Battery charging

[urocav2001]

Does anyone know how long it would take to refresh the batteries when plugged into a generator?


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[raspivey]

Too many variables. Battery size, charger output, and depth of discharge being the main ones.

[bikendan]

Originally Posted by raspivey

Too many variables. Battery size, charger output, and depth of discharge being the main ones.

Yep, no way to answer the OP'S question specifically.

But we have two 12v deep cycle batteries.
We can go 3-4 days without recharging the batteries if we keep furnace usage to a minimum.
It takes about 3 hours to recharge them.

NEVER let the batteries go below 50% charge.

[urocav2001]

Ok I will be dry camping for 3 days, using fridge on propane and a few LED lights before bed, that's about it, we just have 1 battery that came with the unit, and the generator is fairly small


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[raspivey]

A single would probably need an hour or so a day depending on your converter output. One of the first things I did was go to a second 12V...and then two 6V when those gave up nearly five years later. Not incredibly expensive and gives you some flexibility.

[Flybob]

Use the generator to power the RV and let the converter charge the batteries rather than use the 12V DC outlet on the generator even if it says something about being a battery charge outlet.

Originally Posted by urocav2001

Ok I will be dry camping for 3 days, using fridge on propane and a few LED lights before bed, that's about it, we just have 1 battery that came with the unit, and the generator is fairly small


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[urocav2001]

Does the fridge use a lot of battery power while running on propane?


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[raspivey]

Very little. Your biggest concerns will be incandescent lighting (LED is much better) and furnace fan.

[bikendan]

Especially the furnace fan.

[HONDAMAN174]

Not really. But get one of these to monitor when you need to charge:



Here is a reference chart:






2014 Evo 2850 "Woodstock"
2011 Toyota Tundra "Clifford"

[HONDAMAN174]

Originally Posted by bikendan

Yep, no way to answer the OP'S question specifically.

But we have two 12v deep cycle batteries.
We can go 3-4 days without recharging the batteries if we keep furnace usage to a minimum.
It takes about 3 hours to recharge them.

NEVER let the batteries go below 50% charge.

Didn't you upgrade your converter? My WFCO would take about 8 hours to recharge from 50%. That's why I upgraded to progressive dynamics.


2014 Evo 2850 "Woodstock"
2011 Toyota Tundra "Clifford"

[Blackhat6mike]

X2 with FlyBob.
Let the gen run the whole TT and not just charge the battery. The converter will do it's job charging and you can use other appliances while the gen runs. Otherwise, you are just wasting gas and electricity as the Gen will probably have a lesser charge rate than your converter.
I would give serious thought to a second battery if you only have one.

[urocav2001]

Ok thanks guys!


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[bikendan]

Originally Posted by HONDAMAN174

Didn't you upgrade your converter? My WFCO would take about 8 hours to recharge from 50%. That's why I upgraded to progressive dynamics.


2014 Evo 2850 "Woodstock"
2011 Toyota Tundra "Clifford"

Nope.
Original WFCO converter.
It's been working like a charm for 10 years now, Knock on Wood.

[ESDSKeith]

If you have two 12v batteries, do you parallel them together or use a switch to change over to second battery when one is getting good low,

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[bikendan]

Originally Posted by ESDSKeith

If you have two 12v batteries, do you parallel them together or use a switch to change over to second battery when one is getting good low,

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I always use them together.
That way they share the load.

You can install a marine battery disconnect switch that allows you to use both or each separately.

[olwalker]

Originally Posted by bikendan

Yep, no way to answer the OP'S question specifically.

But we have two 12v deep cycle batteries.
We can go 3-4 days without recharging the batteries if we keep furnace usage to a minimum.
It takes about 3 hours to recharge them.

NEVER let the batteries go below 50% charge.

Hi Bikendan,

Curious - how do you ensure you don't go below 50% charge? Meaning do you have something hooked up to your dual 12 volt batteries to be able to see the charge?

[bikendan]

Originally Posted by olwalker

Hi Bikendan,

Curious - how do you ensure you don't go below 50% charge? Meaning do you have something hooked up to your dual 12 volt batteries to be able to see the charge?

Multimeter cause mine was free and installing a good battery monitor, like Trimetric cost more.

[stevejahr]

Originally Posted by urocav2001

Ok I will be dry camping for 3 days, using fridge on propane and a few LED lights before bed, that's about it, we just have 1 battery that came with the unit, and the generator is fairly small

These are modest demands and it should not take much. As noted already power the 110V portion of the RV from the generator and let your RV converter do the battery charging.

It is entirely correct that we cannot tell you what it will take in time. This will even vary for you from one trip to the next. This is why having measurement devices is key. A prior poster gave you an example of a simple plug in voltage measurement device and a battery charge level table. Start with something like this and monitor where things go. If the voltage does not drop much you can run the generator less or vice versa.

The next step up in monitoring is to add a meter which measures both voltage and current. This will enable you to have an idea how much power your devices use and you can use that knowledge to build a power budget or manage use patterns. There are much more expensive and capable versions out there but I put one of these in my Rockwood: bayite DC 6.5-100V 0-100A LCD Display Digital Current Voltage. This meter also tracks power usage over time. The biggest limitation is it only tracks current out and not in so you cannot measure charging power.

Adding heater use to your scenario will be the next step up in consumption as the blower will pull 4-5 amps whenever it is on.

In my TT during summer we survived a few days of boondocking just great with a single basic group 24 12V battery and a 100W solar panel. Refridgerator, water pump, LED lights, and the background draws. I think in winter I would need to add a second battery and jump to 200W of solar to handle the addition of the heater.