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Discussion Starter #1
My wife wants a 1100 watt microwave/convection oven in our van. We will also have a coffee maker. Already have purchased a 12v TF130 (Truckfridge) fridge. I guess she MIGHT want to use a hair dryer though she says this isn't a must have. Will want to power some laptops, phones, led lights. I think any cooktop or heater will be propane powered.

Of course not all that will be running at the same time and some of it fairly briefly. Wondering what is the best calculator to determine batteries (AGM) to power this. Should we just scrap the the micro for a smaller 700 watt non-convection unit?

I was considering 2x6v batteries such as these GPL-6T.

I do know I will need a large enough inverter to handle all this as well.

Thanks in advance for any advice - pretty much a newbie on all this.
 

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Those are some thoroughbred batteries: http://lifelinebatteries.com/wp-content/uploads/2015/12/6-0101-Rev-E-Lifeline-Technical-Manual.pdf (and not in a good way for RV use).

Can you provide 60-80A of temperature-adjusted voltage charge current at them every time they've run down to <60% state of charge? That'd be ~1000 watts of solar panels dedicated just to revive them... Yes they are well designed but have detailed commissioning & maintenance procedures that have to be documented to expect to see any warranty. RTFM, buy a lot of Sam's Club or Costco 6V batteries for that $800.

Okay, fine, back to cooking.

Panasonic has the patent nailed on true "Inverter" microwave magnetron stepped output vs. full output w/ variable on time of EVERYTHING else... The inverter-style power levels 3-9 (out of 10) creep up wattage from about 375 or 400 minimum to the units maximum draw. Yeah, they're only a little more efficient than a bang-bang $40 walmart unit but remember the harder you hit batteries the smaller total output can or will be - 80a draw for a 1000w microwave out of a 100ah battery means 32 minutes run time, 40a means 80 minutes run time (Peukerts' Law). Might not mean much until multi-day usage, along with all the other draws, without engine running, solar or grid battery refresh. Your happiness is my only concern, YMMV.
 

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Discussion Starter #4
Those are some thoroughbred batteries: http://lifelinebatteries.com/wp-content/uploads/2015/12/6-0101-Rev-E-Lifeline-Technical-Manual.pdf (and not in a good way for RV use).

Can you provide 60-80A of temperature-adjusted voltage charge current at them every time they've run down to <60% state of charge? That'd be ~1000 watts of solar panels dedicated just to revive them... Yes they are well designed but have detailed commissioning & maintenance procedures that have to be documented to expect to see any warranty. RTFM, buy a lot of Sam's Club or Costco 6V batteries for that $800.
Please bear with me - just starting to learn about this. So these Lifetimes require higher amps of current to re-charge than run of the mill 6v AGM batteries? Or are you talking about regular 6v golf cart batteries? I doubt I'll have more than 300-400 watts of solar panels so need to find best battery fit for that.

I did check out the Panasonic inverter microwaves - they definitely seem like a better fit.
 

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300 watts of solar for 2-6volt golf cart AGM’s would be the right fit. They are very good batteries for about $350 for two. Don’t overthink this.
 

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Good point about any battery needing a large amperage charge anyway, for example with AGM & Gel it keeps the chemistry balanced by forcing surges of electrolyte convection through the mats to keep all of the liquid 'active', trickle or small charging does not accomplish this and prematurely limits capacity.

Study up on constant current // constant voltage charging schemes. And temperature corrected charging.

To rephrase my comment - the 300 amp hour capacity of the dreamy batteries you linked are still lead-acid (LA), those are great if you have mission critical needs and someone else to pay for them AND the bulk of systems required to support & replace them as needed. It is a better time/motion/cost economics to use cheap(er) golf cart 6V cells and hammer them, learn the when, how and whys and go enjoy your camper in the process!

Generally with LA - including flooded lead-acid (FLA), sealed lead-acid (SLA) and glass-mat (AGM):
● Best practices is only 'use' the top 30, 40 or 50% capacity; deeper discharge seriously reduces user charge/discharge cycles (length of service).
● That top 10% charge is difficult // time consuming // expensive to achieve, off-grid folks scrabble trying to get (economically) at or above 90, 95% charge daily using a mix of solar, small generator run time... over time this often goes to trying to achieve that above 95% weekly, bi-weekly etc.

With solar getting so cheap those 300Ah cells might make a good choice to power an off-grid cabin where all the variables can be permanently accounted for, for a mobile RV install not so much unless it's going to be tethered to a AC power source every third or fifth day.

Being conservative with draw down leaves 20, 30, 40% capacity available usually so 60, 90, 120AH.

If I had $1000 to invest in batteries... it would be for 60, 90, 120AH of LiFePo where 90% of capacity is usable.
 

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Discussion Starter #7
So then maybe the Duracell EGC2 batteries from Sam's Club. Fla batteries. 230A @ 20 hours. Don't know the physical size - or is that in the GC2 code? Anyway I don't know recommended charge current but I'm assuming no prob with 2-300 watts solar. Cheap anyway. I know I will need to vent and maintain.
 

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....cut.... I know I will need to vent and maintain.

That's probably why more people are going to AGMs, or even lithium for those with deeper pockets. I like that AGMs or lithium can be mounted inside without need to vent or have access for routine maintenance.
 

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Discussion Starter #9
That's probably why more people are going to AGMs, or even lithium for those with deeper pockets. I like that AGMs or lithium can be mounted inside without need to vent or have access for routine maintenance.
Well I'd rather go AGM for less maintenance - cost isn't that big an issue - but having a hard time figuring which will be a better fit with 300w of solar than the Lifelines that require huge current to charge. Are all AGM as sensitive?
 

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No. Your 300 watts with a good MPPT controller or the alternator will do well. Golf cart batteries are a specific size and GC2 is it. I have the FLAs and serviced them after 2 years adding distilled water, the vent cost $15 and took maybe 1/2 hour! No biggie, I’d do it again.
 

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hi,
Trojan Battery makes a 220 amp-hr 6 volt golf cart battery as both a flooded lead acid (FLA) and an AGM -- models are T105 for FLA and T105-AGM for the AGM. You could use two of them in series to make a 220 amp-hr 12 volt battery.

These are high quality batteries -- kind of the Cadillac of golf cart batteries.

The user manual for these batteries is: http://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdf
For the AGM then reccommend charging at 10 to 13% of the C20 capacity -- that would be about 22 amps, so not so very much. 300 watts of solar would give you about 20+ amps in full sun.

Trojan does not say its the end of the world if your charge rate is lower than 10% of C20.
If you want AGM batteries and are worried about charging them at less than 10% of C20, I'd call Trojan and ask them about what happens if you can't always achieve the 10% of C20 charge rate -- they have a very good technical support department and they answer the phone.

I like the FLA batteries myself -- they are half the price and they will last through more discharge cycles than AGMs. Its an easy hour job to add a vent to an FLA battery compartment. Maintenance is very minimal -- just check the water level a couple times a year and add if needed (mostly it won't be needed). You should really have a good look at your batteries at least twice a year anyway to see how terminals are doing and if any corrosion or other problems are developing whether they are AGM or FLA.

I used the Costco FLA golf cart batteries. I suspect they are not as good as the Trojans, but are less expensive. They are 3 years old now and still doing fine and are charged with 300 watts of solar and the van alternator.

Gary
 

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Discussion Starter #12
Guys, thanks for taking the time to answer - I know these ignorant newb questions get old.:eek: I do follow all the topics and threads but have to brush up on the basics before I fully understand some things. This is a great forum with very helpful members.
 

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See if you can find a battery recycler. I bought some "recycled" AGM 110Ah batteries here in Denver for $250 for all 3. They also have 150Ah available, but those were out of stock when I was buying. While 300Ah is nice, I'm going to upgrade to those 150Ah as 450Ah is better :)
 

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Class B manufacturers not that long ago offered AGMs as options to flooded, but today it seems to me most offer AGMs as standard, with lithium as options. In many cases when they include solar it's in the 100- to 200-watt range. Obviously that doesn't mean it'll work best, but on the other hand if highly flawed we would be hearing a lot more from irate buyers who paid close to $100k for a factory build.

In my opinion pretty much anything can work. Mostly it depends on budget and our personal tolerance to inconvenience.
 

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I frequent the Class B forum and the Sprinter forum as often as I come here. My personal observation is that people who buy the mainstream manufactured units tend to be less adventuresome and are more likely to plug into shore power. Units aimed at the more adventurous tend to be DIY or manufactured in small shops.
 

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I frequent the Class B forum and the Sprinter forum as often as I come here. My personal observation is that people who buy the mainstream manufactured units tend to be less adventuresome and are more likely to plug into shore power. Units aimed at the more adventurous tend to be DIY or manufactured in small shops.

Are you suggesting DIY need more battery and or solar capacity because they don't plug in as much, or that there is more room for errors by simply being DIY?
 

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Not to put words in MsNomers mouth but I think she is saying DIY’s are "more adventurous" .
 

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Yes. We are more likely to need the capacity because we are more likely to venture where extension cords are useless. High dollar rigs are usually parked in high-dollar spots.
 

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Makes sense. High-cost rigs usually also have a generator (like Onan) or 2nd alternator, so it offsets some of the need for large battery banks. My observation is that DIY builds rely more on solar, or conventional alternator charging, than rigs from large manufacturers. And without a generator, it may take a much larger inverter and battery bank to power microwave, A/C, etc...
 
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