Community Forums

bluegrasser · 06-26-2011, 02:09 PM

My Kwikee slide out battery tray has room for 3 group 27 batteries and I would like to add 1 more to the existing 2. I know to wire them neg. to neg. to neg. and pos. to pos. to pos to keep the voltage at 12. However I am not sure where to connect the charger leads nor the power feed wires. Presently the charger is connected to the pos. of one battery and the neg. of the other. The power feed does the same. The batteries will be lined up with the long sides together. When I add the 3rd battery do I make the connections to the outside batteries, or make all the connections on the center battery. I want to make sure the charging and drawing of power is even in all 3 batteries.

Mike Canter · 06-26-2011, 02:14 PM

We are talking about your house batteries, correct? Are the two you already have 6 volt or 12 volt batteries?

bluegrasser · 06-26-2011, 02:18 PM

The batteries are 12v and power the "house" portion of the motorhome.

Mike Canter · 06-26-2011, 02:24 PM

Then you put them all in parallel. As you stated all positives tied togetehr and all negatives tied together. It doesn't make any difference if you hook up to the center or outside batteries. You leave the charger and power feed hooked up the way they are now for simplicity.

RJay · 06-26-2011, 02:34 PM

You hook up your supply leads to the coach on the first and third battery. It doesn't matter if the positive lead goes to the first or third battery, same for the negative lead, whichever will reach. The charger leads go on the same terminals at the coach leads. Mike is correct that they all need to be in parallel.

Billieg · 06-26-2011, 03:11 PM

Quote:

Originally Posted by RJay

You hook up your supply leads to the coach on the first and third battery. It doesn't matter if the positive lead goes to the first or third battery, same for the negative lead, whichever will reach. The charger leads go on the same terminals at the coach leads. Mike is correct that they all need to be in parallel.

Right on

You want to equalize the load coming out and going in so all 3 charge/discharge the same. Also, if your old batteries are over 3 -4 years old keep an eye on the new battery to see if it's being over charged (water coming out the top) because it will not take as long for the new battery to charge as the old ones. If this happens you will need to buy 2 more batteries.

ga traveler · 06-26-2011, 04:39 PM

As someone who has been far too many battery class's. Why not go to two six volt in series. It will give you more capacity than two twelve volt in parallel.Going to three in series will cause the weakest battery to draw off the other two. If you can lengthen the battery boxes to size 31, you will have more capacity with two size 31 in series than three size 27 in parallel.

RJay · 06-26-2011, 04:56 PM

If your going to change your battery bank size it's a good idea to maximize the your battery storage area. Interstate Workhorse U2200, for example, has capacity of 230 amp/hrs at 6 volts. If you can fit three 12 volt batteries you might be able to squeeze 4 6 volt batteries since they have a smaller footprint. Four 6 volt batteries will give you a total bank capacity of about 460 amp/hrs.

Mike Canter · 06-26-2011, 05:07 PM

OK Ga traveler if what you are saying is true then my eight 6 volts batteries hooked in four sets of two in series will not work yet I have no problems. Also it doesn't make any difference if you hook the charger up and pwer feed to the inner battery battery or the outer batteries. Those batteries cables are big enough that the electrons don't know maybe if you used 12 guage wire it would make adifference. Again my setup would not work if that was so. This is not theoretical physics, this is applied

bluegrasser · 06-27-2011, 04:00 AM

Ok here's what I will do. I need to turn the batteries in the tray so that they all lineup the same way, long sides together. I will add a 3rd group 27 and 2 short 3 ga. or 4 ga. jumpers, negs. to negs & pos. to pos. The power leads and charger feeds will go to the outside batteries, pos. on one outside battery and neg on the other. That way I think the feed and draw should be equal across all of the batteries. The present 2 batteries are 2 years old and have been properly maintained. The new battery will undoubtably be in better condition but I doubt that there will be a significant imbalance. Adding the 3rd battery should give me a little more capacity, perhaps not 50% more, but some more. If the existing batteries had been in poor shape, I would have gone to 4 six volt batteries as I understand that the six volt batteries are better performers in the deep cycling department.

Thanks for all the input

ga traveler · 06-27-2011, 06:39 AM

Quote:

Originally Posted by Mike Canter

OK Ga traveler if what you are saying is true then my eight 6 volts batteries hooked in four sets of two in series will not work yet I have no problems. Also it doesn't make any difference if you hook the charger up and pwer feed to the inner battery battery or the outer batteries. Those batteries cables are big enough that the electrons don't know maybe if you used 12 guage wire it would make adifference. Again my setup would not work if that was so. This is not theoretical physics, this is applied

I did not say it would not work, Mike. I am just saying all the experts preach not using 12v in parallel. The manuf. use 12 volts for one reason. money. the 12v is cheaper than a six volt.

Mike Canter · 06-27-2011, 06:45 AM

OK, my misunderstanding. Sorry. But I will tell you that it does not make any difference where you hook up that power feed or charging line on positive or negative side of batteries in parallel. 3 inches or 6 inches or a foot of 3 or 4 gauge cable is not seen by the voltage or current as being any different. Maybe in theory 3" or 6" of cable that large of a guage makes a difference but not in reality.

RJay · 06-27-2011, 07:24 AM

Quote:

Originally Posted by bluegrasser

Ok here's what I will do. I need to turn the batteries in the tray so that they all lineup the same way, long sides together. I will add a 3rd group 27 and 2 short 3 ga. or 4 ga. jumpers, negs. to negs & pos. to pos. The power leads and charger feeds will go to the outside batteries, pos. on one outside battery and neg on the other. That way I think the feed and draw should be equal across all of the batteries. The present 2 batteries are 2 years old and have been properly maintained. The new battery will undoubtably be in better condition but I doubt that there will be a significant imbalance. Adding the 3rd battery should give me a little more capacity, perhaps not 50% more, but some more. If the existing batteries had been in poor shape, I would have gone to 4 six volt batteries as I understand that the six volt batteries are better performers in the deep cycling department.

Thanks for all the input

That sounds like a good plan. I suggest you put the new battery in the center of the battery bank(#2 position) and that you use #2 stranded copper welding cable for your battery connections.

RJay · 06-27-2011, 07:31 AM

Quote:

Originally Posted by Mike Canter

OK, my misunderstanding. Sorry. But I will tell you that it does not make any difference where you hook up that power feed or charging line on positive or negative side of batteries in parallel. 3 inches or 6 inches or a foot of 3 or 4 gauge cable is not seen by the voltage or current as being any different. Maybe in theory 3" or 6" of cable that large of a guage makes a difference but not in reality.

Hi Mike,
It has nothing to do with the battery's interconnected cabling and everything to do with the sharing of the electrical load and charge current within the battery bank.