Can connecting to a battery charger trigger the Smartcraft system check beep? + RPM Gauge question

[Bootkie2]

I've got a 06' Formula 260 with 06' Merc 496 Mag H.O. When I connected my battery charger the other day to battery #1 after it had been sitting for a little bit it triggered a single beep alarm (that you get when you key on). They key was not even in the ignition at the time. I didn't think connecting to a battery charger with the key off was something that could trigger the alarm? I have never had this happen to me before. It struck me as odd.

Also I have been getting strange behavior from my tachometer while underway recently. When I get to cruise at 3100 RPM the tach will jump and suddenly move to 3,800 RPM and stay there at 3,800 for 20 minutes or so then eventually start reading correctly at 3,100 again. Meanwhile I have have the diacom software so I can check and have confirmed that the readout while underway from the computer does follow the tachometer reading when it is behaving like that. The computer readout stays at 3,100 the whole time.

Maybe something wierd/electrical is going on? Maybe these are related? maybe not?

 

[dingbat]

I've got a 06' Formula 260 with 06' Merc 496 Mag H.O. When I connected my battery charger the other day to battery #1 after it had been sitting for a little bit it triggered a single beep alarm (that you get when you key on). They key was not even in the ignition at the time. I didn't think connecting to a battery charger with the key off was something that could trigger the alarm? I have never had this happen to me before. It struck me as odd.

Also I have been getting strange behavior from my tachometer while underway recently. When I get to cruise at 3100 RPM the tach will jump and suddenly move to 3,800 RPM and stay there at 3,800 for 20 minutes or so then eventually start reading correctly at 3,100 again. Meanwhile I have have the diacom software so I can check and have confirmed that the readout while underway from the computer does follow the tachometer reading when it is behaving like that. The computer readout stays at 3,100 the whole time.

Maybe something wierd/electrical is going on? Maybe these are related? maybe not?

Onboard computer is wired directly to the battery. Either the battery voltage had dropped enough that the computer shut down and it was a “wake up” beep or the power surge when you connect the charger triggered an over voltage alarm.

I assume where talking about a digital tach? No digital to analog converter involved?

Anytime you see a shift in a digital signal it’s almost always a ground or lose wire connection.

Given both problems I would start by cleaning ground at the battery. If that doesn’t resolve the issue, check the wire harness and connectors going to the tach

 

[Bootkie2]

On the battery charging issue: That's really interesting. I did not know the computer was wired to the battery. It all makes sense now. On the tach: I'm going to play with it this weekend see if I can find loose wires. Doing some more research seems everyone who has tach issues like this has solved by checking/adjusting the connection points.

 

[dingbat]

On the battery charging issue: That's really interesting. I did not know the computer was wired to the battery.

ECU typically use a combination of volatile and non-volatile memory to store parameters.
Same as your Radio requires constant power to maintain your radio presents.