parallel or singular lipo charging.

[klampykixx]

Hi guys, ive had a bit of a look around and cant seem to find anything that answers my particular Q.

ive read that its 95% ok to charge 2 of the same lipo (2s-2s, 3s-3s etc,)

so that part of my question is fine, but that scenario is based on both batteries being charged, being at similar charge/discharge status.

what i want to know, is if im running 2x ESC, each with its own 2s, can i link the balance plugs permanantly and just run one balance plug for charging??

i had initially planned to run a little micro switch and switch between charging, which would still leave me one balance plug, but it would keep the 2s's seperate from each other. problem with this setup, is i cant seem to find a micro switch with on-off-on with 3 rows of 3pins on the back. so thats not working in my favour...

so, back to linking the balance plugs together. if i do this, will it effectively make the 2x 2s = 2s2p? therefore going from 2s 2200mah to 2s2p 4400mah ?? <
if i havent made sence, i can draw a diagram. otherwise. can anyone help to clear this up a tad please?

[benoj]

Dont wire them together, do it the smarter, safer way and buy an adapter that both balance plugs hook into and it makes the charger see it as 1 4s lipo and doing it that way will also require a series adapter for the battery plugs


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[klampykixx]

im going to do it the switched way. ive just been out to Jaycar and had a look through their switches. im going to separate the balance wires. run both sets of positives to each side of a DPDT switch, with the center being the charging input. so, the plan is, when not charging the switch will be in the off position and when its time to charge, flick the switch to either side and charge each independantly. ill run the main charge input to the "fuel flap" on the body of the truck using a stereo 6.5mm plug/socket which will then have the lipo balance connector on the end going to the charger. means i wont have to pull my truck apart to get to hidden batteries...

hopefully its going to work the way im visioning.

[Trubble]

Okay, I was following you on your first post, and it all seemed riskier than I would go, but workable. Your second post, you lost me.

How are you going to hook up a 3 conductor balancer to a double pole switch?
And if you isolate the balancers, are the main power plugs still going to remain connected? Series or parallel on the main leads?
And you'll be charging through the balancers?

If you're doing what I think you're going to do, I envision some bad things happening. Let us know what you find out.

[Docwolf]

i am new lipos, but i would say hooking them up in series and charging as a 4s would far safer. lipos go boom.

[klampykixx]

[Trubble]

That diagram clears things up nicely. Should work like a dream going that way.

I had thought you were going to parallel up on the main leads, my bad. Once you paralleled the mains, you'd be charging both batts through one balance connector. Hooking up the mains in series, or keeping them isolated (like in your drawing), would result in the plan you're after working well for you.

Including a switch (and not tying the balance conns together) is another good idea. Had the balancers been tied together, the batteries would have been paralleled at that connection, and if there was a heavy draw on one batt, (say, a shorted ESC or motor), then those small 20 gauge wires would be passing that heavy current to keep the battereis equalized.

I'm sure some will give you guff about charging batteries while the main leads are connected to the ESC, but I'm sure someone else will chime in that they've done it, and once you turn off the ESC, it's electronically 'dead' and it should be fine. Make your own decision on that one. If you have a BEC hooked to either one of those mains, since those generally don't have switches, you'll need to unhook the mains for charging. Otherwise your charger is simply feeding the BEC, and that opens the door for the throttle to go haywire and draw off the battery while the charger's still connected to the balancer. (I've always just torn my rigs down and made sure the mains weren't connected, just my preference.)

On the subject of an external BEC, if you put one in, I wouldn't recommend trying to bridge across both batts, just draw off one. If you hook up more than one BEC, (say one to each servo, rear steer setup), then as per usual, just keep 'em isolated, don't let them power the same circuit. In your diagram you have two ESC's presumably hooking up to one receiver, then the usual applies, remove the red (power) connection at the receiver connector on one of those ESC's, otherwise their internal BEC's will fight each other through the receiver.

Looks like a long way to go, for not a lot to be gained, but looks to be a reasonable plan. Let us know if you decide to go that way. Best of luck.

[klampykixx]

yep, thanks for the detailed reply. Basically what youve described with the dual bec is what i have planned. Over the next week or two, they will be part of my next order. So, bat1 will run say, front ESC+steering. And bat2 will run rear ESC+rear steering. And then off the rx will run three servo boards, one running low beam/park leds. Second one running a relay for my 14.4v led hibeam kit, and third will be a winch channel. so, if im right, the max draw on the rx will be the winch, which shouldnt be too heavy considering its an old venom touring car servo, and when in use, its likely to be used on its own anyway.

[bob1961]

if you are wanting to charge two batteries at once look into holmes new 4 port charger he was talking bout i think he sells now....4 ports to charge 4 batt's at the same time with 4 balance ports as well....i didn't see it on his site or even found it in a thread search of his ????....does anyone know if john made that charger or where his thread went ????.......bob

....

[klampykixx]

that leads to this>>



which goes in here>>



and then looks like this>>



so these can live in here>>

[klampykixx]

Originally Posted by bob1961

if you are wanting to charge two batteries at once look into holmes new 4 port charger he was talking bout i think he sells now....4 ports to charge 4 batt's at the same time with 4 balance ports as well....i didn't see it on his site or even found it in a thread search of his ????....does anyone know if john made that charger or where his thread went ????.......bob

....

i appreciate the input, but trying to do this as cheaply as i can without sacrificing quality to do so.

[klampykixx]

now, i probably should have checked before i sealed it up, but am i correct in saying that it wouldnt matter what order the red/yellow wires go as theyre both positives and the black being negative is the detrimental one to keep correct. because, i have a 6.5 mm headphone type socket that i plan to use as the connection and was planning on running the black wire to ground, and the red/yellow wires to the two (left/right) positive tabs in the plug.

this should be fine yea?^

[Trubble]

Originally Posted by klampykixx

but am i correct in saying that it wouldnt matter what order the red/yellow wires go as theyre both positives

Mmmm, nope.
The red is likely the positive for cell #1. But the yellow is tied in to both the positive tab on cell #2 as well as the negative tab on cell #1. Short out the red and yellow while you're plugging in your stereo plug and you might have a problem. Make sure when plugging and unplugging your jack, the switch is absolutely in the middle (off) position, and the jack is completely inserted before switching on.
I'd probably make the tip negative, but as long as your switch is off, is won't really matter the order.

[Docwolf]

that is trick man, love the mounting location, charging port behind the gas cap?????

[Charlie-III]

Nice battery hideaway, I can understand why you don't want to remove the packs.

[ik632]

So I guess you will flip the switch to one side so you can charge and balance one battery, then flip it the other way to charge and balance the other pack.

As long as you charge/balance one at a time you're good. If you try to connect all of the leads and charge them as one, then you won't be likely to get a good balance on the pack.

You won't be able to use that single barrel connector like you have shown, you'll need to keep the main power leads separate on the batteries from the balance leads. You could put in a second switch so you flip them both one way activating the plugs to one battery, then flip both switches to the other side to activate both leads on the other battery.

You'll still need two connectors:
main charge lead
balance lead

You could get a balance extension cable and mount the female in the back of the truck next to the plug that will go to your mains on the battery. Then plug the balance plug in and then plug in the main charge plug.

[Docwolf]

I think he is charging through the balance ports.

[ik632]

Originally Posted by Docwolf

I think he is charging through the balance ports.

That would make sense, must have one of those fancy schmancy chargers that lets you do that

I have an inexpensive charger and you need to hook up both to get it to charge.

[Docwolf]

Originally Posted by ik632

That would make sense, must have one of those fancy schmancy chargers that lets you do that

I have an inexpensive charger and you need to hook up both to get it to charge.

same here, plus, how much amperage can you push through the balance wires?? course those are not very big batteries.

[ik632]

Yeah, can't be more than 2200's. He'd still want to charge at 2.2A though to get a 1c rate (given that my guess on capacity is close). I think those little wires are 18 awg and that size is usually good for around 2.5A.