Power inverter that runs the refrigerator

[garbonz]

Originally Posted by herk7769

The problem with alternators is that it can't tell you have a trailer deep cycle battery. It is a single stage charger that works off the average voltage across the truck. Once the truck battery is "full"; it tapers the current off. It is OK for keeping a full battery full (and even some light charging duties), but replacing a 40 amp draw is just not possible. Here is a more technical reason why it won't work even with a "heavy duty alternator."

The marine industry makes alternators and regulators designed for this.

Balmar is one company, and there are others.

[Herk7769]

Originally Posted by jonnys_walkers

They are expensive. It puts out 300 Amps

MG Industries Inc.

I checked out that (very) expensive alternator. The webs site says its output is 300% higher than stock (not 300 amps). While this may sound awesome on the surface, the regulator still modulates the output to prevent boiling your battery dry.

The battery can only take, what it can take; and no more. ANY excess incoming power is turned into heat inside the battery which will boil your electrolyte.

The problem with this method is that you are mixing two completely different battery types in the same charging circuit. The starting battery will "fill" MUCH faster than the deep storage battery in the camper and the alternator will detect that and cut back on charging way too soon to give much more than a surface charge to the trailer battery. It will take "forever" to completely charge your depleted camper battery when the charging source is an alternator regardless of size.

As to the Balmar, good news. It is on sale for 3,000 dollars.
http://www.go2marine.com/product/198...-310-amps.html

Note it is NOT for charging batteries. It is for powering a cruise ship with the engines running. (well a cruise ship's lifeboat anyway.)

[RPAspey]

Originally Posted by BarryD0706

Good point, although that would buy him just a bit more time at best.

Another thought. In a different thread just like this, someone suggested that the inverter be installed in the tow vehicle and then run a 120v "extension cord" back to the RV to
power the fridge. With that configuration a larger alternator can definitely power the inverter as long as needed. You'd just need to be careful not to drain the truck batteries when you shut the truck off.

this might be the OP's best solution. He'd best mount the inverter in the engine compartment and run the extensions back. best of all, if sized right, the inverter/cord combo could also charge the TT battery as well. But with the expense of a large alternator it might not be economical.

[garbonz]

Originally Posted by herk7769

I checked out that (very) expensive alternator. The webs site says its out put is 300% higher than stock (not 300 amps). While this may sound awesome on the surface, the regulator still modulates the output to prevent boiling your battery dry.

The battery can only take, what it can take; and no more. ANY excess incoming power is turned into heat inside the battery which will boil your electrolyte.

The problem with this method is that you are mixing two completely different battery types in the same charging circuit. The starting battery will "fill" MUCH faster than the deep storage battery in the camper and the alternator will detect that and cut back on charging way too soon to give much more than a surface charge to the trailer battery. It will take "forever" to completely charge your depleted camper battery when the charging source is an alternator regardless of size.

As to the Balmar, good news. It is on sale for 3,000 dollars.
Balmar - Balmar 98- Series Alternator, Extra large case, 310 Amps

Note it is NOT for charging batteries. It is for powering a cruise ship with the engines running. (well a cruise ship's lifeboat anyway.)

C'mon, get real. I'm just pointing out that there are ways of getting a vehicle to charge an RV battery. This link gives you all the varietys and they are not 3 grand.

Balmar Marine Alternators and Accessories for Sale from Defender

You could even use isolators to do both the car and the RV. Many sailboats use a high output alternator with a good quality temperature compensating regulator to avoid having a separate generator. Nowadays with the cheap Chinese generators, that doesn't seem economical, but it can be done. Having a 110v refer that you need to keep running while on the road is quite a challenge, I think.

[Herk7769]

Robert,

These alternators are designed to work with specific battery types and use external regulators to manage the amperage output by user programmable stages based on the battery type.

Balmar Max Charge Multi-Stage Voltage Regulator

They do not work with multiple battery types at the same time (starting and deep cycle in the same network) since the programs are different and different regulators (with the proper charging program) are required to avoid destroying one or the other.

[Rebel702]

Easiest solution might be upgrading the refer to an RV refer which is offered as an option according to the Salem brochure. Suggest discussing with your dealer so you can travel with propane. You could even save the 110v refer and use it in your man-cave at home.

[Herk7769]

I do have to say that that web site is a wealth of information on battery charging and equipment. II have book marked several PDFs and links to stuff like battery trays and boxes for my next "4 battery" upgrade.

[jlgail4309]

Thanks for all the comments and help this might be dumb but here it go's . A double battery and real small wind mill. It on ebay it for charging a rv battery. I emailed the company he said it would work great at high way speeds. It sounds far out to me.

[BarryD0706]

That windmill isn't going to produce anything like the 40 amps you're going to need. It would be about as good as a small solar panel I imagine.

[jlgail4309]

Thats what I thought even at 60 miles per hour it not big enough,

[garbonz]

Originally Posted by herk7769

Robert,

These alternators are designed to work with specific battery types and use external regulators to manage the amperage output by user programmable stages based on the battery type.

Balmar Max Charge Multi-Stage Voltage Regulator

They do not work with multiple battery types at the same time (starting and deep cycle in the same network) since the programs are different and different regulators (with the proper charging program) are required to avoid destroying one or the other.

Okey dokey. I shut up now. I don't see an acceptable solution for this fellow then without, a big battery bank although I like the idea of the inverter in the TV and a 110 volt line to the TT.

BOB

[Herk7769]

Originally Posted by garbonz

Okey dokey. I shut up now. I don't see an acceptable solution for this fellow then without, a big battery bank although I like the idea of the inverter in the TV and a 110 volt line to the TT.

BOB

Bob, it is kinda "lose; lose" with a 120 VAC only fridge.

Barry's comment is also valid. Short legs to the campground (no more than 5 hours) or a pair (or more) high capacity batteries and an inverter seems to me to be the only options he has.

The inverter in the TV should also work as the amperage would be fairly low; thus voltage loss would also be low.

[jlgail4309]

So bypass the batteries on the TT. Run a large power wire for the TV battery to the inverter. Would that be possible with a HIGH OUTPUT ALTERNATOR 250AMP.

[Herk7769]

Originally Posted by jlgail4309

So bypass the batteries on the TT. Run a large power wire for the TV battery to the inverter. Would that be possible with a HIGH OUTPUT ALTERNATOR 250AMP.

Sounds like an expensive experiment in my opinion.
You, of course, are free to do as you will.
I would advise against it.

I still think the best bang for the buck would be a pair of matched 200 AH batteries and shorter legs if needed.

Good luck.

[garbonz]

Still, Wouldn't an inverter in the engine compartment, with short 12 volt leads, and a 110volt wire back to the camper with a plug and a switch be the cheapest solution, given that OP already has the inverter? The OEM alternator should be able to keep up with that much drain, I would think. No connection to the TT battery at all. Maybe need a higher output alternator

Maybe I am missing something...

[jlgail4309]

I'm not sure both sound like they would work. The 250amp alternator in only 300.00 me and my family not have to walk priceless. But most of my trip are only a couple of hours. About 1 or 2 trips a year will be 15 hours one way. Either Destin Fl or Colorado Springs most of the time. My normal on the long trips is halfway and camp. My backside has had enough at 8 hours.
I would like to say thanks for all the comments.