Lipo arrangment

[shorza]

I'm not too sure where this belongs, so I apologise if it belongs in another thread.
Hopefully it can help another noob with a similar question.

I plan on setting up my 6 x 6s 500mah lipos for a 66v 10ah like this :
(excuse the bad paint skillz)


My question is, can I then make a couple of adjustments to turn it into 44v 15ah:

 

[Lessss]

right click open link in new tab to see full graphic.

 

[neptronix]

Yeah, if you look at less's graph, that layout would present a bit of a problem since electricity flows in the direction of least resistance.

How i do it is such:
Each 5ah has a serial harness on it.
Each serial harness is connected to a parallel harness.
Parallel harness has exactly equal length wires.

If i want to configure for another voltage, i need to switch out my serial harnesses.

Kind of a PITA, but i don't switch voltages often enough..

 

[shorza]

Ok, so it looks as though I'll need a whole different birds nest for a different voltage setup. Unless someone has a better way?
Thanks for the help.

 

[neptronix]

Ok, so it looks as though I'll need a whole different birds nest for a different voltage setup. Unless someone has a better way?
Thanks for the help.

There are many ways to do it, but you want equal length wires.

Also, your AH calculation seems to be messed up friend..

If you did 44v, you would use all the battery packs by using two groups of parallel. x 3 packs.

SO you'd have a 15ah 44v pack or a 10ah 66v pack.

 

[shorza]

So I can arrange them this way as long as all my wire runs are the same length?

In regards to the amp hours, I think what i have marked is right. The last yellow box states the voltage and amp hour. The first pic says 66v 10ah and the second pic says 44v 15ah.

Also, is there any difference in paralleling 2 lots of 18s1p or serialling 3 lots of 6s2p ?. This is all too confusing.

 

[neptronix]

Well i gotta say, your diagram was on the confusing side.

Connectors also increase the resistance some. You have to factor in that.

And when i say wire length being equal, i mean the wire length from the start of the connection to the motor controller all the way to the battery itself... not the wire length from each inter connection.. understand?

If you are confused you can test these things out with some AA batteries and a multimeter

I don't know what you mean by 'lots'.. do you mean parallel groups?

You can make multiple serial connections.. or multiple parallel connections, if you are so inclined.

 

[shorza]

Haha, trust me I know what i'm trying to say, just not how to say it.

By 'lots', I mean groups, but you answered my question, about multiple serial connections and multiple parallel connections. As long as it equals 18s2p, it will work.

Regarding wire length, I understand. I was hoping there would be an easy way to change the setup from 66v 10ah to 44v 15ah, during a trip if I wanted to. I guess it would be easier for me to wire for a 66v 10ah setup and use the 3 way switch on my controller to limit the power I use.

Thanks for your help.

 

[neptronix]

Haha, trust me I know what i'm trying to say, just not how to say it.

No biggie!!

By 'lots', I mean groups, but you answered my question, about multiple serial connections and multiple parallel connections. As long as it equals 18s2p, it will work.

Regarding wire length, I understand. I was hoping there would be an easy way to change the setup from 66v 10ah to 44v 15ah, during a trip if I wanted to. I guess it would be easier for me to wire for a 66v 10ah setup and use the 3 way switch on my controller to limit the power I use.

Thanks for your help.

Yeah, no easy way that i can think of unless you want to just forsake 5ah of the pack, but then you wear the batteries unevenly which over a long term is funky.

Yes, doing the full voltage with a 3 way switch is definitely the best way to go about this.

Your original idea was good - parallel harnesses to the battery, and a serial harness at the end.. then you can break up the serial harness to do balancing if need be.

 

[shorza]

Your original idea was good - parallel harnesses to the battery, and a serial harness at the end.. then you can break up the serial harness to do balancing if need be.

Great, i'll do that, cheers. Would there be any reason to parallel the balance connectors also?

 

[neptronix]

Your original idea was good - parallel harnesses to the battery, and a serial harness at the end.. then you can break up the serial harness to do balancing if need be.

Great, i'll do that, cheers. Would there be any reason to parallel the balance connectors also?

Yes, but there are many other threads that talk about that.
Go hunt around in the battery technology section here, there were a few posts about battery paralleling in the last week.

Also, i found rc-groups pretty informative even though the guys there can be kinda stupid about lipos.. they speak in layman's terms that are very easy to understand

http://www.rcgroups.com/batteries-and-chargers-129/

 

[shorza]

I am thinking of making a 4mm plug arrangement similar to this http://endless-sphere.com/forums/viewtopic.php?f=14&t=25535#p369472 but it will require me to join 3, 12 or 10 gauge wire into parallel.

Can anyone suggest an easy way to do this?

 

[neptronix]

I have done this with a 70 watt soldering iron, it is possible.

You have to basically get a ton of solder on the individual wires first, and then melt the solder on all of them into one large solder lump.

 

[shorza]

Great, cheers.
Ant idea how I can then solder that into a xt60 connector. Will it fit?

 

[neptronix]

Those don't look very easy / stable to solder. I don't think they will take a 10ga. wire either.

Have you considered 4mm bullet connectors?
They come stock on many lipos, and are very easy to solder. They will work with 8ga. wire i think, but 10ga. fits in them nicely.

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9283

 

[shorza]

Thanks for the suggestion.

Any easy way that I can make a 3 wires parallel to 1 connector?

 

[neptronix]

Thanks for the suggestion.

Any easy way that I can make a 3 wires parallel to 1 connector?

Nope.
You're going to have to parallel 3 wires to 1 wire, and then to the connector.

Bust out the soldering iron and you will see what i mean

 

[shorza]

I was afraid of that.

Is the best way to strip a little off the middle of 1 wire and solder the other 2 to that? Hard to explain.

 

[neptronix]

You can do that too.

http://neptronix.org/forumpics/parallelconnector.jpg

This is how i did my big 12-10awg parallel connector.

 

[shorza]

Exactly what I'm after, cheers.

 

[shorza]

Ok, so after a fair bit of soldering and heat-shrinking, I think I have got a set up that will be good for 44v 15ah and can be changed to 66v 10ah with minimal fussing. It is a bit messy, but I think it is great to be able to change capacity while on a ride.

Here is 44v 15ah:


and the setup for 66v 10ah:


As long as I keep the connectors that aren't in use covered, does anyone see a problem with this?

 

[wesnewell]

I really don't see a point to all this unless you plan on using the pack on 2 different bikes. As long as your controller will take 75.6V (fully charged 10ah 18s pack) just do it that way. There won't be any measurable distance gained by using it as a 15ah 12s pack as long as the speed is the same. The watts of the packs will still be the same either way you configure it.

 

[neptronix]

Shorza, those diagrams will work. Now the downside for the 66v setup is going to be balance charging them and doing regular charges.

44v would be nice as you can balance charge it straight with a 14s hyperion. 66v will need to be broken down to charge.

What i do for my iCharger 1010b+ is that i'll run 10s all the time but i have a 4s booster pack i hook up at the end.
Current sharing sucks that way but when i'm done with the booster pack i just take the 4s pack off and close the serial connection. I then charge the 10s and 4s packs separately as two large parallel groups.

You could do that too if you had some lipo lyin' around that you occasionally want to use for high speed blasts and don't mind wearing it unevenly by putting less cycles on it than the big pack.

 

[shorza]

Thanks for the tips neptronix.

Wesnewell, interesting.... so are you saying it would just be easier for me to arrange the packs in the 66v set up and use my 3 way switch that is connected to my controller to limit my speed to say 66%?
66% of 66v is 44v, so I should be using more or less the same amount of wattage than I would if i had connected the packs as 44v?

As neptronix states, the only problem is breaking the packs down to charge them.

 

[dogman dan]

Well, you said you'd have different capacity. I'm splitting hairs here, but your capacity remains the same at either voltage. Simply riding slower some way or another, whether by switch, CA limiting, or just backing off the throttle, is the only way to go farther.

Of course, there is nothing wrong with keeping your set up a bit more changeable, since you can stretch range further easier with a lower voltage. Not tempted to go faster if you can't. And you might get another bike or controller that requires a different voltage. Nothing wrong with what you've done that I can see.