Batteries: What did I accidentally fix?

[Bob Denman]

[QUOTE=dkoldman;28599...
Hopefully someone will get a nice day to go check on, service, and clean their battery; and hopefully avoid some unexpectant failure at a very inopportune time.[/QUOTE]
When they do: they will have you to thank for the trouble that they prevented.

[Chance]

Originally Posted by dkoldman

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By Chance, can we play out the information provided below... Math Alert: Some may wish to stop reading NOW

You State: "Your 2.5 Amps is at 120 VAC, so roughly 25 Amps coming out of batteries at +/- 12 VDC to power inverter. If it ran for 2 hours, you may have pulled up to 50 Amp-hours, which is a lot from two small house batteries even if in great shape."

If I follow this right, you are saying that whenever I have amperage based on 120VAC, I should multiply by 10 if I wish to run the same load from a battery source? I assume you mean 120VAC/12VDC = 10?

So lets say the exact time the Norcold ran off the battery was 2 hrs. That would mean it pulled 50 DC AHs off the battery before the AGS started the genset to recharge. The same batteries new should have 130 DC AHs available capacity, but I have heard that you really on have half of that? So it means I may have drawn 50 AHs off 65 available AHs before the AGS thought it was too low? (or maybe it really is 130AH available?)

If the above is all true, what perplexes me is the 1.5 AH Insignia Fridge that is in the outside kitchen. It is plugged to the Inverter; so by math just learned; it is pulling 15 amps DC off battery? We have gone overnight (Quiet time 10pm - 7:00AM) with that outdoor fridge on batteries plus TV lights etc. That is 8 hrs and 90AHs. So if I only had 65ah available, it would not be possible, but if the 130ahs were available maybe if batteries were in good condition?

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If we were to look at the “numbers” for guidance, or at least evidence of what you observed during test and also regarding outside-kitchen fridge, there are a couple of very important points to be added to the energy-consumption estimates that you would need to include for accuracy. Otherwise your estimates will be way off.

With propane fridge running on inverter, “IF” it uses 300 Watts (and that’s in right ballpark), electrical current from battery will be even greater because of inverter not being 100% efficient. In total, batteries would need to supply about 30 Amps or more in order to make 300 Watts of heat at refrigerator.

More importantly, your batteries may be rated at 65 Amp-hours each, for total of 130 Ah, but that applies only to a very slow discharge rate over 20 hours. That works out to 6.5 Amps for 20 hours. When you discharge lead-acid batteries much faster than that, like at 30 Amps instead of 6.5 Amps, you will NOT get 130 Ah. It will be much less.

As I stated previously, running absorption fridge from batteries is not very efficient because of all these factors combined. I would only do it if driving with alternator powering the inverter, and stopped for gas or bathroom break for a few minutes, in which case I would let batteries power the fridge for a short period. If stopping for more than a few minutes, I’d go back to propane.

As to your outside kitchen fridge running much longer on batteries, it’s not only due to the lower power requirement, but also because it cools with a compressor which means that once temperature is reached, it cycles on and off as needed. Through the night on battery power, the fridge compressor may have only run a couple of hours depending on outside temperature. By comparison, propane fridge barely stay cold enough when running on electricity, so it’s likely it will draw closer to maximum current all night long.

Basically, total energy consumption of those small outside kitchen refrigerators is a small fraction of what your propane house fridge requires when on electricity. It requires a lot lot less. Comparing how long the two refrigerators will run off batteries is like night and day.

[dkoldman]

Originally Posted by Chance

With propane fridge running on inverter, “IF” it uses 300 Watts (and that’s in right ballpark), electrical current from battery will be even greater because of inverter not being 100% efficient. In total, batteries would need to supply about 30 Amps or more in order to make 300 Watts of heat at refrigerator.

The 2.5 amps came from Norcold and the 300 watts is on back of fridge when looking at plug.

More importantly, your batteries may be rated at 65 Amp-hours each, for total of 130 Ah, but that applies only to a very slow discharge rate over 20 hours. That works out to 6.5 Amps for 20 hours. When you discharge lead-acid batteries much faster than that, like at 30 Amps instead of 6.5 Amps, you will NOT get 130 Ah. It will be much less.

This would explain the why My controlled experiment confirms. Today, with outside temperatures 75 degrees, I ran my inside Norcold for 1 hour and 30 minutes off my inverter. Batteries were fully charged at 13.7vdc when I started, the auto genset came on when battery voltage dropped to 12.1 vdc for a duration of at least 15 secs. There was no other load on the batteries

As I stated previously, running absorption fridge from batteries is not very efficient because of all these factors combined. I would only do it if driving with alternator powering the inverter, and stopped for gas or bathroom break for a few minutes, in which case I would let batteries power the fridge for a short period. If stopping for more than a few minutes, I’d go back to propane.

This is exactly my plan

As to your outside kitchen fridge running much longer on batteries, it’s not only due to the lower power requirement, but also because it cools with a compressor which means that once temperature is reached, it cycles on and off as needed. Through the night on battery power, the fridge compressor may have only run a couple of hours depending on outside temperature. By comparison, propane fridge barely stay cold enough when running on electricity, so it’s likely it will draw closer to maximum current all night long.

Point duly noted. However one thing I read a lot but do not agree with is the coldness of our Norcold propane model. Maybe it is still new and will level off year 3 - 5? But our model has 5 frost flakes for setting. When I put on 4 Flakes we get ice in the bottled water and beer is freezing cold. We normally have at 3 Flakes unless we are traveling, then we set to 4 or maybe even 5 flakes if we know the fridge will have to be turned off for a while because I don't want to run generator or use propane. Our ice that we put in the freezer section has yet to melt even when we turn it off for 5 - 6 hours or so.

Based on my findings and learnings, I will proceed to add an additional 110vac receptacle supplied by my inverter in my Norcold Fridge vent area. At first I was thinking I may switch back and forth by unplugging for trips but based on what I learned today, there is no need to.

I will leave plugged into inverter 100% of the time. However I will only use the Inverter power for the Norcold when driving or for a duration NOT to exceed 60 minutes. I will simply use my Norcold mode switch to turn on / off from the inverter. i.e. If I wish to use my Inverter for TVs or outside fridge ONLY... all I have to do is change the inside Norcold mode to Propane, or simply turn the Norcold off.

This is a win win for us as I will always have my Norcold Fridge and Inverter on when traveling. The outside fridge is usually off unless we need extra capacity but that has not occurred yet.

It will require some training with my wife. But it should be simple to look for that green inverter on button and verify the Norcold is set for Electric only. That way no chance for propane to come on while driving

[dkoldman]

Does anyone have any feedback or opinions on the VMAX tank Solar 125 (total 250ah)?

https://www.amazon.com/gp/product/B0...TSR61H8N&psc=1

I was previously looking to buy the Duracell until I saw these, they cost more but are pure Deep Charge batteries with more capacity.

Duracells from Batteries Plus (Total 210ah)

https://www.batteriesplus.com/produc.../sli31dtmagmdc

[dkoldman]

Update: The below is what I chose to go with after quite a bit of research.

https://www.vmaxtanks.com/SLR125-12V...tery_p_38.html

I placed order today. I expect some drama to ensure they fit. I made 2D cardboard cutoffs the length / width size of these batteries and they may rub against the batteries cables on the back wall.

I learned that the dedicated pure deep cycle batteries are better for Hose on applications and can extend out to 8 - 10 years. Plus they are safer in that you do not have the extra exposed posts that could be touched

So I go from the existing 2 1/2 year old stock floods 130ah combined to the new 250ah Vmax Tanks combined

[TLeenhouts]

Usually in August, batteries go on sale. I got my Die hard AGM 31s for $150 each. By the way, 1000 watts at 13.2 volts is 75 amps. Your alternator is probably 150 amps but all the other stuff is running while you are driving.

[dkoldman]

I was able to get both Group 31s to fit. They are really heavy I did not have to remove the chassis battery, but I did take out the mounting brackets to push it further to the right. I was able to put all of my mounting brackets back in their original place; so those batteries are not moving.

Both batteries were 13vdc out of the box. I am allowing the Converter's Charge Wizard to do it's thing for next 24 hours; and then I will start to test to see how much additional time I have.

My feedback from the process.
1. The positive posts were close to the back wall and fuse blocks so I had to use crescent wrench, the negative worked fine with 1/2 socket.
2. I think I prefer the post versus the screws that screws inside the battery. It was a PITA to to get the positive lugs on the screw and then try to force it into the screw holes.