Journey house battery replacement advice needed - Page 2

cbeierl · 07-03-2009, 02:43 PM

One suggestion for anybody else replacing batteries: Take a picture of which cables go where on your present batteries before taking things apart. You may find that to be a life saver when you go to connect the new ones back up.

MrTransistor · 07-04-2009, 08:10 PM

Hi All,

I've been meaning to create this drawing for a long time now and this thread looked like my best excuse. For those of you without a digital camera or a film camera with easy access to developing (remember developing?), this may serve you well as a guide for wiring up those house batteries. Please remember that your batteries may not be connected this way since Winnebago tends to scrimp on wire and the plus or minus cables may not reach. But if you have the cable length, I would highly recommend re-configuring the wiring to eliminate resistance variations in the bank. This will help you achieve the best performance and life from your battery purchase.

http://www.irv2.com/attachments/phot...onnections.jpg

RCtime · 07-05-2009, 07:30 AM

What great helpul diagrams. In the case of the Journey with the standard 3 battery set up, replacing the negative wire is the practical choice, as the positive wire heads towards the front of the coach somewhere.
Now the 2- 12 Volt starting batteries (in my case) are going to be a nightmare to service. The bundle of wires goes directly over the filler caps. They will have to be removed, so a digital picture is a must. Mr. transistor hit the nail on the head when he said Winnebago scrimps on wire.
The 2 extra battery wires I had made up for the house batteries, I made just an inch longer and they now easily make a bend around the filler caps..
Mark, do you also have diagrams for the staring batteries?

SteveG · 07-05-2009, 09:22 AM

Thanks a lot for the helpful drawing. I have tried to darken your drawing a little so it would be easier to read and make a better print out. See below.

I would also like to comment that my 2004 Journey three battery bank (house batteries) seems to have a setup for drawing power from either end as our inverter seems to be connected to our three battery bank at the opposite end. I am going to trace back the wiring to confirm the existing wiring setup.

In my reading on this subject, connecting the positive and negative cable at the opposite ends of a battery bank is equally important for both charging and discharging the battery bank. In effect all the batteries are working pretty close to equal. On your three battery bank example the cables feeding the alternator and the charger would be connected to the same posts?

On the web site I provided a link to in an earlier post in this thread it says: "The chargers should always be connected to the same points as the loads. Without exception." That is correct? And if so how does this align with connecting the inverter to the opposite end? Or is that electrically identical?

MrTransistor · 07-05-2009, 10:32 PM

Hi RCtime,

No, I have no diagram for the chassis batteries. Memory tells me that Freightliner doubled up on the wiring at least for the CAT engine. This may make things a bit confusing when trying to replace the batteries. By all means, take pictures.

Hi SteveG,

I create these drawings in Generic CAD, then print them as .EPS files. Using an old version of Acrobat Distiller, I convert them to .PDF files. Unfortunately, this site doesn’t take anything except 300kByte or less .JPG files. So I have to import them into a .JPG viewer and export as a .JPG file. In the process, all the good vector graphic resolution of .PDF is lost, and try as I might, I can’t seem to get the lines to show up any darker. I think the problem is with line width. It is set essentially to 1 pixel and I believe Explorer as well a other viewers show very narrow lines as a shade of gray. If you go to the Photos section and view the original .JPG, the contrast is much better and it prints okay since it’s 300 DPI.

‘The key to maintaining the current balance is to connect diagonally.’ If the house electrical is connected at one end of the string and the inverter is connected to the other end of the string, then the charge and discharge currents for each battery will not be balanced. It maters not where the charge comes from or where the discharge current goes, as long as the resistance seen by each battery is equal, then all batteries in the bank will be charged and discharged equally.

It would be true that with only one connection to the bank, the charge and discharge currents would be to and from the same points. But there is no reason why a bank cannot be charged from one set of leads and discharged from another as long as each is resistance balanced. In very large industrial setups like telephone switching backup power, they go to great lengths to minimize any resistance imbalance. It usually is much easier given the voltages that the system works with. The individual 2 Volt cells are around 2’ x 2’ x 4’ weigh 1000s of lbs, and are rated in the 10s of 1000s of Amp./hours. Connect 75 of these in series and you get 150 Volts DC. It’s very easy to invert this voltage to 120 VAC and since there may be only one string of cells, there is no problem of balancing. The same current passes through all cells equally.

Just remember to connect diagonally to the bank as shown. Don’t make the mistake of connecting to one end or the other thinking they are the same point because of the big fat short wire connecting the terminals. All connections and wire have resistance and that is what has to be balanced. 1/10 of an Ohm is pretty small but at 100 Amps. the voltage drop is 10 Volts. Not good in a 12 Volt system.

There are other bank arrangements that can be balanced but for practical purposes in an RV, these should be the only arrangements you will run into. And since no one makes the perfect RV battery we are stuck with banks to get the job done. It seems like someone would start to manufacture, lets call it a 16D, for RV’s. It would be a single battery with 6 cells for 12 Volts that was 18” wide, 24” long, 10” high, weigh about 250 lbs., AGM, and be rated in the 500 Amp./hour range. Then there would be no question of connections since there would be only one positive, one negative, and all cell currents would be equal! I hope this explains thing a little better.

wa8yxm · 07-06-2009, 10:23 AM

Quote:

Originally Posted by RCtime

here ya go Wa8yxm

Yup that is half the issue.. Just half.. There is another half

Price is my primary consideration, and that makes the price (And capacity) of two batteries fairly close, as it should be

There is also a secondary consideration and I believe it favors six volt pairs. But, frankly, Cost is the larger issue.

I have to say I am very pleased with the six volt pair Damon gave me.

old68Mustang · 07-14-2009, 08:51 PM

I have an 02 Journey with the three 12V Battery house set up. If you hook it up the way it came from the factory, the positive to the generator comes off the rear battery and the positive to the charger/inverter off the front. The Negative for the generator comes off the front and the negative to the charger/inverter comes off the rear which gives you cross wiring for load equalization. You don't have to try to work out a new scheme, the factory did it right. I found this out, quite by accident, while troubleshooting a generator no crank problem a while back.
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old68mustang