Adding a 3rd battery

[ElSimon]

I thought I had posted this the other day, but i can't find it.

We have a 2019 Solitude 310GK that we bought new last year. We love it. Yes, there have been issues we have had to deal with but overall we are VERY pleased with it. We bought it with the generator prep but no generator (wasn't in the budget at the time). It does have two batteries. We would like to add a third.

Questions:
1. Why are the factory installed batteries, in boxes, 2" apart? Wouldn't make more sense to put them as close together as possible to provide more accessible storage space? Along with that why are they so close to the front. the only reason I can figure out for this is to make easier to remove when you need to.
2. Will the floor support another large battery. I am guessing it would now without the generator. But would it be a concern once we add the generator?
3. I plan on building a shelf to go over the batteries that has the top removable for access to the batteries. To maximize this I will need to add an ABS elbow for the vent hose. The current "Y" looks like it is just that, ABS plumbing fitting.
4. Anything I am missing?

Thanks,
ElSimon

[bertschb]

I thought I had posted this the other day, but i can't find it.

This is your other thread:
https://www.mygrandrv.com/forum/show...736#post284736

To answer some of your other questions-
The batteries are installed by your dealer which means depending on the guy that installed them, the batteries could be close together, far apart, in the front or back of the compartment, etc. There are no rules as to how or where they will be installed. Adding one more battery shouldn't require reinforcing the floor of the front compartment.

[boyscout]

2. Will the floor support another large battery. I am guessing it would now without the generator. But would it be a concern once we add the generator?

Like you we have generator prep but no generator.

Not an expert answer, but I thought I'd relate that I cut pieces of 3/4" outdoor plywood to fit over the entire floor on each side of the generator shroud. We have four 6V golf cart batteries, each pair weighing close to 125 pounds with its box. I have a box on either side of the shroud, and have traveled about 7-8,000 miles this way.

I don't know whether my plywood precaution is required. The Onan generator that our trailers are prepped for weighs IIRC close to 275 pounds, and that sits on the side where the floor has large cut-outs for the generator's intake and exhaust, so maybe the front compartment is stronger than it seems. Maybe the plywood idea on the other side holding your batteries would give you some additional peace of mind.

Good luck with your project.

[traveldawg]

I put 4 6V ACMs in the bay when I replaced my 12v wet cells. No problem with weight. I used ACMs so I didn't have to bother with venting.

You can see them on the left in this photo....

[traveldawg]

This is your other thread:
https://www.mygrandrv.com/forum/show...736#post284736

I went ahead and deleted the second post (duplicate) it didn't have any additional posts to it so I hope I did the right thing..... Larry (traveldawg)

To answer some of your other questions-
The batteries are installed by your dealer which means depending on the guy that installed them, the batteries could be close together, far apart, in the front or back of the compartment, etc. There are no rules as to how or where they will be installed. Adding one more battery shouldn't require reinforcing the floor of the front compartment.

[ElSimon]

Larry, Thanks for fixing my error. Still don't know I couldn't find my first thread.

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. The plan is to buy a regular box at NAPA and then add the vent tube. This will be done using an ABS fitting thru a hole in the top. I will be then adding the shelf above the batteries. We had to trim the edge of the box to get the wires to reach. Once I get the new box installed and the battery set in place I will know what length of cables I need.

On a separate note, I have seen where it is popular to use 6 volt batteries 2 in series creating the 12v. Why is this popular and does it allow for better power life while off the grid? Do the 6v batteries last longer? Are there other advantages?

Thanks,
ElSimon

[Roll With The Changes]

On a separate note, I have seen where it is popular to use 6 volt batteries 2 in series creating the 12v. Why is this popular and does it allow for better power life while off the grid? Do the 6v batteries last longer? Are there other advantages?

Thanks,
ElSimon

A six volt battery of comparable size has a slightly larger capacity in amp hours available. For example, a group 27 twelve volt battery will be about 105 amp hours, while a size GC2 six volt battery will be about 120 amp hours. So there is capacity advantage to using two six volt batteries. But more importantly, I think the series configuration stays more stable over time. The cells stay balanced better in series because the the current through all cells is the same.

There is a LOT of info out there about battery configurations and chemistries, etc. Here is where I started:

https://batteryuniversity.com/

Pretty interesting reading if you're into that kind of thing.

[boyscout]

On a separate note, I have seen where it is popular to use 6 volt batteries 2 in series creating the 12v. Why is this popular and does it allow for better power life while off the grid? Do the 6v batteries last longer? Are there other advantages?

There are lots of different batteries around; not sure which ones @Roll With The Changes is thinking about but our numbers are very different from his.

The battery that comes in the trailer when new is installed by the dealer, not Grand Design, so there is some variance. Our dealer installed a cheap battery with 85 amp-hours capacity.

We replaced it with Trojan T-105 6-volt batteries that have a capacity of 225 amp-hours. We have four of them in two 12-volt pairs, so a total 12-volt capacity of about 450 amp-hours.

These heavy-duty golf cart batteries also have a higher tolerance for deeper discharge than typical dealer-installed "deep-cycle" batteries. Still not a good idea to run them down low, but they'll survive it with less life-reducing damage if that happens. For example the Trojans have a *recommended* discharge level of 50%, which is likely the *maximum* discharge level for your dealer-installed battery, and the Trojans can be taken down to about 80% occasionally without significant damage.

Downside is they are very heavy (about 125 pounds per 12-volt pair with box), they're not cheap, and they take a long time to recharge. If you're just starting to think about upgrading batteries, think about lithium.

[ElSimon]

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!).

[SolarPoweredRV]

On a separate note, I have seen where it is popular to use 6 volt batteries 2 in series creating the 12v. Why is this popular and does it allow for better power life while off the grid? Do the 6v batteries last longer? Are there other advantages?

Thanks,
ElSimon

The short answer is: 6v batteries have more energy storage, last longer and they can take the abuse from an RV application better than 12 volt deep cycle batteries.

The long answer is: Lithium batteries are so much better they are worth the price.

Here is why Lithium are better, they don't need to be vented, they charge up much faster and they can be discharged 100% without harming the batteries.

The configuration you are contemplating, three 12v Lead Acid batteries, will provide you with a little less than 150 usable amp hours. Each time you go beyond that 150 usable amp hours you loose a little bit of battery life and those 150 amp hours become less and less over time. Additionally, every time you have your coach serviced, you can expect to get it back with a dead battery (ask me how I know). The cost for this configuration is about $350 and you can expect to replace your batteries every 2 years. If you upgrade to four 6v Lead Acid batteries you will have around 220 usable amp hours, these will cost you around $450 and these should last 4 years with good care (your mileage may vary).
Additionally, with both of these Lead Acid options, it will take you 8 hours, or more, to fully charge your batteries, 3 hours to 80% and 6 hours from 80% to full.

If you can bring yourself to spend the money for Lithium batteries, you will be able to use 100% of the Lithium Batteries capacity without harming the batteries and your batteries will last for 10 years (10 year warranty in the case of Battle Born Batteries). Additionally, you can charge your batteries in a couple of hours versus all day, this is especially helpful if you are boondocking with a generator.

Yes, Lithium batteries are expensive, but Lion Energy batteries (105 ah) can be bought for $600 at Costco and Escapees has a discount on Battle Born Batteries (100 ah).

If you do decide to install Lithium batteries I recommend you replace your Converter with a Converter that is optimized for use with Lithium Batteries. You will also want to protect your tow vehicle by installing a DC to DC converter (Renogy makes one) that limits the energy drawn from the tow vehicle's electrical system.