OE Porsche Charge O Mat Battery Charger / Maintainer Question

Hello All, I have an original Porsche Charge-O-Mat battery charger #000.043.202.56. I've had it for years and I recently dug it out. I've never used it since I've always had my car on a Deltran Battery Tender unit. Looking closely, it says "battery charger" on it. Question I have.....Is this a battery CHARGER? Or, is it a maintainer? If I leave this plugged in and connected to the battery, will it overcharge it? I'm a bit leery as I would expect a maintainer to actually say "maintainer" on it. Looking online, I noticed that the Charge-O-Mat II is actually called a charger/maintainer, but I can't find anything on this original model. Thanks in advance!

I took some pics:

It looks like a 12v 50ma transformer. So trickle charger not maintainer. Would it cook a car battery? Maybe after a loong time.

Quotes source post: 8763641

It is a maintainer, not a trickle charger, that Porsche sold until they wisely switched to the Ctek line instead. It will do a fine job of keeping your battery maintained.

Thanks for the replies guys! The answers seem to be split on whether it's a maintainer or charger........From people that I've asked directly and on the forum here. Even some avid Porsche guys I've asked really didn't know for sure. I'm thinking that it is a maintainer as well. Has anyone heard any negatives on this unit? I've also heard that the Ctek units were Porsche's new and improved one, but nobody seems to know exactly why they are better than the old one like I have.

Quotes source post: 8767365

Simple, visit Ctek's website. While the older Porsche maintainer was OK in its day, it ran a relatively simple single profile designed for flooded cell lead/acid battery's. The Ctek on the other hand is capable of running multiple profiles depending upon the type of battery in the car (flooded cell, AGM, etc.), with each profile specifically designed for that particular style battery (different starting and finishing voltages, varying charge pulse width, etc.). The Ctek also does something that few other maintainers can: Every charge profile contains a de-sulphation step that is critical to extending battery life. Some battery maintainers have come a long way in the digital age, others not so much, and the Ctek line is one of the best if not the very best.

JFP you and I have different definitions of "Maintainer." To me a maintainer turns off or floats when the battery has reached full charge. Trickle charger just pushes steady state voltage/amperage. OP device indicates "Direct plug-in CHARGER" "Output 12v 500mA" "Class 2 Battery Charger" "Both float and trickle chargers are devices that slowly emit low-voltage charges to your car battery, restoring the battery to a fully charged status over several hours. Subtle differences between the two devices determine which charger is best for you. Float chargers are equipped with electronics that allow the device to cycle on and off. This is beneficial if you are going to have the charger connected to the battery for a long period. The device automatically turns off when the battery is fully charged and turns on again when the battery's charge lowers. Trickle chargers work similarly to float chargers. You connect the trickle charger to the battery terminal and a slow, steady stream of low-voltage electricity recharges the battery. Trickle chargers, however, do not come with the on/off feature of the float charger. Electricity continues to flow to your battery until you remove the trickle charger. A trickle charger is most effective when you are available to turn it off after the battery has charged. Overcharging your battery can cause permanent damage. If you are not available to monitor the charging process, or if your vehicle is in storage for a long period, a float charge that automatically turns itself off and on is your best option. However, if cost is a concern for you, trickle chargers are significantly less expensive." Read more : What is the Difference Between a Float Charger & a Trickle Charger? | eHow

Quotes source post: 8768213

Mine come from decades working in the battery industry, and according to the BCI (Battery Council International, the global lead acid battery industry association), which sets the technical definitions and specifications for the industry. The old style Porsche unit is a maintainer, with a maximum output of 500mA @12V, which diminishes to zero as the battery comes up to charge. Is Achilles heel was that it could only adequately handle normal flooded cell technology batteries, and not the later technologies which have become more prevalent in recent years, which require different current and voltages to bring those batteries to full charge. It also totally lacks a de-sulphation capability, as do those of the company which sponsored the article you listed.

OK BCI technical definition is that chargers & maintainers are equal in operation.

Quotes source post: 8768279

Technically, they are when charging, what makes a maintainer different is what happens as the battery approaches being fully charged, or drops away from that point. That is where a maintainer differs in how it responds. The old style Porsche unit would bring the battery up to full charge, dropping the charging rate (current) as it approaches full charge. At this point, the indicator lights would change, indicating that the battery was at full capacity and the maintainer was in "standby" mode. If, subsequently, the battery drops, or say you opened the door on the car creating a drain, the unit indication would change showing it was again applying current until the battery was back up, when the lights would again change, showing it had gone back into "standby" mode. While "basic" by modern digital maintainer standards, it did the job fairly well. It was kind of an Intel 386 PC on Windows 95 in an iPhone world; not too swift, but it could eventually get the job done. Fortunately, there are much better (and more flexible) units available now that are both quicker and better for the battery in the process.