Two 12V batteries - can't figure wires

12-20-2008, 10:34 PM

Hi guys.

I've read the threads about connecting two batteries by linking the positive and negative connections, but on my Trailmanor I can't tell what's what. The left-hand battery has three black cables - so which goes where?

I have power when I'm plugged in to the house, but not when I try to run on battery power. When I press the "test"button inside the Trailmanor, it says that the battery is fully charged.

The batteries are clearly not connected correctly.

1. The white wire on the right battery is a ground, not a negative wire - right? Is that all this battery needs, a ground and a connection to positive?
2. The left battery wires include a positive wire (red one), but there's no color difference in the other two that lets me know if it's supposed to be a positive or negative.
3. The fuse blew out...

By the way, it's a 2007 2720.

Thanks a lot for any help you can offer connecting these cables correctly. My wife and I bought this unit used a week ago and are hoping to take the kids camping over X-mas (we live in Southern California).

Got my fingers crossed...

**B_and_D** · 12-21-2008, 01:16 AM

http://www.ccis.com/home/mnemeth/12volt/12volt.htm

Check here ...

12-21-2008, 08:50 AM

Hi,

I was going over the link in the diagram, and the wiring is different for six and 12V. If the caps on top of the battery are round holes for distilled water, does that automatically mean the batteries are 12V?

**rtcassel** · 12-21-2008, 09:38 AM

Quote:

Originally Posted by jasongold

Hi,

I was going over the link in the diagram, and the wiring is different for six and 12V. If the caps on top of the battery are round holes for distilled water, does that automatically mean the batteries are 12V?

This link http://discoverpower.com/shop/item.asp?PID=232 has your batteries for sale listed as 6V.

**B_and_D** · 12-21-2008, 09:47 AM

We keep one of these in the trailer "just in case"...they are only about $15

http://en.wikipedia.org/wiki/Multimeter (ours looks like the 2nd one down)

and I bought this book to keep in the TM (I learned quite a bit from reading it):

http://www.amazon.com/Electrical-Sys.../dp/007042778X

Have fun with your TM - I hope you can get it fixed in time to go camping!

12-21-2008, 10:18 AM

Some of you battery experts chime in...aren't the batteries pictured 6v? They have 3 fill holes - the 12v batteries I have seen have 6???

RLDeLay · 12-21-2008, 11:21 AM

The manual for my 2720SL shows the black wire as positive and the white wire as negative (ground). This may be a good starting place.

**ShrimpBurrito** · 12-21-2008, 11:56 AM

I'd definitely take the advice from those here and get an inexpensive multi-meter. I've seen them at Harbor Freight for $3. It's plenty accurate for anything you do with the TM, and is an indispensable tool.

To determine which of the wires are (+) and (-), remove all the wires from the batteries and make sure they are not touching anything. Then plug in the TM. Turn the multi-meter to measure volts (probably to "20" on the volts scale), and touch the (+) lead to one of the wires and the (-) lead to the other one. If you read +12 volts, the wire in contact with the (+) meter lead is the (+) wire. If the meter reads -12 volts, the wire in contact with the (+) meter lead is the (-) wire.

The ground wire should be bare copper -- no insulation. The ground wire is in addition to the (-) wire.

Now that you've identified the polarity of the TM wires, be certain that your batteries are indeed 6 volts. It appears as though your batteries are 6 volts based on the link Tim (rtcassel) posted above, but I'd double-check. Using your multi-meter still set on volts, match the (+) lead to the (+) post on one of the batteries and the (-) lead to the (-) post on the same battery. If the meter reads approximately 6 volts, it's a 6 volt battery. If it reads 10-12 volts, it's a 12 volt battery.

Once you have confirmed that you have a 6-volt battery, look at the diagram at the link B_and_D posted -- screw the (+) wire on the (+) post on one of the batteries. Screw the (-) wire on the (-) post of the OTHER battery. You mentioned there is an extra wire on the battery -- it may be a wire that simply goes from one battery to the other. That wire should go between the two batteries on the remaining (+) and (-) posts.

Does the LED power meter show fully charged while the TM is unplugged? If so, I don't know why that would happen as I believe those LED's simply measure battery voltage. The batteries would need to be putting out 13 volts for that display to show fully charged.

Dave

12-21-2008, 12:07 PM

From the photo, the batteries are clearly 6 volt batteries, 2 volts per cell as someone else has already mentioned.

The battery terminals are clearly marked positive and negative.

To get 12 volts the batteries must be connected in series, not parallel. This means that the negative of one battery is connected to the positive of the other battery. Nothing else will connect to these two terminals or the wire between them. The wire must be insulated wire.

Now you still need to connect the positive and the negative wires from the remaining terminals to the TM. I don't recall which side goes to ground. But whichever it is, that terminal will have two wires, one an insulated wire to the TM converter and a bare copper wire attached to the trailer frame. The other battery terminal uses the second insulated wire from the TM converter.

12-21-2008, 01:23 PM

Thanks a lot for the posts.

I took the batteries to a store and they are indeed 6V, which means that I have to have them positive to negative.

Here's where I am:

1) As I understand it, the battery labeled "right" in my photos is wired correctly. The white wire in the photos is a ground - it leads to a spot on the frame. I don't know why it's not bare. The black cable on the positive post leads to the negative post on the "left" battery.

2) The "left" battery has a wire running from negative to the positive on the other post. Good. But why are there TWO wires on the positive post of the left-hand battery? One has a fuse in it - blown, and I need a 30 amp for that spot, right?

As I'm new to RVing, I appreciate all the help. I plan to get the voltage reader and the RV electrical manual recommended by B _ D.

Thanks again to everyone.

Jason

Oh - we're booked for Tuesday at a campground down the road for a test run. I don't need batteries for full hookup, do I?

Jason