I'm missing something very basic here

[Jethro56]

I'm wiring my battery box and before I connected the batteries in series i checked the potential between then I got a reading of ~24V. If I connect I have a dead short. What am I missing here?

 

[Ypedal]

diagram does not compute..

got a digital camera with a picture of your actual setup ?

 

[Jethro56]

All the Red leads for the left bank go to the left buss bar
All the black leads for the right bank go to the right buss bar

 

[Ypedal]

What is your goal, 48v 20ah ??

 

[Ypedal]

real quick and crappy ms paint time... should be kinda like this

... but DO NOT PLUG STUFF IN UNTIL YOU ARE ABSOLUTELY SURE IT'S RIGHT....... TAKE YOUR TIME AND CLARIFY WITH US BEFORE GOING FORWARD...

 

[Jethro56]

Here's a better picture

I want a 12S 4P pack

 

[Ypedal]

Right now the packs are open circuit...

you will need to hook up the negatives on the left with the positives on the right.. this will give you 48v at the bus bars.

 

[Ypedal]

make sure all your packs are relatively at the same voltage before you parallel them up !!!!! if you hook up low packs with high packs you may have problems !!!!! :wink:

 

[Jethro56]

Yes That was my plan. I just can't see why I'm showing voltage between the left negitive and the right positive.

I checked all 48 cells and they were all ~4.13

 

[Ypedal]

it's a volt meter thing.... you canot measure the voltage potential of an open circuit ! :wink:

 

[Jethro56]

I think what I'll do it get a 1amp inline fuse and connect the two leads that are reading voltage thru it as a test. if it doesn't blow I'll be Ok. Have to go to store. Will post results later. An open circuit should measure 0 volts and that's what I expected. Sometimes I miss my Wiggy as a high resistance tester can give weird results.

 

[Alan B]

Using a fuse or a resistor to make the initial connection is a good idea to avoid problems. Your meter is reading stray voltage, put a 1 megohm resistor across it to make it go to zero unless there is something there.

 

[Jethro56]

I figured it out. The plywood was conducting electricity. When I removed one of the bus bars from the plywood the voltage dropped to zero.

 

[Alan B]

I figured it out. The plywood was conducting electricity. When I removed one of the bus bars from the plywood the voltage dropped to zero.

Of course. If it gets humid or damp it might actually drain your battery eventually.

 

[Jethro56]

Thanks for all the replies. I bought a insulated terminal strip to mount in the box.

 

[Alan B]

Great idea. That's what I'm doing. Used a four position 60 amp strip to do the series and parallel connections, kept the 4mm standard connectors on the batteries. All the wiring is done on that strip. Works well and no soldering required.

 

[K.E.Kopp]

You might consider using a polymer material instead of wood, perhaps a small cutting board raided form the kitchen or purchased from the house wares section of you favorite mass retailer : )

I suppose the conditions could exist given a sufficiently high voltage & some road salt saturated rain water on the wood to cause an uncontrolled plasma display within you battery compartment...

 

[webfootguy]

Video version: http://www.youtube.com/watch?v=hIkNY5xjy5k