Community Forums

TimLoon · 05-13-2025, 05:03 PM

I have had a couple of threads on my replacement of RV fridge with a residential. That is working well and happy with the results.
Better half is convinced I need two more 6 Volt batteries although testing to date shows the current set of 225 AH batteries and 225 watts of solar are keeping up. Keep in mind that that we only dry camp a couple of times a year of 3 days each and have an onboard generator and carry a 2000 watt Honda "Just in Case". The rest of time we are on shore power.
Fridge on average is pulling 64 watts, .55 amps when not in a "Sleep" mode.

Here are the questions:
- Can my current converter/charger (Iota DLS-55) support 4 6 volt batteries?
- Can the additional batteries be in same cabinet as the Renogy PSW inverter that supports the fridge? These will be lead acid so vent will be installed in cabinet.

Not interested in major conversions to Lithium etc as this may be our last year with this 21 YO motorhome.

Appreciate all advice

SafariBen · 05-13-2025, 05:31 PM

Yes, it can support 4 batteries, but it may take longer to recharge if you use more power or go longer between charging. That is not a multistage charger unless you have the "IQ4" whatever that is. You could check the charging voltage, it it climbs above 13.8V for a while, then settles back to 13.6V for float, it is multistage.

Some batteries come with a fitting for the vent to be run with vinyl tube, that would be the easiest way to vent batteries. You'd still want a bit of ventilation in the cabinet, but I wouldn't feel the need for as much that way, and I'd be more comfortable with the other stuff in there that way.

Argosy · 05-13-2025, 05:33 PM

Almost every lead acid battery I've ever seen is essentially open to the air, under the hood, one side of an RV battery box isn't there. They eventually end up rusty and crusty. Not where I'd put an inverter. A second reason they're open to the air is they will out gas as the batteries age, and it's a flammable gas. If the inverter has a pass through ATS it's going to arc, that's not what you want.

TimLoon · 05-13-2025, 05:52 PM

Last time I added dual batteries to a fifth wheel, I had 2 group 24 deep cycle that I installed in a battery box that was vented with hose. May end up that route if I add batteries.

Persistent · 05-14-2025, 08:21 AM

Flooded cell lead acid batteries must be well ventilated and drained for safety. There are flammable and explosive gases as well as highly corrosive gasses present.

It is possible to seal, vent, and drain, but risky if it is not done professionally. Most electronics are not rated for installation in explosive environments. A flooded cell lead acid space is explosive and corrosive.

If you want to install in a residential space, switch to all AGM or Lithium.

It is not worth the risk for a "maybe we need it".

TimLoon · 05-15-2025, 04:56 AM

Paul,
Thank you for your insight and i am taking into consideration your cautions.
I was actually going to install in a storage cabinet under the motorhome (see pic) using the pictured storage box that I previously used in the front storage space of a 5th wheel.
I will most likely try the dry camping trip in a week without additional batteries. (I will be 1 hour from home so if all fails, just head home). I have now been running on batteries for 5 days with simulating generator use 2x times a day for 1 hour each. What is unknown will be the house use of power however that usually occurs when I would be running the generator to recharge.
I have run a 12V box fan all night with the fridge and batteries were at 12.58 volts in the morning. What would be the voltage at 50% draw down of the 2-6 Volts?

twinboat · 05-15-2025, 05:20 AM

Looking for 50% SOC ( State of Charge ) on a battery in service is not accurate. For a proper reading the battery has to have sat at rest for a few hours. No usage, no charging.
Since your not going to do that while camping, it's safe to run the voltage down to 11.2 volts before charging them back up. As far as charging, if you draw 100AH from them, put 125AH back in. With a 50 amp charger, that would be about 2.5 hours.

TimLoon · 05-15-2025, 07:05 AM

Not sure I have ever gone below 12 volts in the 15 years I have had this unit.
This will be an interesting test next week.

Mark_K5LXP · 05-15-2025, 08:00 AM

LA batteries with few exceptions are spec'd to discharge to 10.5V, that's the 100% point. What other threshold of discharge you choose to use, 90%, 80%, 50%, whatever is up to whatever operational goals you're trying to achieve. If you have instrumentation and equipment that can operate over the full terminal voltage range of LA then there's no reason not to use it. For purposes of capacity/system testing for determining operating margin you want to run it out completely so you know what you're working with. Then during operation you know how much is left in the tank and makes managing charging/loads to keep the lights on/fridge cold anything but guesswork.

Mark B.
Albuquerque, NM

d23haynes57 · 05-15-2025, 08:14 AM

Your converter-charger won't care as it is a current limited supply, it will just take longer. However, along the same lines as all the Lithium you need a DC to DC charger, doubling the battery capacity will also double the charging load presented to the alternator. In addition, you now have also have the fridge load. The 4-GC-2 battery bank will peak load over 100 amps. I believe you have ~160-175 amp alternator.
Dropping in a single 300 A/H Lithium will put the alternator load somewhere between the single and dual GC-2 strings and give you much more usable power for the inverter and fridge. It will also get your out of battery maintenance and hydrogen gas concerns.

Persistent · 05-16-2025, 06:26 AM

Quote:

Originally Posted by TimLoon

Paul,
Thank you for your insight and i am taking into consideration your cautions.
I was actually going to install in a storage cabinet under the motorhome (see pic) using the pictured storage box that I previously used in the front storage space of a 5th wheel.
I will most likely try the dry camping trip in a week without additional batteries. (I will be 1 hour from home so if all fails, just head home). I have now been running on batteries for 5 days with simulating generator use 2x times a day for 1 hour each. What is unknown will be the house use of power however that usually occurs when I would be running the generator to recharge.
I have run a 12V box fan all night with the fridge and batteries were at 12.58 volts in the morning. What would be the voltage at 50% draw down of the 2-6 Volts?

Hydrogen gas is lighter than air. Box needs ventilation in at bottom and ventilation out at top to vent hydrogen. Battery emits oxygen and hydrogen. That mix in the box can explode.

That box is good for AGM batteries. AGM do not normally emit gas. The vent is for pressure release in case of failure.

Battery charging and voltage chart attached.

SJ-Chris · 05-16-2025, 03:40 PM

If you are allowed to run your generator(s) where you dry camp, and you are only keeping your RV for 1 more year for a couple of trips, and you haven't had a problem to date, then I would say it is a total waste of $$$ to buy and install two more 6v batteries!

Live with what you have and save your $$$ for something else. Take the money you would have spent on two 6v batteries and surprise your wife with something nice on the next camping trip. She might remember that 5, 10, 20 years from now. She will NOT remember that one time when you bought two extra 6v batteries for the 1-2 camping trips you took before selling your RV that one time years ago.....

Happy Camping!
Chris

TimLoon · 05-16-2025, 06:12 PM

Chris, You are certainly one smart person.
Persistent, Although I have decided not to install the pictured battery box, please note there is an inlet at the bottom and an outlet at the top. When I installed the last one, I drilled a hole through the cabinet floor for the inlet and then drilled a hole through cabinet side for the venting apparatus. This vented to open space under the fifth wheel.
Seems like a reasonable accommodation for the gases. Maybe I was plain lucky that I had no issues.