8 6v batteries, how to make it a 36v pack.

[oldngray]

Originally Posted by galloway

http://www.countrysidemag.com/issues...x_A_Ewing.html

ok after reading this site. It looks like my drawing with the beautiful blue and red boxes is correct. But I am still waiting on a confirmation. hahaha. come on people.

I don't think so. I think you are making it more difficult than it is.
Just wire your pack in Series like normal, just make the two extra bats Parallel to each other and connect them in Parallel to the second bat in your pack

[galloway]

i see. I was trying not to have the extra two hanging out by themselves.

From what I read on the page. they guy says it is easier on the charging system and better for the batteries to spread the connections around so that the motor draws from the pack as evenly as possible.

So I think scotty's does a better job of getting the four parallel batteries together in the middle. hahaha.

[oldngray]

Originally Posted by galloway

i see. I was trying not to have the extra two hanging out by themselves.

From what I read on the page. they guy says it is easier on the charging system and better for the batteries to spread the connections around so that the motor draws from the pack as evenly as possible.

So I think scotty's does a better job of getting the four parallel batteries together in the middle. hahaha.

But Scotty's drawing reflects the first Red Batt would be 18V, 1+2+3 = 18V and the first Red bat is parallel to nbr 3 in the string therefor it would be 18V, then the Second Red bat being in Parallel with nbr 4 in the string would be 24V.
I believe that in order for the two Red batteries to be 12V they must be tied to the second batt in your pack.
Again, please correct me if I am wrong.

[galloway]

i see what you are saying now. I think I drew the wire in the wrong place. I am going to redo the diagram and label the batteries. so it will be easier to hash this out.

Cheers

Nick

[buscopat]

It definately makes sense to keep your current and future pack the same age.
The first question is, how long before you make your conversion to 48v?
Now for your question;
If you pick any one battery out of the pack, it is 6v no matter where in the pack that battery is.
The battery packs always seem to wear out the outer batteries first, so if it is a while, when you do make your system 48v, I would sub your first and last batteries with your paralel batteries.
So if that is true about the first and last batteries (just my observation) I would probabley parallel to those 2 batteries.
I would think Garage Built should have a good input on this.
Good luck.

[oldngray]

Originally Posted by buscopat

It definately makes sense to keep your current and future pack the same age.
The first question is, how long before you make your conversion to 48v?
Now for your question;
If you pick any one battery out of the pack, it is 6v no matter where in the pack that battery is.
The battery packs always seem to wear out the outer batteries first, so if it is a while, when you do make your system 48v, I would sub your first and last batteries with your paralel batteries.
So if that is true about the first and last batteries (just my observation) I would probabley parallel to those 2 batteries.
I would think Garage Built should have a good input on this.
Good luck.

Would really like to understand this so my question is:
If I check the 3rd battery in the pack using a meter, I get 18V. How can you parallel to that battery and end up with 6V?. If I understand what he wants it is 12V so if as you say connecting to ANY battery in the pack will net 6V he is not accomplishing his goal.
I always understood that 2 or more batteries in Series would result in the sum of the Volts.
Not being argumentative.

[gornoman]

Galloway, what you propose is doable. I have not studied the diagrams to determine if they are correct, because any combination you do is gonna lead to battery imbalance. Somewhere in the pack there will be 2-6v cells wired in parrallel with 2 other 6v cells. These 4 batteries will receive charge current intended for only 2 batteries. Eventually the system will be out of balance resulting in poor performance because the chargeing amp load will not be even across all 8 cells.

[scottyb]

That is absolutely correct Gman there will be an inbalance sooner or later because the charger is basing it's "completed" charge cycle upon 18 cels at 2. whatever volts each....... hence my remark that he should be ready to monitor and supplement the charging of the parallel pair.
I think my diagram holds water and old&gray needs to just sit back and read...

[buscopat]

Originally Posted by oldngray

Would really like to understand this so my question is:
If I check the 3rd battery in the pack using a meter, I get 18V. How can you parallel to that battery and end up with 6V?. If I understand what he wants it is 12V so if as you say connecting to ANY battery in the pack will net 6V he is not accomplishing his goal.
I always understood that 2 or more batteries in Series would result in the sum of the Volts.
Not being argumentative.

Pick any one battery in the 36v pack, and measure just the terminal of that battery and it is 6v.
The way you are thinking is that you are going from the main positive or negative and going to battery 3 and measuring voltage, that will give you 18volts.
For tying these batteries in they will only be connected to individual batteries, and not the series of batteries.
I hope this helps you understand.

[oldngray]

Originally Posted by buscopat

Pick any one battery in the 36v pack, and measure just the terminal of that battery and it is 6v.
The way you are thinking is that you are going from the main positive or negative and going to battery 3 and measuring voltage, that will give you 18volts.
For tying these batteries in they will only be connected to individual batteries, and not the series of batteries.
I hope this helps you understand.

You are right and I thank you for the explanation.