Montana high country 338DB needs more batteries

[JCasper]

I need to replace the 1 battery that came in my fifth wheel and add a little more capacity. I'm thinking about 2 Trojan 6V or 1 or 2 Trojan AGM batteries. Any suggestions? We camp with hookups most of the time, but once in a while I'd like to have some capacity. I like the idea of AGM for less maintenance but someone told me that all converters won't charge them. What do I need to look for prior to purchasing and putting these in?

[Veebyes]

GoPackGo wrote:

JCasper wrote:
Lyle, Thanks for that. For the price difference, I think I'm going to buy the 6V batteries at Costco. For $83.99 I don't think I can go wrong. They are Interstate GC2. They are not the HD GC2, but still plenty for what I'm doing and $100 cheaper then buying 2 Trojan T-105.

That's what I did for my trawler. They will work great.

Out of interest, what builder/model trawler did you have?

I have had a couple of Albins. First was a 27 ft cabin pocket trawler. Still have an Albin 32+2. Not a trawler style but a great single diesel cruising boat.

Current drool boat is a North Pacific. Never going to happen.

[GoPackGo]

JCasper wrote:
Lyle, Thanks for that. For the price difference, I think I'm going to buy the 6V batteries at Costco. For $83.99 I don't think I can go wrong. They are Interstate GC2. They are not the HD GC2, but still plenty for what I'm doing and $100 cheaper then buying 2 Trojan T-105.

That's what I did for my trawler. They will work great.

[JCasper]

Lyle, Thanks for that. For the price difference, I think I'm going to buy the 6V batteries at Costco. For $83.99 I don't think I can go wrong. They are Interstate GC2. They are not the HD GC2, but still plenty for what I'm doing and $100 cheaper then buying 2 Trojan T-105.

[laknox]

JCasper wrote:
So, given the same exact draw, how much longer will a pair of T-105 last compared to one Trojan 31-AGM? I'm asking this because it would be about the same cost for batteries.

The capacity of one T-105 is rated at @25 Amps 447 minutes
The 31-aGM is @25 Amps 177 minutes

Does this really mean I'll get 270 more minutes out of them?

The "standard" to compare to is amp-hours and the 20-hour capacity is the one that you'll see most often. Given this, the flooded cell T-105 is 225 a/h while the 31-AGM is only 100 a/h. Even 2 of the 31's would only give you 200 a/h, less than 2 T-105's. The T-105 AGM loses a bit, being 217 a/h, but the lower maintenance, as well as its ability to drop to a lower charge level without damage, might make it a more desirable alternative to the 105 wet-cell. I'll be addressing this myself when I get a new FW, that's for sure.

Lyle

[laknox]

Veebyes wrote:
The AGM advantage is not just the zero maintenance thing. They are rated for far more discharge cycles than a wet cell. They also will take a much deeper discharge & recover than a wetcell. During storage the discharge rate is half that of a wetcell. Leave an AGM all winter with no maintenance, no problem. Adding more batterys in a location other than an area intended for wet cells, no problem. Put them in storage compartment under your bed if you wish, no problem.

That would be cool. Imagine, having 100+ lbs over your axles instead of in the front storage locker. 🙂

Lyle

[JCasper]

So, given the same exact draw, how much longer will a pair of T-105 last compared to one Trojan 31-AGM? I'm asking this because it would be about the same cost for batteries.

The capacity of one T-105 is rated at @25 Amps 447 minutes
The 31-aGM is @25 Amps 177 minutes

Does this really mean I'll get 270 more minutes out of them?

[Veebyes]

The AGM advantage is not just the zero maintenance thing. They are rated for far more discharge cycles than a wet cell. They also will take a much deeper discharge & recover than a wetcell. During storage the discharge rate is half that of a wetcell. Leave an AGM all winter with no maintenance, no problem. Adding more batterys in a location other than an area intended for wet cells, no problem. Put them in storage compartment under your bed if you wish, no problem.

[JCasper]

waltbennett wrote:

laknox wrote:

Since you don't dry camp much, a couple 6v golf cart batteries would certainly give you more capacity, and for minimal cost. < $100 each, at Sam's or Costco, in most places, vs $200+ EACH for Trojans. I did, and I get about 1-2 more days' camping than my dual 12v's gave me, depending on use. Yeah, maintenance is higher, but it's not a huge deal. Buy a watering system to make keeping them full is also a good investment. Now, if you plan on dry camping more than you currently do, the larger investment might be justified.

Lyle

Don't know where in the world you got a quote for T-105s that high. I paid $76 each for the four I've got two years ago. Considering they are the gold standard for flooded golf cart batteries, it was well worth it.

About the AGM vs. flooded thing. I've got 400w of solar charging the batteries and do have to check the water level once a month. It sometimes is down 1/4" or so, but never has been more than that. If you don't want to do that and have the extra money, AGMs are fine. A reminder in your Google Calendar is a lot cheaper IMHO.

You got T-105 for $76? I was quoted $135

[waltbennett]

laknox wrote:

Since you don't dry camp much, a couple 6v golf cart batteries would certainly give you more capacity, and for minimal cost. < $100 each, at Sam's or Costco, in most places, vs $200+ EACH for Trojans. I did, and I get about 1-2 more days' camping than my dual 12v's gave me, depending on use. Yeah, maintenance is higher, but it's not a huge deal. Buy a watering system to make keeping them full is also a good investment. Now, if you plan on dry camping more than you currently do, the larger investment might be justified.

Lyle

Don't know where in the world you got a quote for T-105s that high. I paid $76 each for the four I've got two years ago. Considering they are the gold standard for flooded golf cart batteries, it was well worth it.

About the AGM vs. flooded thing. I've got 400w of solar charging the batteries and do have to check the water level once a month. It sometimes is down 1/4" or so, but never has been more than that. If you don't want to do that and have the extra money, AGMs are fine. A reminder in your Google Calendar is a lot cheaper IMHO.

[laknox]

Veebyes wrote:
AHs are AHs. 2 6V batterys totalling 220AHs are the same as a single 12V battery, probably a 4D case size, rated at the same AHs. The difference is the 4D battery weighs about the same as the 2 6Vs combined & the single 4D eliminates 2 connections joining the 6Vs where there is potential for failure or leakage.

I am a big fan of AGMs, having already invested in 3 stage programable pure sine wave inverter charger. For us the dry camping is more than the occasional overnight at Walmart. We like to be comfortable doing at least 3 or 4 nights offgrid doing things like music festivals & the Albquerque Balloon Fiesta for a week. For those reasons the expense of the AGM is well worth it.

For the FHU camper with only the occasional need for drycamping overnight the wet cell battery bank, single 4D or 2 6Vs are just fine.

I'm seriously thinking of AGMs, too, on the next FW. I'll start with 2 6v then, if I do some solar, might add 2 more.

Lyle

[laknox]

GoPackGo wrote:
I did what Old Biscuit suggested in his last line - I have 2 each 12-volt Grp 29 batteries in parallel.

I am a big fan of 6-volt batteries - had 4 of them in my trawler (replaced a stupidly heavy 4D), but in an RV where you have 2 each 6-volts in series you are completely dead if one of the 6-volts dies. If one of my Grp 29 batteries dies, I still have the other one working until I can get the dead one replaced.

I'm no expert but none of the 4D batteries I see are deep cycle. I understand they were originally developed as tractor/dozer starting batteries. Someone feel free to correct me if that is wrong.

This is the down-side to 12v batteries. True deep-cycle 12v batteries are =very= rare and even more expensive. For lighter use, 2 12v batteries are just fine, and are better than 1, but if you're doing =any= dry camping, then 2 6v are, IMO, the better choice because you can discharge them further, without damage, than you can 12v batteries. The =net= capacity is greater with 6v than 12v since, if you discharge the 12v to the same point as you can the 6v, you'll damage the 12v battery and reduce its life span.

Lyle

[JCasper]

I'm going to purchase 2 6V this weekend. I think it's the best bang for the buck. I'll probably go with the Trojan T105

[JCasper]

I'm not sure yet which route I will go, but I'll need another battery box. Can I purchase one and splice the vents in to the existing one? I'd rather not cut another hole in the fifth wheel if I don't have to.

[GoPackGo]

I did what Old Biscuit suggested in his last line - I have 2 each 12-volt Grp 29 batteries in parallel.

I am a big fan of 6-volt batteries - had 4 of them in my trawler (replaced a stupidly heavy 4D), but in an RV where you have 2 each 6-volts in series you are completely dead if one of the 6-volts dies. If one of my Grp 29 batteries dies, I still have the other one working until I can get the dead one replaced.

I'm no expert but none of the 4D batteries I see are deep cycle. I understand they were originally developed as tractor/dozer starting batteries. Someone feel free to correct me if that is wrong.

[Veebyes]

AHs are AHs. 2 6V batterys totalling 220AHs are the same as a single 12V battery, probably a 4D case size, rated at the same AHs. The difference is the 4D battery weighs about the same as the 2 6Vs combined & the single 4D eliminates 2 connections joining the 6Vs where there is potential for failure or leakage.

I am a big fan of AGMs, having already invested in 3 stage programable pure sine wave inverter charger. For us the dry camping is more than the occasional overnight at Walmart. We like to be comfortable doing at least 3 or 4 nights offgrid doing things like music festivals & the Albquerque Balloon Fiesta for a week. For those reasons the expense of the AGM is well worth it.

For the FHU camper with only the occasional need for drycamping overnight the wet cell battery bank, single 4D or 2 6Vs are just fine.