Adding a 3rd battery

[Roll With The Changes]

@boyscout

Thanks for catching that combination of a typo and an unclear explanation... What I meant to say was 105ah for group 27 @ 12v... 220ah for GC2 @ 6v.

When they are combined (series or parallel as appropriate), the pair of group 27 would yield 210ah and the pair of GC2 would yeild 220ah @ 12v.

A moderate increase in capacity per weight and per dollars, but the other benefits of stability and arguably depth of discharge definitely justify the extra cost.

[JColeman]

@ElSimon - what no one has mentioned yet is that you can't just simply add another 12V battery to your system after any significant amount of time has passed from the installation of the others. Lead acid batteries don't like that and it is recommended to replace all of them at the same time. So you are looking at the cost of three 12V lead acid/AGM batteries or 4 6V.

You haven't told us what your battery requirements are but you can get good lithium batteries from Costco for $700 each. Two will give you ~200 USEABLE aH and they carry a lifetime warranty from the manufacturer. Add in a ~$215 Progressive Dynamics 9160AL converter and you are basically done for life. It's what I did and I no longer think about that system on my rig for my needs. Additionally they only wiegh about 27 lbs each and don't need boxes or venting. More good things.

[traveldawg]

Long story short. In December my sister-in-law rolled her new Reflection trailer after hitting a small patch of black ice early in the morning on the way to a week long camping trip. They totaled the trailer and the truck. They have replaced both. They were able to salvage the battery from the Reflection and pulled the two new ones from the new trailer when they installed the solar panels recovered from the Reflection. They gave us all three batteries. I am not ready to put solar on.....yet. Here are the batteries. The large one is a series 27 (600 CCA, 750 MCA) the other two are series 24 (405 CCA, 505 MCA). I plan on only adding the series 27 at this time.

Both batteries installed by the dealer on my trailer are series 24 and probably cheap too. Just adding the 27 will improve my battery life while off the grid. Or should I put the 27 in the white box (it will fit) and add two boxes in front of that for a pair of 24's? I will try to measure how much room I have in front of the white box to see if or how I can fit two large boxes in that space. Trying put a 27 in the back box could be a bit of challenge if we still have the trailer when I get old (59+ isn't old!).

I'm pretty sure it isn't a good idea to mix different kinds of batteries (e.g. 2 group 24 and 1 group 27). I think they will not charge evenly. There is probably more info on this on the 'inter web'....

[SolarPoweredRV]

For what it is worth, I just returned from a 5,500 mile cross country trip from FL to AZ (20 miles short of the CA border) and back in our 310GK.

We have two Tesla Lithium battery modules from a wrecked Model S, paired with 1,200 Watts of Solar and a 3,000 Watt Victron Inverter.

Most of our trip was Boondocking and I can't begin to tell you how nice it was having that much battery storage and Solar Power on board. Even with our system, between the cloudy days and the low angle of the Sun, we had to monitor our usage to ensure we did not wake up cold early one morning. Because the trip was in the middle of Winter, we experienced some cold nights and we used our 35,000 BTU furnace every night. I will tell you that the Furnace in RVs really sucks some energy out of your battery system.

Basically, what I am saying, is that you really need to figure out how you are going to use your camper and size your battery system to match. If you plan to travel from campsite to campsite (with Electric hookups) then a pair of 12v Lead Acid batteries will probably work for you, if, on the other hand, you want to experience more boondocking, then you are going to need a more robust battery (Lithium) system to support your Boondocking adventures.

One additional thought; your hydraulic system on the 310 GK is a very power hungry system (drawing up to 90 amps) and you want to ensure that your batteries are always in good shape to provide the power you need for your Landing Gear and Slides (including the Schwintek bedroom Slide). A Lithium battery system can also help protect your, very expensive, hydraulic system and Schwintek motors.

PS: check to ensure the breaker for your Hydraulic System is an 80 amp breaker, if not get your dealer to upgrade to an 80 amp breaker for the system.

[JColeman]

For what it is worth, I just returned from a 5,500 mile cross country trip from FL to AZ (20 miles short of the CA border) and back in our 310GK.

We have two Tesla Lithium battery modules from a wrecked Model S, paired with 1,200 Watts of Solar and a 3,000 Watt Victron Inverter.

Slightly off topic, how many aH do you figure on for those Tesla batteries?

[SolarPoweredRV]

Slightly off topic, how many aH do you figure on for those Tesla batteries?

The Tesla batteries are 250ah at 24 volt each, which yields 1,000ah at 12 volts for the battery pack. I have chosen to only use the middle 80% of the battery pack for safety and longevity reasons. Consequently, I have around 800ah available for use.

Because I have a 24 volt system I have a 24v Victron Inverter. The 24v system allowed me to use thinner cables than I would have been able to use in a 12v system. I also eliminated charging from the Tow Vehicle because of the size of my Solar System.

[frank4711]

as has been said how you use our RV will help you decide the batteries you need .... we do not ever boondock with the only exception on a long trip we stay overnight at a Love's or rest area .... I am set up to bring my generator on hitch carrier and will during hot months so we can have a/c .... for shorter trips with no stay over I would prefer to leave generator at home and use hitch carrier for firewood .... I will be upgrading to 2 of these https://www.samsclub.com/p/duracell-...c2/prod3590228 for one reason only .... we have a residential frig and I want to be able to run my frig in case of a power outage at our campsite ... one 12v will only supply a few hours .... also I 2930 came with generator prep and I took it out not easy to do I used saw-all to cut bolts ... much more room with it gone ... I have to say that there is a god chance that my previous RV battery was never cycled even once we are plugged in at home on the road and at campsite ... for the boondockers out there I applaud the systems they use and the technology is amazing ... later Frank

[JTWILCOX]

Have you considered moving to Lithium now? You would need 4 lead to equal just 2 lithium, and at around 30% the weight, less room , and much longer life.

[fez111]

[Okay, I got the 2nd battery moved. It was the larger of the two boxes and capable of holding a series 27 battery, but only held a series 24 (dealer saving money!). I now have room to add the third battery in front of this one. I have the added fittings (just need the hose) to vent the new battery box...

Just a suggestion... We originally had one battery in our Solitude 379FL. After a bad storm we found that even used sparingly the fridge would last maybe 36 hours before low voltage alarm. We needed to add a second battery. We bought a second box similar to the original one. Then i ran into the vent hose issues. Definitely didn't want to add more holes.

We bought this box at Walmart...



When I finished bolting this down, I connected both the vent through the bottom and the outside vent to the new box. There are currently two full-sized batteries with room for a third. I had to purchase the battery cables and lugs but that was all. The door opens fully to allow battery maintenance. Total cost about $40 plus the second battery. Just a thought...

[Malco1]

as has been said how you use our RV will help you decide the batteries you need .... we do not ever boondock with the only exception on a long trip we stay overnight at a Love's or rest area .... I am set up to bring my generator on hitch carrier and will during hot months so we can have a/c .... for shorter trips with no stay over I would prefer to leave generator at home and use hitch carrier for firewood .... I will be upgrading to 2 of these https://www.samsclub.com/p/duracell-...c2/prod3590228 for one reason only .... we have a residential frig and I want to be able to run my frig in case of a power outage at our campsite ... one 12v will only supply a few hours .... also I 2930 came with generator prep and I took it out not easy to do I used saw-all to cut bolts ... much more room with it gone ... I have to say that there is a god chance that my previous RV battery was never cycled even once we are plugged in at home on the road and at campsite ... for the boondockers out there I applaud the systems they use and the technology is amazing ... later Frank

Which carrier are you using with the generator?