Simple solution to run a 1500W microwave for 15 minutes.

[JKFlipFlop]

I want to supplement my lead acid deepcycle bank in my RV with a lifep04 pack for high current applications.

All I want is a simple, easy to charge battery pack that is capable of running a 1500W microwave for a maximum of 15 minutes

What would you guys recommend for a simple, no nonsense setup. I would like to be able to recharge the battery pack directly from my 12v lead acid bank.

[solar pete]

Howdy JKFlipFlop,

Hhmm, well I don't think there will be a easy way to do this with batteries and solar, 1500watts is a big load for RV use, I think the more experienced campaigners around the place will suggest you get a generator and run it off that. Someone might be along who can offer more help

[bberry]

Simplest? Buy a sailboat Lifopo4 system

Practical? A large enough 12v house system to run the microwave, or run the genset, or get an "RV microwave" with variable power output.

What you want to do is not economic.

[JKFlipFlop]

How big of battery would I need? I really don't want to buy an entire commercial battery system.
It looks like smaller microwaves only use 700 watts

Yes I could also add 3 more deep cycle batteries so I can safely draw larger currents without damaging my batteries, but I also add
170 pounds of battery that gets hauled around for the next 10 years.

[Sunking]

Yes I could also add 3 more deep cycle batteries so I can safely draw larger currents without damaging my batteries, but I also add
170 pounds of battery that gets hauled around for the next 10 years.

Your batteries are not going to last 10 years. Maybe two or three.

You don't have to spend the bucks on LFP batteries. You just have to know which of the lead acid batteries can handle the large load currents. They are not true deep cycle batteries. They are hybrids and not all hybrids are created equal.

What you really want is an AGM battery capable of the large currents. AGM batteries have very low internal resistance like LFP. AGM also work very well in mobile applications, no electrolyte to spill or water to add. . Some of the best out there are Concorde Life Line Deep Cycle for RV's, and Odyssey. They are not cheap, but cheaper than LFP and a new controller.

However I will tell you a secret. Don't tell anyone. You can use the batteries you have right now. All you gotta do is buy a Electronic Battery Isolator for $50 yo $70 so your RV alternator can charge your batteries and supply the power to heavy loads when needed. That is what the pros do. . If you drive daily you can toss those solar panels in the garbage where they belong. Driving one hour will generate more power than your panels can generate over a few days. Cool huh?

So here is the secret. Get an Isolator, and idle the engine when the microwave is running using the batteries you already have. Or go spend $800 on a set of new AGM batteries or $2000 on LFP plus controller cost. Take your pick.

[JKFlipFlop]

What you really want is an AGM battery capable of the large currents. AGM batteries have very low internal resistance like LFP. AGM also work very well in mobile applications, no electrolyte to spill or water to add. . Some of the best out there are Concorde Life Line Deep Cycle for RV's, and Odyssey. They are not cheap, but cheaper than LFP and a new controller.

http://www.lifelinebatteries.com/rvflyer.php?id=30

These life line batteries have a cold cranking amp spec. I thought the rule was if it has CCA spec then it isn't a true deep cycle battery

Also, I like the isolator idea, but I do have concerns with the .7V drop you get from them causing your batteries to not charge fully

[reed cundiff]

There are a number of RV'ers that use 1500 W microwaves off their battery suite. Most do it with lead acid but others have moved to LFP. One of the posters at the Open Range Owner Forum has eight lead acid batteries in the front bay (rated to hold 400#) and is quite happy with the result.

We have a Dometic energy hog micro-wave that takes around 1500 W. We have sufficient LFP (8.6 kW-hr at 48 V nominal) to heat water for tea and coffee even when "camped" in rain forest such as Olympic Peninsula for 5 days. Have to change energy management and turn off the inverter when not in use, not run fridge or hot water on AC etc under these conditions. Our primary interests in LFP are much lighter weight (critical in a light-weight 5th wheel) and far faster charging rate. Among the first users of LFP were the couple that have the blog "Technomadia" and they made some major mistakes which they candidly discuss in their blog: having the battery suite overheat due to being in a tight compartment with the inverter, not careful with high voltage in individual cells, etc. The one I found most telling was being hooked into line power and keeping the battery suite at 100% SOC for months, which resulted in degradation. I did not know about this but we have only been hooked into line power once in two years. There is as much to be learned from the pioneers who made major mistakes as there is from those who have done things correctly.
reed and Elaine

[SunEagle]

There are a number of RV'ers that use 1500 W microwaves off their battery suite. Most do it with lead acid but others have moved to LFP. One of the posters at the Open Range Owner Forum has eight lead acid batteries in the front bay (rated to hold 400#) and is quite happy with the result.

We have a Dometic energy hog micro-wave that takes around 1500 W. We have sufficient LFP (8.6 kW-hr at 48 V nominal) to heat water for tea and coffee even when "camped" in rain forest such as Olympic Peninsula for 5 days. Have to change energy management and turn off the inverter when not in use, not run fridge or hot water on AC etc under these conditions. Our primary interests in LFP are much lighter weight (critical in a light-weight 5th wheel) and far faster charging rate. Among the first users of LFP were the couple that have the blog "Technomadia" and they made some major mistakes which they candidly discuss in their blog: having the battery suite overheat due to being in a tight compartment with the inverter, not careful with high voltage in individual cells, etc. The one I found most telling was being hooked into line power and keeping the battery suite at 100% SOC for months, which resulted in degradation. I did not know about this but we have only been hooked into line power once in two years. There is as much to be learned from the pioneers who made major mistakes as there is from those who have done things correctly.
reed and Elaine

I understand that running a microwave from batteries is being done with success but why would the OP enlarge his battery system to run that microwave for just 15 minutes a day.

Why not get a small 2kw honda gen set. It is not like you going to use a lot of fuel in a day and now you have a portable power supply that can be used for any remote areas.

[reed cundiff]

I would guess that the OP does not want to deal with the noise of a generator. Not using a generator at dispersed camping spots means a lot more wildlife coming by/ignoring our presenceBull moose.jpg completely: Elk, Moose, Deer, Coyotes, birds of varying kinds. Had two young Bull Moose fighting/sparring for 45 minutes within 25 m of our dispersed site in Wyoming.
Reed and Elaine

[SunEagle]

I would guess that the OP does not want to deal with the noise of a generator. Not using a generator at dispersed camping spots means a lot more wildlife coming by/ignoring our presence[ATTACH]7037[/ATTACH] completely: Elk, Moose, Deer, Coyotes, birds of varying kinds. Had two young Bull Moose fighting/sparring for 45 minutes within 25 m of our dispersed site in Wyoming.
Reed and Elaine

Sounds wonderful to have nature come up to your door.

I would give up my micro knowing I could see that wildlife. But then I have different priorities then some people.

[reed cundiff]

With sufficient solar/battery suite it is possible to run microwave as desired (provided it is not snowing and one has 6" or more snow on roof). Son Charlie took the photo of the Moose from the door of the fifth wheel (attachment 7037 on above response). The Moose were there around 6:30 am and everyone else was awake but I. The rest were so enthralled that I was not awakened until the end. Charlie tried to video-tape the sparring but the young bulls were beat and were just leaning into each other's antlers as if to say "OK, I'll take it easy if you shall as well!" Been there in high school and college wrestling and Tae Kwon Do training (been a while since then - quite a while)
Reed and Elaine

[jkirkebo]

I want to supplement my lead acid deepcycle bank in my RV with a lifep04 pack for high current applications.

All I want is a simple, easy to charge battery pack that is capable of running a 1500W microwave for a maximum of 15 minutes

What would you guys recommend for a simple, no nonsense setup. I would like to be able to recharge the battery pack directly from my 12v lead acid bank.

I'd use 2 modules from a Leaf battery pack. These are perfect for this application. The weight only 16 pounds for the two modules, which in series will be 15.2V nominal and 66Ah capacity. That is nearly 1kWh of energy, 1500W is only 1.5C which these will do just fine (they do 3.75C in the car).

Get a 1500W or larger 12V sinus inverter that can handle up to 16.4V input and has remote on/off (like an Outback FX). Get a BMS (like the Orion Jr.) to monitor the pack and turn off the inverter if any cells fall below a certain voltage (I'd recommend no less than 3V). The BMS will also give you SOC status via CAN-bus and they sell a separate SOC display for it.

Charging is best done with a balance charger that charges each cell independently, like the BC168. You can get a power supply for it that runs of 12V. I'd recommend charging only to about 4.05V which is 80% SOC or so, for good battery life (should easily last 10-15 years).

Leaf modules can usually be had here: http://www.hybridautocenter.com/HAC4...cks&Itemid=605

If more power is needed, one can use for example 7 modules in series and a 48V inverter. That will however need a different charging setup, probably easiest to charge the whole bank as one then.

I am going to build a portable battery pack from Leaf modules soon. 4 modules in series and a Victron Orion DC-DC that takes 18-35V input to convert to 12V which in turn will run my Waeco portable fridge. Much better than lugging around a heavy 200Ah FLA battery and 30% more usable energy too.