3 stage charger?

[_DJ_1]

Within the next 30 days I am getting my new Dometic 12 volt fridge installed. Also at that time I am getting an AGM battery. I'm afraid to plug in to shore power when possible as the wet cell battery is inside the TC. It is in a vented to the outside box but I've looked at the box and it is not air tight.

Anyway, just wondering if getting a 3 stage is more critical with an AGM battery.

Thanks......DJ

[wa8yxm]

There are basically 4 or 5 types of chargers. I will describe.

Some, like the Magnetek 6300 series do a slow charge and do not know when to stop, These will kill your batteries,, With flooded wet cells you can keep adding distilled water so it's not too bad, but with AGM's you can not do that.

Some (And the Magnetek can also fall into this group) are single stage and again, charge slowly and NEVER finish the job.

Some are Two Stage (Parallex 7300T.. They charge faster but.. See the above line.

Then we have true 3 stage chargers... These start out with a fairly rapid (BULK MODE) charge, then when the battery approaches full they switch to a much slower "ABSORPTION" mode.. NOTE in some cases there is no actual switching done the charge just naturally slows down.

Then once they battery is "Full up" they switch to a "Float" mode, where, hopefully little, if any,current goes into or out of the battery.

I said 4: Some 3-stage units are 3-stage PLUS, The Plus is an andditional feature, I will mention two such units.

The Progressive Dynamics Charge Wizard units (Optional or built in) after 20 hours of float go into a short "Equalize" (Overcharge) mode,like15 minutes, just enough to stir things up a bit and mix the electrolytic up, perhaps a bit of desulfacation as well.

I also have a Prosine 2.0 Inverter/charger from Xantres (no longer made) that measures battery voltage and adjusts the charge pramaters according to the temps, So the charge voltages today (45 degrees), are different than say High noon in August (100 in the shade).

Some others have yet other special features.

Watching Danial Boon rerun.. Coronel asks "What about Daniel Boon, did you take care of him?" And the "Spy" he is talking to says "I would say he was very well taken care of." and sips his wine. Yup, It's Daniel.

[64thunderbolt]

can't leave em plugged in every day here in Az. With temps approaching 120* it will fry them unless the a/c is running. It would probably be 150* in that box if left on 24/7. My neighbor figured that out when he replaced his the third time.

[big_whitey]

IMHO a 3 stage charger is no more important for one than the other as i feel a 3 stage charger should be standard equipment on ALL campers regardless of battery type. it will maximize battery life and greatly simplify things. i have a PD 9200 series 3 stage charger and leave it plugged in 24/7/365 except when in use. they are not that $pendy and actually will pay for itself over time by extending the life of your battery. good luck with the new fridge,we love ours.

[msiminoff]

Hi DJ,
The "3-stage" part isn't critical. However maximize the capacity and service life of your new battery you will want to have some control of the absorption and float voltages. You'll need a high enough absorption (typically ~14.7V) to reach 100% SOC and a low enough float (typically ~13.6V) so you don't overcharge and potentially cause the battery to vent.
Temperature compensation would be a big plus too.
Cheers,
-Mark

[btggraphix]

Hey DJ, I believe so. And it is certainly worth protecting your new investment so even with a new wet cell battery that seems to me the time to get a charger that won't cook it. I leave my TC plugged in 24/7 with no worries about the battery getting overcharged. And if you get one that is 'controllable' you can tweak the charger's stages to match whatever the AGM manufacturer recommends. It isn't completely different, but it is subtly different.