How to check if Charging

[stul]

Hi
I have a 75 hp two stroke Mercury engine (about 3yrs old) ELPTO (not opptipmax all singing plug into the computer type ),how do i find out if it is sending out any charging current, Volt gauge showing at most 12.1 volts dropping after a an hour to a reading of 11.2 on garmin chart plotter
Thanks Stuart

[doggypaddle]

with the motor running you should get much more than that, around 13.8-14.4 volts. 12 volts is definetley too low.
use a digital multimeter across the battery to check, although the Garmin built in ones are usually very close, its worth checking at the battery in case theres aome dodgy wiring common to the garmin and the dash gauge.

[Top banana]

Originally Posted by stul

Hi
I have a 75 hp two stroke Mercury engine (about 3yrs old) ELPTO (not opptipmax all singing plug into the computer type ),how do i find out if it is sending out any charging current, Volt gauge showing at most 12.1 volts dropping after a an hour to a reading of 11.2 on garmin chart plotter
Thanks Stuart

It was three years old 13 years ago Have you been fiddling with electics again

[BogMonster]

A decent digital multimeter will show about 12.6-12.8 volts for a good healthy charged battery and an alternator (at least on a vehicle - I've not really had cause to measure a boat) should charge at 14.2-14.4.

12.4 or less is a pretty low battery, if it's less than 12 then the engine shouldn't even start!

[jyasaki]

I'd disagree with that a bit; My boat batteries routinely show about 12.0 to 12.2V after several hours of idle time (that's idle as in not being charged; not running the motor at idle.) They start the motor fine in that state. Charge voltage is about 13.4 at idle, 14.4 or so at speed.

Basically, any voltage over the unloaded voltage state of the battery will charge. So if your battery shows 12V while not doing anything, and when the motor is running, shows greater than that, you will be putting current back into the battery.

If you want to know how much current you're pushing, get an automotive ammeter and wire it into the circuit. Shouldn't cost too much, and it's a simple job to connect. Personally, I'd make it temporary so you can remove it when you've satisfied your curiosity.


jky

[BogMonster]

I should perhaps clarify my experience is with wet lead-acid vehicle batteries and charging systems. Maybe some of the specialist marine batteries behave a bit differently. My boat had a regular lead-acid in it. Also probably depends on what you are measuring it with. Anything I have ever worked with would be pretty flat at 12v but I admit my experience is in a specific area.

[doggypaddle]

Originally Posted by BogMonster

I should perhaps clarify my experience is with wet lead-acid vehicle batteries and charging systems. Maybe some of the specialist marine batteries behave a bit differently. My boat had a regular lead-acid in it. Also probably depends on what you are measuring it with. Anything I have ever worked with would be pretty flat at 12v but I admit my experience is in a specific area.

12 volts with no load= flat as a witches tit. and definetley not charging

[waverunner]

Originally Posted by stul

Hi
how do i find out if it is sending out any charging current, Thanks Stuart

Try putting your tongue across the pos and neg if you don't get a shock, fit a new rubber band and lollipop stick.

[Top banana]

Originally Posted by waverunner

Try putting your tongue across the pos and neg if you don't get a shock, fit a new rubber band and lollipop stick.

or to be on the safe side go for a twin settup this will balance the boat better
and stop it pulling in to port.