Battery Capacity t

[Elev3100]

Hi everyone, new owner. We will be boondocking for a while. My plan is batteries and generator first and add PV later. What is a recommended battery capacity for an extended weekend? I realize this question has a lot to do with how much is consumed so let's say propane fridge, propane heat and range, mostly D.C. Lights and 12v tv. Where are your batterie stored? Also, if anyone has the wiring diagram for the Mallard M29 I would appreciate you sharing that with me.

Thank you much!

 

[deardorffs]

https://www.batterystuff.com/kb/tools/ac-to-dc-amperage-conversion-run-through-an-inverter.html

https://www.batterystuff.com/kb/tools/calculator-sizing-a-battery-to-a-load.html


I happened upon this website that has several calculators for backing into your battery packs required design capacity.

First figure your ac amperage that your likely to need to draw from the batteries between re-charges.

For example a residential frig when its running draws about 6 amps, which using the first calculator draws 66 amps DC, through the inverter that converts DC to AC.

Typically a res frig is only runs about 8 hours out of 24.

Figure up your total DC amps for all the gear you want to run (including your 12V stuff like lights, etc.).

Use the second calculator and the specs of your battery(s) and it will tell you how long you can draw those DC amps you added up without depleting the battery below its 50% discharge level.

If you draw the batteries down below 50% on a regular basis you drastically reduce the number of charging cycles it will accept before its capacity starts to fade.(flooded & AGM)

For example lets just use only the residential frig drawing 66 amps DC. Plug in the specs for (1) $200 Trojan 1275 12V flooded cell battery (I plug in its 20 hour and 10 hour specs). The calculator says you can run that 66 amp draw for 48 minutes and then you'll hit its 50% discharge level.

Again figure the frig only runs 33% of the time, and you can get a 2.4 hour window of time that (1) battery can support the frig. (Again without drawing it below 50%)

Plug in the specs for the deep cycle batteries typically supplied by manufactures and you'll find a drastically smaller window of time, than the Trojan's or anything of its caliber.

Hope this helped.

 

[Lynn1130]

For example a residential frig when its running draws about 6 amps,

I gather you are using that as an example but for clarification in order to use a residential fridge and boondock he would need to run his generator full time. They will not run off of 12 volt or propane to my knowledge.

You will find a number of threads here, with a search, on battery life and boondocking as well as suggestions about which batteries to use but most of us who boondock ( dry camp) use 2 or more 6 volt batteries and the generator to help refresh batteries and for microwave and other 120 volt items. I have camped as long as two weeks with the two golf cart batteries and the generator even down to 10 degrees where the heater is running hard most of the night but you then have to run the generator 3-4 hours in the morning and evening to bring the batteries back up. I also have LED lights throughout the trailer to keep battery drain down.

Most all of our camping is without hookups and the only time I killed the battery was right after I bought the trailer and it still had the single 12 volt battery. I had not had time to get the 6 volts in before making a hunting trip. I was up at 2 AM jumping the battery with my truck because the furnace was dragging the battery down to nothing.

 

[Jim.Allison]

I recommend anyone start with installing a Bogart Trimetric, or similar device. But with the specs provided by the OP, given two 150 ah batts in parallel for 300 ah total X 50% usable = 150 amp hours. Discharging at an average rate of about 4 ah, they would last 37 hours. Keep in mind that at night your draw should be in the neighborhood of 1 to 2 ah, and during the day, 3 to 4 ah and TV at about 10 ah. You can bulk charge with a generator, but you will run the generator to death trying to achieve a full charge.

 

[Bogie]

We boondock regularly, sometimes for two weeks at a time. While you can calculate your usage and use the battery monitor provided by the manufacturer, you really only can estimate your usage. Also, the battery monitor is iffy at best. I installed a Xantrex Link Lite. It's works much like a gas gauge but for batteries and tells you exactly how many amp hours you have used at any given time. It can also be used to tell how well your generator is doing when re-charging. Installation is relatively easy. Here is a LINK to take a look.

 

[Lynn1130]

That is all good advice but I think you can throw big bucks at this and I have never found that necessary. Two 6 volt batteries, a few hours of charge in the morning and a few in the evening, maily while watching the news and cooking and I go weeks without issues. LED lighting for all your interior lights help greatly. I never expect to get the batteries to full charge with the generator but really do not need it. If I am going to run something that is going to pull a load, turn the generator on, that's what it is for and after 5 years I still have low hours on the genny. I have been using this system, about half the time during cold winter hunts for 10 years or more and have never had an issue nor have I needed a bunch of extra equipment to monitor the electrical system.

 

[SNOKING]

I created this spread sheet quite a few years ago to help understand battery amp hr use. If anyone wants a copy of it send me a PM with an email address. I set this example to 300 amp hours. I also recommend an AMP HOUR METER. Chris

 

[Jim.Allison]

Neat chart, you should put a "Volts" column next to the percent charged for quick reference with a volt meter.

I created this spread sheet quite a few years ago to help understand battery amp hr use. If anyone wants a copy of it send me a PM with an email address. I set this example to 300 amp hours. I also recommend an AMP HOUR METER. Chris

 

[SNOKING]

Neat chart, you should put a "Volts" column next to the percent charged for quick reference with a volt meter.

Volts are very dependent on load. For voltage to be an accurate state of charge, the battery needs to be at rest without charge or draw for 24 hours. That is why we recommend an amp hour meter.

Chris

 

[Silverado23]

Hi everyone, new owner. We will be boondocking for a while. My plan is batteries and generator first and add PV later. What is a recommended battery capacity for an extended weekend? I realize this question has a lot to do with how much is consumed so let's say propane fridge, propane heat and range, mostly D.C. Lights and 12v tv. Where are your batterie stored? Also, if anyone has the wiring diagram for the Mallard M29 I would appreciate you sharing that with me.

Thank you much!

I have a North trail 32 BUDs and installed solar on the roof and all my batteries are mounted on the tongue in a box that fit 3 group 29/31 115 AH batteries.
I can run the fridge and lights off the batteries and propane using less than 500 watt/hours per day. The lights are mostly LED. Adding propane heat and tv will consume more power. The atwood furnace I have uses around 120 watts of 12v power per hour of run time.

I have enough installed solar power to fully charge the batteries and run most of my dc power items simultaneously. I don't have a permanently installed inverter yet but that is in the future. No generator needed unless I need to run air conditioning or the microwave. I even turned off the power converter in June and have yet to turn it back on for any reason.

 

[Alan_B]

Hi everyone, new owner. We will be boondocking for a while. My plan is batteries and generator first and add PV later...

Sorry, what do you mean by PV ?