How Long Should Batteries Last Boondocking?

[sgpd1sam]

Two 6V golf cart batteries here. My rig is 13 years old and I’m only on a second set. All of my camping is boondocking and it gets used almost monthly during the cooler time of year in SoCal.
Although the heater is an energy sucker, I seldom use it. Warm clothes and a down comforter and I’m good during the winter.

I also have a Mr Buddy propane heater I use ONLY for taking the chill out of the rig, with proper ventilation of course.

[DesertRatz]

Originally Posted by pasdad1

This is what I would buy.

Attachment 351259

I came close to buying that yesterday. I decided that I'm leery of more things that require phones, apps, logging in, passwords and all that bother and over head. I'm still thinking about it.

[pasdad1]

Originally Posted by DesertRatz

I came close to buying that yesterday. I decided that I'm leery of more things that require phones, apps, logging in, passwords and all that bother and over head. I'm still thinking about it.

But in this case it makes your life easier because you don’t need to run wires from the shunt to the inside of the RV since it communicates wirelessly.

[hans-barak]

Hello. Wondering how RV residential fridge that operates only on electric will do in terms of batteries usage, etc… when dry camping. I will have at least 2 gulf cart deep cycle batteries paired and generators to re-charge but only when allowed to run them. I guess my thing is to find out how long the fridge will run before it kills the batteries, etc… any feedback is appreciated.

[BCam]

Before buying an expensive battery shunt/monitor, check out these two videos from Will Prowse on shunt/monitors. Will is a respected Youtuber on solar, batteries, etc. Although he covers a wide range of applications from RV to whole house solar, the principles are the same. Here's a positive review on the inexpensive version from 2019.

https://www.youtube.com/watch?v=E6O76Okmt08

I have one that I purchased from Amazon and it's doing a good job.

If I wanted something more sophisticated, I'd go with the Victron SmartShunt at about $130. Will Prowse reviewed it in Jan 2021:

https://www.youtube.com/watch?v=_GjcGZsK4fI&t=50s

[paul65k]

SmartShunt...................PERIOD!!!

[Mark_K5LXP]

Knowing your Ah throughput using a monitor is one half of the equation, the other half is knowing what your actual battery capacity is to begin with.

Knowing your battery capacity is as simple as doing a timed capacity test. You apply a known C/20 load to a fully charged battery or set of batteries, and count the hours until it reaches 10.5V. This will tell you the capacity of the batteries without having to guess. From there one can determine if there's a charge, discharge, or battery problem.

Folks are quick to point their finger at the heater as a power hog and relatively speaking it draws it's share, but it's not running full time. I'd be surprised if it was running more than 20-30 minutes every hour. So the actual Ah being drawn can add up but you should be able to easily go overnight on a set of good batteries. 8 hours running an 8 amp furnace blower for 20 minutes an hour is around 22Ah, a modest draw for even a small battery. So if they're giving up before morning they might be bad but it should first be proven that they're getting fully charged and there aren't other loads pulling them down, via the battery monitor. Testing the batteries will answer the question if they're good or bad, and what you can count on them to deliver.

The hooey being tossed here about batteries having 50% "actual" or "usable" capacity and such is crap. When challenged, no one who says this can provide any supporting data to prove it, so going forward just know that batteries have all the Ah and cycle life the manufacturers say they do. There can be a strategy to managing discharge depths and maintaining a given degree of charge margin depending on what you're trying to do, but for casual boondocking the only real management is controlling the stuff you run vs the capacity you have, until the next time you can charge. Once you understand the relationship between your loads and capacity you won't believe how easy it is to keep stuff running. But the biggest part of this is a battery monitor, without one you're flying blind.

Mark B.
Albuquerque, NM

[jl.kauai]

If your rig is an 04 chances are your converter charger is old style and doesn’t have a 3 or 4 stage system. When I had an 03 Lazy Daze I upgraded the system to a newer converter that conditions your batteries. A friend of mine bought batteries like yours at a Napa store and had to change them out very soon as they didn’t hold a charge or put out enough amps. If you charge your batteries overnight and use your heater in the morning the batteries will probably show 12.2 volts pretty soon after usage. You might as well replace them with two 6 volt and run in a series. You should think about changing the converter if you haven’t already done so. It is not that difficult to do. Mine was a Progressive Industries and had good instructions. You have to swap out the fuse panel also. Good luck
Travato John

[Ldubs]

Originally Posted by DesertRatz

My Rig: 30' Minnie Winnie 2004 E-450 V-10

My batteries are lead acid interstate brand 70AH 18 months old.

So, after driving all day until 5pm, and the panel shows FULL CHARGE, or batteries were dead by 4 am. We had a couple 12v overhead lamps on for 3 hours, and we'd had the furnace blower coming on about 3 times per hour for 5 minutes each time between 8pm and 4am. At 4am, i heard the furnace delay clicking trying to come on but no dice.

I got up and the panel showed one LED, and one overhead light would barely glow. I turned the engine on for 15 minutes and the panel indicator jumped to read Full Charge. We ran the furnace for Free minutes and the batteries were dead again.

Feels like I'm not getting much out of my batteries, but we don't have a lot of non docking experience.

Comments?

Couple weeks ago we were at the coast for a couple of nights. Sunny days but chilly nights. The furnace fan was kicking on/off for two nights. It ran our battery down just like you describe.

Just running lights & water pump on battery for a couple nights has not been an issue. Seems the furnace fan pushed us over the edge.

We have a single 88AH group 27 marine/rv battery. Same one that came with the travel trailer.

I can't offer any tech advice. Only that I shared the same experience.

[ArtJoyce]

It's all going to depend.
- how many battries do you have and what are the AH rating and volts.
- inventory of what using electrical power. Lights, fridge, water heater, fans, interverter, Co or propane detector, did you run you generator when you put out you slide.
- 18 months old battries. Could be in great shape, or needing to be replace. Primary depends on how they were maintained and how offen they were discharged below 12v and how long they sat below 12v.

[Marine359]

Originally Posted by paul65k

SmartShunt...................PERIOD!!!

X2
Not having one is like driving drunk.

[Ldubs]

Originally Posted by Mark_K5LXP

The hooey being tossed here about batteries having 50% "actual" or "usable" capacity and such is crap. When challenged, no one who says this can provide any supporting data to prove it, so going forward just know that batteries have all the Ah and cycle life the manufacturers say they do. There can be a strategy to managing discharge depths and maintaining a given degree of charge margin depending on what you're trying to do, but for casual boondocking the only real management is controlling the stuff you run vs the capacity you have, until the next time you can charge. Once you understand the relationship between your loads and capacity you won't believe how easy it is to keep stuff running. But the biggest part of this is a battery monitor, without one you're flying blind.

Mark B.
Albuquerque, NM

Ooops! Answered my own question. Sorry about that.

[Ldubs]

Originally Posted by Marine359

X2
Not having one is like driving drunk.

Maybe more like driving blind. Kind of like if I don't go to the doctor I won't have to worry.

Anyway, I don't have one of these gadgets. Moved it to the top of my list (of which always seems to grow ).

I trust these meters don't consume much batt power! Lol.

[RV Vagabond]

We can't really give you valuable info because we all have different size battery packs and use different amounts of power. You have to test it out yourself and that depends on how low you want your batteries to go.

My best advice is to get lithium batteries and as many as you have room for.