4.8 for a 4800 mah battery. At 4.8 amps you are at the max of your charger.

If you want to charge multiple batteries of that size you need a more powerful charger.

Lone Star Charles

The guy at the hobby shop told you correctly. You should set your charger to 4s. trax de max is also correct about the charging current. Since the charging is completely handled by the balance leads and they are rated at a max of 3 amps you should set your charging current to 3 amps. 14.8v * 3a = 44.4w. Your 50w charger should be OK. If your batteries are empty, it will take a little less than two hours to completely balance charge the batteries.

rgburrill

Bingo, we have an correct answer. Yes it takes a little more time to charge the batteries but that
s typical when you try to do more than one at a time. I found with more cells (e.g. 6) there is still a wattage limit as to what the charger will handle so you still can't get max charge rate.
You must be patient.

electricsmooth

OK, looks like we are all kind of on the same page here now. So, basically, instead of setting the charger to 4.2 amp ( batteries are 4200mah), I set it to 3 amp, correct?

Also, any suggestion on a good battery charger that will do 4 at a time with a parallel board?

Was just looking at some chargers that have higher wattage (200w). This is my understanding, if I connect 4x 4200mah lipo 2s 7.4v batteries, the wattage required will be 16.8 amps x 7.4v = 124.32. So, it looks like a 200w charger will suffice for this. The only problem is that most of the chargers I see have a 10amp max charge rate but it looks like what I require is 16.8 amp (4.2 x 4). If I can still get a full charge out of this by setting it at 10 amps and just waiting longer, I don't mind.

I could be horribly wrong with my calculations above as I only have a rudimentary understanding of all of this.

Thanks everyone for your help!

trax de max

200watts will suffice,
I always use max current and max voltage (4.2A x 4 = 16.8A). 16.8A x 8.4V = 141Watts + 20% for any losses = 170Watts.
But you need a charger that will charge at 16.8A and not limited by its software also.
Some high power chargers are limited to 10A the next step is 20A and over which is what you want. These require a power supply as they'll be DC.

electricsmooth

OK, I'm getting ahead of myself here. I'm gonna stick with my charger and just charge 2 at a time at 3amps for now.

I'm assuming the only downside to charging at 3 amps is that it will take longer. Anything else? I can live with waiting an extra hour or whatever.

Thanks again everyone!