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Old 09-20-2015, 10:59 AM   #1
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trailer plug charging

If I am not mistaken when your trailer is hooked up to your tv you are charging your battery thru the converter, right? Why not make up a cable using just the 12+ and ground, then hook those wires directly to the trailer battery? This would bypass the converter for charging but it would still work for lights, fridge and such.

You might want to install a disconnect on the lead that supplies power to the battery from the converter or pull that fuse. This would eliminate the converter charging but still allow everything else to work.

Again, this is just a thought brought on by another thread. You would want to use the heaviest wire possible to the plug. If possible I would pull all the plug pins except the 12+ and ground.

Jim
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Old 09-20-2015, 11:09 AM   #2
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Even better...

Run a pair of 4ga from the truck battery, directly to the rv battery.

I do that, when installing a second battery and winch on car haulers.


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Old 09-20-2015, 11:17 AM   #3
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Originally Posted by oldtool2 View Post
If I am not mistaken when your trailer is hooked up to your tv you are charging your battery thru the converter, right? Why not make up a cable using just the 12+ and ground, then hook those wires directly to the trailer battery? This would bypass the converter for charging but it would still work for lights, fridge and such.

You might want to install a disconnect on the lead that supplies power to the battery from the converter or pull that fuse. This would eliminate the converter charging but still allow everything else to work.

Again, this is just a thought brought on by another thread. You would want to use the heaviest wire possible to the plug. If possible I would pull all the plug pins except the 12+ and ground.

Jim
I might be wrong but you shouldn't be going through your convertor, the convertor will not come into play without 110V. Your not going to get much more then a trickle charge from the TV. You can get 14 volts on a volt meter but the wire is not big enough to give you any real charging valve in amperage.
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Old 09-20-2015, 11:30 AM   #4
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It does not go through the converter, there is a power wire at the plug and it charges through it.
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Old 09-20-2015, 12:15 PM   #5
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Originally Posted by gljurczyk View Post
I might be wrong but you shouldn't be going through your convertor, the convertor will not come into play without 110V. Your not going to get much more then a trickle charge from the TV. You can get 14 volts on a volt meter but the wire is not big enough to give you any real charging valve in amperage.
I have got to be missing something. You are right, 110V required for the converter to be running and charging, I know that. But the fuses still protect everything when the 110V is disconnected. So the power from your tv has got to be supplying power thru the converter. I don't recall any small wire hooked up directly to the battery but there could be a splice I am not seeing. The fuse panel on the converter has got to be getting its feed from the trailers battery.

Again you are right, a small wire will limit the amperage so will limit the charge. This is why I said to use a large wire from 7 pin plug. Is the 12+ feed to the 7 pin plug on the tv fused? I would think so. That would control how much charge can be supplied to the trailer battery.

So now the question is, How does the battery get charged from the 12+ pin on the tv.

This is requiring too much thinking, I getting a headache!!

Jim
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Old 09-20-2015, 12:25 PM   #6
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Originally Posted by DDC View Post
It does not go through the converter, there is a power wire at the plug and it charges through it.
Yes there is, the 12+ pin I am talking about. We are aware of that. The question now is, where does that wire connect at? And what size fuse is used on the tv to feed that pin on the plug? That fuse, and the wire size, would limit the amount of charge to the battery.

Jim
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Old 09-21-2015, 05:53 AM   #7
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Originally Posted by oldtool2 View Post
I have got to be missing something. You are right, 110V required for the converter to be running and charging, I know that. But the fuses still protect everything when the 110V is disconnected. So the power from your tv has got to be supplying power thru the converter. I don't recall any small wire hooked up directly to the battery but there could be a splice I am not seeing. The fuse panel on the converter has got to be getting its feed from the trailers battery.

Again you are right, a small wire will limit the amperage so will limit the charge. This is why I said to use a large wire from 7 pin plug. Is the 12+ feed to the 7 pin plug on the tv fused? I would think so. That would control how much charge can be supplied to the trailer battery.

So now the question is, How does the battery get charged from the 12+ pin on the tv.

This is requiring too much thinking, I getting a headache!!

Jim
I'm using a WFCO converter and board. Your battery connects directly to the board. saying that the converter also connects directly to the board. You would have a fuse in the TV, Where is depending on your TV. Look at the diagram below it shows the 12 volt section directly to the board not through the convertor. So you TV is really only putting a charge to your batteries.
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Old 09-22-2015, 12:49 PM   #8
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Originally Posted by gljurczyk View Post
I'm using a WFCO converter and board. Your battery connects directly to the board. saying that the converter also connects directly to the board. You would have a fuse in the TV, Where is depending on your TV. Look at the diagram below it shows the 12 volt section directly to the board not through the convertor. So you TV is really only putting a charge to your batteries.
Thank you. Now I ve a big head-ache!

Lets see, the 110VAC supplies power to the converter which supplies 13.75VDC to the battery. There is a 30 amp fuse on the wire from my converter to my batteries about a foot away from the batteries. This tells me that only 30 amps is used for a maximum charge even though my converter can put out 55 DC amps. The same DC voltage goes thru the fuses and circuits such as lighting. The converter/charger and the battery or battery bank is connected in parallel with the rest of the 12 volt distribution system.

For those that don't know, In "parallel" means where the charging source (converter/charger) positive and negative output is electrically connected to both the battery bank positive and negative, and the 12-volt distribution system positive and negative, at the same time. The voltage output of the converter "smart charger" is based on a "detected" battery voltage.

When the 110VAC is disconnected the converter takes the 12 VDC from the battery and distributes it to the same circuits. The batteries measure 12.70 - 12.74 and dropping very slowly because of the load still attached.

Now put the TV into the equation. Measured at the battery, with the trailer plugged into the TV, I am measuring 13.94 to 14.01 VDC. tells me that my TV my truck) is charging the trailer batteries but probably not as fast as my converter does.

At the truck battery I measure about 14.7VDC from the alternator. That is a .7 volt lose? Because wire size maybe?

The converter I have in my 5er is a Parallax 7155 30 converter, see link below.



http://www.parallaxpower.com/7155-power-center-7155

Ok, what's all his mean? I am going to get a quicker charge from my converter than I would from my TV. In order to get a faster charge I would need to use a battery charger larger than 30 amps. This battery charger could be run off of a generators 110 VAC.

I still don't know where that splice or connection is on my trailer. From what I have learned though it doesn't matter. It is not worth getting out the signal tracer to find it.

Jim
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Old 09-22-2015, 01:00 PM   #9
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OK the TV directly charges the battery of the RV when the TV is running. On my F350 the charge lead is feed from a 30 amp fuse through a relay that breaks the connection when the TV is shut off. The wire from the TV fuse and relay is 12 gauge. The charge lead connects to your 7 pin connector and therefore to your RV. The TV will only charge the RV battery and the converter has nothing to do with this.
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Old 09-22-2015, 01:05 PM   #10
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Originally Posted by oldtool2 View Post
Thank you. Now I ve a big head-ache!

Lets see, the 110VAC supplies power to the converter which supplies 13.75VDC to the battery. There is a 30 amp fuse on the wire from my converter to my batteries about a foot away from the batteries. This tells me that only 30 amps is used for a maximum charge even though my converter can put out 55 DC amps. The same DC voltage goes thru the fuses and circuits such as lighting. The converter/charger and the battery or battery bank is connected in parallel with the rest of the 12 volt distribution system.

For those that don't know, In "parallel" means where the charging source (converter/charger) positive and negative output is electrically connected to both the battery bank positive and negative, and the 12-volt distribution system positive and negative, at the same time. The voltage output of the converter "smart charger" is based on a "detected" battery voltage.

When the 110VAC is disconnected the converter takes the 12 VDC from the battery and distributes it to the same circuits. The batteries measure 12.70 - 12.74 and dropping very slowly because of the load still attached.

Now put the TV into the equation. Measured at the battery, with the trailer plugged into the TV, I am measuring 13.94 to 14.01 VDC. tells me that my TV my truck) is charging the trailer batteries but probably not as fast as my converter does.

At the truck battery I measure about 14.7VDC from the alternator. That is a .7 volt lose? Because wire size maybe?

The converter I have in my 5er is a Parallax 7155 30 converter, see link below.

http://www.parallaxpower.com/7155-power-center-7155

Ok, what's all his mean? I am going to get a quicker charge from my converter than I would from my TV. In order to get a faster charge I would need to use a battery charger larger than 30 amps. This battery charger could be run off of a generators 110 VAC.

I still don't know where that splice or connection is on my trailer. From what I have learned though it doesn't matter. It is not worth getting out the signal tracer to find it.

Jim
Okay, what I just read you have a 55 amp DC charger that runs off a 30 amp a/c circuit. I think your confusing the A/C amp side with the D/C side.
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Old 09-22-2015, 01:34 PM   #11
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You all really got me confused (not hard to do) I always thought the TV alternator always charged the trailers battery directly, not through the converter.......... My other trailers (Not RVs do not have converters) the batterys' (one has two) are charged through the TV (truck).

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Old 09-22-2015, 01:37 PM   #12
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Follow the cable from the plug on the trailer that connects to the tv, it goes under the trailer to a junction box where it distributed to the various places it needs to go including the battery for charging.
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Old 09-22-2015, 01:52 PM   #13
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Okay, what I just read you have a 55 amp DC charger that runs off a 30 amp a/c circuit. I think your confusing the A/C amp side with the D/C side.
In their question section they state that the max charging rate is 55 amps for this converter. What is confusing me is that on the wire coming from the converter to the batteries is a 30 amp fuse.

That fuse would pop like a dead short if hit with 55 amps, right? So yes, I am confused just not with the AC / DC sides. I know the AC is 30 amps and it is protected with a 30 amp breaker. Also there are fuses to protect the converter in case of reverse polarity. These are both 30 amp fuses.

From their web site:

"Provided there are no other 12-volt systems operating and if the battery is discharged enough, the maximum rate the converter will recharge the batteries is the maximum amount of amps created by the converter. The last two digits of the part number indicate its maximum current capability in amps." My converter is a 7155, so capable of a 55 amp charge? But what about the 30 fuses?

So what am I missing?
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Old 09-22-2015, 02:06 PM   #14
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OK the TV directly charges the battery of the RV when the TV is running. On my F350 the charge lead is feed from a 30 amp fuse through a relay that breaks the connection when the TV is shut off. The wire from the TV fuse and relay is 12 gauge. The charge lead connects to your 7 pin connector and therefore to your RV. The TV will only charge the RV battery and the converter has nothing to do with this.
I haven't really looked at my truck but do have a 30 amp marked trailer plug. I am sure that is the 12+ lead used for the charging circuit on the trailer.

Jim
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Old 09-22-2015, 02:09 PM   #15
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It's called marketing!

Even though the converter may be capable of producing 55 amps at 12VDC, there's no way it's ever going to get there. The internal resistance of the battery coupled with the circuit/wire resistance will reduce the maximum charging current to less than 30 amps.

If you turned every 12V light and appliance in the RV on at the same time, the converter may in fact produce the 55 amps it's designed for, it can never all be used for charging the battery. And you actually don't want it to charge the battery that fast. 10 amps is about as much current as you want for charging on a regular basis.
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Old 09-22-2015, 02:13 PM   #16
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You all really got me confused (not hard to do) I always thought the TV alternator always charged the trailers battery directly, not through the converter.......... My other trailers (Not RVs do not have converters) the batterys' (one has two) are charged through the TV (truck).

You are not confused. By charging the battery it is indirectly running all 12 volt circuits in the converter. The converter only charges the batteries on shorepower or generator.

Jim
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Old 09-22-2015, 02:16 PM   #17
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Follow the cable from the plug on the trailer that connects to the tv, it goes under the trailer to a junction box where it distributed to the various places it needs to go including the battery for charging.
You are probably right. I am just not willing to tear the underbelly apart to find out for sure, LOL!

If I had a problem then it would be a different story.

Jim
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Old 09-22-2015, 02:21 PM   #18
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It's called marketing!

Even though the converter may be capable of producing 55 amps at 12VDC, there's no way it's ever going to get there. The internal resistance of the battery coupled with the circuit/wire resistance will reduce the maximum charging current to less than 30 amps.

If you turned every 12V light and appliance in the RV on at the same time, the converter may in fact produce the 55 amps it's designed for, it can never all be used for charging the battery. And you actually don't want it to charge the battery that fast. 10 amps is about as much current as you want for charging on a regular basis.
I would guess you are right. It just gets me they tell you one thing but do something else!

I also agree, a slow charge is always better. 30 amps is a little gh unless you are in a hurry for some reason.

Jim
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Old 09-22-2015, 02:21 PM   #19
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The +12V aux pin in the 7 pin Bargman connector does not go thru the converter. You need to check to insure that the fuse and relay ( if used) are installed in the fuse block of the TV. For some reason even a 3/4 truck with a tow package may not have the +12V fuse installed. I have seen them totally not supplied or in a small plastic bag in the glove box. Keep in mind that the length of the wire and the gauge will not provide enough voltage to the battery to do much more than a low level charge. If you have something running on 12V during travel, you may not get any charging.
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Old 09-22-2015, 02:37 PM   #20
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Most TVs will have an 'engine-running' relay on the +12 (probably a solid-state e.g. thyristor one, thus the .7 volt drop due to the semiconductor barrier voltage) so that you can't kill your TV battery by leaving it sit with a trailer with a bad battery plugged in. Mine does... no +12 at the connector until the engine is on.
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