Casita battery charging while driving

[ehoepner]

Originally Posted by Raspy

Every vehicle seems to have a different number of amps available at the seven pin. Some will run the fridge and charge, and some will only slowly charge, but not keep up with the fridge. If yours won't do both, just run the fridge on propane and see if the batteries charge up.

The size of wiring on the tow vehicle determines the amps that flow to the Casita battery. If you are not getting enough amps to charge the battery and run the frig then the tow vehicle wiring is too small. You need a 10 gage wire, but some of the vehicles have only a 14 gage wire installed.

[Glenn Baglo]

Originally Posted by ehoepner

You need a 10 gage wire

And a heavy duty alternator.
It still might not bring your house battery up to full when running the fridge on 12V.

[Raspy]

Originally Posted by ehoepner

The size of wiring on the tow vehicle determines the amps that flow to the Casita battery. If you are not getting enough amps to charge the battery and run the frig then the tow vehicle wiring is too small. You need a 10 gage wire, but some of the vehicles have only a 14 gage wire installed.

The best way to achieve this is to skip the 7 pin completely for charging and install an Anderson plug at the rear of the tow with #8, or #6 wires coming from your tow battery, with a relay and fuse.

My trailer came with an Anderson plug wired with #8, or #6 from the trailer battery to the front of th tongue, with a loop to reach the tow vehicle.

Then you just plug the Anderson plug in when you connect the 7pin. When you start the tow, it connects the tow battery and alternator directly to the trailer battery and you get full alternator output to the trailer battery. Alternators come in all sizes too, but on my 3500 Ram, for instance, it's 220 amps. That won't be the actual amount you'll get back at the trailer battery, without going to even larger wires, but you will definitely get enough to run the fridge and charge the batteries quickly.

The Anderson plug at the tongue also serves as a place to plug in the suitcase solar while camped.

I would never go through all of that installation, just so I could run the fridge on 12 volt while driving. But it will serve well for charging the batteries after some time off grid, or to charge them up in the middle of your trip by simply plugging in and idling the tow for a while.

I really see very little value in running the fridge on 12 volts. Propane works incredibly well, and is much less hassle than trying to keep up with the high amperage draw on 12 volts. I spend a far greater percentage of my time with the tow vehicle not running, than running. Which means I should, and must, spend a far greater percentage of my time on propane than on 12 volts. Further, when camped, I want to preserve my batteries as much as is practical. I want my solar to provide energy for lighting, and other 12 volt needs that are far more important than running a heating element. Propane is much more practical for the fridge. A 12 volt heating element is a terrible waste of energy, and if it depletes the batteries, I lose the other things that only run on 12 volts.

[Mike_L]

Thanks

[Peder_y2k]

I did an underground low voltage garden lighting system 11 years ago simply twisting the copper wire ends together an dipping in tool dip. Still working fine today, and easily modified when/if required. Being buried contributes to no movement of the connection. Using a twist lock plus dipped in liquid tape is a step up for improved longevity. I'm actually amazed how well the tool dip/electrical tape works.

[sheilasabo]

Didn't read all three pages of messages. I would just like to say we have a new 2019 Casita and we were told, by Casita, not to start out with the fridge on DC unless we knew the battery was totally charged...

[Len S]

Some very good information here and some very bad. Reason for crimp connections vs a solder joint are factory labor costs . Solder being the best but still needs taping or similar secondary insulation.
12v circuit fridges take a huge amount of power in current consumption to run properly. There is the lead length from the tow vehicle alternator/battery to the battery/ fridge source and with lite gauge wiring
there is too much lead loss ( resistance) to do both jobs at the same time
because of the voltage loss. Capacity of the tow vehicles alternator is not that relevant ; to a point; as it still takes voltage to push current through to the fridge/battery to be able to charge correctly. A quick way to see if the system is up to snuff is to turn the fridge on while the tow vehicle is running and doing a voltage check at the trailer battery . You should be getting around 13 to 14 volts. I know I will get getting arguments on this
but I am in the ballpark.

[GaryDon]

My brother-in-law who went to Army electronics school taught me to first make a mechanical connection and then solder the wires together. They will not separate. He repaired radar in Vietnam, and then in civilian life repaired plotters, CAT scans, etc. I have never had a failure doing the soldering this way.

[computerspook]

Frankly for outside connections, I put a shrink tube sleeve over the wire. Then I solder the connection. Then I cover the connection with calk and shrink the sleeve down on it.

[Len S]

Originally Posted by mary and bob

In the truck shop where I worked (Ryder) we had butt connectors that had shrink tube on them plus solder in the center that would melt when we heated it with a mini torch. Currently available from Ryder fleet products, about $.75 each

Most heat shrink ( except Teflon ) shrink at about 90 degrees C (194F)
and resin core solder melts at about 315 degrees C ( 600F) . I have a hard time believing that a mini torch would do both.

[ellen95616]

Originally Posted by Lisle

I've only had my 2018 Casita for a couple of months but am full timing. Noticed if I had the frig on 12V while driving, the batter would be dead by the end of the day. Posted on this forum and lots of folks said, yes, you won't be able to charge your battery and run the frig at the same time. When I told my RV repair guy this, he said he didn't agree. And then he did some testing which showed the battery wasn't getting charged at all while I was driving, even though the charge was coming out of the 7 prong plug on my tow vehicle. Took him about an hour under the front R corner of the camper to find the problem: seems Casita uses a kind of wire connector which is crimped onto the wire, with two prongs supposed to pierce the insulation and make contact with the metal of the wire. Trouble is, the crimper didn't do the job -- the wire was flattened but the prongs never pierced the insulation -- no contact between prongs and metal wire and no charge to battery. Now it's fixed!!! Charges like a champ!! I'll let you know if it can charge and run the frig, but he says it should. By the way, if you are in NE Virginia, this is the guy to see for repairs: Affordable RV in King George. Wayne and Jeremy both are great -- honest, expert, love RVs. They will take care of you. I met a woman in a campground in Harper's Ferry who recommended them and I'm so glad she did.

Lisle.... I have a 2008 Casita. Daytime battery charging was also a huge concern of mine. I use propane for the fridge, but I had no way to charge the battery while I was on the road. This was a huge problem if I arrived late to camp and could only get an hour of late-afternoon sun on my portable solar panel. I decided solar power on the trailer's roof was the best solution, so I put an 80 watt panel up there. It has been a life-saver. My battery is always topped off by the time I reach camp, and it frees up the portable panel to charge my Bluetti, a lithium generator I use to run a small 600 watt microwave. Works GREAT! Good Luck.

[computerspook]

Originally Posted by Len S

Most heat shrink ( except Teflon ) shrink at about 90 degrees C (194F)
and resin core solder melts at about 315 degrees C ( 600F) . I have a hard time believing that a mini torch would do both.

Certainly both products seperately are like you said. The plasgtic would melt off before the solder melted and made the connection. But yes this is a product that exists. I think they have lowered the melting temp on the solder, but mostly this is a plastic that shrinks at a much higher temp.

[gordon2]

Originally Posted by computerspook

... But yes this is a product that exists. I think they have lowered the melting temp on the solder, but mostly this is a plastic that shrinks at a much higher temp.

In a measure of confirmation, for a similar product from another manufacture they say:

Minimum temperature for solder to melt: 138°C (280 F)
Shrink temperature : ＞160℃ (320 F)

[computerspook]

Originally Posted by gordon2

In a measure of confirmation, for a similar product from another manufacture they say:

Minimum temperature for solder to melt: 138°C (280 F)
Shrink temperature : ＞160℃ (320 F)

Yeah several HAM radio organizations have checked these out and said they work.

[redbarron55]

Originally Posted by Len S

Most heat shrink ( except Teflon ) shrink at about 90 degrees C (194F)
and resin core solder melts at about 315 degrees C ( 600F) . I have a hard time believing that a mini torch would do both.

I promise you that they work well.
There are a lot of plastics other than Teflon that will stand a high heat.
As far as I know Most Teflons will not shrink.

https://www.youtube.com/watch?v=7Wh5gM8GM70

[redbarron55]

Here is a battery booster that Hams use to boost b attery voltage to 13.8 as the battery discharges with the engine off.
One of these in the trailer will take the lower voltage due to the IR drop and boost it up to 13.8 VDC.
There are others that are made to be battery chargers as well.



https://www.mfjenterprises.com/Produ...ctid=MFJ-4416C



This 40A DC to DC Charger is designed to charge secondary batteries while driving using the primary battery connected to the alternator. It is able to charge: Flooded, Gel, AGM, and Lithium batteries using multi-stage charging.

Idle Power Consumption: <0.4A
Input Voltage Range: 8V-16V
Equalization Voltage: N/A
Float Voltage: 13.2-13.8v
Boost Voltage: 14.1-14.7v

https://www.walmart.com/ip/Renogy-40...QaAjOvEALw_wcB

[M. Bober]

Seems there are two parallel threads here.

First: Can your TV provide enough current to power the fridge on DC?
And
Second: What electrical connectors are satisfactory?


Regarding keeping the battery charged--from the TV--while running the fridge. Most TVs have adequate alternators but inadquate wiring to the seven pin connector to carry the current required to keep the battery charged. Some replace the wiring--from the alternator to the seven pin connector--with heavier gauge cable/fusing (#8 or even #6).



Regarding cable connections: I prefer crimped butt connectors installed with a racheting crimp tool (this is required by AYBC standards for marine service). Soldered connections are not well suited for vibration unless supported and protected from the vibrations. Additionally if the connection is subject to overheating (a short circuit perhaps) the solder can melt and the connection fail. Heat shrink for water proofing is always a good practice.


You pay your money and you take your chances.

[Jon Vermilye]

Originally Posted by Len S

Most heat shrink ( except Teflon ) shrink at about 90 degrees C (194F)
and resin core solder melts at about 315 degrees C ( 600F) . I have a hard time believing that a mini torch would do both.

While I am still a firm believer in making a mechanical joint prior to adding solder, I suspect the manufacturers of these products use eutectic solder, an alloy of 63% tin & 37% lead that melts at 183°C. There are plastics that shrink in that temperature range.

[Raspy]

Originally Posted by Jon Vermilye

While I am still a firm believer in making a mechanical joint prior to adding soldier, I suspect the manufacturers of these products use eutectic solder, an alloy of 63% tin & 37% lead that melts at 183°C. There are plastics that shrink in that temperature range.

Jon, I think you are right. It seems this low temp solder, and the fact that the wires are not twisted or crimped together, would lead to a joint failure if the wire began to heat under electrical load. Certainly at a much lower temp than if they were crimped. Those connectors appear to be very simple to use, but a convenrtional butt connector with normal heat shrink tubing looks much better to me.

[CarlD]

Raspy, You should specify a shrink tube with an inner melt wall or adhesive for water proof applications.