TheSamba.com :: View topic - Solar/Truckfridge/House battery unscientific case study

Tue Sep 03, 2013 1:15 pm

I've seen lots of threads looking for and getting opinions on house battery/solar/Truckfrige setups. I just completed mine and will give my opinons based on live data from our first trip after the install.

A little background on the vehicle: 1984 Westy, auto, Bostig, rocket box, pretty much stock with the exception of the solar project and the Bostig. My wife and I travel to quite a few music festivals and got real tired of the Dometic's shortcomings. After a lot of reading here and other places I decided to take the plunge and purchased all of the following:

- Solar panel - Renogy 100 Watt Monocrystalline panel http://www.amazon.com/RENOGY-Monocrystalline-Photovoltaic-Battery-Charging/dp/B009Z6CW7O
- Refrigerator - Truckfridge TF49 http://www.truckfridge.com/tf49.html
- Batteries - Sams Club Duracel EGC2 6 volt golf cart batteries (2) http://www.samsclub.com/sams/duracell-golf-car-battery-group-size-egc2/prod3590220.ip?navAction=push
- Solar charger - Yoosmart 10A controller and remote meter http://www.yoosmart.com/epsolar-mppt-tracer1215rn-...-mt-5.html
- Separator - Blue Seas http://www.amazon.com/gp/product/B000OTIPDQ/ref=oh_details_o02_s00_i00?ie=UTF8&psc=1
- Fuse box - Blue Seas 5029 (it looks like the model has changed since my purchase)
- Battery boxes - http://www.amazon.com/gp/product/B004RCV1TG/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

The panel is mounted to my Yakima racks using standard Yakima wing nuts. However I carry 50' extension cables so that if parked in a shaded area I can take it down pretty fast and move it to sunlight. The wires are routed through the rear hatch defogger holes and through the rear cabinet to under the seat.

The batteries and battery boxes are beneath the passenger side of the rear seat, with the fuse box, separator, a cheap inverter I had laying around, solar controller, and remote meter mounted on top of the rear heater box, with the small space on the driver's side of the heater taken up by the Bostig computer. I can post pics if anyone is interested. I decided early on to give up the storage under the rear seat for "electrical only" as the rocket box more than made up for the loss of interior storage.

Anyway, it was my hope to get four solid days of use out of the aux batteries in hot conditions, with only the fridge and a couple 12 volt power outlets as a load. We rarely use the inverter, and the 12 volt outlets are used primarily to charge phones and our Kindles. The refrigerator was installed in the Dometic's spot, and no additional insulation or refrigerator modification were performed.

In preping for the trip, I precooled all our food and drink that was to be put in the fridge. I also packed the Truckfridge freezer with Otter Pops as I have read on The Samba that a full freezer mass helps increase fridge efficiency.

We were camping at a festival in VA (about a 5 1/2 hour drive for us), and on arrival, we grabbed a nice, flat, grassy and shade free spot in the middle of a field. I purposefully placed the driver's side of the van towards the sun which would not only give me the most extreme temperature effect on the refrigerator, but also would somewhat put my solar panel in partial shade at times during the day as my rocket box occasionally casts a shadow on the panel. The box is on the driver's side and the panel is on passenger side of the roof racks.

The temperatures for the five days we camped ranged from 60-65 degrees F. during the night, and between 85-90 degrees F. during the hottest part of the day. Not Arizona numbers, but pretty hot for us east coasters. In addition, the humidity seemed especially high during the trip.

Although I have been somewhat pleased with the Yoosmart, I would probably go with a higher-end unit from a more well-known manufacturer if I had to do it again. During the trip I took numbers from a voltmeter directly from the battery separator, and saw inconsistencies between those number and the ones observed from the Yoosmart remote meter, especially in regards to voltage and state of charge. It could be the way I have the meter configured, and I plan on working on the settings.

Results:

Simply, I made more electricity than I used. The Truckfridge is very happy between 3.5 and 4, and definitely does not have a 50% on and off cycle as others have mentioned, but rather something closer to a 30% on, 70% off... this is something I plan on getting more exact numbers on in the future as opposed to this seat of the pants observation. By early afternoon each day, the solar panel had fully recharged the house batteries from their overnight draw to the point that the battery combiner lit up and pushed the excess voltage to the starting battery (this was confirmed through voltmeter readings). The fact that this scenario ran true for a full five days tell me that the system as designed will cover the draw of my fridge and light power outlet use. I am now in the process of researching and installing interior LED lighting, which will also be put on the house battery circuit with additional testing to take place. Plans are to add power draws one at a time till I have reached equilibrium between the panel's ability to recharge and our power needs.

Sorry for the length and lack of technical terms, but I am a novice and this system was designed mostly with the information gleened on this site. I hope this helps set a somewhat baseline of the capabilities of a moderately priced system and adequate power needs.

Tue Sep 03, 2013 1:35 pm

Nice write up.

Tue Sep 03, 2013 2:11 pm

whynotvw wrote: Nice write up. X-2 Yes better solar charge controllers are nice. I have Morningstar SunSaver TrackStar love it. But they do cost a lot. I've had results like yours. But in bad weather rain, snow, ect. I will still put out enough watts to keep up. But then I had to go with more than twice your watts. The USA does not always have good weather. Yes the front one can be a remote mount like yours. :D

Tue Sep 03, 2013 2:13 pm

would love to see some pics if you had the time..Especially under the rear seat

Al

Tue Sep 03, 2013 3:28 pm

Yes, the Beijing EPSolar Tracers that you can buy through sites like Yppsmart do not display quite right on the MT-5 display panel. The state of charge / temperature sensing seems to be the issue, I kind of have noticed.

Yes, something like the MorningStar may give better data, true. i like the idea of the Modbus standard they use.

I too would like to see how you have yours setup. You have all your loads going through the controller, right?

Have you ever hit your low voltage cutout?

Tue Sep 03, 2013 3:57 pm

MSmyth wrote: Plans are to add power draws one at a time till I have reached equilibrium between the panel's ability to recharge and our power needs.

In the fall and winter you will have far fewer watts coming in so you can;t go too crazy with additional loads, which you probably already know.

A 100 watt panel is plenty IMO of you are not using a laptop, when it gets cooler in the fall, your primary draw, the fridge, will be notably less too so it all works out pretty well.

Tue Sep 03, 2013 5:16 pm

I have a similar setup and it has worked well so far. I have yet to test it out in cloudy/short day conditions but since I can run 2+ days on battery alone I think I'll be good.

Tue Sep 03, 2013 5:22 pm

I think I was just very pleased that on the first trip out the basic numbers I crunched were significantly exceeded (as were my expectations). During the hottest part of the day the side of the van facing the sun was almost too hot to touch, and the panel was in partial shadow for a good portion of the day too.

We have no plans on running a laptop or any significant audio on the house batteries... those are the things I am enjoying NOT having access to when camping. As I keep tabs on things through the fall and cooler weather I'm curious to see if cooler temperatures and clouds balance each other out (lower demand/lower output). However the conditions I was in during this initial trial run were less that ideal. The fact that I was topped up by 1:30 pm at the latest each day tells me I have significant extra capacity built in to the system.

My only planned additional power draws right now are for six LED interior light fixtures controlled by a switch on the inside of the B pillar, a 12 volt power outlet and LED reading light in the upper bunk, and possibly three voltage displays (aux battery, starting battery, solar output), unless I can (ideally) find one display that will cycle through multiple inputs.

To answer some questions:

- All my loads are NOT pushed through the controller... I might change my mind on this if I can get the readings on the solar controller to be a little more accurate... right now all house loads go directly from the house batteries to the fuse box.
- As I've only done driveway testing and one trip, I haven't hit the low voltage cutoff. Actually, my lowest state of charge has been right around 80%.

I'll get some photos up this week.

Tue Sep 03, 2013 5:25 pm

jackbombay wrote: MSmyth wrote: Plans are to add power draws one at a time till I have reached equilibrium between the panel's ability to recharge and our power needs.

In the fall and winter you will have far fewer watts coming in so you can;t go too crazy with additional loads, which you probably already know.

A 100 watt panel is plenty IMO of you are not using a laptop, when it gets cooler in the fall, your primary draw, the fridge, will be notably less too so it all works out pretty well.

That's my thinking too... BTW, we love our pop top shocks.

Tue Sep 03, 2013 5:28 pm

Nice write-up and thanks for reporting on your rate of consumption/production. Do you have a pic of the wires running into your top and the routing on the inside?

Tue Sep 03, 2013 5:32 pm

singler3360 wrote: Nice write-up and thanks for reporting on your rate of consumption/production. Do you have a pic of the wires running into your top and the routing on the inside?

I'll get some pics up hopefully this week... I have a major project going on and downtime is in short supply.

For bringing the wires in I pretty much ran them back and down between the hatch and rear cab and into the interior through the access hole the rear defogger/wiper uses. It then goes over the rear cabinet and down through the coat closet to the bench seat well. I have some scuff guard on the cable where it passes through the gap in the hatch, but there appears to be plenty of clearance.

Tue Sep 03, 2013 5:34 pm

If the loads do not go through the controller, all bets are off.

It was not designed to have loads directly to the battery.

How can the controller tell the state of the battery if an unknown load is pulling it down?

You are, likely, confusing the controller.

Ditto, the low voltage cut out may not work as designed.

Who knows what evil lurks with the hardware not wired according to the manufacturers design.

Tue Sep 03, 2013 6:13 pm

r39o wrote: If the loads do not go through the controller, all bets are off.

It was not designed to have loads directly to the battery.

How can the controller tell the state of the battery if an unknown load is pulling it down?

You are, likely, confusing the controller.

Ditto, the low voltage cut out may not work as designed.

Who knows what evil lurks with the hardware not wired according to the manufacturers design.

I did not run the loads through the controller, as I was attempting to get accurate readings on SOC and voltage before adding load control to the solar controller. For what it is worth, with 0% actual load on the house batteries, I still cannot get accurate voltage and SOC on the controller.

I will however route the load through the controller as a test to see if that helps get accurate readings... thanks for the advice.

Tue Sep 03, 2013 6:25 pm

Please note again the values displayed are only close, I just don't know the effects of not wiring it as they designed it.

Tue Sep 03, 2013 8:58 pm

r39o wrote: If the loads do not go through the controller, all bets are off.

It was not designed to have loads directly to the battery.

How can the controller tell the state of the battery if an unknown load is pulling it down?

You are, likely, confusing the controller.

Ditto, the low voltage cut out may not work as designed.

Who knows what evil lurks with the hardware not wired according to the manufacturers design.

You shouldn't have the controller connected to the aux. battery and all loads coming off the aux. fuse panel that is connected to the aux. battery also? I thought the load side of a controller was for something you wanted to power directly from the solar panel, but maybe I've missed something or don't fully understand the situation.

Tue Sep 03, 2013 9:20 pm

Excellent writeup, lots of useful information and links. That was a pretty massive outlay of cash so you must feel vindicated! I hope the system is relatively trouble free in coming years and that you enjoyed a visit to my home state..Ole Virginny. Humid is an understatement. It has taken me 2 years in SoCal to get used to air I can't see.

Neil2

Wed Sep 04, 2013 3:49 am

furrylittleotter wrote: Excellent writeup, lots of useful information and links. That was a pretty massive outlay of cash so you must feel vindicated! I hope the system is relatively trouble free in coming years and that you enjoyed a visit to my home state..Ole Virginny. Humid is an understatement. It has taken me 2 years in SoCal to get used to air I can't see.

Neil2

We do a couple festivals in VA every year... our favorite is FloydFest... right off the Blue Ridge Parkway in Floyd, VA. Great, great time, and they have a "Westy Village", where a camping area is reserved for VW buses only. It doesn't get any better than good music, moonshine, and lots of VW mercenary talk.

As for the cost, this seemed minor compared to the Bostig outlay.

Wed Sep 04, 2013 3:53 am

singler3360 wrote: r39o wrote: If the loads do not go through the controller, all bets are off.

It was not designed to have loads directly to the battery.

How can the controller tell the state of the battery if an unknown load is pulling it down?

You are, likely, confusing the controller.

Ditto, the low voltage cut out may not work as designed.

Who knows what evil lurks with the hardware not wired according to the manufacturers design.

You shouldn't have the controller connected to the aux. battery and all loads coming off the aux. fuse panel that is connected to the aux. battery also? I thought the load side of a controller was for something you wanted to power directly from the solar panel, but maybe I've missed something or don't fully understand the situation.

Right now my aux. feed goes directly from the house batteries to the house fuse box, and then to the 12 volt outlets, fridge, etc. r390's point is that it is possible the inaccurate numbers I am seeing on my solar controller's display may be caused by NOT routing the aux. power through the solar controller's load ports. I'm going to set up an experiment with looking at numbers with and without aux. power running through the controller and report back.

Wed Sep 04, 2013 7:35 am

Nice write up. I can't find anything wrong with your setup and actually, it's very close to what I have except that I'm still searching for the right combination of solar equipment.

I used Blue Seas equipment throughout with 2x 6V AGM Lifeline batteries. They were on sale for a ridiculous price but I installed them so that I could use lead/acid batteries next time and I mounted them where you did.

All marine grade wire and equipment is a good way to go. I stuck with Ancor brand cable and connectors through out with heat shrink/glue skirts on the smaller connectors.

I'm using a Progressive Dynamics PD9270 Power Converter / Charger for charging and battery maintenance when home or when I carry my Honda Generator. http://progressivedyn.com/power_converters_9200.html

Hopefully after getting the solar setup, the power converter will see very little use and I can leave my generator at home no matter what electrical toys I bring. Remote controlled toy batteries can eat up a fair amount of your battery over a weekend.

The only other difference is that I used the Blue Seas Remote Battery switch instead of an automatic one. It creates no parasitic draw. And if things go as planned, there will be very little need for the alternator to charge the house batteries.

BTW. I run the Vitrifrigo Refrigerator AND an ARB Chest Freezer along with charging my laptop, camera batteries and the batteries for my RC Quadcopter.. not to mention the Espar Furnace and a full array of LED interior and exterior lighting.

Wed Sep 04, 2013 7:36 am

I read that your CC is 10A. If you ran all loads from the "load side" of the CC my understanding is you are limited to 10A total. On my Morningstar Sunsaver controllers, they specifically advise NOT to put inverters on that circuit, but to connect them direct to battery. I also have an amp and subwoofer connected directly (with fuses of course) to the aux battery. Been working fine for 3 years but I guess time will tell. Also, our controllers don't have displays, so all I look at is system voltage under various conditions. Accurate enough for our use. Best bet IMO would be following the wiring instructions for your controller.