I have a Schumaker 1.5A maintainers on my motorcycle, Cub LT1050, Kubota tractor and gas powered Yamaha golf cart. Maintainers charge constantly (about 13.7V) while a second kind (what's the word for it!) cycles on and off. I've noticed no heat or boiling water so I don't remove the caps. I wouldn't do that anyway because some batteries are really sealed and doing so might damage them. Either kind would work fine.

I've learned that its not good to allow batteries to sit in a discharged state. This probably does happen with equipment that has a minimal type of charging system (dynamo). Sulpher comes out of the electrolyte and coats the plates. That coat of sulpher keeps the battery from charging up to its full potential next time and eventually shortens the life of the battery.

The one problem I've had with my chargers is that in handling them I will sometimes move the 6V/12V switch on the front panel to the wrong position and that will discharge the battery. I need to block that switch so that it can't happen.

Ray

Trickle chargers charge at a constant rate. Battery maintainers cycle on and off.
I have several of the Schumaker 1.5 Amp battery maintainers.
Battery maintainers automatically turn on and off according to the battery's level of charge, so there is no worry of "boiling the battery dry".
The recommendation in the manual to "remove the cell covers" is mainly just usage of the "CYA factor" by the manufacturer. This way, if there is a blockage of the venting ducts of the caps or the battery case, or other defect, you can't sue them if the battery explodes.
If your battery does not explode while your are driving the tractor, or when you engage the starter..........there is no additional expectation for the battery to explode while under the care of a battery maintainer.
I DO SUGGEST that when you are connecting the battery charger, or maintainer to the battery that you connect the leads to the battery BEFORE PLUGGING IN THE CHARGER OR MAINTAINER to house current. When disconnecting the leads later, unplug the charger or maintainer from house current before disconnecting the leads from the battery. It's all about "Make no sparks near batteries".

The word I was searching for was "Battery Tender". At least in the motorcycle world a battery tender is a trickle charger that maintains a 14.4V charge rate until the battery is fully charged then falls back to a 13.2V rate until the higher rate is needed again. It automatically switches back and forth. A maintainer keeps a steady lower charge rate, never shutting off or changing. None of the four I have ever change their rate or shut off. Perhaps these are different. In my auto mechanic background a trickle charger is simply a small charger like a Sears unit I have that will deliver up to 5 amps or any of the small chargers like discussed above.

Ray

I have to clarify that the battery maintainers I have do charge at a higher rate for a few moments when they are first connected. Actually, sometimes, if connected immeadiatly, they don't. They just go right to the normal rate. If I turn on a light or the switch they go to the higher rate but other than that they never cycle back and forth like the battery tenders do.

Ray

Battery tender jr's are great, come with the wire in harness and ~ ~25 bucks usually on Amazon.

Any of the Trickle Chargers that I have ever owned were the 1.5 - 2.0 Amp Version . They Charged at a Steady Rate . My Current Atlas Charger has Multiple Amperage Settings which also has a Manual and Auto Setting . The Auto Setting Cycles the Charging On / Off at what ever Amp Setting that is selected to avoid overcharging .

I had a little battery operated toy that used the outlet plug-in transformer and the small siamese cord with the push in plug on the end. It had a description of 120 vac in and 12 vac out at something like 1 amp. I put alligator clips on the wires and use it to maintain my tractor during the winter when I'm not using it very often. It's worked for 2 winters now and this summer the battery is fine. If you have to buy, buy something made for the job. If you're going to throw one of those little transformers away, check the output first. It might work for you too.

Listen up! A transformer is not a battery charger. No matter what the "voltage output".
Transformers only change the voltage input value to a different voltage output value. Transformers DO NOT rectify the Alternating Current (AC) into Direct Current (DC).
Batteries REQUIRE Direct Current in order to build/store a "charge".
Whenever you apply AC voltage to a battery, the current flowing into the battery during one half of the alternating pulse of engery ADDS a bit of charge to the battery, but the second half of the energy pulse REMOVES the same amount of charge from the battery.
The overall net charge imparted to a battery when fed a source of AC is ZERO, so the battery gains nothing from the activity.

Well Mownie, not to question your authority, but I'll risk it. Being some watts below the brightest bulb in the pack, I can only base my actions on what I can read so here goes.

Brand: SEL
Type: Plug in class 2 transformer
Listed: UL
Model #:D12-300
Input: 120V 60Hz 9W
Output: 12VDC 300mA

The operative thing here is the output listing, 12VDC (direct current).

So I can only assume that maybe there ARE transformers that contain rectifiers and can convert AC to DC. I'm just saying.....hope you understand!

Now, is this the best way to go? I have no idea, but it works. My battery stayed charged throughout the past 2 winters. Will it eventually destroy the battery? Maybe. But how long will these cheaper batteries last anyway? So, like I stated above, if you have to buy, get the right thing for the job. But if you have one of these 2-wire guys lying around, check it out. It might work.

I have a Deltran Battery Jr. maintainer on my LT. I leave it on year round and works great...been on 2 1/2 years now. They claim it will increase the life of the battery.

horsepen, the data you provided in your second post is quite a bit different from your first post. Here is why.
In your first post you state ***"120 vac in and 12 vac out at something like 1 amp""***
120 VAC means 120 Volts, Alternating Current in.
12 VAC means 12 Volts, Alternating Current out.

In your second post, we learn the real output is actually Direct Current, though at 300 milliamp (.300 Amp, or 1/3 Amp roughly).
This transformer is indeed "rectified", and will impart a very small charge to a battery..........IF, it is connected with correct polarity.
At only .3 Amp, feeding a battery of 230 CCA (for example), I would venture to say that you may be observing a placebo effect. Or you may actually be getting enough activity to stave off some of the changes that occur on the surfaces of the cell plates that cause batteries to degrade from lack of activity.
Bottom line here: A rectified transformer of .3 Amp will do no harm to the battery if connected correctly with regard to polarity.

Mownie,

Horsepen doesn't know what he knows and doesn't know what he doesn't know...

To him, a wall wart is a transformer but to you and I and those who know, a transformer IS a transformer and an electric circuit that includes a transformer and a rectifier is NOT a transformer.

I have found that storage battery use, service, and maintenance is one of the most misunderstood subjects in general and the discussion is populated mainly by people with anecdotal evidence for the most part with very few people involved in the discussion that actually know what they are talking about.

Sorry to be one of those who "don't know". But tell me, what is a wal wart? I'm just not sure I know what that is and I usually (as you well know) don't know what it is that I don't know. I'm going shopping with my wife and she mentioned going to Walmart. Is that the same? Do they charge batteries at wal wart? Can I charge a battery charger at wal wart? Do they sell battery chargers at Walmart or is that strictly a wal wart item? I know that Walmart sold something called a Trickle-Me-Elmo and I installed one on my tractor and the battery kept dying...so much for trickle chargers.
Seriously, thanks for setting me straight. Now I'm going to the shop and plug my box fan into the 240 Volt dryer outlet (which I think is AC) so I can really get some air moving out there. I just changed the wire plug on the fan, so I know it'll work. At least I think I know, but I don't know what I know either.

Well, I do know you have a pretty good sense of humor. Thanks for the chuckles horsepen.

Horse: ROFLMBO DUDE ! :) .

Walmart in my area has the Schumaker battery tender (cycles on and off) listed for $20.97 (if memory serves me correctly). I use one on my motorcycle and I have one for my lawn tractor, yellow light shows it is charging and green light shows it is charged.