Twelve volt battery maintainer for ten bucks

I just bought two of these. Prior lowest price I’ve seen was at twelve dollars.

Few remain and uncertain if supply will last long at this price:

Link to deal

This maintainer is capable of only about an amp. I suppose you could actually charge a battery with it if you had a lot of time. But battery maintenance is really what this is designed for.

When batteries just “sit”, that’s not a good thing at all.

1 Like

This is an automatically-generated Wiki post for this new topic. Any member can edit this post and use it as a summary of the topic’s highlights.

My two units arrived quickly and were placed into service straightaway.

So far so good . . . appear to be working as advertised.

Deal remains available as I write this. No regrets. I can use these things but was unwilling to pay the higher prices elsewhere.



Sad to report there is a HUGE problem with these maintainers which I’ve only just confirmed:

These things are ginormous generators of EMI, sometimes also called RFI. That aspect does not interfere with their ability to maintain a battery. In fact, if you never listen to AM radio this is not even an issue for you.

I operate four Sangean PR-D5 radios in various rooms around my home. The PR-D5 model is noteworthy for its ability to pull in distant radio stations and sadly, as well, EMI from battery chargers like those in the OP.

I’m guessing now these maintainers are completely unsuppressed where EMI is concerned. Maybe that contributes to the low price.

1 Like

Try a Faraday cage. DIY by lining a box with aluminum foil to cover the mainainer. If maintainer gets warm/hot, may need to make a few holes in the cage.

Caveat, I don’t know if this will solve your EMI.

Thank you, frugalpete, much appreciated.

Unfortunately these maintainers plug into the wall, in addition to having leads which latch onto the battery terminals. Both of those are antennas. But I imagine most of the EMI is coming straight into the house through house wiring.

EMI is a real PITA. Decades ago I spent weeks alone inside a huge Faraday cage, taking measurements in process of trying to find a way to suppress certain DC motors. The room was also an anechoic chamber. You could become lonely in there. It was not a happy or rewarding experience.

I might try throwing a cap across the outlet where the maintainers are plugged in. But that probably would not work satisfactorily. More likely I will simply not leave them plugged in.

1 Like

A couple of possibilities, I hope:

  1. Put them on timers to run when you’re asleep / working in the back 40.
  2. I’ve had some luck using a surge protector, but it’s been hit or miss.
  3. Just return them. Since they’re maintainers instead of chargers, how effective will they be if not plugged in continuously (at least in the winter)?

Good luck.

1 Like