Inverter/Battery Question

[drhuggybear]

We have a Wildwood 29QBDS. We don't typically do boondocking so I haven't really ever looked into running things when I don't have access to shore power.

My daughters are now getting to the age where their events last most of a Saturday or Sunday. I have a few questions for the experts on here:

1) If all I was going to run was some lights, a fan or two, how much power (size of an inverter, number of batteries, size of batteries) would I need?

2) If I added the use of a microwave how much would that change question 1?

3) I am fairly handy. Given some decent instructions I typically can do things myself. Is this something that I could install myself or do I need to bite the bullet and have the dealership install this?

Thanks

[CavemanCharlie]

SoundGuy wrote:

CavemanCharlie wrote:
Your circuit board in the fridge is going to draw a small amount of 12 volt power even when it is running on propane. Nothing you can do about that.

Well that's not entirely true ... yes, a 2-way gas absorption DSI fridge does need 12 vdc to run it's electronics and operate the gas valve so whatever that draw is there's not much you can do about it - it is what it is. However, many of these fridges also have a climate control circuit to prevent condensation forming around the freezer section in particularly warm, humid conditions. It works well but the Achilles' Heel to this system is that it draws a considerable amount of power ... a non-issue when you're camping on an electric site and the converter is constantly restoring power to the battery but when dry camping it can significantly draw down the battery reserve. Solution - turn it off if you can, if you can't then modify the fridge as I did so you can disable this heating element when dry camping.

Fridge Climate Control Switch Mod (2 pics)

Good call. my older fridge doesn't have that part so I forget about the fact that some do. Glad you caught that and let the OP know about it.

[SoundGuy]

CavemanCharlie wrote:
Your circuit board in the fridge is going to draw a small amount of 12 volt power even when it is running on propane. Nothing you can do about that.

Well that's not entirely true ... yes, a 2-way gas absorption DSI fridge does need 12 vdc to run it's electronics and operate the gas valve so whatever that draw is there's not much you can do about it - it is what it is. However, many of these fridges also have a climate control circuit to prevent condensation forming around the freezer section in particularly warm, humid conditions. It works well but the Achilles' Heel to this system is that it draws a considerable amount of power ... a non-issue when you're camping on an electric site and the converter is constantly restoring power to the battery but when dry camping it can significantly draw down the battery reserve. Solution - turn it off if you can, if you can't then modify the fridge as I did so you can disable this heating element when dry camping.

Fridge Climate Control Switch Mod (2 pics)

[Gdetrailer]

christopherglenn wrote:
A small inverter to charge phones and tablets + watch tv and a Costco inverter generator will do what you need to do for less then the cost of a 2kw PSW inverter and 200+AH of batteries (and all the 0 to 2/0 interconnects.

Daughters rock, but all the hair appliances (driers, curlers, straighteners) are going to require a lot of batteries. If you aren't there yet, wait for it. I have 255 AH of batteries, and a 3KW PSW inverter. I get a few minutes out of the microwave, I can reheat - not cook off the batteries. The low voltage alarm on the inverter is beeping long before the hair is dry.

Costco 2800 watt inverter generator.

This one is $700, and already has a 30 amp rv plug. If you are a 50 amp trailer the dogbone to plug into this is cheap.

For comparison a Honda EU3000iS operates at 49 to 58 dBA @ 9 feet, the Costco is 58 Dba @ 23 ft. The Costco is louder then the Honda, but for less then half the cost.

As I mentioned in my post above, tablets AND cellphones you USE a 12V TO USB charger..

Like this..



Which has TWO 2.4A 5V USB charging ports for $7 HERE

It is absolutely silly stupid to install or use a inverter to charge a cellphone or tablet.. Doing so introduces a huge amount of conversion LOSSES into the mix..

12V to 120V (inverter) then 120V to 5V (120V charger)????

In other words, you take 12V and convert it to 120V the inverter will only be 80%-90% efficient using 10%-20% more battery than if you used a direct cig plug charger..

Then you use a 120V to 5V USB charger introducing some losses there..

Buying a 12V cig charger for devices like tablets and cellphones means you do not need to leave the inverter on, saving a lot of battery capacity..

Boondocking is about CONSERVATION of energy.. Needlessly using an inverter for items that 12V direct chargers can be used is not conserving energy.

[christopherglen]

A small inverter to charge phones and tablets + watch tv and a Costco inverter generator will do what you need to do for less then the cost of a 2kw PSW inverter and 200+AH of batteries (and all the 0 to 2/0 interconnects.

Daughters rock, but all the hair appliances (driers, curlers, straighteners) are going to require a lot of batteries. If you aren't there yet, wait for it. I have 255 AH of batteries, and a 3KW PSW inverter. I get a few minutes out of the microwave, I can reheat - not cook off the batteries. The low voltage alarm on the inverter is beeping long before the hair is dry.

Costco 2800 watt inverter generator.

This one is $700, and already has a 30 amp rv plug. If you are a 50 amp trailer the dogbone to plug into this is cheap.

For comparison a Honda EU3000iS operates at 49 to 58 dBA @ 9 feet, the Costco is 58 Dba @ 23 ft. The Costco is louder then the Honda, but for less then half the cost.

[CavemanCharlie]

As others have said convert your lights over to LED bulbs and buy a 12 volt fan. Hopefully you have 12 volt jacks already installed in your TT.

Your circuit board in the fridge is going to draw a small amount of 12 volt power even when it is running on propane. Nothing you can do about that.

If you have a built in radio the memory circuit in that will draw a little currant at all times too. Some people add a second cut off switch to the memory wire to the radio to eliminate this .

If you have built in smoke/ carbon monoxide/ propane detectors they draw currant too.

I have 2-12 volt deep cycle golf cart batteries. I run the Television maybe a hour or so day on a small 300 watt power inverter. By eliminating my parasitic loads like the ones above I can go camping for 3 days no problem.

Give up on the microwave idea. It is going to draw so much currant it would be difficult to build a buttery bank big enough to make it work. It can be done but, not easily

[Gdetrailer]

drhuggybear wrote:
We have a Wildwood 29QBDS. We don't typically do boondocking so I haven't really ever looked into running things when I don't have access to shore power.

My daughters are now getting to the age where their events last most of a Saturday or Sunday. I have a few questions for the experts on here:

1) If all I was going to run was some lights, a fan or two, how much power (size of an inverter, number of batteries, size of batteries) would I need?

2) If I added the use of a microwave how much would that change question 1?

3) I am fairly handy. Given some decent instructions I typically can do things myself. Is this something that I could install myself or do I need to bite the bullet and have the dealership install this?

Thanks

#1 Change 12V incadescent lights to 12V LED lights, that makes the lighting pretty much a non issue.. Fans, well they do make 12V fans..

12V Lights and fans eliminates the need for a 12V to 120V inverter, thus saving a lot on battery capacity. Typically you could get away with a size group 27 (about 60-80 Ahr) or a pair of group 27 batteries (about 120-160 Ahr)

#2 General consensus around here is it IS better to run high wattage/high 120V demand items DIRECTLY FROM A GENERATOR.

Some folks have managed to run a microwave from inverter and batteries BUT it typically takes two PAIRS of 6V GC batteries (400 Ahr or more of battery capacity) to get enough capacity for 5-10 minutes or so of microwave.

Then you NEED a generator to recharge the battery bank as soon as possible to avoid reducing the battery capacity.

#3 12V LEDs are typically a DIY project and 12V fans should also be no problem.. If you use a generator to run your microwave there is nothing needed to be installed by a dealer..

If you want 120V for a SMALL LED/LCD TV/DVD then you could possibly get away with a small plug in inverter (cig plug), provided it doesn't draw more than about 80W (limit of cig plug)..

Cell phone, tablet and even laptop PCs all can be charged directly from 12V if you purchase 12V chargers..

Most Cellphones now days use a 5V USB port charger so you can buy a $5 12V to USB charger..

Many tablets also can use USB port for charging, the caveat there is they often will charge very slowly if your 12V to USB adapter can only supply 5V at 1A..

Tablets recharge much faster with 5V at 2.1A chargers.. A bit more expensive but much better than running an inverter to charge these devices..

For Laptop PCs you can buy a generic 12V to laptop power supply which you can run or charge your laptop directly from 12V.

[SoundGuy]

drhuggybear wrote:
My daughters are now getting to the age where their events last most of a Saturday or Sunday.

Sorry, but curiosity has the best of me so I have to ask - what has this got to do with running on battery power? :h

1) If all I was going to run was some lights, a fan or two, how much power (size of an inverter, number of batteries, size of batteries) would I need?

Conservation is the key so if you've not already done so you want to swap out all your incandescent bulbs with equivalent LED versions that will draw significantly less power out of your battery. I've got an Endless Breeze 12 vdc fan mentioned and although it doesn't draw an excessive amount of power, ~ 2 amps or so on low fan speed, it is pretty noisy so I usually instead power a much quieter 120 vac fan with a true sine wave inverter even though the total power draw can easily be double that of the Endless Breeze. With conservative use a single G27 12 volt battery can suffice for many for a couple of days of dry camping but a dual set of G31 12 volt batteries or dual set of 6 volt GC-2 batteries would considerably improve your battery reserve.

2) If I added the use of a microwave how much would that change question 1?

Some do it but since the power requirements are so great I don't see the point - either forget the microwave oven when dry camping or use a genset if you just can't live without it.

[rbpru]

I have a small 12 volt inverter that will handle 300 watts and plugs into a 12 volt port. It is not nearly big enough to handle a microwave or toaster or coffeemaker or hair dryer type appliances; it does well when we need to power 120 volt lamps, charge a computer, or watch a small TV.

My 300 watt inverter is at best 80% efficient at full load, so it is drawing close to 360 watts from the battery. That means it is drawing about 30 amps.

A pair of car head lights draws about 120 watts. So in rough figures, how long would your battery last if you had to power three automobile with their headlight on and their motors off? And, that is only asking for 300 watts.

The bottom line is it can be done but you have to understand your energy needs. They can accumulate quite rapidly.

There is a reason most folks just opt for a generator.

[beemerphile1]

1. Lights are 12 volt and already operate off the battery
2. Buy a 12 volt fan like the Endless Breeze which operates off the battery
3. Microwave will require an inverter of probably 2,000 watts and a couple batteries.

How important is this? A quality inverter, cables, and two batteries are going to cost you about $500 or more. Maybe you could use your LPG stove instead of a microwave.

[2oldman]

drhuggybear wrote:
1) If all I was going to run was some lights, a fan or two, how much power (size of an inverter, number of batteries, size of batteries) would I need?
2) If I added the use of a microwave how much would that change question 1?
3) Is this something that I could install myself

1) no inverter. those are 12v items. 2 batteries
2) a lot
3) maybe ...

You should read this before attempting any electrical work:
12v side of life.

and this...
Battery FAQ

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