Somewhere, I read that it was important to not let AGM batteries completely discharge, that they should have a good battery tender with a charge wizzard to keep them fully charged. Would that be true of 'open top' deep cycle marine batteries as well?

Lead acid batteries do not like deep cycling.

Normally, lead is converted back and forth to lead peroxide when charging or discharging. The hydrogen from the sulfuric acid picks up the oxygen from the oxide and turns into water.

When the acid level gets low enough, side reactions which convert lead into lead sulfate (permanently) can occur. The longer they sit discharged and the deeper the cycle the worse it gets. As sulfation proceeds, battery capacity goes away. Below 50% charge they will degrade quickly. (ie below 10 volts) The deeper they are cycled the more promptly they should be recharged.

Deep cycle batteries are made with thicker/different plates and can stand deeper cycling but it still isn't good for them.

AGM stands for Absorbed Glass Mat battery. They have essentially a fiberglass mat between the plates to soak up the acid, to prevent spillage, etc. They don't like deep cycling either.

When stored fully charged they will last indefinitely. Unfortunately, lead acid batteries will self discharge over time. Rate varies with temp and battery style but is about 5% per month so you can't leave them forever.

Too much charging will electrolyze the water into hydrogen gas, battery will go dry, also bad.

Fast charging should be done without too much heat or gassing. Battery tenders with modern charge controllers are very good. I haven't put water in my batteries for a year now.

Contemporary converters usually have programming that desulfates and trickle charges.

I replaced my 1994 converter when lightning hit it, the RV next to it and a tree I just took down. This new thing has more computer chips than the mainframes I worked with in 1969.

It comes with a hand held thing to attach to it if you want to order it as an add on to get everything you ever wanted to know about a battery.

Tom Taylor

So, what replacement converter did you get?

I have a Progressive Dynamics unit. Does all of the above. I've had it a year and I'm pleased with it.

I also have a PD 9260 with the Charge Wizard; my SOB had a 9160, and had the optional Charge Wizard. I was intrigued by the hand-held unit Tom has.

Rusty, i should have included that. At your recommendation, I went with a Progressive Dynamics. The orig was a 70 amp unit and PG offers 60 and 80 so I went with the 80. Had to do little adjustments as the physical layout of the box was different but it works great. I did not opt to buy the diagnostic device as to me either the battery is charged or not.

Tom Taylor

Hello fellow Barthmobilers with more electrical knowledge than I:

I really need some help in this department, but I'm afraid that I'm thoroughly confused. I went and took some photos of my set-up, sent them to photobucket, but now I can't get the photo addresses copied here, so if someone can place them here for me, it might help.

Problem: Our coach is tucked away in the pole barn for winter. My batteries are showing a charge in the range of 12.4 V and I understand this is getting a bit low. I don't think I can just plug in the shore power cord and they will charge all winter as I don't think our coach has a converter/charger to do this. Perhaps it does and I don't know what to look for.

I've read and read search results here on barthmobile concerning this topic and between automatic desulfating chargers, isolators, cutoff switches, deep cycle, and wiring in parallel; my head is spinning. I confess, electrical comprehension is my weakness.

I guess my question is this: Short of going out and purchasing what sounds like the best thing since sliced bread (the PD 9260 or 9260 with Charge Wizard) and then asking more questions about how to hook it up; can I simply plug in a trickle charger and attach it to one of the batteries and will this charge all three batteries? I'm thinking it might do the coach batteries, but not the chassis battery. I'm also thinking that it's not really the best way to go over the winter with the batteries. I keep my gel batteries in the Harley and Porsche on trickle chargers all the time with no problems, but I understand these lead acid batteries are a little different than Optimas.

I also have been reading about how undesireable the isolator is that they should be removed and desecrated to the nearest landfill... and wish I had the smarts to figure out how to replace it with one of those nifty switches like BillNY has.

I understand that my coach's PO installed Marine/RV (almost deep cycle, but not quite, and okay for starting) batteries and I should replace these with proper batteries when possible. There's a photo floating around in the photobucket that shows my batteries, but I can't get to it.

Sorry for the long rant. I've been wanting to post these questions with photos for sometime, but now that it's getting colder, I'm ready to simply pull all the batteries inside for the winter and run each one intermittently on a trickle/pulse charger... but that seems like more work than I really need to do. I did find one post by BillNY where he recommends just this though.


Kirk

Footnote: The PD 92xx includes the Charge Wizard; it'a an option on the 91xx. Both have the desulfating and trickle charge cycles.

Best solution is to remove all the batteries to a warm, dry place.

Another excellent portable battery charger/maintainer is the:

NOCO GENIUS WICKED SMART CHARGERS

I bought the G3500 model and am very pleased with it.
Go to WWW.geniuschargers.com when you open that site go to videos and select G3500 to learn about it.
It handles 6/12 volt,large & small wet, gel,MF, and AGM batteries. It also comes with two types of connectors and disconnects.

Thanks Rusty, I'll do just that.

Kirk

This was on Photobucket:

(never mind, wrong one!

That one's not mine (which is probably a good thing).

Removing the batteries and storing them with occasional charging is good for many reasons. In the process you will be checking the battery terminals and connections. When you reinstall next season you will have full charged happy batteries and good wiring

Since we have dual battery setups with different types of batteries (ie starting vs deep cycle) they are best kept isolated and charged separately. This brings in the concept of the battery isolators (available in diode or relay switch types, each with pro/cons)

For the above reasons, most coach chargers only charge the house batteries, while the running engine will charge all (with isolator)

I have a PD 9245 charger and it is very good but charges only the coach batteries. It is plugged in all the time and I haven't needed water for a year!

The crank battery only charges with the engine but can sit for about 2 months and starts easily. I usually start it about monthly so I never worry about it.

I still have the diode style isolator. For numerous reasons I plan to replace it with a relay type. It is not a bad job. There are a few options in terms of how it is set up (what controls the isolator and when does it function) I will post discussion and photos when I get to the project.

Meanwhile, if you can't get to the batteries for a while, bring 'em home. If you don't have a fancy trickle charger you can always put a generic one on a timer for 1 hour/day etc to prevent overcharging.

BTW, there are some very high end charging systems that will maintain multiple sets of batteries of different types on separate isolated circuits. Marine stuff, way pricey, way cool but probably overkill for most coaches.