Adding 2nd battery

alesure · 07-04-2021, 07:27 AM

I want to add a second battery to increase our capacity. Is it OK to mix battery brands as long as specs are the same? I mix smaller batteries all the time of course but unsure about larger batteries. I suspect you can but wanted to get some other opinions. Thanks in advance!

**chuckster57** · 07-04-2021, 07:30 AM

If they are the same size, age, and amp rating you MIGHT get away with it.
If the battery is over 6 months old I would start fresh. The old one will draw down the new one.

**flybouy** · 07-04-2021, 09:41 AM

What are trying to accomplish? Do uou want to dry camp (no hook ups) or an occasional night at Walmart on the road? What battery do you have now? What trailer do you have. Just curious but what "smaller batteries" fo you mix?

GHen · 07-04-2021, 10:28 PM

I agree, you need to keep them separate.

You can wire them with a marine disconnect switch.
A, B, Both, None.

When your old one gets low (A), switch to the new one (B). You will also need to switch them to keep them both charged.

If you just add them, here is what could happen. This is just a simplistic example, Let’s say your old one is only 80% strong, you add a second one. Your system will only charge to the weakest battery level, so your old AND your new will only be at 80%.

My advice same as most everyone that will respond, buy two new batteries….

Once you agree, then what you buy depends on how you use them. I have four 6volt batteries since I boon-dock most of the time. Wish I had six 6 volt batteries.

alesure · 07-06-2021, 03:14 AM

Quote:

Originally Posted by flybouy

What are trying to accomplish? Do uou want to dry camp (no hook ups) or an occasional night at Walmart on the road? What battery do you have now? What trailer do you have. Just curious but what "smaller batteries" fo you mix?

We like to stay in state parks because we find them a little quieter with a little more space between sites. Downside is no hookups. All I'm looking for is a little more capacity so I can use my porch lights and my radio, etc a little more without worrying about draining the batteries.

**flybouy** · 07-06-2021, 05:08 AM

Quote:

Originally Posted by alesure

We like to stay in state parks because we find them a little quieter with a little more space between sites. Downside is no hookups. All I'm looking for is a little more capacity so I can use my porch lights and my radio, etc a little more without worrying about draining the batteries.

I would suggest going to two 6 vdc golf cart batteries and a simple on/off battery switch.

ChuckS · 07-06-2021, 09:09 AM

I also boon docking a lot.. if you have the space two GC2 golf cart batteries are hard to beat.l have been running a set from Costco for six years now…

Currently they are $98 a piece and a good battery .. Trojan T105 is nice also and of course an AGM GC2 is even better but more expensive

alesure · 07-08-2021, 04:18 AM

Quote:

Originally Posted by ChuckS

I also boon docking a lot.. if you have the space two GC2 golf cart batteries are hard to beat.l have been running a set from Costco for six years now…

Currently they are $98 a piece and a good battery .. Trojan T105 is nice also and of course an AGM GC2 is even better but more expensive

Why golf cart batteries and not RV/Marine that came with the trailer?

**chuckster57** · 07-08-2021, 04:45 AM

Quote:

Originally Posted by alesure

Why golf cart batteries and not RV/Marine that came with the trailer?

When you boondock you need all the amp hours you can get. If you look at the ratings on a 12V deep cycle and a 6V GC battery you’ll see the 6V is a lot more. More amp hours means power for a longer period of time. It does take a little longer to charge but they are well worth the upgrade.

GHen · 07-10-2021, 09:16 AM

Quote:

Originally Posted by alesure

Why golf cart batteries and not RV/Marine that came with the trailer?

Rv/marine batteries are not true deep cycle batteries, they are also used as starting batteries for marine applications so they are designed for starting which is why they show CCA (cold cranking amps) and not the Amp hour capacity like true deep cycles. They are less expensive than a deep cycle which is why the dealers put them in rv’s.
True deep cycles can handle being drained low and then recharged but are not as good doing engine starting tasks.

Many peoples first rule when buying a new rv, throw out the mattress, tires and batteries and put in higher quality items.

bbells · 07-15-2021, 08:14 AM

Quote:

Originally Posted by alesure

I want to add a second battery to increase our capacity. Is it OK to mix battery brands as long as specs are the same? I mix smaller batteries all the time of course but unsure about larger batteries. I suspect you can but wanted to get some other opinions. Thanks in advance!

Why bother? Just get a 220ah 12v real deep cycle battery from Batteriesplus. You will be doubling your capacity without messing around with 2 batteries. Remember, if it says cca, or marine battery, or weighs less than about 90 pounds it isn't a deep cycle battery.

JDDilly · 07-15-2021, 09:26 AM

Even going with a true deep cycle, I would go with 2 batteries. Gives you more hours and is a piece of mind. I think it is well worth the investment, even before we had a rig with a residential frig.

bbells · 07-15-2021, 09:30 AM

Quote:

Originally Posted by JDDilly

Even going with a true deep cycle, I would go with 2 batteries. Gives you more hours and is a piece of mind. I think it is well worth the investment, even before we had a rig with a residential frig.

It isn't the number of batteries that matters, it is the number of amp hours. 2 100ah batteries have less ah than 1 220ah. Plus, if you don't need more than 220ah you don't need to mess around with putting in another battery holder.

larryflew · 07-15-2021, 10:38 AM

I just had that experience 2 years ago when one of our pair of 5 year old batteries crapped out. Replaced the one one with a new deep cycle but the dealer only had one in stock. For 2 weeks it was like running on a single mediocre battery until we got back and replaced the other. Have been using the other for a hoist to remove my 5th wheel hitch when I need the truck bed and it's great but just didn't have enough oomph to do the trailer very long. Go with both and deep cycle for sure.

P&DZ · 07-16-2021, 06:50 AM

We do a bit of boon docking. Last year I replaced our two mismatched 12v batteries with two 6v GC2 batteries, (230Ah Duracell Ultra from Batteries Plus). We can now be without hookups almost indefinitely by managing our power usage and using a 100watt solar panel to top off the batteries each day. Happy with this setup.

{tpc} · 07-23-2021, 05:10 AM

I run 2 12v batteries in parallel and they were installed fairly close together and are about the same age (according the the date codes) and haven't had any issues as of yet. In fact my battery did a good job with them connected together even over the winter.

We don't boondock, but we have a 12v fridge. As a result, one battery only gives it about 6 hours of runtime, where 2 batteries double that...well at least I think they do. The last time I had to do this, they ran for 6 hours and it had hardly put a dent in capacity according the meter inside the trailer.

Our issue is that in order to park at our house, it has to be across the street, so I have no AC power unless I lay an extension cord across the street. Seems like a good way to have to replace extension cords lol.

I miss our propane/ac fridge sometimes, but this one does get cold pretty fast and is huge, so that part is nice at least.

Village Idiot · 08-30-2021, 07:09 PM

In late July my camper battery gave up so I replaced it with an Interstate HD24-DP. Picked up my 2022 30 RLS last week and am thinking about adding the HD24 as a second battery on my new rig. The new rig has an SRM 27, Interstate battery store guy told me it would work fine but I am reading different opinions elsewhere. Thoughts?

**flybouy** · 08-31-2021, 05:23 AM

Quote:

Originally Posted by Village Idiot

In late July my camper battery gave up so I replaced it with an Interstate HD24-DP. Picked up my 2022 30 RLS last week and am thinking about adding the HD24 as a second battery on my new rig. The new rig has an SRM 27, Interstate battery store guy told me it would work fine but I am reading different opinions elsewhere. Thoughts?

Do you camp without shore power? If you boondock then a dual purpose battery won't last long. You would be better off with two 6 volt golf cart batteries wired in series. If you never boondock then there's no need for a second battery.

Canonman · 08-31-2021, 05:27 AM

I'm a fan of having two batteries. We do a fair amount of dry camping and need two batteries.
I'm also a fan of having those batteries match.
The specs on each battery are shown below. The group 27 battery is physically larger and provides significantly more reserve power. I'd recommend spending the $135 and getting another matching SRM27. I'm betting you could sell the HD24 on line and recover a fair piece of that cost.
You have a major investment in your new rig. IMHO spending another $100 for a second matched battery is a reasonable upgrade.

SRM27
600 Cold Cranking Amps (CCA)
160 Reserve Capacity (RC)@25 Amps

HD24-DP
405 Cold Cranking Amps (CCA)
100 Reserve Capacity (RC)@25 Amps

RogerThat99 · 08-31-2021, 06:34 AM

My trailer already has 2 12V batteries. One connected to the trailer power, and the 2nd is connected to the other battery.

On the Golf Cart Batteries, would I just buy two GC batteries, and connect them the same way? Are they roughly the same size and fit in what I would consider the standard sized battery box?

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