94 2.5 litre 200hp XRi current draw on battery

[mstang]

i have traced the current draw to the voltage regulator's located behind the plate that holds the spark plug coils. One is drawing 5ma the other 15ma. This is with the key off. Is this an indication the regulators are bad? It also was starting hard last fall the last few times I ran it. acted like it was missing until it got warmed up, about 1 minute give or take, and that was after letting it idle for a few minutes. Found my battery bone dead last week, and when I put a new battery on it the main cable going to the starter drew an arc. Lifted the wires going from the starter solenoid to the regulators and it quit drawing an arc.

 

[j_martin]

Re: 94 2.5 litre 200hp XRi current draw on battery

I think it's normal for the 20 amp regulators to draw a little current when they aren't running. They have a capacitor in them that will cause it to arc more than you'd expect for the miniscule amount of current draw.

The amount of draw you describe will kill the battery in about 3 months. Most batteries will kill themselves almost as quickly, so I'd call it insignificant.

Never store your boat with the battery connected for several reasons. For instance, a mouse chewing on a wire could cause a fire. I always pull the batteries and put them on a shelf in the cool basement, on a soak charger. They're good to go with a ten minute freshening in the spring.

The hard starting is an indication that something's wrong. The electrical system is not involved except for the cranking motor. If it cranks good, and starts hard, it's not the charging system.

hope it helps
John

 

[Chris1956]

Re: 94 2.5 litre 200hp XRi current draw on battery

I also think the current drain is insignificant. A 20Ma draw for 50 hours will drain 1 Amp hour off the battery. Since the battery is 200 Ahrs or so, it will take some time to kill it.

Although I have never measured it, I am surprized that J_Martin thought it normal.

 

[j_martin]

Re: 94 2.5 litre 200hp XRi current draw on battery

I also think the current drain is insignificant. A 20Ma draw for 50 hours will drain 1 Amp hour off the battery. Since the battery is 200 Ahrs or so, it will take some time to kill it.

Although I have never measured it, I am surprized that J_Martin thought it normal.

I have been experimenting with Mercury charging systems for a couple of years. Every Mercury 20 amp regulator I've seen does this. That's the reason I think it's normal.

It seems reasonable to me that a rectifier/regulator like this, with an overvoltage AC source and a capacitor filtered output could build up a lethal charge in certain failure schenarios. The current drain is to draw off that potentially lethal charge.

hope it helps
John

 

[Chris1956]

Re: 94 2.5 litre 200hp XRi current draw on battery

John, If I understood you correctly, you imply Mercury built in a short to ground inside the V/R to bleed off the cap's charge. This implies the short is downstream of the rectifiers, which makes sense, I guess. They couldnt use some sort of zener diode or DC-DC power converter?

 

[mstang]

Re: 94 2.5 litre 200hp XRi current draw on battery

Thanks for the replys and the discussion. I found a thread that told how to check the VR's with a VOM. Look lke it was straight out of the tech manual. Forward byass on the diodes was supposed to be between 100 and 400 ohms. Both of mine showed 25 ohms. Also i have an onboard battery charger. Can I leave the batteries hooked up if I keep the charger on it?

 

[CharlieB]

Re: 94 2.5 litre 200hp XRi current draw on battery

Lifted the wires going from the starter solenoid to the regulators and it quit drawing an arc.

?

Doesn't anyone else think that he should check to see if these 'wires' have vibrated/chaffed/melted and shorted against something?