I got an engine/cabin heater installed into my car right before winter, which was great for driving comfort this winter. One of its "side-effect" features is that it charges and keeps your battery at 14.1 volts while it's connected.

Does this have any effect on the battery's lifespan or is it just going to hide issues with a failing battery? Does it really influence anything at all?

  • 2
    it might improve your fuel economy by charging the battery on grid power instead of using the alternator (for about a minute). the block heating will have a much greater effect than this, however
    – costrom
    Apr 12, 2016 at 18:33
  • How does an engine block heater connect to the battery?
    – user15009
    Apr 13, 2016 at 2:38
  • @nocomprende The system I bought isn't just an engine block heater. It's a full system with theft protection/GPS tracking, remote control of on/off through GSM, and, as mentioned, a built-in battery charger. You can watch a short video about the system if you're interested. (It's plugin based, so I have more components than the basics covered in the video.)
    – Alex
    Apr 13, 2016 at 10:40
  • Wow. I get by with a 20 year old car (no worries about theft) and equalizing the battery occasionally. Even in cold climates the battery should pretty much stay charged in normal use. The most important thing though is to clean those battery terminals. A few milliohms of resistance there will kill the battery faster than anything. You can buy a terminal brush for a few dollars. No jewelry when you work near batteries! And wear old clothes.
    – user15009
    Apr 13, 2016 at 20:22

1 Answer 1


As long as it is not overcharging your battery, it will increase the useful life of the battery. The reason behind this is, as a battery sits, it loses power. Some of the electrolysis which goes on to make a battery work, also breaks down the battery. During this period, the battery goes through a sulfating period, where sulfur crystals grow on the lead plates. This only happens during discharge. The better charge which is on the battery, the less sulfation occurs. As your charger is keeping the battery topped off, it is also slowing the sulfation condition, which prolongs the life. Please realize a battery is not going to last forever, but a well maintained battery is going to last much longer than a battery which just sits. Maintaining the battery in this sense helps keep the battery in good shape, which is never a bad thing.

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    I used to "equalize" my car battery using a 4 amp solar panel a few times a year. The battery would "boil" for a couple hours when I did this. Also I put EDTA in it. The battery lasted 11 years. Good results with Golf Cart batteries connected to solar panels too. Proper charging prevents poor performance.
    – user15009
    Apr 13, 2016 at 2:37

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