battery advice- new trailer

[RVCamperDan]

Hi all,

I recently purchased a jayco x213... most of our trips will be without electrical hookups and I am planning on upgrading batteries and probably adding solar in the near future... question is: the trailer came with one interstate srm24 marine battery, (which seems to be an ok battery, but not great for this use)- if you were me would you: 1) add another 12 volt batter of similar capacity, 2) buy 2 golf cart batteries? I am convinced golf cart batteries are better in the long run, BUT since I have 1 12v battery already, is it really worth justifying 2x the cost to buy the golf cart batteries now? or wait for the next round of batteries? After buying the trailer, and buying the basic start up items, I am definitely not feeling rich - otherwise I would probably buy the 2 golf cart batteries.

thanks in advance for the sage advice!
dan

[Jmooney]

Batteries can become parasitic to one another if they are at different stages of eventual deterioration and sulfation, so generally, when you have more than one battery, they all should be the same make, model and manufacture date (or pretty close)

I added more 12 Volt batteries to my array, but did so within a month of the others.

[RVCamperDan]

@jmooney- that makes sense, but since it is a new battery and I could add another new battery (presumably similar specs, or even the same one) does that change your answer at all?

[Rebecca]

I am interested in hearing the outcome of this discussion! We were wondering the exact same thing about adding an extra battery...

[Mustang65]

Based on what is being said, yes, there are issues with combining 2 batteries of different dates. Ideally, they should both have mfr dates close to each other (same month if possible), but being this is your maiden journey with setting up a TT for dry-camping, I would recommend purchasing another matching 12Volt Interstate srm24 battery and get your learning experience done on an inexpensive setup. When these batteries need replacing, move up to the REAL deep cycle batteries. It is a lot cheaper to learn on the interstate batteries than $400 worth of deep cycle batteries, and it will be a learning experience.

As Jmooney mentioned, there are issues with connecting batteries of different dates and usage. You can do an easy experiment to prove this by using 5 small flash light batteries (AA or AAA), with 2 flashlights. Take one flash light and let the flash light run the batteries down for a while (notice when the light has becomes much dimmer, about 1/2 way). Take one of the batteries from the run down flash light and replace it with a NEW battery. Now place the two flash lights next to each other (one with 2 new batteries and one with one old and one new battery) and turn them on. You will notice that as time goes on the flash light with the old and new battery will not produce as much light (power) as the one with 2 new batteries and drain it down to nothing a lot faster than the one with the 2 new batteries. This is what happens on a bigger scale with the TT batteries, that have a different age.

You will also need a way to charge the batteries, be it Solar, generator or the TV.

The best thing to do is set up your TT with LED's, watch your usage and ALWAYS check your battery's water level.

Just my thoughts,

Don

[Bassdogs]

Originally Posted by Mustang65

You can do an easy experiment to prove this by using 5 small flash light batteries (AA or AAA), with 2 flashlights. Take one flash light and let the flash light run the batteries down for a while (notice when the light has becomes much dimmer, about 1/2 way). Take one of the batteries from the run down flash light and replace it with a NEW battery. Now place the two flash lights next to each other (one with 2 new batteries and one with one old and one new battery) and turn them on. You will notice that as time goes on the flash light with the old and new battery will not produce as much light (power) as the one with 2 new batteries and drain it down to nothing a lot faster than the one with the 2 new batteries. This is what happens on a bigger scale with the TT batteries, that have a different age.

Don

While I generally agree with your thoughts on marrying batteries of the same series and dates, I think your simple test is flawed in that you are comparing 2 fully charged [new] flashlite batteries to one new and one half discharged battery. Naturally you will get much less "life" from the 2nd set. In an RV application you would not set out with a half charged and a full charged [new] battery, rather you would fully charge the older one and match it with the new one. My contention is that a newer battery with only a few discharge cycles will not significantly reduce the amp hours capacity when paired with a new battery of similar specs.

I am a believer in 2-6v golf cart batteries but am faced with the same
decision as the OP. To date I have stuck with the 12V that came with my 2014 WH but plan on updating the battery situation before our trip south in January. I need a battery for the trolling motor in my fishing boat, so thats where the 12v TT battery will go and I will POP for 2 new golf cart batteries for the WH.

[SecretCoveDave]

We bought 2x 6 volts plus solar and inverter when TT was new. (2011).

Now going back to one 12 volt and leds everywhere.

It was our first TT, takes a while to figure out what you personally need for your kind of camping I guess.

Someone said "your first RV is an investment in your RV education."
regards,Dave

[RVCamperDan]

Thanks for the thoughts- keep em coming... So far one vote for buying 1 additional 12v to match the new one.

@mustang65- trailer came stock with all LEDs, our first trip I was a crazy power nazi and we made it 5 nights and still had about 50% left. I would like to use the trailer amenities more though.

[Mustang65]

Originally Posted by Bassdogs

While I generally agree with your thoughts on marrying batteries of the same series and dates, I think your simple test is flawed in that you are comparing 2 fully charged [new] flashlite batteries to one new and one half discharged battery. Naturally you will get much less "life" from the 2nd set.

An imbalance of internal resistance looks the same as the outcome from the 1/2 charged battery.

Let me try to explain it this way.

The point I was trying to show in using the half charged battery as an example, was to illustrate how the difference in internal battery resistance affects the output of the battery bank (same outcome as a half charged battery example). In the RV, the battery with more internal resistance (usually older or abused battery) will draw down the power of the newer battery until it reaches the level of the older battery, and will drain the bank to the 50% level faster than 2 new or internally matched batteries.

The trouble starts when those batteries are being charged and they are not charging at the same rate (due to the difference in internal resistance), which could cause the older battery to draw to much current and overheat. Eventually shortening the life of both batteries. Granted there are no 2 batteries that have the same internal resistance, but when they are new and installed together (with proper connections) they will usually stay close to each other, provided that they are properly maintained. Whether in series or parallel the outcome may not be exactly the same, but it does have an effect on the battery bank.

That is why I usually recommend that campers that have not had experience with batteries start out with less expensive batteries and learn the in's and out's using them, as it is MUCH cheaper than going with high priced deep cycle batteries at first.

But those are my thoughts,

Don

[RVCamperDan]

@mustang65- I mean that makes sense, but can you ever really get two batteries that are the same? Ours are a couple weeks away from installation, but manufacturing date probably matters more... also aren't there slight differences between each battery?

[mtelkhntr]

When we bought our Jayco new in '97 it had only one group 27 deep cycle battery. With two young daughters and a wife, it didn't take long to drain it dry. I ended up replacing the single group 27 with two group 24 deep cycle 12V batteries and it nearly doubled the time before needing recharge. For that purpose I packed along an 1800 watt gen. that I'm about to replace with a honda eu2000i inverter. When it comes to batteries, the more you have the longer you'll last.

I pulled into a public dump station last year and a family pulled in with a trailer that I counted 5 batteries mounted on it. I can't even begin to imagine what they did to his tongue weight but needless to say he impressed me!

[Mustang65]

Originally Posted by Mustang65

Granted there are no 2 batteries that have the same internal resistance, but when they are new and installed together (with proper connections) they will usually stay close to each other, provided that they are properly maintained.

When I said new I should have mentioned same mfg date.

Enjoy

Don

[RoyBraddy]

Here is my two cents on what to expect performance wise when camping off the power grid...

Your two 12VDC Interstate Batteries connected in parallel will give you around 170AHs capacity and will produce 12VDC @ 25AMPS for around 280 minutes (4.6Hrs) before being totally discharged. Of course you will would never want to fully discharge your batteries so you can expect to use half of that or 2.3HRS of use.

If you replace them with two each 6VDC Golf Cart batteries connected in series to give you 12VDC you will get around 220AHs capacity. The bigger thing is these two batteries will produce 12VDC @ 25AMPS for 447 minutes (7.5Hrs) before totally being discharged. You will be able to use half of this or 3.75 hours of use. The golf cart batteries are very rugged and will hold up much long than the Interstate batteries will over time.

Keep in mind 25AMPS of 12V DC Battery power is alot of juice. You will most likely only use less than half that of that much current in your daily use camping off the power grid.

My battery bank is 255AHs capacity and I have planned on what I can use in my trailer to drain my batteries down to their 50% charge state by 8AM the next morning. This is when I connect my 30AMP trailer directly to the 120VAC Outlet on my 2KW Honda Generator using a RV30A-15A Adapter(WALMART) and can then run my smart mode on-board converter/charger unit to re-charge my battery bank back up to their 90% charge state in a three hour generator run time. Now I can do all of this all over again for the next day/night run off my batteries.

It does take some planning on what you may want to do when camping off the power grid...

My camping off the power grid story...

Roy Ken

[KiltDog]

I'm gonna get another 12v from my dealer. I just took delivery a few weeks ago, so I'm sure the batteries will be close enough as far as age. I thought about switching to a 6v system, but it seems like a waste of the new 12v battery that I have. I'll see how this setup works for me and possibly switch to a 6v system in the future.

[Jmooney]

Originally Posted by KiltDog

I'm gonna get another 12v from my dealer. I just took delivery a few weeks ago, so I'm sure the batteries will be close enough as far as age. I thought about switching to a 6v system, but it seems like a waste of the new 12v battery that I have. I'll see how this setup works for me and possibly switch to a 6v system in the future.

Thats the same choice I made. No regrets so far, but I have added solar so i canoff grid for much longer.

For future readers of this sting, i have also read a added benifot in that if a cell in one of your twin 12 v shorts out, you can disconnect one the the two batteries and you are back in business

[tjpolsin]

my advice - based on 4 days of boon docking this past weekend - buy a 2nd 12V battery, then when they wear out, replace them both with 6v deep cycle batteries.

In the mean time, invest your money in LED lights. a few years ago with fresh 12V batteries and old lights, I would barely go a 2 night weekend before my batteries would start to fade. I just replaced all my lights with LEDs and my worn out batteries with two 6V deep cycle (NAPA) batteries. The batteries were barely 1/2 gone after 4 days, and that was AFTER I put the slide in to come home. LEDs rock!!

Tim

[RVCamperDan]

so many variables! I plan on adding solar in 6 months or so- does that change anything?

[cb1000rider]

It only changes things if your batteries will outlast your days of un-available sunlight. And I'm assuming that your array will charge fast enough to top off the batteries daily.

[Jmooney]

Step 1. Change all bulbs to LEDs

[RoyBraddy]

I added a third GP24 12VDC Interstate that someone gave me. That gave me 255AHs of battery capacity. Been running my off-road trips just fine with 255AHs of batteries.

Roy Ken