House Battery / Inverter / Appliance Question

[photographix]

Originally Posted by 2horsegarage

alright... So I feel like I am getting to the bottom of this...

It appears as though a set up with a pure sine wave inverter, (1) 100aH AGM battery, battery box, Solenoid, battery box, misc AC parts and cabling is going to run around $1000. Does that seem in the ball park?

Also, after doing some math, (1) battery should be enough to run my small (45 watt) fridge overnight, as long as I am getting a charge back to the battery everyday.

Would you guys agree?

The only thing left (I think) is where/how to mount the actual battery

The one thing I would be concerned about is having the ability to charge your house battery back up to 100%. As most here will tell you, running the engine for a couple/few hours will charge your house batt up, but only to about 90%, at best.

Since you don't have solar (yet?), you should probably have a way to get the house batt to 100%. An inverter with battery charging capability when plugged into shore power would be good for your house batt's long-term health. Of course, they cost more than an inverter alone.

Balance the cost, convenience, and particularly space considerations of an inverter plus a charger vs. an integrated inverter/charger.

Any van seems physically large initially before a build-out, but by the time all the furniture, electrical boxes, water tanks, plumbing and wiring are done, the space for installing extra stuff quickly becomes scarce. I'd go for an integrated inverter/charger rather than 2 separate boxes, if you can swing it from a financial standpoint. It will save you space, most likely.

As an example, I recently installed a solar controller. One option I looked at involved a large-ish controller that was about 5x6x11", or about the size of a shoebox. It also needed some additional air space around it for cooling. I couldn't figure where I could put something that large. And this is coming from an owner of a Ford EB van, which is a pretty big vehicle.

I added a simple 2x2x4" switch box to my separator yesterday, and had to hunt for a good place to install it.

[boywonder]

Originally Posted by 2horsegarage

I may be looking at the wrong style inverters, as I am still not sure how I would go from the inverter to 110 outlets.

For the style inverter in the picture, go to your local Home Depot/Lowes and buy a 110V 15A mains plug (with ground). Wire that plug onto some romex 12-2 or 14-2 then route the romex to your outlet boxes, just like in your house. The mains plug would just plug into the receptacle on the inverter.

If you need a picture I can draw one up and post it.

The inverter I'm planning to use has built-in receptacles just like the one in your image. It's a 1000W. Seems like you need to get to 1500-2000W or so to get AC screw terminals. In that case, you just wire your romex directly to the terminals.

[jony101]

100 ah battery would be too small. I had a 75 ah agm battery and many of times my 12 volt fridge would be blinking low voltage at 2 am.
I currently have a 145 ah agm battery and that took care of the low voltage problem.
Whatever battery you get divide it by 2 and thats what you really have, ie a 100 amp battery actually has 50 ah usable, unless you want to run near empty everytime.
I had the edgestar fp430 fridge and using a wattmeter I measured it to use anywhere from 24 to 29 amps in a 24 hour period at 40 degree temp setting. as long as you dont run anything else with your battery at night it might last you till morning.
If you decide to go solar get the biggest panel that will fit on your roof. I have a 240 watt panel and wouldnt go any lower. 12 amps of charging power is plenty for most people.
One last thing I notice in my setup, even when my fridge stop working because of low voltage, the inside stayed cold and my food didnt spoil. But you need to get your battery charged up in the morning before you lose all the cold.

[daveb]

How are you doing the math? I understand some refrigerators pull more than others but if you go to the usage calculator in the FAQ's here, it will show a 50Ah battery should be able to run 2 amps for 10 hours for the battery to reach 10.2V. Not saying a 100Ah battery (rated at the 20Ah rate) isn't kind of small. There is a lot of other stuff to figure in.

[2horsegarage]

I used a calculator on the web and entered the data from the manufacturer for the specific fridge, and it spit out data... But the calculator I used didn't factor in not draining below 50%.

The fact is, for my actual use a house battery system will mostly be a waste without solar, or shore at a minimum --- but for the times I do want a fridge, I want a fridge. So, I gotta figure something out. The whole set is just more expensive than I thought it would be.

The local RV place tried talking me into a propane fridge, but I'd be starting from scratch there too. For now, I think I will wait and see.

[1der]

Your desired set up is not too different from what we started out needing. Here is what we had / have:

A Norcold 60 fridge, laptops, phones, etc. nothing major. Our set up was the single Group 65 starter battery for a V10 and a 1000w Xantrex inverter. Additional AC outlets accomplished via a extension power strip with six outlets. For convenience, the fridge (12V) was connected directly to the 12V input terminals on the inverter, this is 12V power coming from the battery

Before leaving the house , I would connect a charger to the starter battery to make sure it was fully charged. The fridge was run on AC to pull down the plates so the fridge was ice cold. Food going in was already cold. We actually could go 48 hrs without charging on this setup, in cooler weather, with the fridge at around 36 deg. A thermal blanket (cover) around the outside and a couple of towels inside across the top are used so we can keep one side covered when opening and accessing food. I would run the engine for about 45 mins to an hour on the third day to put juice back into the battery. ymmv under this scenario. Up until a week ago, we did this only on the Group 65 starter battery and could still start the V10 after 48 hrs to recharge the battery. I would not recommend this, but I also carried a generator and battery charger as a fall back.

We wanted to add a microwave and move away from the starter battery as the house supply. I installed two Group 31 AGM's @ 105Ah each (House Battery bank) on the passenger side frame rail, They fit really nicely and it can be done in modified 2006 and later twin frame rail mount battery boxes. I was even able to use the stock battery cables for the install. The isolation is via a manual BlueSea 6007200 switch mounted in the side cargo door foot well step area. The inverter is wired to this switch and can be powered by either starter battery , house bank or both. With this switch I can also combine all the batteries fro starting and charging off the alternator. Tie into the alternator is at the starter terminal where the battery cable comes in from the starter battery.

Costs were:
Switch $35
140Amp Breaker $30
Battery boxes and cables and bolts/nuts from wrecking yard $110 nice thing is the harness has jumper block built in!
Welding of battery boxes together $50 ( I do not have a welder )
Paint $6
Lug terminals $5.
2 DEKA AGM 31 batteries $480 ( only one care available)
Had the Xantrex Power 1000w ($150)
Had the power strip ($15)

I already have a battery charger which I can connect to the jumper block for the house bank to charge that bank. The charger gets plugged into the source via extension cord. I can do this at home, at campground, or to my generator if I am going to think I need that (which I do not). Yes, a bit ghetto with external charger but I have one and do not need a "built in" one. At some point I would like to add solar and a battery monitor that provides Voltage, Amps in and out, etc. But for now my multi-meter can get me by.

Next trip (maiden trip for new house bank) will include a microwave. This is new for us. The MW will be connected to the power strip which is plugged into the inverter. This is way more flexible. I will estimate usage and determine when the engine needs o be run for charging. I am expecting we could go three days with no engine start. Will batteries be charged to 100% at the end of the trip even with a long drive home? No. But when I am home, I can connect up the 3 stage charger for days and get the batteries back to 100% full charge. My plan is not pull the house bank down by more than 50% at anytime before putting something back in, even if not 100%.

So, yes I think you will need two batteries (min. close to or in excess of 200Ah total bank TRUE DEEP CYCLE capacity) and it is going to cost $800+/- in just parts to do what you want to do. It will cost more for battery monitors and built in charger/inverter units.

Ray

[daveb]

Originally Posted by 2horsegarage

I used a calculator on the web and entered the data from the manufacturer for the specific fridge, and it spit out data... But the calculator I used didn't factor in not draining below 50%.

The fact is, for my actual use a house battery system will mostly be a waste without solar, or shore at a minimum --- but for the times I do want a fridge, I want a fridge. So, I gotta figure something out. The whole set is just more expensive than I thought it would be.

The local RV place tried talking me into a propane fridge, but I'd be starting from scratch there too. For now, I think I will wait and see.

As far as batteries are concerned, you have to watch out on how the battery is rated. IIRC a 100 Ah battery can supply 5 amps for 10 hours at the 20Ah rating. So yes you figure 1/2 of that because you want to recharge at 50%. But most refrigerators pull about 2.5 amps (some draw more) so you're back at 20 hours at full duty to 50%. Then you should figure the refrigerator works about 1/3 of the full duty cycle so you gain some time there as well. But that is a brand new battery with no line losses. It doesn't leave much extra left over but should be able to handle the day to day load of the refrigerator. Of course load is everything and more is always better. That applies to both battery reserves and solar.

Other issues would be how hot it is inside the van vs. cycle rate of the refrigerator, how many amps the refrigerator actually pulls, the line losses, the age of the battery and the fact that an alternator might let the battery reach only 85% of charge. That can be hard on a battery.

Also be aware of those manufacture who sell batteries rated at the 10 hour rate and they are out there. Make sure any battery you purchase is rated at the 20Ah rating.

If you throw in solar you'd reach a full charge (provided the panel is large enough to supply a positive charge with the refrigerator running) unless there are other loads depleting the charge. A 100 watt panel might be OK in full unobstructed sun and pointing at the sun as much as possible during daylight hours. Again you would be factoring in that the load (the refrigerator) is cycling at 1/3 of the full duty cycle. In most cases a 100Ah battery should be OK.

I do agree that a 100Ah battery is on the light side for what you're wanting to do. 200Ah battery plus a 130w solar panel is a fairly good balance and is a standard build with many vans coming out of SMB. With LED lighting and being conservative that would be what I'd shoot for as a minimum. Without solar you really need to be plugging into shore power on a regular basis to keep the batteries health up. Another solution is to run the inverter while driving that powers a separate multi-stage charger, which might be a cheap way to go but requires running the engine for a specific length of time depending on the battery SOC, total Ah and the size of the charger. A high output alternator might be required. You could also add a smart regulator controller to the alternator circuit but they are kind of expensive as well. No sense to mention lithium batteries or fuel cells cause they are very high priced.
There are a lot of people that use a 105Ah battery to supply their refrigerators in the jeeping world so they work, you just need to keep the other loads separate. What ever happened to those portable solar panels that were for sell somebody posted on here? That was a good deal if they are still out there and might be an inexpensive way to go.

[2horsegarage]

So, not to confuse the conversation here but... If I decided I didn't really need 110, the set up stays the same with the exception of a converter/charger versus an inverter--- right?

[daveb]

Originally Posted by 2horsegarage

So, not to confuse the conversation here but... If I decided I didn't really need 110, the set up stays the same with the exception of a converter/charger versus an inverter--- right?

Pretty much but if your running 110 to the converter why not throw in a single GFI outlet? You need to cut in a 110 shore power inlet anyway.

[Eatmorefish]

1der, if your still out there, can I ask how you raise and lower your batteries, safely, from the location under the body? thanks.