Another battery question

If you know how full they are then you know how much they have left.

Meanwhile, you can get some detail on which items are using up your AH if you get a Trimetric, but you don't really need that. Your voltmeter is telling you what is generally happening.

You could do with "some" solar. I have left the fridge on propane with us gone for a few days. Battery draw turned out to be 17AH/day which a little solar can easily stay on top of.

If you really let the battery-bank go down during a week without recharging you have problems.

Batteries should be recharged immediately after a weekend trip to full charge. During the trip the batteries should be brought back to at least 85 to 90% every day or two with a generator or other source.

Your batteries have been allowed to sulfate and you might find out the hard way that their capacity is now far below new capacity when you start out this new camping season.

A clamp-on meter can easily read current amps coming out of the battery-bank at any given moment based on the total load on at the time. The reading represents how many amps would be used over a hour's time. Reading is taken at one of the battery cables next to the battery. The POS terminal would show (-) amps reading output correctly. The NEG terminal would read (+) amps reading for output. Incorrect but you already know you are discharging the battery. The amp reading is correct for amount discharging.

Knowing the amps used at any given time for different items gives you an early warning. Much better than just checking voltage to find out your battery is already 50%soc or worse Saturday morning.

By the way; if your battery is already shot you might find the battery-bank you thought was full (12.7 volts) reading 50% (12.06 volts) after only an hour or two due to lost capacity on your next trip.

I use a standard DC VOLTMETER setup for my battery monitor panel that I can watch from the inside of my trailer.


This is not absolute but is close enough without getting into all the inner workings of things...

I use this simple CHART to determine the % of charge for my battery bank when camping off the power grid.



When I read around 12.0VDC I know my battery bank is somewhere around 50% charge state. This is where I either quit using the batteries or start re-charging using my smart mode on-board converter/charger unit direct connected to my 2KW Honda generator using a RV30A to 15A Adapter.

I plan out what is being used when camping off the power grid so that my batteries make it through the one day/night run off the batteries and end up with around the 12.0VDC reading at 8Am the next morning.

Here on the east side of the USA this usually fits in with most of the campgrounds that have generator run time restrictions in place and I can re-charge my batteries back up to their 90% charge state in as quick as three hours so we can do all of this all over again for the next day/night run off the batteries.

Works pretty successful for us when camping off the power grid...

Roy Ken

uintafly wrote:
Over the course of the next few months I really want to figure out how much juice I have in my batteries and what draws them down. We do a fair amount of boondocking so I would like to know timelines of how long I can go without briging a gen. I have a multimeter and can measure how full my batteries are, but how do I measure what is drawing what, and how many amp hours I have left? A couple times last year we would park our trailer and use it in consecutive weekends, but the parasitic draws would really run the batteries down over the course of the week, to the point I didn't really trust it to leave any perishables in the fridge for fear it would kick off. Any advice woud be greatly appreciated.
Thanks,
Chris

How much battery capacity do you have in the TT?

As others have said, if you are going to boondock you need to get solar going.

I can run happily off of batteries/solar for everything except AC and the microwave.

Can't believe you solar guys ! Like solar is the answer to everyone's problem.
Seems ya all forget that solar needs sun ! Buy a small quiet generator first, then you don't have to worry what each little thing in your rig is using.
Go camping, then you will find out how much your daily AH requirements are.

Here's a poor many battery monitor,.......
If you have the sat tv playing, and a couple lites on, and the water pump comes on, and you don't notice any noticeable lite dimming, or the sat tv skippin a beat, you are well over 50% yet, and good till morning.
I couldn't care less what each dc item is drawing, I just care how often I need to recharge !
And I dint just start dry campin yesterday.
But yep, I got ammeters and voltmeters all over the place, but I know how often I need to recharge, and that doesn't change by much.
And yep, my solar works fine, when the sun is shining, but that hasn't happened in a week now.

Thanks for all of the replies. I like the idea of having a DC voltmeter in the trailer that I can monitor. How difficult are those to install?

I currently have 2 group 24 batteries. Not a ton of AH I know, but I want to make due with them for at least a season since they are new with the trailer this year. As for solar, for the most part we are forest folk and try to get the shadiest place we can find, which would negate a lot of the solar benefit for us. We do usually take a trip or two to the desert but have no problems with a generator iin these areas.

Thanks again,
Chris

I was curious just like you. My volt meter also has the ability to test amperage. so DW would turn on each 12 volt switch and then off again while I read the meter display. I wrote down each amp user and I now know how long I can camp to keep the batteries at or above 50%. I use the voltage indicator on the meter to determine draw down on the battery. In conserve mode, we use about 24AH per day.

Hi,

I went for 14 years with only solar, as far as camping goes. I mostly boondock. I did have a genny--but it was to run the block heater in winter time. I left it behind when camping. It failed and the replacement was no good. (mea culpa)

Then I switched to full time and I thought a genny was needed. Turns out I would have been better to do more solar. The new genny has run less than fifty hours in 10 months. Over 1/4 the run time is exercising it. (I.E. running it for no good reason).

Since I started full timing in Oct, I've not run the generator *once* except to exercise it.

RJsfishin wrote:
Can't believe you solar guys ! Like solar is the answer to everyone's problem.
Seems ya all forget that solar needs sun ! Buy a small quiet generator first, then you don't have to worry what each little thing in your rig is using.
Go camping, then you will find out how much your daily AH requirements are.

Here's a poor many battery monitor,.......
If you have the sat tv playing, and a couple lites on, and the water pump comes on, and you don't notice any noticeable lite dimming, or the sat tv skippin a beat, you are well over 50% yet, and good till morning.
I couldn't care less what each dc item is drawing, I just care how often I need to recharge !
And I dint just start dry campin yesterday.
But yep, I got ammeters and voltmeters all over the place, but I know how often I need to recharge, and that doesn't change by much.
And yep, my solar works fine, when the sun is shining, but that hasn't happened in a week now.

I do like Roy. I picked up a DC and a AC volt meter on Ebay for about $6 each including shipping. I installed them on a counter end just inside the entry door with a on/off switch for each. The blue lit meter draws next to nothing and makes for a nice night light. I leave mine on all the time except when not camping.

I have the chart Roy shows, laminated and taped inside a cabinet door and another one near the batteries. Recharge at 12.0, my 3 stage Power Dynamics 9260 does a great job of caring for the batteries.