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Old 08-24-2020, 05:19 AM   #41
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If that is true.......outside of price and issues with the cold, why would one not buy 2 lithiums?

Just wondering.glenn
I think you must go lithium if you eventually go compressor fridge. MexDoc has shown us they can be real energy hogs. I donít have and wonít get 300 watts of solar so from his data I need 200ah of lithium and a 100 amp charger to be powered by the generator. A generator run of less than 30 minutes twice a day will be necessary.

Gonna keep the propane fridge running for now. Will keep 100ah of lead acid, too. When I go compressor fridge it means another $950 lithium battery and probably a larger charger.
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Old 08-24-2020, 10:26 AM   #42
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So I have a 100AH LifeLine AGM. I know that I can occasionally draw it down below 50% but probably not as a usual daily practice. So I basically have 50AH to go with. If I add another LifeLine I'd have 200AH total/ 100AH usable.

I believe (and I could be wrong...who would have guessed) that lithiums can be drawn down to 20% without any harm or problem. If I had 200AH of lithium I'd actually have 160AH usable, the equivalent of having 3 LifeLine 100AH AGMs.

If that is true.......outside of price and issues with the cold, why would one not buy 2 lithiums?

Just wondering.glenn

Lots of people are running compressor frigs on AGM batteries. I would suggest you read the discussions on the 50% rule and cost analysis that goes with it, as the cost penalties of going lower than 50% aren't all the large. AGM will charge a s quickly as lithium, at least Battleborn, if they are in the lower 80% of state of charge at .4C



You might also need an AGM in the system anyway, depending on the charging equipment you have to activate charging sources.


If cost is no issue, then lithium may be better long term, but we really don't know that yet as they haven't been in common use that long yet. But, if cost is no issue, just run AGMs to 20% and replace a bit more often as it will still probably cost less.



Bottom line, I think, is not if you need AGM or lithium, it is that you need to figure out how often you will need to charge based on your use patterns and how often you drive. How the energy is going to replaced easily and conveniently is often harder to determine than how much you need to store.
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Old 08-24-2020, 12:26 PM   #43
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For Glenn & Others,

Please be patient, I am slowly working my way around to the front of horse in the dark.

I know my Solar needs some fine tuning.

I know it's ridiculously hot.

I know the fridge is performing flawlessly but it is using 50ahs per day

I just realized that I may have my Battery Meter set up incorrectly.

I have 2x100ah Batteries but I have the bank set for 200 when in Truth, its only 100ah.

Should I change this?


As it is, I may not have truly reduced the amp hour debt from Saturday so at 2.15am when I got back I had to run the generator until 3.50am to get it at 100% for sure.

I did run the Generator for 25 minutes today but I was gone all afternoon & evening & the loss is real.

Very frustrating for a moment.

As to Lithium, I won't get involved with them but in working out will 200ahs run a dc fridge, yes.

But that's $1000 for the fridge

A $1000 for the battery.

Plus other electrical upgrades.

Especially if your needs are only that of some weekends camping.
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Full Timer in a 2005 Roadtrek Versatile 190/Super Modified & Lifted, Two 220ah Lifeline 6 Volt AGMs in Series, 250 watts Solar, Victron BMV712 Meter & Victron MTTP 100V/30A Solar Controller, Magnum MMS1012 Inverter Charger, Onan 2.8 Generator, Novakool R3800 Fridge & more ...
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Old 08-24-2020, 12:42 PM   #44
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For Glenn & Others,

Please be patient, I am slowly working my way around to the front of horse in the dark.

I know my Solar needs some fine tuning.

I know it's ridiculously hot.

I know the fridge is performing flawlessly but it is using 50ahs per day

I just realized that I may have my Battery Meter set up incorrectly.

I have 2x100ah Batteries but I have the bank set for 200 when in Truth, its only 100ah.

Should I change this?


As it is, I may not have truly reduced the amp hour debt from Saturday so at 2.15am when I got back I had to run the generator until 3.50am to get it at 100% for sure.

I did run the Generator for 25 minutes today but I was gone all afternoon & evening & the loss is real.

Very frustrating for a moment.

As to Lithium, I won't get involved with them but in working out will 200ahs run a dc fridge, yes.

But that's $1000 for the fridge

A $1000 for the battery.

Plus other electrical upgrades.

Especially if your needs are only that of some weekends camping.

We keep getting back to the 50% rule in AGM batteries, which IMO is really exaggerated, but if you are willing to haul around 60% more batteries to get the same capacity as taking a smaller bank to 20% SOC, that is your choice. It will save you about 15% in actual battery replacement costs over the years is all.


If you are going to hold fast on using 50% SOC as the lowest you want to use, you can set the meter to 100ah bank size, just like if you take them to 20% you could set the bank size at 140ah so it read zero SOC when you hit the limit. Most of us tend not do to those things are we prefer to see the actual SOC of the bank, not the % usable we have left, so personal choice. It will only affect the % reading, and nothing else, if the monitor is programmed to synchronize off voltage an amps.



IMO, even at 50ah per day of use for the frig, with 200ah of AGMs and the amount of solar the DR has, in sunny California, plus lots of driving, there is no reason that there should be any shortage of battery capacity unless there is a bunch of power going somewhere else or he sits in the shade a lot.


Can the frig do better than 50ah per day? Maybe, as that is running 100% of the time at 2.1 amps that has been measured. Turning up the compressor speed might help a bit to put it in a better efficiency spot for the conditions, and improved venting might improve it a bit for efficiency. At 100* or 3.1cf Isotherm was at about 40ah per day, so the DR is not that far off if he was at the same 38* internal temp that we run.
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