6x12 Cargo Conversion. New Guy, New Build

[Viper_Twig]

That is a beautiful battery box. However, I would be concerned about heat.

Below is a link to “battery university” web page that says:

Heat is a killer of all batteries, …

As a guideline, each 15°F rise in temperature cuts the life of a sealed lead acid battery in half.

This means that a … battery … specified to last for 10 years at 77°F would only live

5 years if continuously exposed to 92°F and

30 months if kept at a constant desert temperature of 106°F.

http://batteryuniversity.com/learn/arti ... ttery_life

Interesting article thanks. I guess that's my trade-off for needing the interior space and not wanting to vent the batteries from the interior.

Thankfully, we are only in Las Vegas for one more summer before we move next year.

I wonder if a heat-reflective blanket over the battery box would help while it is parked between trips? It would at least prevent the black box from absorbing so much solar heat and might keep them a bit cooler?

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[hankaye]

featherliteCT1, Howdy;

I live in the desert, Arrey, N.M. Look us up. We only experience the triple digits maybe a dozen times
a year it ain't as constant as most folks think. Even Yuma and Phoenix don't bake in the triples much
more then I do. Winter can be down right frosty at times ... maybe even get below 20°F.

hank

[featherliteCT1]

I wonder if a heat-reflective blanket over the battery box would help while it is parked between trips? It would at least prevent the black box from absorbing so much solar heat and might keep them a bit cooler?

Good point … I suspect any cover to provide shade would help a lot, especially a reflective shield … and the batteries would be out of the sun most of the year while the trailer is parked.

And when you amortize the cost of diminished life over the life of the batteries, the cost is not so bad.

[Viper_Twig]

Grabbed a small can of rust o leum to paint the welds. Ended up doing the whole tongue frame, makes a big difference to clean it up. Took 30 minutes with a roller and small foam brush. Will probably do once a year.

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[lrrowe]

I wonder if a heat-reflective blanket over the battery box would help while it is parked between trips? It would at least prevent the black box from absorbing so much solar heat and might keep them a bit cooler?

Good point … I suspect any cover to provide shade would help a lot, especially a reflective shield … and the batteries would be out of the sun most of the year while the trailer is parked.

And when you amortize the cost of diminished life over the life of the batteries, the cost is not so bad.

I am thinking about moving my two 6 volt batteries from inside and on the left of my CT to a box on the tongue. Then these comments about the heat issues have me concerned about doing this. But I just thought of an idea. I heat my CT by recirculating RV heater hot water through a "radiator" of sorts. I control the on/off flow with a 12 volt thermostat. Ok, why could I not use a similar thermosat and when the inside the box temperature reaches a particular level, turn the fans on, and circulate outside air through the box. I believe without any analytical facts to back me up, that this mod could not hurt.

[hankaye]

Howdy All;

Just remember that there are several hundred thousand Travel Trailers out there that
have their batteries mounted on the tongue and they all (from my own experience),
work fine last as long as they were supposed to (with adequate maintenance). True it is
that most of the ones I refer to hide behind the propane tanks (some even have covers),
yet they (batteries), reside within black plastic boxes. Sometimes we tend to over think
some things, or at least I do if I don't stop and look around to how it's (whatever), has
been done before by the pros.

hank

PS I prefer to think that I'm not trying to invent the wheel, just tweak it a bit...

[John61CT]

Consistently high heat kills batteries early, no question.

Other things 90% of battery owners do / fail to do, has the same effect.

Some people don't care.

Some don't know.

Others learn how, do the best they can within reason, and get much longer lifespan.

Yes fans help, but obviously eat power, need watching and replacing, etc.

Preventing as much heat gain as possible at zero energy cost is the best first step, then fans may not be needed, or would at least run less often.

[McDave]

Solar fan. Runs only when sun is on it?

McDave

[lrrowe]

Solar fan. Runs only when sun is on it?

McDave

Which is a cornor stone for my idea with my planned solar panel installation n the CT. Yes it may be overkill, but what can it hurt?

[Viper_Twig]

I'll be wiring everything together soon. Looking for feedback on my wiring diagram. Where should I add in the battery monitor? I plan on tying the batteries, PD4045, and charge controller to the junction posts inside the trailer. Any issue with the location of my battery switch? My idea is that isolates the PD4045 but allows the MPPT to continue maintenance charging while in storage. My two chassis ground points are the battery negative and the AC ground buss bar from the PD4045. Correct?

I've drawn this after reading dozens of posts and articles but there is a chance I have confused something, so feedback is appreciated.

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[McDave]

My DC meter runs to the battery through a shunt. My Master Kill Switch is wired similar to your diagram, however I don't have solar. The charge circuit from tow vehicle is where your mppt is. Also the refrig. and inverter are wired to battery, both have a in -line fuse as well as built in fuses.
That diagram looks good to me. And yes, battery neg to chassis grnd, and grnd from pd4045 to chassis.(also DC neg buss bar)

McDave

[MikeL]

You should have fuses on the +DC lines from the battery.

One fuse from the MPPT to the batteries using the largest wire the controller accepts and the shortest wire run possible. Also use the largest/shortest wire from the panels to the controller. This will help maximize the amount of power you get out of the solar panels.

One fuse feeding you disconnect switch and DC distribution bus.

The Blue Sea 6 circuit split bus with cover seems to be very popular.
https://www.amazon.com/dp/B000THQ0CQ?ref=emc_b_5_t
They also make a 12 circuit version but that would probably not be necessary.

ETA: looks like the PD4045 already has the DC distribution fuses. But it is probably better to run dedicated DC GND wires to each of your loads from a terminal block instead of relying on the chassis to provide the return path. Even with the DC GND tied to the chassis.

[Viper_Twig]

Mcdave and Mike thanks for the feedback. I do intent to shorten the panel run to the batteries. it should only be about 6 feet or so. i also have a DC neg buss bar and plan on running dedicated dc neg wires for everything with all the pos connections blade fused appropriately at the PD distro panel.

I have added a 150amp block fuse at Batt + to my plans and will fuse solar wires into the MPPT as well.



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[Viper_Twig]

Some progress. Made all my 4awg battery cables, ran the solar cables through the roof entry gland inside. Ran the battery cables to the box. Installed 150amp block fuse at battery +. Painted my fridge slider and put utility mat down underneath. Tomorrow I am connecting solar to the batteries for the first time! My MPPT controller has a 20amp fuse already so I'm not going to add another.

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[McDave]

That is a sweet fridge. The chest type are way more efficient, and that's a good one. I know they are spendy, but it's a good investment. Front load fridges are power hogs. That's money well spent.
Making real good progress. That is going to be a very capable unit. Nice job on the cables, they look very professional.
Thanks for the updates and pics.

McDave