There were far fewer mobile electronics when my Accord was built in 1999, so I wanted to add some 12v receptacles. I miss the heated seats in the Subarus I had, and sometimes my passengers need to charge their phones - actually often need to. Of course there's dual adapters, but if I put the heated seat cushions in this winter (would not have both on simultaneously) I wouldn't have anywhere to plug in the FM transmitter, and I don't like having the seat power cables showing and possible interfering with the (manual) shifter.

This post is for tips for anyone wanting to do the same. There was a lot less to it than I thought. I did see elsewhere that the cup holder can be pulled right out. After that carefully pry the trim around the shifter. It doesn't need to come off, just loose. That exposes 2 screws that hold the compartment below the radio that houses the 12v receptacle.

The screw on the right has been removed. Once both screws are out the compartment can be lifted out, but not very easily. Carefully bend the shifter trim so it can be lifted above it enough for the 12v receptacle plug to be accessed and removed. I exposed a small amount of the conductors and spliced on the wires to the new dual receptacle and insulated with electrical tape.



I always put a small cable tie on any taped connection. I was considering and cutting the leads and connecting the new wires with wire nuts, but the wires to the plug don't have much slack. I tucked the new wire under the center console housing. The dual receptacle I had just happened to fit snugly between the driver's seat and the console.

 

The only issue to keep in mind when doing this is that you are running all the power through 1 15amp or 10amp fuse (I can't remember which). I also did a similiar thing the first time, which worked find years ago, but today , for example, my daughter and I were driving and both charging iphones at the same time. These are more recent versions (like an 8 and an SE) and it popped the fuse repeatedly. I considered simply upping the ampsin the fusebox, but felt safer running separate lines and then a new fuse in the fusebox. At the very least, keep some spare fuses in the car because I can't remember what else might be tied into that line, which will go out if it pops.

In a minivan last year I helped a friend put in about 6 plugs into his car so every passenger had one, because as you said there are a lot more electronics being used today. GPS, phones, tablets, laptops, games, power converters, etc.

 

Yes - important not to overload it. According to the manual, it's a 20A circuit also feeding the radio. Was surprised that the wire appeared to be maybe 22 gauge, was expecting thicker.Recently my friend and her friend both needed to charge their phones. They weren't iphones so there wasn't any trouble. I didn't realize iphones tend to draw a lot when charging. The heated seat cushions would be used (if I even put them in) sparingly, typically just before the heater temperature is adequate, which in itself happens in a surprisingly short amount of time.

It's interesting how a some auto ads/promotions will mention how many USB and/or 12v outlets there are in a vehicle. Probably today's minivans have several, so now your friend's minivan is almost as good as new. When my kids were little all this media wasn't yet popular. Thankfully I'm no longer paying for 5 cellphones - and back then they weren't even smartphones.

Speaking of electronics - so much in vehicles these days that seem to draw considerable power when idle. I've seen several posts on a Subaru forum where 2020 Foresters had dead batteries if they weren't driven consistently. That's why I like the simplicity of the '99. Just add what you really need, sensibly.

 

It's not just iphones, I was using them as an example. Older smart phones chargers were only drawing about 3 amps, but now they are all drawing closer to the limit of the car fuses, at 5amps each, and they try to fast charge, so they can easily pop a fuse. And yes, that's what it is, the radio dies.

To your other point, very true that one should drive the cars more often to keep them charged and often should upgrade the batteries to handle more. Yes, my friend's minivan upgrade was necessary with all those kids and devices.

As long as you add a new line, you are fine. just make sure it's triggered for ignition so you don't kill the batter accidently with the car off.

To me the 99 was like a template, just added what I needed. backup sensors, USB ports, hands-free talking, bluetooth, and Alexa so I can just tell the radio what to do (it's built into the latest aftermarket radios).

Glad you are having fun with it.