An alternate to generators

[cpaharley2008]

Thought this was an interesting set up
Zero Emissions Rechargeable Electric Generator - Herrington Catalog

[dfandrews]

Interesting, yes.
It's basically an un-interruptable power supply very similar to those used for computer backup power. I suspect the biggest plus feature would be if they have lithium-ion batteries instead of nickel-cadmium. (and that would explain the price).
Don

[jamman]

A 100 amp hour group 31 AGM battery, a charger and an inverter. Rather expensive for that: Goal Zero Yeti 1250 Solar Generator | Power Packs | Goal Zero

[Greggo]

Doug, do you have a Yeti? I've been thinking about one but having trouble with the price. Might build my own.

Greg

[jamman]

Originally Posted by Greggo

Doug, do you have a Yeti? I've been thinking about one but having trouble with the price. Might build my own.

Greg

Don't need one. I have dual 6V batteries and a 1500W inverter. When I had a Casita I some times took along an extra group 31 battery with Anderson powerpole connectors instead of a generator. I do have an cheap 2000W inverter I have only used once, not sure what I'll ever use it for.

[MyronL]

Got a Fridge/Solar surprise this morning. In my yard four days ago, Began a little test.

Last Wednesday at 1 PM, hooked up to my 100 watt panels of solar power, I switched on the Dometic RM8551, to 4 dots. Strictly now on battery power with my solar panels in charge. Starting temps were 51° in fridge, 63° in trailer. Two hours later it was 35° in the fridge and 64° in the trailer, and Xantrex battery voltage reading is 12.9v. So, I dropped the power to 3 dots.

I’m happy. Thursday and Friday’s readings continued about the same. Inside fridge temp never higher than 38°. We’re cool.

This morning, at 9:15AM I go out to check my readings. Fridge is 37°, Morningstar battery voltage reading is 11.14 volts. I turn on the Xantrex and it’s screaming an E01 alarm! Run, get the owners manual… E01 means poor battery condition and the remedy is plug into shore power or change the battery. I immediately plug into shore power. Alarm stops, all systems indicate a jump back to 13.1 volts in the battery.

What the hell??

[cpaharley2008]

Myron,
What is your battery capacity?

[MyronL]

I have the standard issue two 6's Escape installs.

[cpaharley2008]

So about 120 a/h available for use? Correct. What is the refer pulling while in 12v operation? If I recall about 12 amps??

[MyronL]

Here are the Morningstar/Xantrex stats I have been collecting since Wed. We were gone all day yesterday (Friday) so only checked at 9:15AM/Fri--- and then this big surprise, this morning. Been sunny all the days... thinking this sudden crash means the solar just can't handle the fridge.

[cpaharley2008]

Doesn't seem like you were ever at 100% at the beginning nor any time, it was just a constant draw down.

[jamman]

Originally Posted by MyronL

H
...
Been sunny all the days... thinking this sudden crash means the solar just can't handle the fridge.

This time of year that is certainly true. I doubt if the solar would be adequate to run the fridge on 12V even in the summer.

Absorption fridges are not as efficient as compressor fridges - you are surely drawing more power than hotfishtaco's NovaCool.

[J Mac]

MyronL,
with an LP Fridge it's common practice to run the fridge on shore power, fill with cold food, then turn on the LP and unplug the shore power. Do you think a 'head start' like that would provide better or longer lasting results?

[Brian B-P]

Originally Posted by cpaharley2008

Thought this was an interesting set up
Zero Emissions Rechargeable Electric Generator - Herrington Catalog

Describing a battery pack (with inverter and charger) as a "generator" shows that the seller is trying to take advantage of the ignorance of potential customers. I wouldn't buy anything from them.

They do use the word "battery" once... in this incorrect statement:

Total battery capacity is 1250W with a 1500W max.

This is the inverter output rating. The battery capacity is not listed, which is even worse.

The manufacturer's page - Goal Zero Yeti 1250 Solar Generator - is even worse in a way, because they call it a "solar generator", and it is neither a solar system nor a generator.

There's nothing wrong with a "power pack" like this, consisting of a battery, inverter, and charger. It makes some sense to me for the home standby use that they describe. I can even see using one with a very basic camping trailer that doesn't have it's own power system (like the tent trailer we rented once), but I don't know why I would use one with a travel trailer, rather than just building the same stuff into the trailer, at appropriate capacities.

[MyronL]

In my case it was a test to see how battery power supported only by my solar would perform under the fridge load. I wasn't expecting miracles, just needing to learn base technical limits, nothing more. Sure got that answered.

[jamman]

And that is why we have LP appliances in the trailer world. It is much easier to carry energy in the form of propane than stored electricity. (And it is also why most off-the-gridders use LP fridges and stoves, saving their solar generated power for lights and electronics.) This site says 1 gallon of propane equals 27 kilowatt-hours: Propane Vs. Electricity - A Comparison

[MyronL]

Ooo-rah.

[Brian B-P]

Originally Posted by MyronL

Here are the Morningstar/Xantrex stats I have been collecting since Wed...
Been sunny all the days... thinking this sudden crash means the solar just can't handle the fridge.

Is the Morningstar amp-hour reading the accumulated output of the panel? If so, it appears to be about 30 amp-hours per day, which seems pretty good for (nominal) 100 watt panel in the winter. Even if the weather is clear, the days are short and the sun angle is unfavourable.

The result isn't surprising, since a refrigerator which takes 12 amps when running could only have about a 10% duty cycle (power on 10% of the time) to stay within that energy budget... that's not much, even in the winter. The situation would be much better with a compressor-based refrigerator, but even then one 100 watt panel seems marginal at best for winter sun.

[hotfishtacos]

Originally Posted by Brian B-P

Is the Morningstar amp-hour reading the accumulated output of the panel? If so, it appears to be about 30 amp-hours per day, which seems pretty good for (nominal) 100 watt panel in the winter. Even if the weather is clear, the days are short and the sun angle is unfavourable.

The result isn't surprising, since a refrigerator which takes 12 amps when running could only have about a 10% duty cycle (power on 10% of the time) to stay within that energy budget... that's not much, even in the winter. The situation would be much better with a compressor-based refrigerator, but even then one 100 watt panel seems marginal at best for winter sun.

Brian, when my MorningStar solar controller gets my batteries up to 14.8 - 14.9 it starts to throttle back using PWM so my totals often don't represent what the panels could really put out if needed.

[MyronL]

Now-- I cannot say my Morningstar solar controller never reached 14.8 like yours, before I began this fridge-load test, because I hadn't paid enough attention to the readings.

Will give solar a chance to do its stuff with no load getting in the way. Let it pump my batteries up. Then will make them do their job and pay better attention. It changes nothing of course. My fridge is clearly a hungry beast -will never be satisfied with my solar limits. Should, though, inform if my solar array is at least as good a performer as der Taco-meisters'. Then can continue this probies'-probing, and learn applicable limits.