Power cord access while TM is closed - Page 2

**Cateye** · 05-21-2003, 06:46 AM

Bob...this sounds great. Can I get the diagram and source for the relay. My e-mail is [email protected]

Thanks, Cateye

05-21-2003, 12:42 PM

I would like the information also! My email is [email protected]

05-22-2003, 09:32 AM

I would also like this info - [email protected].

WOW! You hit on a biggee here!

thanks for the post!

06-25-2003, 10:42 AM

Thanks for your work on a great solution to this problem. Would love to have your diagram and source for the relay. [email protected]

**mjlaupp** · 06-25-2003, 12:31 PM

I read this thread several months ago and had uneasy feelings about what is not being accomplished here. The idea of charging the battery and running the fridge when the TM is closed sounds good.

My problems with this are:
How are you getting rid of the heat generated by the converter and the fridge?
What are you doing to remove the explosive H[sub]2[/sub] gas generated by the battery when it is charging?

The 12v fridge fan needs to run to exhaust the heat from the heat exchanger when the TM is closed. The converter has an automatic cooling fan that should operate properly. However, the vents for the converter box are covered by the bathroom walls when the TM is closed.

If the battery(s) are located on the tongue, then there is no problem with explosive gasses. If the battery(s) are located inside, then the gas vent is between the lower body and the upper shells. My batteries vent out the back and onto the inside of the rear window when the unit is closed.

The idea of a relay changing state and the resulting spark as the contacts open happening in a hydrogen charged atmosphere does not present a pretty picture.

:-/

Anyone care to comment? 8)

06-25-2003, 02:13 PM

Mike,

I also wasn't sure what was being solved here.  When I have my TM closed with the refer running I want it on 12 v power, not AC.  This way I can hitch up and tow without reopening to change over the refer power.   Of course the refer fan must be on to exhaust out the heat.  

My solution is to externally support the TM battery power using a battery charger while closed and the refer on.  You can put the battery charger current through either the 7-way Pollack connector or into the battery box using a plug if accessible.  I get by with a 6 amp but a 10 amp min. charger is better suited.

06-26-2003, 06:03 AM

Guys:
I asked Bill some of these same questions - and they are GOOD and VALID questions.

First, you will find that the converter box is located below the tub UNDER the trailer. This area is OPEN to the outside air from below your trailer. Therefore it IS NOT technically a sealed and enclosed space.

Heat should NOT be a problem under there.

Now in my case - a 2619, my battery is on the toungue and the converter is way in the back, so I'd have NO problems with outgassing.

IF you are worried about the outgassing in your batteries, you CAN add, into your battery compartment, a small low voltage DC pancake exhaust fan that is similar to the refridge fan we all have.

In fact, an exhast fan is recommended for batteries stored in an enclosed sealed space.  

Best,

Gregg

**mjlaupp** · 06-26-2003, 07:47 AM

Yes the converter is in a compartment that is open to the outside through the 4 inch hole in the floor for the bathroom exhaust fan. You could cool the compartment by running this fan while the converter is running. However, the converter is cooled by passing air through the grill in the hallway side of the bath wall and this opening is covered by the bath walls when the TM is closed. The fridge is in the same type of compartment that is open under the floor and it needs an outside exhaust fan to operate when the unit is closed. What is the difference? If the TM is in tow, the natural air circulation would take care of the heat. You are talking about non-moving unit with no natural air circulation. I don't think that the heat in this area would cause a fire. It would slowly bake the converter electronics and bake the esters out of the fiberglass tub. This will reduce the life of the converter and make the bath tub brittle over time.

I can think of no simple way to exhaust the battery gasses. If you install a fan, it must be small enough to fit into the 1[sup]1[/sup]/[sub]2[/sub] inch vent tube opening of the sealed battery box. There is a possibility of using a 12v CPU fan from a computer here, but, it must be explosion proof and it needs to exhaust the gasses out the bottom of the trailer. Since hydrogen is lighter than air, it also must pull the gasses from the top of the battery box. You woul need to arrange for a second set of vents for this purpose and to keep from pressurizing the battery box. They do not put "WARNING - FLAMMABLE/EXPLOSIVE" labels on batteries for no reason. If enough of you do this modification, I'm sure that sooner or later someone will find out the hard way about battery gas. This is what brought down the Hindenburg!

Simple solution to battery gas: Replace the internal mounted battery with a fully sealed battery.

**Bill** · 06-26-2003, 09:31 AM

Quote:

I read this thread several months ago and had uneasy feelings about what is not being accomplished here. The idea of charging the battery and running the fridge when the TM is closed sounds good.

My problems with this are:
How are you getting rid of the heat generated by the converter and the fridge?
What are you doing to remove the explosive H[sub]2[/sub] gas generated by the battery when it is charging?

The 12v fridge fan needs to run to exhaust the heat from the heat exchanger when the TM is closed. The converter has an automatic cooling fan that should operate properly. However, the vents for the converter box are covered by the bathroom walls when the TM is closed.

If the battery(s) are located on the tongue, then there is no problem with explosive gasses. If the battery(s) are located inside, then the gas vent is between the lower body and the upper shells. My batteries vent out the back and onto the inside of the rear window when the unit is closed.

The idea of a relay changing state and the resulting spark as the contacts open happening in a hydrogen charged atmosphere does not present a pretty picture.

Well, let me toss in a couple things.

Re the heat from the refrig. Yes, the refrig fan should be running when the TM is closed, so I try to remember to leave the switch on as we travel every day. But most of the time, I admit, I forget to do it. And sure enough, if the fan isn't running, nothing critically bad happens - the refrig just doesn't cool quite as well.  The heat DOES escape - this is in no way a sealed compartment.

Re heat from the converter. First, there isn't much heat because there isn't much current flowing through it. Remember, we're not charging the battery, just maintaining it while we run the refrig. But you're right, there is some heat. But unless your bathroom wall fits a lot closer to the vents than mine, the vents aren't really blocked. And we're not trying to blow a hurricane through those vents. Normally there is just a small amount of circulation through them (you can't even feel it with your hand). Most of the cooling comes from the rear of the converter - there is a big empty space behind the converter, and a 4" screened hole through the floor, all the way to the outside. This is where the bathroom vent fan exhausts. There is LOTS of ventilation back there. If you pull the converter out, you'll be surprised.

Re hydrogen gas, you have the same situation when you are driving down the road and your tow vehicle is charging the battery. And few trailers end up filled with hydrogen gas. A battery actually produces very little hydrogen if you are charging it correctly, although it can produce a very small amount. However, because hydrogen is such a tiny molecule, it diffuses extremely rapidly through the walls of almost any container - even containers that hold propane (for example) very well. This is, in fact,one of the chief roadblocks in developing the hydrogen-powered car - it is really hard to contain hydrogen in any kind of normal tank, piping, and seals. In the case of the TM, with the battery vented out the back (as both yours and mine are vented), there is no seal that would even begin to contain hydrogen and let it build up.

And finally, the relay is located in the converter box, not the battery compartment. And the relay is sealed, so any spark is kept within the relay housing.

Your concerns are good ones, but in my opinion not of concern for this application. I hope this alleviates some of your concerns.

Bill

06-26-2003, 01:58 PM

If any of you are concerned about your lead-acid battery's vented hydrogen gas collecting in a confined space, then replace your conventional battery with an absorbed glass mat battery when you need a new battery - or batteries. The AGM batteries, such as the Concorde ones, come equipped with special caps that convert the hydrogen and oxygen back to water.

Bill, wouldn't it be possible with your circuit to run the power line into a 115 volt outlet mounted inside a weather tight aluminum enclosure located on the outside of the TM? Then, when you want to provide 115 volt AC power to a closed TM, you would connect the TM to a live 115 volt AC outlet with a cord containing a male plug at each end.