Have a 2008 Extreme megalite. After boondocking this weekend I had a couple issues. The 2 12v batteries in there are a few years old and won’t hold a charge (there ready for replacement). Want to replace there with 2 6v batteries, And possibly a separate battery just for starting the generator??? what’s your thoughts on using the genny a few hours a day to charge back up the batteries? I have all LED interior lights but do have the fridge and furnace running all day and night for the kids during these colder NW Trips. TV and a couple lights on throughout the day. 1) My 2 12v batteries went dead 2 times and had to just with the truck 2) would live some sort of alarm letting me know the Genny (Onan 4K microquiet) needs started to charge the batteries before its to late3) a possible way to make my generator auto start when it senses low voltage level.4) how to tell if my current converter is doing its job?

The best thing you could do would be to buy a $4 voltage meter from China. Get one with 4 decimal points, so you can see the difference between 12.5 and 12.4 evenly.. you will see 12.56, then 12.54. With that, you will begin to see your requirements and needs, and then you can learn when to recharge, and the benefit from charging for one hour or two hours. Those few things will make your life so much better, and all the people around you will be happy that you run a generator only as much as you need.

#4) when charging a low battery the voltage should steadily climb to 14.3+ volts.

1. Get a Voltminder. Connect it directly to the battery and it will give you a accurate read of what your battery level is at. It has a low battery alarm that you can set.https://www.amazon.com/VoltMinder-Digital-Volt-Meter-Batteries/dp/B001IQ1XW42. If your draining two batteries in two days you have a significant drain. If you use your furnace batteries won't last long.You will need to run your generator longer. Watch your Voltminder and try and keep it between 12.4 and 12.7 when not charging and batteries rested.3. Add more batteries. Two group 24 12 volts will have about 170 amp hours, two 6 volts will have about 220 amp hours. If you add two extra batteries to the two you already have you will double the amp hours. You can see you will end up with more amp hours with 6 volts.4. Solar would be nice but you will need at least 300 watts to do any good. That will cost you around $1000+

1L243 wrote:1. Get a Voltminder. Connect it directly to the battery and it will give you a accurate read of what your battery level is at. It has a low battery alarm that you can set.https://www.amazon.com/VoltMinder-Digital-Volt-Meter-Batteries/dp/B001IQ1XW42. If your draining two batteries in two days you have a significant drain. If you use your furnace batteries won't last long.You will need to run your generator longer. Watch your Voltminder and try and keep it between 12.4 and 12.7 when not charging and batteries rested.3. Add more batteries. Two group 24 12 volts will have about 170 amp hours, two 6 volts will have about 220 amp hours. If you add two extra batteries to the two you already have you will double the amp hours. You can see you will end up with more amp hours with 6 volts.4. Solar would be nice but you will need at least 300 watts to do any good. That will cost you around $1000+Thanks for the detailed response. The batteries are charging, but they are just a couple of old crappy car battery’s. I will be upgrading to good dual 6v setup. I was running the furnace nonstop, so I’m sure that was a big draw. Don’t think the solar panels would be worth the investment since the place we boondocks are heavy with trees and then on shore power when at campgrounds. You talk about batteries being rested, how long are you meaning? When at home and not using the trailer so I leave it plugged in all the time or is this hard on the battery’s? Thanks again.

Living in the northwest like you do 1L243, Shaft may need need more than 300 solar watts.

To cover my dry camp needs | Good Sam Community

Artum_Snowbird
Explorer
Mar 19, 2018
The best thing you could do would be to buy a $4 voltage meter from China. Get one with 4 decimal points, so you can see the difference between 12.5 and 12.4 evenly.. you will see 12.56, then 12.54. With that, you will begin to see your requirements and needs, and then you can learn when to recharge, and the benefit from charging for one hour or two hours.

Those few things will make your life so much better, and all the people around you will be happy that you run a generator only as much as you need.
time2roll
Nomad
Mar 19, 2018
#4) when charging a low battery the voltage should steadily climb to 14.3+ volts.
1L243
Explorer II
Mar 19, 2018
1. Get a Voltminder. Connect it directly to the battery and it will give you a accurate read of what your battery level is at. It has a low battery alarm that you can set.
https://www.amazon.com/VoltMinder-Digital-Volt-Meter-Batteries/dp/B001IQ1XW4

2. If your draining two batteries in two days you have a significant drain. If you use your furnace batteries won't last long.

You will need to run your generator longer. Watch your Voltminder and try and keep it between 12.4 and 12.7 when not charging and batteries rested.

3. Add more batteries. Two group 24 12 volts will have about 170 amp hours, two 6 volts will have about 220 amp hours. If you add two extra batteries to the two you already have you will double the amp hours. You can see you will end up with more amp hours with 6 volts.

4. Solar would be nice but you will need at least 300 watts to do any good. That will cost you around $1000+
Shaft0201
Explorer
Mar 19, 2018
1L243 wrote:
1. Get a Voltminder. Connect it directly to the battery and it will give you a accurate read of what your battery level is at. It has a low battery alarm that you can set.
https://www.amazon.com/VoltMinder-Digital-Volt-Meter-Batteries/dp/B001IQ1XW4

2. If your draining two batteries in two days you have a significant drain. If you use your furnace batteries won't last long.

You will need to run your generator longer. Watch your Voltminder and try and keep it between 12.4 and 12.7 when not charging and batteries rested.

3. Add more batteries. Two group 24 12 volts will have about 170 amp hours, two 6 volts will have about 220 amp hours. If you add two extra batteries to the two you already have you will double the amp hours. You can see you will end up with more amp hours with 6 volts.

4. Solar would be nice but you will need at least 300 watts to do any good. That will cost you around $1000+

Thanks for the detailed response. The batteries are charging, but they are just a couple of old crappy car battery’s. I will be upgrading to good dual 6v setup. I was running the furnace nonstop, so I’m sure that was a big draw. Don’t think the solar panels would be worth the investment since the place we boondocks are heavy with trees and then on shore power when at campgrounds. You talk about batteries being rested, how long are you meaning? When at home and not using the trailer so I leave it plugged in all the time or is this hard on the battery’s? Thanks again.
Lwiddis
Explorer II
Mar 19, 2018
Living in the northwest like you do 1L243, Shaft may need need more than 300 solar watts.
Y-Guy
Moderator
Mar 19, 2018
Shaft0201 wrote:
The batteries are charging, but they are just a couple of old crappy car battery’s. I will be upgrading to good dual 6v setup. I was running the furnace nonstop, so I’m sure that was a big draw.

I'm surprised they even lasted as long as they did. Once you have some good deep cycle batteries then you'll be fine. There is no need to separate the battery system, that will just make it more complicated.

Factory converter/chargers are bad, check to see what you have first. There are better ones out there but find out what you have. I had a Progressive Dynamic Inteli-Power unit, great unit.
dedmiston
Moderator
Mar 19, 2018
See if you can find an Auto Start module for your Onan. I found a couple of hits with a Google search. This will automatically start your gen when your batteries are low and then shut it off once they're charged.

I don't have any experience with the auto start, but it sounds like a good idea.

More Info
1L243
Explorer II
Mar 19, 2018
Shaft0201 wrote:
1L243 wrote:
1. Get a Voltminder. Connect it directly to the battery and it will give you a accurate read of what your battery level is at. It has a low battery alarm that you can set.
https://www.amazon.com/VoltMinder-Digital-Volt-Meter-Batteries/dp/B001IQ1XW4

2. If your draining two batteries in two days you have a significant drain. If you use your furnace batteries won't last long.

You will need to run your generator longer. Watch your Voltminder and try and keep it between 12.4 and 12.7 when not charging and batteries rested.

3. Add more batteries. Two group 24 12 volts will have about 170 amp hours, two 6 volts will have about 220 amp hours. If you add two extra batteries to the two you already have you will double the amp hours. You can see you will end up with more amp hours with 6 volts.

4. Solar would be nice but you will need at least 300 watts to do any good. That will cost you around $1000+

Thanks for the detailed response. The batteries are charging, but they are just a couple of old crappy car battery’s. I will be upgrading to good dual 6v setup. I was running the furnace nonstop, so I’m sure that was a big draw. Don’t think the solar panels would be worth the investment since the place we boondocks are heavy with trees and then on shore power when at campgrounds. You talk about batteries being rested, how long are you meaning? When at home and not using the trailer so I leave it plugged in all the time or is this hard on the battery’s? Thanks again.

After charging your batteries will need to rest for about a hour for a accurate read on what your battery voltage actually is. For example if you run your generator your batteries will be charging at what ever output your Converter is charging at, let's say 13.7 volts. When you turn off your generator your batteries will read probably 13.2 volts and you will grab your fishing pole and run out the door. But when you come back in about a hour your batteries will read their more accurate level(depending on how long you have been charging) let's say 12.5 volts because they have had time to rest.

Voltminder you can order it from Amazon or direct from the company

When you open up your Converter you will see where the battery cables are connected. This would be the best place to connect your Voltminder. These cables go directly to the battery with the least amount of voltage drop.

Who ever put car batteries in your trailer made a mistake. Two 6 volts will be better but if your going to do a lot of dry campingand running your furnace you will need more.

My 300tq had two new 12 volt deep cycle batteries so I added two more. This gives me about 370 amp hours. Four 6 volts would have given me 440 amp hours but I could not see throwing away new batteries. I will replace them when the day comes with 6 volts.
I got the battery box from Harbor Freight. I also put in a battery disconnect switch.
Shaft0201
Explorer
Mar 19, 2018
Good to know information for sure. I to am looking to get a enclosed compartment for my batteries as well and I will defiantly order a voltminder ASAP. I was looking at The Duracell 6 V batteries battery plus the website and they are anywhere from 250-370amp hours each. Seems like 2 of them would be ideal ito me but then again I have not been down this road before.
theoldwizard1
Explorer II
Mar 19, 2018
A low battery voltage cut off combined with with a generator auto start are two good ideas, together !

This an easy project with an Arduino or other tiny singe board computer. You would need a HD relay to cut off the batteries and another relay to start the generator plus associated wiring.