traxxas parallel connector for charging?

[Money pit]

Hey guys, I am going to be parallel charging 2x2s lipos and wanted to know if the parallel connector for the minis would be ok? I know it is a lower gauge wire, but has anyone done this? It would make it a lot easier on me by not having to make another parallel connector (or buy one) with thicker wires. My charger will be set at 5 amps max. and they are 2x5000mah 2s packs. (largest 2s ones that I have). Any help is always appreciated, Thanks!

[mike-susieq1]

i heard you can charge x2 lipos in parallel with that connector as long as you get a parallel splitter to balance each lipo. look at progressiverc.com and look for a parallel balance connector that splittes 2 plugs to one plug to go to the charger balance board. the wire gauge will be fine.

[mike-susieq1]

this is what i'm talking about: this isnt my charge setup though i wish it was then i would be in business for sure, this is pavementsufer's setup have it for reference incase i forget what i need for when i do mine:

[fuzion]

if it is balancing 6s batteries, i would go series balancing. dont go parallel. serial is a bit better for the cells. its like balancing a 6s lipo.

i was advised to in this forum, i didnt listen and went parallel and my cells died. dont know if that is the reason, but i took it out of the equation to be safe.

[chapinb]

Series charging is better but your batts all need to be the same mah. It is also easier to set up the charger wrong if your not paying attention. You neeed a series balance plug, and they are hard to find.
Stick with parallel. Adapters are easier to get and its still safe.
Your mini adapter will work fine.

[ducati777]

I don't think series is better for the batteries... I've had trouble getting them to stay balanced.

But, series charging is at higher volts, and takes advantage of a charger's higher watt outputs. For example... my current charger is 150 watt, but limited to 7 amps... well 7 amps at 12.6 volts is only 88 watts. If I want to max the charger, I have to series charge as 6s, then I'm watt limited... but it charges much faster this way. If I'm in a hurry, I'll series charge.

Lately I've been uses a parallel board. That sure is handy... and it balances really well.... the downside is at 88 watts I'm not charging very quickly... My 20 amp charger should be arriving any day now... that will help things out... but I'll still need to go series if I want to reach the new chargers 400 watt limit.

[BL-Bob]

+1 series. Amps start adding up quick charging big packs in parallel over a 1c rate. How big are your charger output wires? Things start to heat up. Or you can charge your lipo array all night at a .5c rate.

I use both all the time it just depends what connector is available at the time.

[BrianG]

Once again, here is my take on series vs parallel balancing:

I personally prefer series charging. Why? Because each cell is monitored and balanced individually. If you have two packs where there is a weaker single cell in one pack, the charger/balance circuits will see it and "pay special attention" to it (electrically speaking). If you were to simply slap two of those packs in parallel, that same weaker cell is "masked" by the cell it is being paralleled with. Not to mention the potential for fairly large current flow in those small balancer wires on initial contact as the stronger cell "charges" the weaker one - it's not a whole lot typically, but could be if one cell was a lot weaker. Please do not tell me "but voltages are the same in a parallel circuit so both cells will be equal". Of course that is true, but for that to happen, the weak cell and the strong cell have to "meet somewhere in the middle" voltage-wise, and my problem is how that convergence is happening. This is also why I do not even like 2p packs; if the pack needs to have multiple parallel cells internally to make up the capacity you want, then just use larger cells or re-think the system to maybe use higher voltage instead.

Also, coming from an electronics background, the idea is to keep currents as low as possible (high current creates voltage drops, heat, etc). Need proof? Power companies transfer power using very high voltage over long distances to keep currents lower. Ok, we aren't charging batteries with mile-long wires, but the same principles of v-drop/heat/efficiency is present since for a given power, current is twice as high when charging two 5Ah pack at 2C (or more) in parallel vs series.

Theoretically, there is nothing wrong with parallel balancing as long as both packs are in "ideal shape" where all cells have the same voltage, no deviation in cell IR, etc. But we live in a world where things are not ideal and situations arise where some cells have higher/lower IR, which does change things.

One might argue that if parallel charging is so "bad", then why are charger manufacturers making chargers meant for balance charging? Well, I can think of a few reasons; 1) Simplicity. It's likely easier to take a 100w 6s charger and make some relatively small modifications to make it a 1000w 6s charger than to completely redesign the charger from the ground up for higher voltages. 2) Market. Not too many people are running HV setups where more than 6s is needed. And for those that are using 10s or more, they figure the user can just parallel two 5s packs when charging. So, charger companies have the market covered with a typical 6s charger that is capable of much higher currents. 3) Liability. 6s-8s voltages aren't much of a big deal, but when you start getting to in the 12s or higher range, the voltages are getting pretty high and can cause damage easier. So instead of dealing with possible safety issues from using 16s, just charge two 8s packs in parallel to keep the voltage lower.

[ducati777]

I mostly agree, and maybe its a shortfall of my charger, but it can't seem to pay special enough attention when i'm series charging.

It'll show imbalance on the charger, but afterwards when I cell check it... they look ok....

As far as high amps through the balance tabs... you're correct, however you can lower that risk by using the main leads first. Once the two packs have the same overall voltage, the inter-cell differences are going to be low.

I was surprised at how quickly 2 packs will reach the same voltage... which implies there's a decent amount of energy being exchanged quickly.

[Money pit]

WOW! I was not expecting this many replies this quickly! I will be getting a parallel balance connector(forgot to mention that in my first post) I would be parallel charging my batteries for quicker charges in racing situations, or when I am in the field, but when it is the end of the day, I would charge them individually to ensure balancing accuracy. Brian, I agree with you 100%, but everything I have seen is that parallel balancing is safer, and the main leads would be connected first to transfer the voltage differences( and my batteries are only used in series, so the voltages are extremely close to each other, but individual cells can vary from each other). Thank you all for your input, if anyone else has any thing else, I am still taking ideas! All of this help has been great, and is going to make less work for me on the soldering end!

[BrianG]

...I was surprised at how quickly 2 packs will reach the same voltage... which implies there's a decent amount of energy being exchanged quickly.

Makes perfect sense because without the presence of anything to limit how fast that energy is transferred (like a resistor or active circuit), they will reach the same level almost instantly. That's the nature of a parallel circuit.


And for everyone else, I just want to be clear that I am not saying series charging is THE best just because I said so, which is why I tried to explain my technical reasoning. Yes, parallel charging is probably easier and faster. Despite that, I still prefer series-charging for the greater control and monitoring of individual cells.

The only instance where I would parallel charge would be if I have the two packs hard-wired as a parallel set. So, they'd be seperate physical packs, but electrically connected as a single pack right out of the box. Like if I want to run 5000mAh @ 5s, I'd use two 2500mAh 5s packs in parallel. But even then, that's not really any different than a single 5s2p pack comprised of 10x2500mAh cells, which I don't like if you remember, so there would have to be a very compelling reason to do so.

In actuality, this is really a non-issue for me as I only own and use single packs. Makes for cleaner wiring and no worries about making sure packs stay paired up.

Just thought I'd throw in my $0.02. Take or leave it, call me a nutter, I don't care.