Replacing converter/charger: What's this cylinder? Do I need it?

[MohawkDaddy]

In my '89 Excella 34', I'm replacing my old MagnaTek converter/charger with a Boondocker BD126C converter/charger (60 amp 4-stage) from Best Converter:
http://www.bestconverter.com/Boondoc...l#.WF2cglUrK9I

It looks to be a direct replacement - take three wires out of the old one, plug them into the new one. Bu I'm wondering about that capacitor-looking thing on the red wire leaving the converter, that distributes to the batteries and the 12V panel.

My Airstream is in a 'permanent shore power' situation (used as a guest house), and I'd like to take the batteries out altogether to reclaim some space in the living room.

So, what is that capacitor thing anyway?
Can I take it out altogether and go directly from the converter to the 12V panel?
Or do I need to keep it in line on the red wire?

Thanks in advance --

[dcopps]

Looks like a battery disconnect switch to me

[Al and Missy]

That sure looks like your battery disconnect switch, not a capacitor, but the wiring you pictured is not typical. I have seen the switch wired two ways: between the batteries and everything else, and between the power panel and everything else.

If you are not planning on batteries, it is largely superfluous. I would suggest, however, that if you permanently reclaim the battery space you will likely be reducing the value of the trailer by limiting its use to shore power only. Also, the battery(ies) are used to operate the trailer brakes in the event of a disconnect from the tow vehicle, which may (I don't know) be a legal issue, particularly if you have an accident. If you really want to do it, your middle drawing, leaving it out, is the way to do it.

All of the above, just my opinion, YMMV.

Al

[MohawkDaddy]

Thank you! I'll remove the battery disconnect switch and wire directly to the 12V panel.

Also, I'm engineering my battery removal so it's completely reversible, should a new owner wish to reinstate it.

Thanks again!

[nvestysly]

MohawkDaddy,

Seems like you found the answer you needed regarding the switch but I still have questions. I hope you have time to answer:

If your trailer is being used as a guesthouse and permanently attached to shore power, and you're going as far as removing the batteries and the battery disconnect switch...

Why are you removing the existing converter/charger and replacing it with a more modern multi-stage converter/charger? The old converter/charger you're removing probably makes and audible hum. Is the humming noise the reason for replacing the existing unit? Does it not work (i.e. doesn't produce voltage)?

Otherwise, your new layout doesn't have batteries so you won't benefit from the multi-stage charging features of the new converter/charger.

[WayneG]

I am not sure about the 89's converter but in earlier converter/chargers, they were meant to only be used with batteries attached so that the DC output is the correct voltage and to reduce ripple & fluctuation from turning high draw loads on & off.
That is definitely a battery switch and if it not causing problems, I would leave it in the circuit.

[dames7]

You should call Airstream first and run it by them.

[Picinisco]

Originally Posted by MohawkDaddy

Thank you! I'll remove the battery disconnect switch and wire directly to the 12V panel.

I'll take the disconnect from you. When my Argosy is parked and the outside temp falls below 55 (the lowest setting on my thermostat), the furnace fan kicks in and drains my battery.

[guskmg]

I have a slightly used converter: Parallax Power Supply 4455TC(S) rated at 55amps, that Lew took out of my trailer when we went full solar earlier this year. It is temperature compensated, but you would not need that feature if you were not going to use batteries. It is yours for $ 100.00 plus shipping at my FedEx discount.
guskmg
817-292-7062

[MohawkDaddy]

Thanks for the thoughts, all.

Yes, the old unit hummed like crazy, and threw off an incredible amount of heat. Even the wooden box enclosing it was quite warm to the touch. In Texas, pumping heat into the living room in the summer is counterproductive.

I already installed the Boondocker and it's working like a champ and doesn't hum at all. I can now build a much smaller vented enclosure and push my sofa right up to the wall.

As to upcycling the old one - it's really seen better days. Again, it hums loudly, gets really hot, and all the internals are really rusty. Plus I drilled out all the rivets to get the cover off so I could cut off the output wires where they connected to the innards (to gain a little more length to work with when installing the new one).