Which fridge?

dreadlocks

Well-known member
With such a fluid goal I would suggest in building up your battery monitoring across your platforms so you gain the insight of predictability.. then re-inforce anything you need as you collect data.. try to stay off your starter batteries as they are not designed to be anything but fully charged all the time.

However with such a fluid design, it seems having a very robust system built for the worst is kinda off the table.. so any investments you make on the front end to make this design as power efficient as you can will pay off in the long run as your goals expand and your experience grows.. do try to keep it simple, I realize your ambitious with lofty goals, but I think you need to get grounded w/some more fridge boondocking experience first.
 

Photobug

Well-known member
With such a fluid goal I would suggest in building up your battery monitoring across your platforms so you gain the insight of predictability.. then re-inforce anything you need as you collect data.. try to stay off your starter batteries as they are not designed to be anything but fully charged all the time.

That is kind of the idea of the home built system. Both boat and truck have a house battery and the LFP travels with all the support equipment, MPPT, and inverter. Short term plans have no long term voyaging so no need to change AH needs probably till next year.
20191119_132249.jpg
 

dreadlocks

Well-known member
in my system I can see all the power being consumed in/out of my LFP w/a shunt, gives me nice historical data and lets me figure out base power needs in dry runs at my house in simulated poor conditions (high heat here in July w/everything sealed up tight).. I know my base needs are 400-500wh a day, I can then add a warm 12 pack to the fridge and see how much more energy that just cost me, if I wanna make ice I can do that and measure out how much thats costing me.. I dont have all the stuff written down but most of my conveniences I have I know in my head how much energy its gonna take to operate it just from experience, and I can tailor a diet as I go along.

Then out in the field I can make decisions on what capabilities I have depending on the situation, each site is different, each season is different, each day the weather could be different.. being able to ride all that out without a really robust system takes flexibility, and predictability.. knowing when to hypermile, and when to make ice.. the only way you getta boondock for any considerable time and stick your head in the sand without worrying about any of that is when you've built for the worst, and know it'll take the worst.. then the day to day details dont matter so much.
 

Photobug

Well-known member
in my system I can see all the power being consumed in/out of my LFP w/a shunt, gives me nice historical data and lets me figure out base power needs in dry runs at my house in simulated poor conditions (high heat here in July w/everything sealed up tight).

Because I just scratch the surface of my LFP's capacity I don't need a monitor yet. I am conflicted between the Victron and Balmar. No rush just yet.

If my primary source of AH is a FLA bank in each vehicle/vessel, do you see the need to monitor the battery bank there or can I just rely on voltage to get an estimated SOC? Right now on my truck I have a simple voltmeter that I have calibrated with a high end multi-tester to get an accurate voltage for SOC guestimate.
 

dreadlocks

Well-known member
I'd suggest at least a simple power meter of some sort on your aux stuff, that way you can know exactly how much power its taking, and your victron solar will tell you how much your putting back in and then you extrapolate your level of comfort.. the fridge cycles will be variable and voltage under load is not a great indicator of SOC.

Might take 20AH a day in truck, and 40AH a day in boat with no shade.. needa be able to determine that stuff.. if you have a heatsource like a furnace/sunlight it'll up its power usage.
 
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Photobug

Well-known member
The boat is white and sits in 60 degree water and the truck is dark blue. I would guess the boat is 20 degrees cooler in the day and warmer at night. It is all around more comfortable and when at the dock we have shore power for now but designing for the future.

Which cheap meter do you recommend? How would it work with a two battery system?
 

dreadlocks

Well-known member
you could use a lil DC killowat type thing and a notepad if you want, solar charger and charger will give you an idea of battery state and how much solar your getting, on the simple end to a nice full battery SOC monitoring system that figures it out for you.. wont matter on a dual battery system as the combined batteries are setup like one big battery.

There's efficiency losses and stuff where it takes more AH to recharge a battery than the AH you get out of it with lead that LFP dont have, so the trying to figure it out in your own thing gets old pdq..

The sweet spot is just being able to look in the morning before solar comes up the consumed amp hours and it already be pretty close to what you expected, then by evening you know what your solar is capable of in that location, and weather.. if there is a deficit you can calculate your debt, figure out your runtime before you need more power and if you needa hypermile to stretch to next recharge, if there is a surplus you can start relaxing and cranking up conveniences to make stuff like ice or chill a bunch of room temp beer, then you move to the next location or the weather changes so you recalculate.. thats about the only way to reach long term nirvana with a small fluid system.
 
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Photobug

Well-known member
you could use a lil DC killowat type thing and a notepad if you want, solar charger and charger will give you an idea of battery state and how much solar your getting, on the simple end to a nice full battery SOC monitoring system that figures it out for you.. wont matter on a dual battery system as the combined batteries are setup like one big battery.

When/if I do step up to a two battery system, I will likely run it as I have on boats: two independent batteries with a switch to choose either or both. That way I can control the SOC and usage of each battery.

My initial thinking was to get the 73 dz domestic because it fits the space in my truck and in my boat. It checked off all my needs except I question the energy efficacy. I thought about trips where might be taking a lesser vehicle and the massive fridge would not fit or make us rearrange everything.

Now I am leaning towards the suggested Engel or possibly the Dometic CX3 55IM. I am not sure the 40liters will cut it capacity wise and the Dometic does have an ice making tray.
 

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