Chinook RV

Now that I have some solar I want to add more batteries. I think I read someone had taken out the battery tray to make room for more batteries. How or where can I squeeze in 2 more 12v's? Right now I have 2 house batteries but they are flooded. I would need access to monitor the water levels. Or should I wait until they go bad and get 4 AGM's?

Here are the options I know of:

1) Two Group 27, or Group 31 on the stock Concourse tray.

2) Three Group 27 or Group 31 in the compartment with the tray removed (I think they could fit a couple different ways, maybe even right side up although it might be hard to check or "water" them - but they do make watering gizmos). If AGM's then of course no need to water them, and they could also go on end at the back of the compartment (AGM's can be put in any orientation except upside down).

3) Basically as many as you want under the couch, most likely AGM (but you could conceivably do flooded with added overboard venting and a really good box). I have three Group 31 AGM "puffies" (125 amp hours each) under the couch.

4) Lithium under the couch.... but that requires even more changes to charging/equipment than AGM. Not that it isn't possible though, and they have some great benefits. Reason I would put lithium under the couch vs. in the battery box is they don't like heat and they can't be charged below freezing. Under the couch the temp tends to stay pretty consistent. Cool but not freezing. Given the givens, I decided to wait until the (theoretical) next round for lithium and went AGM this time. I'm happy with the setup.

3 group 31 AGM duracell's from SAMs club here. Removed the tray. I stated a thread about it. Even without extra solar, they were well worth it to me.

Thank you both. I love the idea of lithium but after reading your separate post on what has to be changed, it's too much for me.

Heh, don't feel bad. I decided the same thing (too much right now in terms of money, attention needed, and changes to my system) and I'm "into it" and have the skills and tools to change stuff. I can see the next round possible being lithium though....

One thing to keep in mind. Well, two things:

1) Your batteries will thank you if you choose chargers that have a adjustable charge parameters and temperature compensation (the typical converter upgrades do not). My priority order would be solar controller, AC charger, and then alternator (which I doubt I will ever do, but it's possible to put in a "battery to battery" smarter charger). That's because I charge 90% of the time with solar, very little with the alternator, and almost none with shore power or generator.

2) A large battery bank is great, but just make sure you can put back what you take out. Otherwise it's just heavy to carry and expensive to replace.

For me AGM's are currently the sweet spot, but it all depends on usage patterns, installation parameters, inclination, and preference. If you are interested, we could talk specifics.

Oh yea, did the progressive dynamics retro fit too. 3 new batteries were like $6-700, don't want to cook them with the dumb charger(added benefit of quick recharging too). I think the PD unit was like $300(?).

Just to add to what I said above, the whole charging system is inter-related. As a part of this, batteries like specific charge voltages. So you need to have a charger (AC [shore, generator] and solar) that can be adjusted to the voltages your battery brand specifies (you typically set two voltage parameters, absorption and float; there is also equalizing which you may do infrequently and which also has a settable parameter). The other really important thing is temperature compensation. Here's why: Those very specific voltages you just set your programmable charger for? They only apply at 77ºF. Any colder or any hotter (the battery, not the room) and that voltage changes. So even if you have a programmable charger, if it's not temperature compensated you will be using the 77º setting all the time. My batteries are often at 40-50º and that's a huge difference.

Take right now. I'm poking a few buttons on the solar controller display for this info. I'm boondocking and so solar is the only thing charging the battery bank right now.

My batteries are in the absorb stage. The "setting" for this (as specified by battery mfgr.) is 14.3 volts. So that's what I set into the controller for the absorption voltage. But guess what? The solar controller is putting out 14.55 volts (a huge difference in the battery charging world). Why? Poking the display again I see that the battery temperature is 55º F (and that's with the batteries under the couch, not outside). If I had a non-temperature compensated charger - even if I set it perfectly in the custom settings - my batteries would be getting chronically undercharged every time they were below 77ºF, and overcharged any time they were above 77ºF.

From a charger owner's perspective, temperature compensation is easy as long as you buy a charger that provides for it. Along with the charger will come a thin wire that has a pre-made way to fit into a special terminal on the charger, and then a ring terminal (usually) on the other end. You click the one end into the provided receptacle on the charger (solar charger or AC charger), and then fasten the other end to one of your house batteries (typically on the terminal, although I have seen some older ones that you tape to the side of the battery - not quite as good, but worlds better than none at all). Nothing hard about it.

One more step you can take is to look in the battery mfgr's manual again, and see how much they want the charging voltages to change for each degree up or down from 77º. That, too, can be set in the charger (there was a default setting in my solar charger, but it was not correct for my batteries so I re-set it as provided for).

My guess is that incorrect charging is the main reason many batteries die. Taking them below 50% shortens their life, but it's likely ocassional. Incorrect charging is chronic and happens every day - even if you are being really "good," and only taking them down to 80% charged. Even on those "good" days it's stressing the batteries by charging them at incorrect voltages.

I'm not as up on flooded batteries, and my sense is they will take a bit more abuse. But I did just have a look at Trojan's website (they are a premier maker of flooded cell batteries) and they DO specify charging voltages and temperature compensation and also do say that under/over charging will shorten their life. I downloaded the data sheet and here is a screen shot from it. Flooded cells may well be less "delicate" than AGMs (pretty sure they are) but this tells me they will still do better with precise charging and temperature compensation (although somewhat less expensive to replace when they die).

This is for a common, T-105 sized "golf cart" flooded battery by Trojan. If you click on it it will open in focus.
I think I remember that when I was charger shopping that the typical "converter upgrade" chargers didn't have temperature compensation, and may not have had adjustable charging either. If this is true, I'm not saying they don't have a place. If you have $100 batteries and it's not an issue to replace them (easy access for removal, you are near battery stores) then it may be just the ticket for a balanced system. For myself, with a larger (more expensive) system, it wouldn't make sense because I want to keep everything up to the same "level" (if that makes sense?). I mean, my system is puny compared to many RV-ers and boaters (can you say 1500 watts of solar and a 1500 ah battery bank - I read of that size system often on larger rigs). But just the three batteries I have are around $1200 total, so I had lots of motivation (and even cost justification) when I went to choose solar and AC chargers.

(Perhaps I misread, or maybe things have changed, but when I was charger shopping the "converter" upgrade chargers didn't have temp compensation and I don't think the charging voltages were adjustable - although that kind of makes sense if they aren't compensated. If I misunderstood that, then never mind anything I said about those, specifically. The main idea is just to know what you are and aren't getting, and balance the system to your preference. The only thing that really makes me cringe is either a dangerous setup, or one in which the batteries keep dying and the owner doesn't know why?!?? or just assumes they only are supposed to last a year, etc.)