Multiple Batteries

[karon]

Originally Posted by BigBee

Hello, All. I want to know how to extend the battery power life for the house electricity on my van. Right now I have 1 battery that charges for house power as the engine runs. Is it possible to extend battery power life on my van by connecting another battery to the one already charging as the engine runs??

If this is not the correct set-up, please correct me or, if there is a better or safer way to do this, please let me know.

Look forward to receiving your feedback!

I have a class B, it had one twelve volt battery, it would cook over and not be reliable, I purchased two six volt batteries and connected them in series this way they both charge equally, I installed them in January 2013, they have a charge of 6.3 volts each, I check the water once a month and make sure they are secured in the battery box.

[Red Eye]

Originally Posted by karon

I have a class B, it had one twelve volt battery, it would cook over and not be reliable, I purchased two six volt batteries and connected them in series this way they both charge equally, I installed them in January 2013, they have a charge of 6.3 volts each, I check the water once a month and make sure they are secured in the battery box.

I agree. For me, I found 2 six volt flooded batteries work better than a 12 volt. Purchase the deep cycle type type.

[Jim86301]

While you could spend a lot of money on a fancy battery monitor to measure your am-hour battery drain, you could simply make some rough calculations on the back of an envelope that would suffice. For example our Norcold compressor-style 12 volt refrigerator draws about 31 amp-hrs/day at a 50% duty-cycle, our 12 volt propane detector runs all the time and draws about 3 amp-hrs/day. Our water-pump, furnace fan and LED lights are all run very little during a 24-hour day and are estimated to draw about 4 amp-hrs/day. That makes for a total of 38 amp-hrs/day. We have two 12 volt Trojan 100 amp-hr batteries hooked in parallel for a total of 200 amp-hrs. Assuming a 50% draw-down we could go for about 2-1/2 days without a recharge. However we have a 100 watt solar panel that puts out about 44 amp-hrs a day assuming 8 hours of sunlight. With 44 amp-hrs coming in and 38 going out we could theoretically camp forever without another charging source. Practical experience bears this out. We have never run the batteries below 60% no matter how long we camp in one spot without running the engine. As they say, your mileage may vary.
Jim

[avanti]

Originally Posted by Jim86301

While you could spend a lot of money on a fancy battery monitor to measure your am-hour battery drain, you could simply make some rough calculations on the back of an envelope that would suffice.

I couldn't disagree more. Sure, if you have plenty of battery and modest consumption, you can stick a finger in the wind and get by. But if your goal is to get maximum value from your system, there is simply no alternative to actually being able to see what is going on. You are groping around in the dark otherwise.

IMO, the real value of a good current monitor is less in monitoring the battery than in gaining visibility into how much power you are actually using as you live your life in camp. How much difference does it make by setting your lights on "dim" rather than "bright"? Assuming you have an adequate inverter, what kind of a hit will you take by making microwave popcorn? How about reheating a meal in the microwave on "reheat"? Does watching a DVD make any real difference compared to streaming? Is it worth unplugging all your power bricks to save vampire loads or can you just forget them?

All of these questions (and dozens more) can in principle be calculated from sufficiently good specs. Are you really going to bother? And, even if you do, are you going to put numbers on everything like Lisa Douglas trying to keep her genset running in Green Acres?

I camped for years without a monitor. When I finally got one, it was like lifting a veil from my eyes.

[hbn7hj]

Nothing replaces a shunt based battery monitor for managing an RV electrical system. Period.

[Jim86301]

To each his own. My idea of camping is to get out in great outdoors to enjoy hiking, photography, fishing, bird-watching and sunsets; not to spend my time fretting over optimizing my power consumption.
Jim

[hbn7hj]

Power consumption is not the issue, battery state of charge is the issue.

[SteveJ]

https://www.classbforum.com/forums/f...tml#post105308

Shunt based monitors. You'll need two. Good info for $30.

[ChicagoTom]

You must have a leak or something. I full timed and had the fridge on 24/7, made coffee via the top burner, ran the hot water heater each morning (Would shut off once it got hot and I was good for the day) and I only had to fill once every 3-4 weeks. In the winter, So Cal mostly, I would have to fill once every 10-14 days due to the furnace running. Ave temp 40-50 at night, then basically off during the day
I have a small portable 50 watt, and it keeps everything charged and running, including 30 watt on low fantastic fan. At night, before bed I would run the engine for 5 minutes, and then 2 old man pee breaks at night for 5 more minutes each time IF THE FURNACE WAS RUNNING, otherwise I was good to go.

[ChicagoTom]

BTW my tank is 10lb, says to fill 80%, I've actually run dry and have never ever had more than 6 gals go in. So I'm not sure why my manual says 10 gal, 80% 8 gal, it's only 6 gallons. You definitely should not be running an electric heater off the battery, and I would not run the fridge, even driving, off the 12V. Numerous studies show it just beats the crap out of the battery, and does very little to keep it cool. I simply just try not to open it while driving, and when I stop I turn it on via propane. If it's really hot, and the drive is long, I flip on the generator while driving for a half hour or so every couple of hours. The fridge will hold a decent temp for about 2-3 hours, unless extreme temps. (Gas from tak generator) All JMHO

[booster]

Originally Posted by Jim86301

To each his own. My idea of camping is to get out in great outdoors to enjoy hiking, photography, fishing, bird-watching and sunsets; not to spend my time fretting over optimizing my power consumption.
Jim

You obviously have enough power to cover your use patterns even if not minimized power use. Of course, your power capacity will go down over time as the batteries age, so theoretically you would need about 20% more capacity when new to cover the rule of thumb end of life of 20% capacity loss. If you have very little invested in battery cost, like some do, battery life extension is not all that important as long as you have enough power to suit your needs. As power use goes up and banks gets bigger and AGM, so do the cost risks, so it changes things. 50-100 amp hour use per day is getting pretty common with compressor frigs taking over a lot and with electronics and device running and charging. At 100ah per day all the stuff needed to support that use is substantially more costly in almost every way.



I agree with all that say a monitor makes it much easier and more seamless to run the van, not more complicated, unless you obsess watching it like some of us have been known to do sometimes.

[gksmith]

Your refrigerator is possibly at fault. I had to replace my Dometica after finally going bad. The new one is basically the same model but with electronic controls. It is MUCH more efficient I have only a five gallon tank but we went on the road for about a month, always using LP for thr fridge plus cooking with it in the evenings and occasional furnace usage. I could not do that with the old fridge, but I never used as much as what you state.