I'm thinking about getting a battery maintainer for my '21 Touring car. When charging the battery in the car will the fumes given off damage the interior?
Charging a car battery creates oxyhydrogen around it, so avoid any sparks or any open flame close by.
I wasn't as careful as I should at one time when I was young and tried to help start an old car with an extra battery and jumper cables. Didn't start at the first tries, and the help battery started to weaken, so I took another and connected the last clamp to the car's battery. It exploded. Got really lucky and only ruined a pair of jeans..
The empty battery in the car had been charged for a while and created explosive oxyhydrogen that was ignited from just a little spark when the new circuit was closed. So always close such a jumper circuit in the chassis metal, far from both involved batteries - but especially far from the one that has been recently charged.
So the fumes isn't harmful if you're careful - but with a spark at the wrong time you may ruin both the interior - and your eyes.
I have been using a maintainer on my 6v jeep for a few years. In my experience, it trickles at so low a charge as to make me converned about varpors or gassing. I have a wired in connector that runs through my headlight housing and I plug in and out the maintainer. It has a rid/green light on it to let me know that it is charging or not charging.
If I am a low battery charge, it will NOT charge the battery up to full charge, but just trickles in enough current to keep it at it's present level. I have had to put a "normal" charger on my battery after having the maintainer on it for a week or so in a few cases, which surprised me.
I'm planning on putting the same connector on my T battery so I can use the same maintainer on either vehicle. But I have an access door in the wooden bed of my T WWI machine gun carrier that I will leave open during the process.
I think there is enough open space in the T to prevent extreme discharged gas build up. JMO
I got a Battery Tender and hard-wired the round terminal ends to the battery cables. It has a quick-disconnect feature that hangs down below the car so it is very easy to connect the power pack to the car without having to remove the floor.