I just bought a AGM battery to use as a house battery on the XJ and eventually SanFord to run the refrigerator. It will be charged by solar panels most of the time, but on occasion I will need to top it off with a charger.
My go to charger at the moment is this. A Schumacher 2/6/10 amp smart charger. It charges batteries. I don't know if it charges them correctly. It does have a AGM setting.
Is this good enough? Should I spend big money on a better charger? If so, which one. The battery was expensive enough that I want it to last a long time.
If you're just using it for a top-off and not leaving the charger on and are willing to monitor voltage, that should do ok (although those are pretty E36 M3ty chargers). A better charger wouldn't hurt though. A good 3 stage would be good, as you could leave it hooked up all the time without issue.
Personally I've got a 25 amp Black and Decker charger that I keep around. Not very expensive and it's 3 stage. Bulk and absorb voltages are good for an AGM. It wouldn't be a good long term float charger though as the max float current is very low (so any draw on the battery will drain it some) and the float voltage is a bit too low as well (only around 13.1 volts from what I've seen). Model number is BC25BD. There's also a Stanley branded version (BC25BS) that's the same charger in a different color. Sometimes one version is cheaper than the other.
I bought the optima 400 charger for my red top. That thing is incredible for only 89$ on Amazon.
$89 is pretty pricey for a 4 amp charger, IMO. There are definitely better choices out there.
I use the CTEK Multi US 7002. It'll take care of Odysseys which are a little fussy. I have a couple of pigtails so it can be clipped into the cars that don't get much use. It has AGM and wet settings.
Costs a few bucks ($103.99 at Amazon) but I don't like to screw with batteries. This thing always works. My old Schumacher did not.
rslifkin said:
$89 is pretty pricey for a 4 amp charger, IMO. There are definitely better choices out there.
Read the manual. It does more than most for less money.
8valve
New Reader
1/30/18 3:39 p.m.
I have a lower amperage Schumacher. I want to say it was $35ish and 5 amp max? I like it, works fine.
In reply to Trackmouse :
That only matters if the extra functionality is really needed. Which for most cases, it's not. But having more output than 4 amps is useful in a lot of situations.
I have been using one like the Picture For close to 10 years , No it won't Jump Start a Car ,Sometimes If a Battery Is Completely Dead It doesn't want to Kick it into charge Mode, But reading the alternator output and % of Charge is a bonus.
grover
Reader
1/30/18 9:02 p.m.
I've been needing a charger for a while, do we not use the old roll away type chargers anymore? Why not? 
In reply to grover :
I have a jump box. That kind of eliminates the need for a boost charger.
AGM??????....for those of us not down with the alphabet please............
codrus
UltraDork
1/30/18 11:23 p.m.
759NRNG said:
AGM??????....for those of us not down with the alphabet please............
Absorptive Glass Mat. https://en.wikipedia.org/wiki/VRLA_battery
In reply to 759NRNG :
AGM = absorbent glass mat.
Instead of sulferic acid sloshing around in liquid form, it's soaked in to fiberglass mats. They can be mounted in any orientation, and are sealed so they can't leak like a normal lead acid.
In reply to grover :
Those old-school chargers are fine for use if being closely monitored, but the newer design chargers are a lot smarter about how they charge the battery. So you can leave a good one hooked up forever without hurting the battery. And the ones that don't have big transformers in them are a lot smaller to store as well.
