Diagram for 3s 2100 to 6s 4200

[morbeious]

Gang,

Working with epc2, a knowledgeable gentleman, I was able to create this diagram in which some of you, whom just hover and fly around in circles like me, may want to use, on their Trex-600, or any other bird that requires 6s 4200.

This will allow me to use my current trex 450 lipo's and charger, which will save money, inwhich will go toward broken parts on the Trex 600 as I learn to fly it.

[Arven]

I had the idea of running the first 2 packs in parralal so that you can charge the two packs together (only 11.1volt but 4400mah) on a charger that can not do 6cell at (22volt). That would halve the charge times.

My charger only goes up to 5cell which is a bit of a pain!

Only then you might have problems with the two packs being unbalanced...

Just wondering if when you hook two packs together, you add the MAH but do you also add the C ?? So 2x 2100 16c then become a 4200mah 32c pack?

[Arven]

Ok, i think i have worked it out. The C does not change. it would become a 4200mah 16c pack that could output at 67.2 amps...

Which is still about the same as the align ones huh?

[Inch High]

Just looking at that pic you posted, I have a 6s 4900 mAH which I’m using in a T Rex 600. I hear people running their batteries in parallel, is this what this pic is? If so, I would really, really like to do this as I only have the one 4900 battery.

Just a question, I see there are 4 x 2100mAH wouldn’t that make it a 12s pack?? Silly question??

Thanks

[chinookmark]

Originally Posted by Inch High

Just a question, I see there are 4 x 2100mAH wouldn’t that make it a 12s pack?? Silly question??

Thanks

It depends on the arrangement of the batteries. If the 4 batteries were set up in serial, then you are absolutely right -- it would be a 12s 2100mAH battery. If they were arranged in parrallel, it would be a 3s 8400mAH battery. If you look at the pic, you will see the top and bottom pairs of batteries wired together in series. Basically, this creates two batteries, each 6s 2100mAH. Then these two pairs are wired in parrallel, creating one 6s 4200mAH pack.

[raylepper]

Isn't this more exactly referred to as 6s2p?

[cmsilvoy]

Originally Posted by raylepper

Isn't this more exactly referred to as 6s2p?

That is correct.

[DierWolf]

Just so everyone knows, using 2 in series is OK, using 2 Parralell sets in series starts to become dangerous... .Reason being one may not be charged the same as the other and discharge rate is different. Fire can start VERY easily if it happens that one is not charged properly or even if one has a different C Rating.

Numerous accounts of 4 in series setups catching on fire... Its safer to use 2 in series alone.

My question to you is, whats the difference? get your 6s (2x3s in series) and fly 2 seperate sets, works out to be the same flight time. Why take the chance of fire.

[driftless]

Originally Posted by DierWolf

Just so everyone knows, using 2 in series is OK, using 2 Parralell sets in series starts to become dangerous... .Reason being one may not be charged the same as the other and discharge rate is different. Fire can start VERY easily if it happens that one is not charged properly or even if one has a different C Rating.

Numerous accounts of 4 in series setups catching on fire... Its safer to use 2 in series alone.

My question to you is, whats the difference? get your 6s (2x3s in series) and fly 2 seperate sets, works out to be the same flight time. Why take the chance of fire.

Flying 2 packs in parallel DOES double the C rating. Example:

2 of these:
3cell, 1250MaH 11.1v 15c
(exact same brand/model of battery)

In parallel, you are pulling 1/2 the required amperage from one pack, and 1/2 the amperage from the other.

It becomes a 3s2p 2500mAh, 11.1v 15c pack. (the 15c is the same, but instead of 15c from 1250 being 18.75A, it is 15c of 2500...37.5A.)

When in parallel, you will have both positive, and both negative connected together, and each pack will balance the other one out to have the same total voltage. I know many folks that fly planks that charge their packs using only the deans connector. In the short amount of time that you have it connected before flying, there isn't any danger of overvoltage. (overvoltage only)

However, you are correct in the discharge rate problem. After flying, one pack may be at 3.6 volts, and the other may be at 3.8. Then in each pack the cells are different. At this point, the packs are trying to balance that 0.2v out, and there may be some high amperage going through those connectors. Here, there is a fire danger.

I would NOT recommend doing paralled Lipos, even if it does double the capacities and discharge-rate amount.

Tom

[fenderstrat]

I dont see how if the cells are .2V out at the end of a flight how this is any type of danger,how long do you leave your packs plugged in after a flight? a few min maybe?and on a 600 size bird what amps are you pulling in flight?70amps+.I really dont think the connectors will catch fire balancing .2V after taking peaks of 70A or more repeatedly.you use these same connectors to charge and balance the battery on a charger,why all of a sudden are they a fire hazard?

If you run 2 identical lipos in parallel,there is nothing to fear,especially if they are paired when new and charged /discharged together.if you follow the rules of safety and common sense,they are just as safe as any other set up

[Terror]

Hello I just bought rid and flew it once had a small crash now the motor keeps cutting out systematically after about 3 seconds what could be wrong