Battery Upgrade Suggestions Please

[AlanC]

Hello,

I'm looking for some guidance for upgrading my battery system for our XLR Nitro 25KW toy hauler.

Current batteries are the stock pair of Interstate HD24-DP 405 CCA 5050 MCA.

I really dislike the plastic Camco battery boxes the trailer came with. They are shoved so close together that you can't even get the lids to seat properly.

We have an on-board ONAN Cummins 5500 generator on board, so we can recharge our batteries as needed during the day, but we've had several instances of batteries getting depleted far enough by running the heater overnight that they were too low to start the generator the next morning. (I posted another thread here a while ago about this.)

Since that post I've added a Xantrex 2000W 807-2055 Inverter Charger and a Victron BMV-712 Smart Battery Monitor.

I'd like to know what my options are for upgrading the batteries. I'm not sure if I'm ready to make the leap to lithium batteries, but I would like to at least upgrade to something better than what we have now.

I would really like to upgrade the battery boxes and was wondering if changing to a single, larger battery such as an 8D would make any sense?

One more issue I'm trying to figure out is that the Xantrex inverter will not charge our batteries at the highest current setting of 55 amps or event 35 amps. If I set it to the higher settings it will charge for a few minutes and then shut off. Does this sound like a cooling problem? Or is it related to the type of batteries I have?

I do realize there are a lots of threads here that cover this, so I'm just hoping you can get me pointed in the right direction and then I can dig in and do some more research.

Thanks!

Alan

[clr]

Well from your post it appears that you have added an inverter/charger to the mix feeding your existing battery bank. Therefor you will have two chargers trying to both sense and to recharge the battery bank. That will not work will since the charger needs to be able to sense the state of charge of the battery. The charger will see the output of the other charger and be fooled into thinking that the battery is charged when it is in reality not. Therefor use only one charger to recharge the battery.

Since you have a type 24 currently you should be able to replace it with either a type 27 or 31 true deep cycle battery for increased capacity. Since you are also looking at replacing the battery boxes this should not be a problem. I prefer cg2 type battery for rv use but of course you need two connected in series to get 12v. Therefor the capacity of the batteries do not add together, like they do when you parallel batteries. Bottom line is you may be able to get larger capacity with two larger 12 batteries in parallel, than two 6v batteries in series.

[AlanC]

Originally Posted by clr

Well from your post it appears that you have added an inverter/charger to the mix feeding your existing battery bank. Therefor you will have two chargers trying to both sense and to recharge the battery bank. That will not work will since the charger needs to be able to sense the state of charge of the battery. The charger will see the output of the other charger and be fooled into thinking that the battery is charged when it is in reality not. Therefor use only one charger to recharge the battery.

Thanks for the reply!

Just to clarify, the factory charger was replaced by the new inverter/charger.

[MtBiker]

The cables size from the charger to the batteries may be hindering the charger capacity. Smaller cables tend to make the resistance higher so the charger thinks the batteries are at a higher State of charge than they actually are.

[AlanC]

Originally Posted by MtBiker

The cables size from the charger to the batteries may be hindering the charger capacity. Smaller cables tend to make the resistance higher so the charger thinks the batteries are at a higher State of charge than they actually are.

The cables between then inverter and the batteries are No. 2/0 AWG.

The inverter install guide specifies this gauge and that they are no longer than 5 feet long and I made sure to follow these guidelines.

[boondocking]

I would go with a pair of GC2 (6v). You will get more capacity (amp hours) with a pair of 6v than you would with a pair of 12v at the same physical saize of the 6"s.

[AlanC]

Originally Posted by boondocking

I would go with a pair of GC2 (6v). You will get more capacity (amp hours) with a pair of 6v than you would with a pair of 12v at the same physical saize of the 6"s.

Is there a recommended brand/size for this setup?

Best bang for the buck?

[clr]

OK just for clarification here, an RV of most types has a converter that takes 120vac and makes 12vdc to power the unit and to charge the batteries. An inverter takes 12vdc to create 120vac so that your can run ac items when you are not connected to shore power. So I am thinking that you replaced the converter and not the inverter.
May have recommended CostCo for the best bang for the buck when purchasing a battery.

[AlanC]

Originally Posted by clr

OK just for clarification here, an RV of most types has a converter that takes 120vac and makes 12vdc to power the unit and to charge the batteries. An inverter takes 12vdc to create 120vac so that your can run ac items when you are not connected to shore power. So I am thinking that you replaced the converter and not the inverter.
May have recommended CostCo for the best bang for the buck when purchasing a battery.

For further clarification, this inverter is a combination inverter/charger.

Inverter Charger | Freedom HFS Inverter/Charger | Xantrex

It takes 12vdc and converts it to 120vac when running on batteries.

When running off of shore power or generator, it takes 120vac and charges the batteries.

There's a separate switch that takes power from the shore plug or the generator depending on which one is providing power.

Thanks!

Alan

[clr]

So did you disable the charger in your converter? If you did not then you have two chargers trying to charge one battery bank.

[AlanC]

Originally Posted by clr

So did you disable the charger in your converter? If you did not then you have two chargers trying to charge one battery bank.

There is no converter. It was removed when the inverter/charger was installed.

[rk06382]

Originally Posted by AlanC

Hello,

I'm looking for some guidance for upgrading my battery system for our XLR Nitro 25KW toy hauler.

Current batteries are the stock pair of Interstate HD24-DP 405 CCA 5050 MCA.

I really dislike the plastic Camco battery boxes the trailer came with. They are shoved so close together that you can't even get the lids to seat properly.

We have an on-board ONAN Cummins 5500 generator on board, so we can recharge our batteries as needed during the day, but we've had several instances of batteries getting depleted far enough by running the heater overnight that they were too low to start the generator the next morning. (I posted another thread here a while ago about this.)

Since that post I've added a Xantrex 2000W 807-2055 Inverter Charger and a Victron BMV-712 Smart Battery Monitor.

I'd like to know what my options are for upgrading the batteries. I'm not sure if I'm ready to make the leap to lithium batteries, but I would like to at least upgrade to something better than what we have now.

I would really like to upgrade the battery boxes and was wondering if changing to a single, larger battery such as an 8D would make any sense?

One more issue I'm trying to figure out is that the Xantrex inverter will not charge our batteries at the highest current setting of 55 amps or event 35 amps. If I set it to the higher settings it will charge for a few minutes and then shut off. Does this sound like a cooling problem? Or is it related to the type of batteries I have?

I do realize there are a lots of threads here that cover this, so I'm just hoping you can get me pointed in the right direction and then I can dig in and do some more research.

Thanks!

Alan

Yes. Cooling of your Inverter/charger is important. I had a problem with the cooling of my Inverter/charger. I also used 4/0 AWG cables to the batteries.

Get an Infrared Temp-Gun to find out:

[boondocking]

Originally Posted by AlanC

Is there a recommended brand/size for this setup?

Best bang for the buck?

The size for 6 volt is GC2. You can pick up GC2 batteries at Costco for $100 each or less. Also Napa Auto Parts, a little bit pricier. Walmart also has them sometimes.

My pair of Napa brand GC2's are 8 years old and still going strong.

[GlennW]

Hello Alan

If you are seeing the charger shut off early it could be because the batteries are old and have lost capacity. This could be why your furnace drains the batteries overnight. The batteries have lost capacity and this doesn't show on a battery tester. When you get the new batteries, your charger will work at a larger current for a longer time after being depleted. Don't go below 50% charge.

Glenn

[menekaunee]

When I bought my Fifthwheel the dealer installed a 1-24 group battery.
I replaced the 24 group battery with 2-27 group 12v AGM batteries. I purchased Trojan Batteries because they are made in America and have a great reputation.
I stayed with 12v instead of 6v batteries so even if one battery went bad, I would still have 12v power.

[boondocking]

Originally Posted by menekaunee

When I bought my Fifthwheel the dealer installed a 1-24 group battery.
I replaced the 24 group battery with 2-27 group 12v AGM batteries. I purchased Trojan Batteries because they are made in America and have a great reputation.
I stayed with 12v instead of 6v batteries so even if one battery went bad, I would still have 12v power.

You would have power if you caught the bad battery in time and disconnected it before it totally discharged the good one.

[camaraderie]

My thoughts...
1. An 8D will get you 250 a/h's in a big, heavy unit. A pair of good golf carts will get you 220 a/hs in a form factor that is easier to work with and is widely available. MANY 8D's are dual purpose type plates internally so you would have to be careful to get a real deep cycle. Your choice. I had 8D's (4) as my marine bank and was well satisfied.

2. I think you are dropping out of BULK charging early because you're getting to resistance levels quickly as you go from 50% to 70% and transition into absorbtion phase. It also may be that since you have 150 amp hours of wet cell battery ...that 25% of that or slightly less is the charge current capacity...of 37 amps or so which is a limitation of wet cells.
If you want to try to charge faster and not get lithium pricey or have to change other charging components...you might look at the Oasis Firefly carbon foam design which takes exceptional ammounts of current and charges fast with no sulfation due to design materials. Another exotic design is the Odyssey thin plate pure lead AGM type battery which offers charging capacity up 1C and high current availability as well. Both of these designs have been in production for a while and Odyysey built some DieHard Platinums for Sears. Firefly only comes in a Grp. 31 but they have limited capacity and sell quickly. Both are more expensive than standard AGM and much less than LiFEPo and are drop ins for any 3 stage charger that has an agm setting.

3. If your Xantrex inverter has a temp sense function...it would be a good thing to employ it to insure you don't get charging temps over 120 degrees on expensive batts!
Good luck!

[dbledan]

I just did something similar. I plan to go to battleborn but did not want to replace the converter until I had time to move the batteries and upgrade the wiring. I can reuse the batteries for other applications next year when I have time to do the moves.

I went with 2 6v CG2 batteries for now from a single group24 to get to 235Ah.

I also replaced the battery box with one of these and replaced the lock with a matching key cam I had. https://www.harborfreight.com/2-13-c...box-61602.html

It was a perfect fit for my trailer behind the propane over the existing rails. I installed some L brackets to hold they batteries in place inside the box. I plan to move the shut-off inside it as well but that will need to wait for things to cool down to do that.

[dbledan]

Originally Posted by dbledan

I just did something similar. I plan to go to battleborn but did not want to replace the converter until I had time to move the batteries and upgrade the wiring. I can reuse the batteries for other applications next year when I have time to do the moves.

I went with 2 6v CG2 batteries for now from a single group24 to get to 235Ah.

I also replaced the battery box with one of these and replaced the lock with a matching key cam I had. https://www.harborfreight.com/2-13-c...box-61602.html

It was a perfect fit for my trailer behind the propane over the existing rails. I installed some L brackets to hold they batteries in place inside the box. I plan to move the shut-off inside it as well but that will need to wait for things to cool down to do that.

Battery box picture. Had to drill a few vent holes and add trim to keep cables from chaffing.

[FFred]

By your posted description it sounds like you have start batts not deep cycle batts.

These do not work at all well as house batts.

I would measure the case you will keep them in and see of more batts could be fitted.

6V in series is usually best bet as long as they are golf cart,,true deep cycle batts , but 12v works almost as well.

CCA or MCA on the batt label is a start batt, a "20 hour rate" is used on true deep cycle batts.