Electrical issue. Narrowed problem but need knowledgable advice

Hi all,

I have a 1997 Prowler 5th wheel model 27 5N. I have been having issues with the trailer only powering up when connected to shore power. The only thing that operates under battery power are the jacks, which I understand are directly connected to the batteries.

I went through and was checking things out. Here is what I found out.

1. Converter is taking in shore power and converting to 12 volt as expected based on the voltmeter.

2. Batteries are new and charged, but do not seem to charge when plugged into shore power and not as expected when connected to the tow vehicle all of the time.

2. In the fuse panel I disconnected the battery positive wire and see a faint light on my test light, but nothing when it is connected to the panel. Naturally the volt meter blew the fuse so I couldn't see what if any was making from the battery through the wire. On both sides of the fuse block at the batteries before the fuse blew I found full voltage.

Based on this finding I am figuring that the wire from the battery block to the fuse panel is damaged someplace and that would explain no battery power in the trailer and no charging.

Here are my questions.

1. Can I just abandon that supply wire and run a new one from the supply side of the fuse block to the fuse panel? I believe the answer is YES, but that leads to another question.

2. There are two wires on each side of the battery fuse block. How do I know which is the one I need to replace???

I assume that the shore power wire to the fuse panel is running from the converter straight to the fuse panel. Since the battery wire is attached to the same spot next to it, I figure the shore power is back feeding through the battery wire to charge the batteries. Or is there a whole other circuit that does that?

I am thinking I am on the right track but need someone that has some knowledge and experience to guide me so I stay on course.

Thank you so much for your help and advice.  ;D

1. Can I just abandon that supply wire and run a new one from the supply side of the fuse block to the fuse panel? I believe the answer is YES, but that leads to another question.

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Yes

What make & model of power center (breaker and fuse panel) is installed in your Prowler?  Is it a Magnetec 6300 or 7300, perhaps? It helps to know what sort of fuse block and converter we are talking about.

Generally the converter provides the DC power to the fuse block, using either 120v conversion or battery as the source. Typically the fuse block has only hot (12v) wires and the ground side of the circuit is provided via the RV chassis, with thebattery and the converter both wired direct to chassis ground.

2. Batteries are new and charged, but do not seem to charge when plugged into shore power and not as expected when connected to the tow vehicle all of the time.

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Sounds like two separated problems but.... All 12V items (like lights in the trailer) should light without being plugged in or connected to the truck, but if not....

Just to be sure... Use a handheld voltmeter and measure across the battery terminals before plugging in and after disconnecting from the truck. Plug in and measure again. You should have read 12.6V or so when unplugged with a fully charged battery and 13.2 V when plugged in IF the converter is charging.

Note that there are usually one or two fuses on the converter itself or on the power panel to protect the converter from damage if the batteries are connected backwards by accident, but they have been known to blow for other reasons. Note that charging from the truck should not be affected by this problem but this may depend on the wiring methods used or a fault in the wiring from the truck/trailer wiring that caused the fuses to blow.

In the fuse panel I disconnected the battery positive wire and see a faint light on my test light,......

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Although I used test lights for a good part of my former life as a tech, the independent voltmeter was the more reliable way of verifying once 'dim light' stuff happened. This sure looks like 'feedback' from other circuits in the panel.

Thank all,

I have to buy a replacement fuse for my voltmeter today as I had started with that.

I was getting just over 13 at the wire in which I have found is coming from the converter on the dc side of the converter and at the fuse panel, at all of the fuses and at the batteries and the battery block fuse on both sides. The fuse on the voltmeter popped before I could isolate and check the battery line that connects to the fuse panel. When connected to the truck I do have lights and everything powers on inside the trailer.

One thing that I had noticed is someone has the batteries wired in series using the same type of wire used to supply the panel and the wire coming from the converter, rather than the battery cables I have had on my other trailers. Could this be bottle necking the voltage when the trailer puts a draw on the batteries?

All great advice. In response to one of the question regarding the type on converter. It seems fairly new and I will not have the model until I get home, but it is a Intellipower.

Having the connecting cable between a pair of series connected 6 volt batteries the same gauge as the other wires is fine.  It won't "bottleneck" the connection.

Something that will limit current flow is corrosion on or around the terminal connections.  If you have crimp-on connectors corrosion can hide inside where the terminal is crimped onto the wire.

It only takes one bad connection to block current flow.

Okay now I am very confused. I picked up a fuse for my voltmeter and checked the batteries, 13.2v. Then I checked the battery line that is connected to the fuse panel, 0.2v. So I decided that I would run a jumper line straight from the battery terminal to the panel. I hooked it up to the battery and tested the end of the wire., 0.2v and the battery shows 12.9v. Off the batteries I am getting the same 0.2v when connected to the battery in the fuse panel.

I do not get it. One of the batteries is a 11 months old and the other is 3 months old. I get a massive drop in power even when bypassed by a jumper. Now, I did not connect the other wires when I did this. If there is a drain from another connecting wires on the batteries, could that be causing me the issue in power loss? Everything seems to be isolated around the batteries and that is what is driving me crazy.

I would start checking the ground connections to the frame of the trailer/motor home (rust etc). Then you are down to checking what that panel serves, start by removing all the fuses and see what you get at that point on the panel. (I assume you are measuring from the bus bar on the panel that supplies the fuses on the other side of it.) Once you get past the connections to the panel there is only battery (12V) present, you need to be sure the other side (-) of the meter is well grounded in order to get a good reading.

As Stu said, make sure you are measuring from the battery / bus / hot wire to GROUND, which is any bare chassis metal.  If you measure one side of the bus to the other (not to ground), you will get no voltage.

The basic circuit is from the battery + side to where ever, via fuses, wires, switches, appliance and back to ground.  No ground, incomplete circuit.  Any corrosion in any ground connection, on the appliance end or on the battery end, and the circuit is blocked.

Good Luck!

First things First ?

Dis-connected from each other.. and the Rig.. Load Test the Batteries. Then continue your trouble shoot.

Batteries of different age (and even Brand) can be the root of a lot of 12v issues ?

Joe (a new guy)

mookiex4 said:

Okay now I am very confused. I picked up a fuse for my voltmeter and checked the batteries, 13.2v. Then I checked the battery line that is connected to the fuse panel, 0.2v. So I decided that I would run a jumper line straight from the battery terminal to the panel. I hooked it up to the battery and tested the end of the wire., 0.2v and the battery shows 12.9v. Off the batteries I am getting the same 0.2v when connected to the battery in the fuse panel.

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I think Stu and Grashley are right on.  If I'm understanding you correctly:
1. When you test across your battery terminals, the batteries are showing a full charge
2. At the + connection between the batteries and the fuse block, you're only getting 0.2V and that's even when you run a jumper directly to it from the batteries.
3. Your converter is putting out 13.2VDC but it's not charging the batteries.

To me that says a bad ground connection between the fuse block and the batteries.  Were it me, I'd test this by running my jumper line to directly connect the battery ground to the ground side of the fuse block.  If the 12V systems in your Prowler start working at that point, you know where to start inspecting connections.

Old Blevins said:

To me that says a bad ground connection between the fuse block and the batteries.  Were it me, I'd test this by running my jumper line to directly connect the battery ground to the ground side of the fuse block.  If the 12V systems in your Prowler start working at that point, you know where to start inspecting connections.

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The fuse block is likely NOT GROUNDED!  The fuse block receives 12V power, runs this to different fuses to run to various circuits, i.e. lights.  The light gets POWER from the fuse block, and the circuit is completed by the other wire from the light going to ground.

To test the fuse block, test voltage between your chosen point and GROUND, not the fuse block.

Grashley, I believe you.  But I'll admit that leaves me stumped on what could knock out all his 12V systems except a bad + connection between the fuse block and battery - and he's jumpered a substitute with no improvement.  Bad battery ground to chassis? except then his electric jacks wouldn't work.  Might the other 12V circuits have a common ground connection to the chassis somewhere?

Since it seems to affect all 12V systems, it is either a bad / corroded connection between the battery and the fuse box, or (more likely) between the battery and ground.  Often the wire connection to the camper chassis will become loose or corroded.  These connections are sometimes hard to find and rarely checked.

I really appreciate all of the discussion. The jacks work as I am assuming that they have their own grounding separate from the trailer panel.

It is correct the the battery fuse block has no ground. It is just a pass trough that trips with a flag should there be a surge of some type. It is starting to make sense to me about the ground from the batteries to the frame. A vehicle grounds the battery to the engine block or frame. I have three ground wires coming off of my batteries I will trace them all and report back.

My boss is a former Air Force Master Electrician who maintained the Patriot Missile Silos and the first thing he said was that he thought I dropped a ground from the batteries. I will definitely be checking the grounds and will report back. There has to be someone else having my issue.

Or just connect the neg battery pole to the frame with a jumper cable. If it's fixed,  repair/replace the ground cable.

Ernie

You might inspect the grounding wires/cables for internal corrosion (?), flex'm.. If they make a crunchy sound and feel.. replace them ?

Joe 

Okay I have t get this straight in my head. Sorry haven't been able to get back to the trailer since I found that jumping the hot lead form the battery straight to the panel wouldn't work.

If the batteries are not grounded to teh frame I may as not even have batteries in the first place? Is this correct?

I just took a look and found three ground wires on the battery. 1 of the 3 is the ground coming from the other battery since they are in series. I have to trace them down but I am assuming one is going to the panel and the other is coming from the converter.

If this is the case it seems nobody grounded the batteries to the frame when they did whatever they did before I got the trailer.

If the batteries are not grounded to teh frame I may as not even have batteries in the first place? Is this correct?

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Pretty much so, at least in standard vehicle 12v wiring. It's possible, though, that the chassis ground connection is made from the power center/converter rather than right from the battery negative. And since you have two batteries, the connection can be from the negative terminal on either one - it makes no difference sine all are wired together.

The mental picture I have is that you have a pair of batteries, a separate Intellipower converter/charger, and a power distribution panel (fuse bus). If your batteries are a series pair of 6v, they basically form one large 12v battery, and 12v is measured from the positive terminal on one battery to the negative on the other.  The Intellipower should have positive and negative wires to the matching 12v battery terminals, which essentially put them all in parallel and that set-up feeds power to the fuse bus with a pair of cables. Either the Intellipower converter or the batteries will feed +12v to the fuse bus, and you should be able to measure +12v from either side of the fuses to either chassis ground or the negative side of the battery terminal (where the Intellipower also connects). Typically only the battery plus cable will run to the fuse bus, though., and the negative side cable will atach to the chassis.  The wiring for lighting, fridge, etc., though will have its negative side connected to the chassis at some point and generally will not run a negative wire all the way back to battery or fuse bus.

I am sorry all along I have not paid attention to the use of the term, "In Series". I am not using 6 volt batteries in series to make 12V. I am actually using two 12v batteries in parallel to maintain 12V with higher amps. I believe that is how it works. Sorry for the incorrect information.

At least every diagram I have seen it always shows for Parallel connections, + to +, - to - and from the last - it goes to ground from the battery to the frame, engine block, etc. I know these are simple drawings showing the basics, but if the ground from the battery to the frame is dropped, corroded or just not there at all, wouldn't that be causing my problem? I realize there are grounds to the panel, converter etc., but if one thinks about your house or your car, everything has a ground, but ultimately you home leads all the way to the grounding rod or something similar at one central point or in your vehicle everything grounds, but ultimately there is point where you ground to the frame and in some occasions, I have seen the ground as part of the exhaust systems.

Using this logic, everything in the trailer should have its' own ground ultimately terminating to a Master ground of sorts at the frame or something similar. sounds right in my Pea brain, but I am surely going to check it out tonight and trace some ground wires. And stop calling me Shirley, LOL  :