3 days boondocking - Amp hours needed for

[McGeorge]

Will a two 27 dc 12 v with 115 amp hr each give me enough for three days using lights and propane heater as needed, water pump?

Is there a add on meter to monitor useage?

[al2ride]

It's hard to tell. You can try and use math to figure it out, but it would be difficult not knowing what all will be on and for how long. I believe you have a Class C from your avatar. Does your engine charge your house batteries?

[John Hilley]

It depends a lot on the temperature and the type of lights you have. If you don't have LED lights and it is cool, probably not. regular incandescent lights use a lot of power as does the furnace fan. If you monitor the battery with a volt meter it will five you a rough idea of battery state of charge. To accurately measure, the battery has to be at rest for awhile. You can use a Trimetric 2025 to monitor battery state of charge. It measures amps in and out. With a lot of conservation you could make it.

[pasdad1]

Originally Posted by McGeorge

Will a two 27 dc 12 v with 115 amp hr each give me enough for three days using lights and propane heater as needed, water pump? Is there a add on meter to monitor useage?

Do you have an onboard generator for backup in case the batteries don't hold up? Also, to get the best life from your batteries and not damage them, you don't want to draw them down below 50% charge. If you have two 115 ah batteries wired in parallel, then you don't want to use more than 115 ah before recharging. (57 ah taken from each battery)

[vsheetz]

The Trimetric monitor is the definitive way to monitor battery consumption. You can also motor battery voltage to give you an idea of the state of charge in percentage. There are voltage to percent of Charge tables readily found via Google.

[sailsam]

McGeorge - Although I'm new to R/Ving my wife and I spent 4 years mostly "boondocking" in our 39 foot sailboat in the Sea of Cortez. You indicate that the only significant use of electricity will be lights and water pump. The water pump will be minimal unless you take many showers a day. It greatly depends upon how late you stay up and how many lights and what type you have. Until we installed solar panels we needed to conserve electricity and we did it by using head lamp flashlights for reading at night. We still used the regular cabin lighting if we were cooking or washing or playing games at night. I assume that your motorhome has a separate starting battery. I'd suggest that you try it as an experiment. It should be fine, but if you do get low you can always start the engine to recharge - on that trip - and then get a solar panel to recharge the batteries during the days when you won't be running the engine.

[mpierce]

The furnace fan is a big elec user. If the furnace runs much, it will not last 3 days.

[94-Newmar]

McGeorge,

First you need to find out the total wattage you will be using and for how many hours a day. Once you have those numbers you can figure amp hours needed and then make a determination based upon your coach's load.

As mentioned, LED lights are the quickest return on investment (ROI) if you're looking to extend your boondocking time.

Use this load worksheet to figure up your total load, and then figure your amp hours. Each light bulb you use must be counted, water pump, and furnace - all have informational nameplates on them showing the wattage they use, except of course for the lights, but the wattage will be listed on the base of each bulb.

http://lib.store.yahoo.net/lib/wind-...preadsheet.xls

If you don't have MS Office, here is PDF version:
http://lib.store.yahoo.net/lib/wind-...-loadsheet.pdf

[sailsam]

McGerorge
Sorry. I forgot about the furnace fan. We had not heating on the boat and we didn't need it in the Sea of Cortez. And our fans were dry cell powered - until I installed the 420 rated watts of solar panels. And the Trimetric monitor is a very good idea. I have one on the boat.

[vsheetz]

Originally Posted by mpierce

The furnace fan is a big elec user. If the furnace runs much, it will not last 3 days.

Agree, this can be a major impact. A catalytic heater eliminates this draw.

[sailsam]

Originally Posted by vsheetz

Agree, this can be a major impact. A catalytic heater eliminates this draw.

vsheetz - A catalytic heater will eliminate the need to run the furnace. But a catalytic heater does produce both carbon dioxide (CO2) and carbon monoxide (CO) and so needs ventilation. CO2 suffocates by crowding out oxygen in the air you're trying to breath. CO is worse because it is poisonous. I believe that the poisonous mechanism is that it is absorbed into the bloodstream in preference to oxygen. Both are odorless. With CO2 you start breathing faster and MAY recognize that you need fresh air. CO has no symptoms other than you feel a little light headed, then you go to sleep and die. If you're sleeping you will die very peacefully. So IF you use ANY heater that consumes fuel (not electric) it needs adequate venting. Furnaces heat the ventilation air which passes by a heat exchanger and then goes to the outside of the motorhome. The air in the motorhome is forced by the fan to pass the heat exchanger to get hot. The products of combustion do not enter the motorhome. So a furnace is safe to use, even while sleeping, with all windows and doors in the motorhome closed, the less than airtight motorhome provides sufficient ventilation for a few people. A catalytic heater requires much more ventilation and can be deadly.

[McGeorge]

Thanks to all. I do have generator and propane refrig. I will look in charts to see how much the consume per hour. I like the idea of LED lights to save. Any other tips to save battery usage .

How long to run gen to re charge batteries?

Mac

[jackfish]

Originally Posted by sailsam

A catalytic heater requires much more ventilation and can be deadly.

The is a vented catalytic heater called the Vented Platinum Cat.