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Me again....I have a question about the readings I am getting on the battery readings on my boat.....The gauges indicate 12 when I start both of my engines....after boating for awhile ( on plane)...and coming off plane the gauges drop to 11 and sometimes lower....I have taken out my batteries and gave the post and connections a great cleaning ( I replaced my starboard battery...so it is brand new) yet I still get the drop on the gauges.....before doing all of the charging and cleaning of my batteries ..my boat gauges were dropping to 10 when I came off plane....both engines shut down on me and wouldnt restart until I switched the batteries onto parallel..........I thought that the problem might be either poor batteries or bad connections....but this doesnt seem to be the case....If anyone can assist me in trouble shooting this problem b4 having to get a mechanic involved it would be greatly appreciated....
Thanks and Cheers
Payner

Do you have a multimeter ? If not, then I recommend ou get one, they are pretty cheap and they are invaluable for chasing down the causes of electrical issues on boats (and cars etc).

Assuming:
Your batteries are OK (you can check their voltage with a multimeter; "at rest" it should vbe ca 12.8V)
Your alternator is ok ( i.e. charges the batteries; the voltage at the batteries should rise when the engine is running)

Then it's probably:
a poor connection somewhere causing a voltage drop ( there's a 2 wire 12V connector to the helm that on my boat was making poor contact, could also be the multipin connector to the instrument harness)

or the gauge might be faulty.

You need to check the actual voltage at the helm using the multimeter. If it's down compared to the battery, then there may be corrosion/ poor contact somewhere near the engine ( on either the +ve or -ve side; corroded studs on the started solenoid ( +12V) or on the engine block ground connections. A myriad of different metals are used for those and corrosion is often found there ( it was on mine)

This also fooled me for a while. The voltage meter on my boat reads about 1 volt lower than actual. Get a digital multimeter at Radio Shack and you can read the actual voltage at the battery and at on the back of the installed gauge under the helm.

_________________
2006 Sundowner 255, 5.7 GXi, 320 hp
"Simply Irresistible"

If you have a battery isolator, bypass it and see if that increases your voltage output.

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2004 Vista 298
Twin 5.7L Volvo Penta GXi-E

I agree with the above. With the isolator, you should see about a 0.6 voltage gain bypassing it. Remember, the on-board voltmeter is not that accurate.

I keep a multi meter in each tool bag/box. Never believe gages at the helm, they are just there for looks, and reference, but not for actual metering.

_________________
2000 248 5.7L DP
'92, '94 SXI 750, '08 STX 15F, '12 Ultra LX 300
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