Second Battery Charger - Additional Batteries.

Renogy 400 watt eclipse premium, 40CC, 2000 watt inverter charger and 4 six volt golf cart batteries. Best investment ever made on any my RV'S I've owned.
Mel

cpeebles wrote:
My question is, if I add say 3 or 4 more batteries to the existing system I am pretty sure the stock battery charger will not do the trick. Can I add another (leave the stock one in tact) good 3 stage charge controller (suggestions please). Or I guess I can just unhook the original cables to charge the house batteries?

If you have a good converter you are ready for 400 to 600 amp/hrs of battery.
Post what model number you have now for best suggestions.

I have 300 watts of solar and 4 X 6 volt batteries. I installed a separate PD9260 in the compartment next to the batteries, hooked up with the proper sized cables. We dry camp almost exclusively, use a toaster, microwave, coffee maker with a 2000 watt PSW inverter. We can stay out as long as the water holds. When camping in the forest I run the genny for a couple of hours in the evening directly hooked to the stand alone charger.
I have left the stock charger alone, only added a separate breaker to turn it off.

I'm happy with this .....100A charger I added.

Also, if you look at a 120 volt AC device and it says that it uses 2 amps when you run it through an inverter it will be pulling about 20 amps DC plus whatever your inverter is using which could be .5 an amp. If you want to avoid an inverter you can charge your phone or run a laptop directly on 12 volts with the proper adapters and avoid the inverter losses.

If using AGM you may need to limit the charge voltage to 14.4 but it depends on the manufacturers recommendation. AGM will usually accept more amperage than wets. You may go for a couple weeks for incomplete charges but battery performance will drop off and plate damage can occur. With wet or agm you need to drive the charge all the way back up so sulfation and battery damage doesn't happen.

All of this depends on your energy usage. You are going to use and replace energy in AMP HOURS AH. Every device that you power will usually have an amp or wattage requirement listed on it. Every charging device will have a rating of what it can produce. An average RV just sitting there with the propane frig running but not being used will probably use about 36 AH in 24 hours. The radio, propane detector, monitor panel, card and propane valve for frig all draw some power and it's usually in that range.

An average 100 watt solar panel will give about 30 AH of power per day in good sun. So you have to figure that it's probably going to take more than a 100 watt panel just to keep it going if you never even use it. Now you need to add in all of your usage so lets picture a full battery and the sun has just gone down. I run an 2000 watt inverter which uses .5 amps just to be turned on. I also use my house furnace which pulls 5.5 amps and runs about 1/3 of the time at X temperature so in 12 hours it uses 22 AH. My 42" led Tv uses 6 amps and operates for 6 hours so that's 36 AH. My resi frig uses 7 amps and almost runs 50% of the time so that's 42 AH. My led lights probably pull 2 amps so add in 12 AH for a total of -118 AH. I have also been down 170 AH over night so there is a wide variation in power use between people. If you didn't use any additional power at night you could only be down 12 to 18 AH in the morning and 100 watts may carry you. I have 1000 watts of panel and pretty much use it all.

That gives you an idea of how it works. If you were to list the items that you want to operate and give us an idea of how you want to live we can give you better advice as to what you need. The first thing is to have some idea of how much power you will consume. That will tell us how big your battery needs to be to carry you over night and give some buffer. Your battery is your bank account. Your usage is your withdrawals and your charging ability is your income. You also have to pay the banker who is the inefficiency in the system. Roughly, you cant withdraw more than 50% of your account or you are penalized.

westend wrote:
One of the main factors in charging batteries when boondocking is the level of the goal. Most folks charge until the batteries are 80-90% charged in a daily regimen. That is because that last 10% takes a long time. This is where solar charging shines as a user can get to that 80-90% and count on the solar getting the last 10% done.

If you are committing to a year of travel, a single 100+W solar panel and small charge controller will greatly benefit your 12V system. When you park in storage, the solar panel can keep your batteries charged so that their longevity is the best. If you look at the ROI of a small solar system vs. the shortened interval of replacing batteries due to lack of charge, the solar system becomes quite attractive.

Thanks for this... AGM batteries, is there a problem if I go say from 60%-80% all the time and not really "top them off". My thought is I really do not "care" if I reach 100% if I have the battery time I need each day? Thanks again all! Very helpful to get the feel for it. Dont want to jump into solar until I know I can live in a toy hauler with to motorcycles:) C

One of the main factors in charging batteries when boondocking is the level of the goal. Most folks charge until the batteries are 80-90% charged in a daily regimen. That is because that last 10% takes a long time. This is where solar charging shines as a user can get to that 80-90% and count on the solar getting the last 10% done.

If you are committing to a year of travel, a single 100+W solar panel and small charge controller will greatly benefit your 12V system. When you park in storage, the solar panel can keep your batteries charged so that their longevity is the best. If you look at the ROI of a small solar system vs. the shortened interval of replacing batteries due to lack of charge, the solar system becomes quite attractive.

Buy an 80 amp boondocker that goes to 14.8 volts. Save your old converter or install the boondocker close to the batteries and run 120 volts to it. Charge time depends on how low your batteries get. If you are down 100 amp hours in the am it may take 4 or 5 hours. You may not reach 100 % in that time but close. The heavy amps will go in at first. As the amps drop ad the volts rise the end part of the charge can take a good deal of time.

A good battery charger will cost $400 plus, a good converter like a boondocker will cost $250ish.

What model converter do you have? Problem with some converters like wfco is that they only go to 13.6 volts.

How big is the charger in amps? Don't forget that AGM's do taper their charge acceptance.