Ford Transit Connect extra battery, solar, etc. questions

[WithAlligators]

Hey guys,
I've been coming here to drool at vehicles and trips but never posted before. I'm a biologist that works seasonally and hates wasting money on housing. My previous rig was a 94 3/4 ton cummins with a cap on the back and a clever use of interior space. Now, I have a semi stealth 2014 Ford Transit Connect in the works. Oven roaster cargo LWB version. This thing gets hot in the sun, and only the front windows open. So, I'd like to do solar, an extra battery, a vent, a 12V freezer, and some insulation.

I'm going to run wire to a sideways AGM battery under the seat, and from there to a 300W and a 1200W set of inverters. For the run to the second battery, what gauge of wire will I need? It looks to be a 6-8' run. Can I wait a bit before doing the whole solar system (ie, can my stock alternator handle two batteries?) or do I need to do it all at once? What kind of battery isolator do you guys suggest? Anything else I should know about this part?

I'll ask about solar when I know a bit more.

Thanks!

 

[WithAlligators]

It sounds to me like you are suggesting that my alternator is going to be working pretty hard to maintain any level of charging. Draw would be a 12v freezer, occasional 700w microwave use, and eventually a computer and monitor. Would I be alright setting it up and only powering the 12v freezer for now? Then attaching the rest when the solar was in place?

Thanks

 

[Herbie]

Once you've determined roughly how much current your alternator will be trying to shove into your house battery, here's the ampacity (current capacity) chart to help you pick the size cable you'll need: http://www.usawire-cable.com/pdfs/nec ampacities.pdf

I've found that the best way to get a nice flexible high-current cable is to get jumper cables and chop the clamps off. I have a long run of 2-gauge in my van made just that way. I encourage you to run both positive and ground cables and not try to use the chassis as ground. Easy-peasy if you use jumper cables!

 

[Vanaroo]

Just as a side note, a 1200watt inverter will draw around 100 amps DC (divide watts by voltage) if you are using its capacity (actually a bit more due to inefficiency). That's a *really* hefty draw unless you have a large house battery bank (I'm not speaking of if you are plugged in or driving). It's doable, but for example, I have a buddy with a 500ah 12 volt house bank and a 2000 watt inverter, and it still puts a heavy load on his batteries (and would not be used for long duration in anything like top capacity). Another note is that a larger inverter will have a fairly high tare load (i.e. just the power to run the inverter). I think his is something like 4-5 amps. Essentially, use the smallest inverter you can get away with (smaller tare load) and shut it off when you are not using it.

Even better, IMO, try to run everything on DC. I only have a couple of items that require an inverter, and for that I have a very small one (< 150 watts). Laptop, camera, power tool batteries, fans, lights, refrigerator.... all run or charge on 12 volts.

I don't know much about your usage pattern based on your original post, but just given that you have a small vehicle and speak of one house battery... I'm guessing this will be a smaller system. The easiest way to keep things happily running along, in my experience, is to stick with either 12 volt DC items and/or occasional use of smaller inverter for oddball items (charging toothbrush, etc.). (This doesn't apply if you will be plugged in or running a generator or engine while you are using your loads, but then if that's the case it's all easy.)

 

[WithAlligators]

The highest draw item will probably be the 700W microwave, which will be be used for short bursts, and I'll probably run the engine while its on. I doubt I'll ever use the full 1200W of the inverter, it just happens to be one that I had. I also have a 300W that will see more use as most of my stuff is small. The computer will be a fullsize desktop because I'm a nerd like that, and monitor which will probably draw between 300 and 400W total. The 12V freezer is already 12V, but will be plugged in most of the time, but only kicking in when needed.

I've considered jumper cables, but I feel like Amp power cable kits are a better buy. They come with flexible wire, fuses, and terminal ends, and are meant for permanent installation. I can't post links yet, but there are several 0 guage kits on amazon and ebay. And that would be for the run from the hood battery to the house battery, And I would get a couple of feet of 4/0 from the house battery to the inverter + fuses.

Sound good?

Thanks again!

 

[Vanaroo]

Those sorts of draws are way over what I take from my system, so I can't really say. Adding the charging of the engine or plugging in introduces a factor that I don't count on. I run my computer quite a bit, and refrigerator 24/7, but it's all on a smaller scale and DC powered. I use only solar to re-charge 95% of the time.

Although I have more battery bank and perhaps more solar than you are planning, I'd never be able to run the sorts of loads you are mentioning if I wanted to keep my house bank healthy. My initial thought was that your energy draw plans sounded like too much for what sounded like a small DC system. But using the engine for auxulliary power, driving a lot, or plugging in changes things, so my use pattern probably doesn't apply. (At first I thought maybe you planned on longer times staying in one place without hours of engine running, etc. since you mentioned housing.) I mostly just wanted to bring up the DC draw of the 1200 watt inverter in case you didn't realize how high it was.

There's a couple sides to wiring things in. One is for the wire/fusing/etc. to be able to handle the draws and charging amps; the other is to be able to put back what you take out (from the battery bank).

 

[WithAlligators]

I will be mostly out and about on remotish sites, maybe spending every other weekend in LA. Plugging in isn't something I had planned on implementing. I would run the engine for the microwave, but probably not for the PC, which would see occasional use for an hour or two at a time. I have only briefly searched for batteries that will fit under the seat, so I'm not sure yet how big I can go, but there is a decent amount of space there, and I could put another one under the other seat if it became obvious that it was critical.

What battery isolator is recommended?

As for solar, I've been looking at some of the Renogy kits on amazon, cause they seem pretty cheap. I am looking at primarily 2 panel, 200W systems, but could upgrade with a 3rd for a 300W system. I don't think I could fit a 4th and a roof vent.

Should I be looking at PWM or MPPT systems?

These are the kits I'm looking at:

(still not allowed to post links) various 200W kits but with different controllers: the Wanderer which is a 30A PWM controller with minimal displays and controls, the Tracer which is a 40A MPPT controller, and the Viewstar, which is a 20A PWM controller with an LCD readout. I'm also open to putting together a setup from different pieces. There is a guy on CL here selling 320W panels for about 300 bucks, but they are 24V. Can I step that down to 12V? I have tried to understand AC and DC but never really been able to wrap my head around the stuff. I'm a scientist that's flummoxed by math. Go figure.

I don't understand enough to know if the more expensive ones = better.

Thoughts?

Thanks!

 

[WithAlligators]

I'm going to post this more general Renogy question in a separate thread. Thanks for the input!

 

[jonyjoe101]

the 12 volt freezer alone will drain most batteries within 1 day, unless its well insulated. Solar wont keep up with it. Also it will heat up your van. You might want to build some sort of vent to get rid of the heat from the freezer. I got rid of my 12 volt fridge because of the heat it produce everytime the compressor came on.

My advice forget about the roof vent, even the one with fans, if the roof is hot, it will just suck hot air into the van. I got 3 vents on my roof, two of them with no fans and I just covered them up I dont open them anymore. No vent on the roof , lets you use it all for solar.

On my van I have a 240 watt (36 volt) solar panel connected to an ecoworthy 20 amp mppt, It produces up to 13 amps of power. The 320 watt panel 24 volt will have no problem charging a 12 volt battery. Even my 36 volt panel will work. The charge controller will reduce the power to make it work on the battery you have. My advice here is under 30 volts use a pwm controller over 30 volts use mppt. mppt needs high voltage to work properly, it will work with a low voltage panel but it wont produce more amps for you. What mppt does is take the high voltage and convert it to extra amps, on a low voltage panel it doesnt have any extra voltage to work with.
Example If the back of the 320 watt 24 volt panel says ipmax 8 amps, thats all you get with pwm or mppt, if the same panel was 36 volts and it said ipmax 8 amps with pwm you get 8 amps, with mppt you get over 15 amps. The extra volts converted to more amps.

Since you got a van with no windows in the rear, you can take care of the heating problems easily. Home depot sells rtech foam insulation its 1/2 inch thick and comes in 4x8 foot sheets. On my van i removed the oem roof insulation and put 2 layers of this foam on the roof. I used a 20 dollar hotglue gun I got at harbor freight to do it, it dries fast and does a very good job at securing foam to metal.

I also put foam on the rear windows and as much of the sides as I could. I built an insulated sliding door to separate the front of van from the rear.

For air, just cut some holes on the side of your van and install some vents, there's round ones and rectangular ones available at home depot. You can get a cordless jigsaw at home depot for 30 dollars that will do quick work of cutting holes on metal. On a hot day fans wont keep you cool but a swamp cooler will, its all I use. When I park In the hot sun, I dont open any windows, I just close my sliding door to the front of the van turn on my swamp cooler and I am very cool in the back of my van.

As far as computer, the desktop computer aint going to work too well in a van. 400 watts will heat up your van very quickly and even the largest batteries wont run it too long. If you need power get a gaming laptop, those you can run 3 4 hours without draining your battery. I use a small netbook with ssd and I can use 24/7 just on solar power.

 

[WithAlligators]

This is the first I've heard that a 12v freezer will kill your battery that quickly. Even some of the new efficient ones? I've heard nothing but good things and people running them even off cigarette lighter 12v.

Also, roof vents exhaust hot air building inside the van out, they don't suck it in,at least the one I had didn't.

Years ago, I saw some hippy dudes with a mini swamp cooler in a van window. I will have to look into that.

 

[DiploStrat]

I Run Those Loads

How much does your freezer take? A 50l ARB claims about 1Ah at normal refrigerator temperatures. My NovaKool pulls around 2-3Ah, but my freezer is below freezing.

I run a microwave, an induction cooktop, and an electric toaster. You might want to look at my site and documents for ideas: https://diplostrat.org I include links to many useful sites, including Handy Bob (always a good place to start), a voltage drop calculator, and some extended technical discussions of dual battery systems.

It can all be done, but you will need a LOT of battery (Peukert is NOT your friend! http://www.smartgauge.co.uk/peukert3.html), a lot of charger(s), and BIG wires to make the mojo happen. In lieu of a 4/0 cable, consider a pair of 1/0 cables - much easier to work with.

FWIW I run an MPPT controller.