Battery recommendation? Whatcha running?

[68camaro]

Thanks all good info but this quickly went over my head. I'll need to re-read and try to figure out what some of the posts mean.

1. As the battery would be inside, I decided to go AGM with just a couple of circular vents on the front of the seat in case it ever got overcharged.

Kdarling, does this mean AGM are not good for locating outside? I have 2001 and two batteries are located in compartment you access from outside. It's vented but not weather controlled.

[Blue~Go]

68,

I was thinking that I really owe your thread an apology. My post about inverter/alternator had nothing to do with your original question. The reason I hadn't chipped in initially was you were looking for something relatively quick and inexpensive, which isn't my battery bailiwick.

But now that you are asking about AGM (even though I'm not kdarling), no, there isn't really anything wrong with putting AGM's outside. It's the opposite: You CAN put them inside less inconveniently than flooded cells (due to lesser venting requirements plus the ability to orient them numerous ways). They don't love heat (most batteries don't), but unless you are in a very hot area (and keep your rig air-conditioned all the time), inside probably won't be that much cooler than outside so I don't see that as a big thing.

Most batteries don't mind cold, although IIRC they may be slightly less efficient while they are cold (but MUCH happier than if they are kept in a hot place). Basically, back in the day when boats all had flooded cells, winter storage could be just charging them up and leaving them (very little self-discharge at cold temps). So flooded cells, outside usually (but could go inside with some design considerations); AGM can also go outside but easier to put inside than flooded cells.

With lithiums there is a bit more impetus to put them inside (vs. either/or), because they can't be charged below freezing (and they don't like heat). They can be discharged below freezing though. Probably not on your menu though, because if you want to make AGM's look cheap, price lithiums (they do pencil out pretty well in the long run, but that's dependent on use case and other factors, plus you have to buy them initially).

I see a few advantages to lithium, depending on how you use your bank:

1) They don't have the lengthy absorb stage. Not such a big deal if you are plugged in (almost unnoticeable), but if you are running on solar power, then giving up 2-3 hours of prime sun time to stuff wee bits of power through the eye of a needle is a sacrifice.

2) They don't have the big Peukert penalty. This is of no importance to me as I don't tend to run that type of loads; but things like microwaves, Air-con, and induction cooktops make a difference.

3) They don't mind not getting up to 100% charge, and you can draw them down further.

4) Lastly, they are lighter weight (maybe not such a big deal in a 10,000# RV unless you plan to stuff a large number of batteries in).

If I had to replace my batteries right now, with my boondocking/solar use case... I'd consider lithium but not sure I'd go with them. They'd be nice, but I am already able to get up to 100% most days, I don't tend to run big Peukert loads, and I am still way below my GVWR. Since my AGM bank is still healthy, I can put off any decision (and meanwhile things are still being learned about how best to treat them, charge them, etc.). Not that I'd discourage anyone if they wanted them now.

To me the big benefit of going AGM (this was back in 2014) was being able to bring them inside. It made the wiring easier/shorter, and I find the vented/outdoor storage SO valuable (where the batteries used to be). And the lack of outgassing/corrosion is nice. But that's an individual thing so others would likely feel differently.

BG

PS: kdarling, that's interesting about Trojan making lithium now. I am comparing different lithium options for another project wherein weight is super important (and I don't have room for more than two batteries or much solar so space/no-absorption is too). The Battle Borns look interesting, and they were really nice when I called; but I'm SO SPOILED by the Lifeline battery manual! Even some of the more expensive lithiums don't have the equivalent literature. If Trojan is going to put out better documentation, fantastic.

[68camaro]

I was thinking that I really owe your thread an apology. My post about inverter/alternator had nothing to do with your original question. The reason I hadn't chipped in initially was you were looking for something relatively quick and inexpensive, which isn't my battery bailiwick.

No apology necessary, this is all good information. I did stick two deep cell 24's in just to get me through 4 days of boonedocking, I really wasn't an energy hog but had to run generator each day to recharge but even though batteries new not sure I got to 100%.

One night temps got down to 25*, I was heating by using furnance (no shorepower) and at 4am Low Voltage Alarm went off (meter read below 12) so I put rig in storage mode and cranked up Mr. Heater Buddy to stay warm. But interestingly when I woke up a couple hours later voltage on battery bank was back up around 12.2 volts. I wonder if cold had impact on Low Voltage Alarm going off, however when I awoke it was still mid-20's.

I will post a message or start threat topic on this, but my #1 goal going to Overland Expo was to figure out best battery bank, solar, inverter, charger etc...I spent a lot of time talking to experts in these fields but I will say the one area where everyone had difference of opinions and favorites was on batteries. There really was no consensus on best battery for my use. So really, even though I am a little more informed I am still way off in making decision on what batteries to get.

But now that you are asking about AGM (even though I'm not kdarling), no, there isn't really anything wrong with putting AGM's outside. It's the opposite: You CAN put them inside less inconveniently than flooded cells (due to lesser venting requirements plus the ability to orient them numerous ways). They don't love heat (most batteries don't), but unless you are in a very hot area (and keep your rig air-conditioned all the time), inside probably won't be that much cooler than outside so I don't see that as a big thing.

I am in VA and do most all stuff in hot south in summer, if I go AGM probably keeping outside could be better because when rig sits, it bakes in sun even especially cover on. Plus not sure where they'd fit inside with club floorplan.

2) They don't have the big Peukert penalty. This is of no importance to me as I don't tend to run that type of loads; but things like microwaves, Air-con, and induction cooktops make a difference.

Ability to run A/C here in South would be soo nice, if not on shorepower summer nights can be crazy hot humid. Costs to run a/c I think would be cost prohibitive.

If I had to replace my batteries right now, with my boondocking/solar use case... I'd consider lithium but not sure I'd go with them. They'd be nice, but I am already able to get up to 100% most days

I don't believe my deep cell get to 100% so already I am at 20% lost capacity. Whatever I do I will go with a Redarc battery management system that replaces both current smart solenoid (separator) and charge controller. It will assure what ever battery type I chose charges to 100%.

Thanks for taking time, I can't believe how difficult the battery choice is.

[68camaro]

what did you end up doing?

I ended up buying cheapest deep cell I could locate very fast, Walmart had two group 24's in stock at $70 each (may have been $65), they were out of group 27's. So for $150 bucks I was out the door. It will be dead money unfortunately, but I literally had no time to look around.

[Blue~Go]

It can definitely be confusing, and although there may be wrong answers, there also isn't just one right answer. The biggest factor for me is identifying your primary use case (or use cases if you have more than one).

For me this was simple: I boondock most of the time, hate noise, and don't expect to be able to run giant loads without plugging in. Also, from years of living on boats, my life is mostly 12 volt and I'm used to monitoring my energy consumption. I'm also used to the idea of spending money if I need to upgrade components for good reliability/safety/performance. That doesn't mean there was only one way to set up my system, but it did point in a certain direction.

What's your primary use case?

[kdarling]

AGM also have a lower Peukert number than most FLA, so there's that.

Re: Trojan lithium coming out soon:

https://www.trojanbattery.com/trillium/

I love that most include a SOC indicator on top. I think every lithium should have that plus a cycle counter. The latter won't be important at first, but over the years it might become quite good info to know.

https://www.trojanbattery.com/pdf/Trillium_Brochure.pdf

[chin_k]

Now that you have pay for them, I would keep the $150 batteries, and use them until they are dead. In the mean time, keep educated yourself on the technology. It is a improving technology, and the longer you can wait, the better chance you will be end with a better deal. Have you every heard anyone said "Oh, I wish I got that NiCd battery pack for my RV back then when it was more readily available!" The reason is that in this arena, the weak (is that a pun?) one will be eliminated, and it is very competitive. The surviving ones (AGM, flooded, etc.) are around because they have specific advantage (cost, power, ...) that make they attractive to specific use cases.

[Blue~Go]

Another comment, since you have batteries that are getting you by for now. If it were me, I'd take the time to improve the basic DC distribution system (wire runs/connections/over-current protection/switches) scheme.
That's a weak point for most RV's. In other words, plan and implement a more robust, logical, and safe setup for the main DC power distribution. This would include things like bus bars (or equivalent), main battery switches, proper fusing, wiring sized for moderate-to-little voltage drop AND the ability to fuse them at their typical power draw.

This is one of the first things I did, and I have never been sorry. Even if you decide to change something down the line, it's easier with a good "framework." Essentially it becomes more easily modular.

Some lithium setups utilize a "load bus" and a separate "charge bus." (Not usually the "drop in" types, but the types with an independent BMS, etc.). I actually think that's a nice, logical division even if not strictly necessary with all setups. Unless space is incredibly tight, it's not that much more space consuming.

But the main thing is having something that's organized, properly fused, labeled, and logical. Once you have that you can build on it. The stock setup (in most RV's not just Chinook) sticks you with that "all in one" brown box power center, and makes it difficult (I heaved that joyfully out the door first thing). There is also the issue of long/skinny wiring runs, no or inadequate over-current protection, and lack of true switches. All solvable though (and nothing you'd avoid in any other typical RV I know of).

Once you have a component setup, you can choose your various devices (shore charger, solar controller, batteries, meters) and even change them (modularly) as times or usage changes.

So yeah, if it were me (and if a robust DC power system is something you desire), that's what I'd spend my time doing while my cheap Group 24's went down the slow death slide. (In fact I did kind of do that, as my Chinook came to me with one lonely Group 27 cheapie house battery, and the stock solar panel; I lived with that while I built up my DC distribution system, then got a battery bank that suited my use case.) My AGM bank (chosen in 2014) are still suiting my purposes, get up to 100% most days, and did respectably well when I put them through a 20-hour load test last spring. So whew, I don't have to choose new ones right now

[68camaro]

Hi, does anyone know if four (4) size 27 batteries will fit in battery compartment in Concourse? Would they fit on tray or will they fit if I take tray out? These are Full River 6V AGM so no need to check water level.

Thanks,

[Blue~Go]

I think you probably could get four in there. I've seen a photo of three standing on end, up against the "back" wall, terminals facing out. Then perhaps a fourth one in front of it "right side up." You would need to remove the tray to do that (four bolts on mine). Plus measure the specific battery of course (or look up sketches). All Group sizes aren't EXACTLY the same in each brand. Terminals may be taller, handles may stick out, etc.

BUT.... I would be nervous about that. Here is why:

If you look at that battery box, it's just a fiberglass box laid up against the floor and tabbed into place. I'm not saying it's weak, but I'd wonder about it if I put twice as many batteries in there, as a concentrated load and then bouncing down the road. Might not be a problem but...? The two original batteries and tray would have weighed something like 155# or so I think. That's a judgement call since you don't know unless it does break. It might be fine. Or one could reinforce.

Also, I think that fourth battery would make it a real bear to do all the connections, and/or to get to them if needed in future.

Since there is no advantage I know of in getting 6 volt batteries with AGM (vs. in flooded guise, where they were tougher than other flooded cells) -- I think in AGM it's just a different shape), I don't think I would. You then have to have an even number (to make 12 volts), and four is going to be a pain. What would the amp hours be, something like 400? Three Lifeline GPL31XT (12 volt AGM) would be 375 amp hours, and I think they would fit in a lot easier (minus the weight question - they would be 225# total for the three, each one is 74# and 125ah). A group 31 is nearly the same size as a 27 (Lifeline has precise sketches on their website of each battery).

(I had Full River 12 volt AGM previously in another vehicle, so nothing against them as a brand.)