What do you think went wrong here?

Can be a coincidence as a cam would not draw significant power to drain a battery in minutes as you had in your situation. I personally would have done a load test on the battery to test condition under load, however since you have changed the battery i would just give it another try as you know the battery is now good and shouldn't present any problem there.

Others can add their thoughts/comments.

Ballroomblitz1 wrote: ↑ Can be a coincidence as a cam would not draw significant power to drain a battery in minutes as you had in your situation. I personally would have done a load test on the battery to test condition under load, however since you have changed the battery i would just give it another try as you know the battery is now good and shouldn't present any problem there.

Others can add their thoughts/comments.

Could this problem have been from a bad ground point of connection?

You already bought a new battery so hust plug it in and test it.

findmesumdealz wrote: ↑
Plugged the fusetap into an empty circuit, and ........

Just because there was no factory fuse in there doesn't mean that Honda hadn't wired something up on the load side of the bus. Something used in different trim levels or other markets possibly.

Quite possible that the fuse tap energizes that unknown circuit which messes up the signals needed for a successful start condition.

When you say the engine failed to start, do you mean no cranking at all, or continued cranking but not firing?
Not that it matters either way really, but might help narrow down the issue.

But anyway, I would just pick another ignition-switched location for your fuse tap - an innocuous one serving something like heated mirrors for example.

Probably nothing wrong with the battery you replaced.

While installing your dash cam, did you have have your doors open for a long time with the interior lights on?

That would drain a battery.

I plugged the fuse tap back into an empty circuit - number 23. It's currently powering a radar detector, which also has a volt meter..

When the car is idling, the voltage is coming through as 12.5 volts...

When I previously was driving and had the radar detector plugged into the cig lighter, it was showing 14.5 volts.

Now, would you say this is normal or something is wrong here?

findmesumdealz wrote: ↑ I plugged the fuse tap back into an empty circuit - number 23. It's currently powering a radar detector, which also has a volt meter..

When the car is idling, the voltage is coming through as 12.5 volts...

When I previously was driving and had the radar detector plugged into the cig lighter, it was showing 14.5 volts.

Now, would you say this is normal or something is wrong here?

It's all normal. Just try the dash cam again. Your ground is fine as well. Most likely a coincidence. I have hardwired a few dash cams, never an issue. It's pretty simple, 12V and ground, pretty hard to mess that up.

don't plug the it into any circuit. you really need to know what the amperage is for that slot before you plug stuff in

azmongold wrote: ↑ don't plug the it into any circuit. you really need to know what the amperage is for that slot before you plug stuff in

It shouldn't matter, it's a camera not a hair dryer. The draw should be minimal.

findmesumdealz wrote: ↑ I plugged the fuse tap back into an empty circuit - number 23. It's currently powering a radar detector, which also has a volt meter..

When the car is idling, the voltage is coming through as 12.5 volts...

When I previously was driving and had the radar detector plugged into the cig lighter, it was showing 14.5 volts.

Now, would you say this is normal or something is wrong here?

12.5v is what your battery is at when engine isn't running. 14.5v is when the alternator was charging the battery.

No way to tell fuse#23 is correct or not with a voltmeter, just basic reading of the battery and the alternator which is normal.

I agree with above poster that spending around 1hr - 2hrs with the doors or dome lights on with the 7yr old oem battery drained it.

The first thing that stands out to me is that you put the fuse tap in an "empty circuit". You should have used an existing circuit, like for the cigarette lighter or something. That's the whole point of a fuse tap.

macnut wrote: ↑ Just because there was no factory fuse in there doesn't mean that Honda hadn't wired something up on the load side of the bus. Something used in different trim levels or other markets possibly.

Here's an example of just that: a fuse plugged in where it shouldn't be causing a parasitic drain and dead battery.

I would tend to agree that what circuit to use should be the cigarette/12v adapter. That would have been wired with a higher circuit breaker and thicker cables. Just wiring it to a circuit that possibly has less write thickness can melt wire jackets without seeing them