Adding AGM batteries to a Lance 845.

daveshan wrote:

deltabravo wrote:

daveshan wrote:


My latest direction however is putting 2x100w panels on top wired in series

I think you meant to say "wired in parallel"

Wiring in series increases (doubles) the output voltage.

I have two 150 watt panels on my AF, and would like to upgrade to AGM batteries, because the wet cell batteries are failing, and it's impossible to check the water in them without un-wiring them and completely removing them.

Nope, wired in series, gets the voltage up there and the MPPT controller steps it back down, more efficient in low light like early mornings/clouds etc. Now if I used 100w/24v panels then series would be the way to go.

You have it backwards. Any shading and a panel's output can be cut by two thirds very easily regardless of the diodes employed. Higher voltage does nothing in terms of efficiency beyond minimizing current loss from the panels to the controller. My run from the panels to the controller is less than 8 feet and I used 8ga wire so the current loss is less than 3%. Had I used 12ga wire the same 3% loss would have required 24 volts. I would have looked for two 34 volt panels and still wired in series as the optimum choice.

There is way too much concern about current line loss. As my two 100 Watt panels recharge my 220 AH at 12v batteries in 2 hours of daylight on average, I could have half the current flow and still recharge the batteries in 4 hours which is hardly a problem.

I don't know the specs for the 85 Watt panel that Lance provides but if it provides 34 volts output then the 12ga wiring that Lance installs will not be a problem in terms of charging performance for a single house battery and may be OK most of the time with two batteries in the bank.

deltabravo wrote:
I priced some Deka AGM batteries, I knew they were pricey. About $250 for a group 31.

Actually, that is an economy priced AGM and a well respected mfgr.

If price is an issue, I know Sam's Club has 100AH grp 31 AGMs for $180. They are relabeled as Energizer. Costco may have something like that.

I should add that in the eastern states Sam's you get a Duracell which is a relabeled Deka for $180.

HTH;
John

My 2011 silverado 1500 has a space under the hood for an extra battery. I guess its there for a plow setup or something. Dont know about the 2500 but thats where I would go if an extra battery was needed.

I priced some Deka AGM batteries, I knew they were pricey. About $250 for a group 31.

CHeck out AM Solar. I have them do my solar install.

The current battery is an Armor Plate 36, APDC 24-36.
The compartment measures 8 deep x 11.5 tall x 15.5 wide.

I'd like to start with a good solid battery, or two if I can fit them, in that location.

I'll do some reading on the links posted and get started on the solar panel this winter!

bcbigfoot wrote:
To me the real advantage of the AGM batteries is their ability to be heated by cabin heat. If I camped in 50f+ temps I would stick with flooded lead acid batteries. However I typically camp in the shoulder seasons and can see 10f to 30f temps for weeks, it is difficult to keep cold batteries charged up, they take a charge very slowly and drop to approx. 50% of their capacity at 10f. The colder it gets the more the batteries are needed for furnace, lighting so on, but the less you have available. I like my heated AGM's because I have full capacity when they are most needed.

At the advise of Sleepy I added battery warmers to my battery's. They work off my genset,s a/c

To me the real advantage of the AGM batteries is their ability to be heated by cabin heat. If I camped in 50f+ temps I would stick with flooded lead acid batteries. However I typically camp in the shoulder seasons and can see 10f to 30f temps for weeks, it is difficult to keep cold batteries charged up, they take a charge very slowly and drop to approx. 50% of their capacity at 10f. The colder it gets the more the batteries are needed for furnace, lighting so on, but the less you have available. I like my heated AGM's because I have full capacity when they are most needed.

tplife wrote:

narcodog wrote:

tplife wrote:
S Sean, we highly recommend the Optima AGM batteries for your application. No degassing, no need for a battery box, can be mounted inside occupied enclosures (like under the dinette), can be mounted at any angle, no explosive degassing or need for vents, the advantages are many. Note that the "Rock my RV" program shows inside applications involving Group 24 Blue-Top Optimas under dinettes linked to roof-mounted solar panels. We use an Optima Blue-Top ourselves as a "house battery", and it has a lot of features over a lead-acid battery.

You can do better then Optima AGM's they have a max of 55amphrs. For the price you pay for the Optimas you can get battery's with 110 for the same price or very close to it.

Except that you can use more of the AH from an AGM battery because they can be discharged lower than lead-acid batteries. That is why an AGM battery is smaller and lighter - it will deliver the same Ah load as a higher Ah battery for its Group Size because it is a very different animal altogether than a lead-acid battery. That 110 Ah battery you would use has a lot of limitations due to installation, safety and handling that aren't an issue with an AGM battery. The OP wants to know about an install under a dinette, which is a very stupid idea if using a lead-acid battery inside an occupied enclosure. While costing more, switching from lead-acid to AGM for our "house battery" and my Harley batteries is one of the best decisions I ever made.

I guess I didn't make my self clear. 110 amp hr AGM's can be had for about the same price of the over priced Optimas that only have 55amp hrs. I had Optimas and in fact I have one now. i had one replaced under warranty and the current one will not hold a charge for longer than a week.

My other two AGM's are group 31's 110 amphrs and they work great and they cost just a few dollars more than the Optimas at twice the amps.

AGM's are not necessarily lighter mine weigh 65 lbs each.A group 24 AGM weighs about 50lbs and has about 55 amp hours.