Charging problems twin Honda 50s

[johnrmarshall22]

Hi Guys, my first real post is unfortunately a question for you electrical gurus who can speak(type) in laymen terms to my dumb self.

New 2006 CD 22’ boat to me has some electrical glitches . First problem is that port and starboard (Honda 50s 2006) voltmeters read different. And I get low battery warning on GPS unit when idling, running radar, radio, GPS, Port engine charging just over 12 at idle, starboard 12.3. At 1500 rpm port barely 12.8 (checked at starter to ground to verify in dash meters ok) Starboard shows 13.8. I have two batteries that appear to be wired dedicated to each engine, are same, one (port brand new) and starboard is less than year old (same size/ type). Electronics add-ons installed by previous owner (Radar, GPS, radio, Wallas appear to be running off port engine – separate fuse panel). It seems that if anything the port engine would have greater demand therefore be charging at a higher rate even at lower RPM. If running at 3500 and beyond the voltmeters on both engines are about even at just about 14 volts – but port is a little lower. In general I suspect the wiring that was done by a non-electrician and is not the optimum configuration, and / or the alternator or regulator on the port engine is not functioning normally.

Next issue, my starboard tachometer suddenly goes off while running intermittently. When I shut engine off then re-start engine tack works for a while. I suspect loose wire/ connection/ corrosion. Looked behind tack, appears clean. Just for giggles I unplugged main wire harness/ coupling at front of engine to see if corrosion might have been issue… no change, no corrosion.

Be gentle guys with technical solutions…. I could get over my head real fast with this electrical stuff. Thanks in advance!

[Matt Gurnsey]

If the bulk of the electrical demand is on the port engine, then it will have a lower voltage reading as it charges and supplies power to the electronics and other devices.

Are your readings with everything turned off? If you run both engines with no electrical demand, they may be closer to the same.

If you suspect regulator, you could swap the regulators on the engines and see if the issue migrates from port to starboard. You coluld also swap the gauges and see if there is a difefrence in them- no two analog gauges will read exactly the same.

Double check all your grounds. Do you have wing nuts on the batteries? Remove them, dispose of them, and install nuts with lock washers. With today's motors you should never use wing nuts, as they will loosen over time and voltage spikes could kill engine electronics.

[johnrmarshall22]

[digger]

Another cheaper and easier thing to try is to swap batteries. It is possible that the battery condition is causing the variation.

[T.R. Bauer]

I will say this from years off automotive experience....those gauges are just maybe an indicator of what might be happening.....Does that sum it up????

[johnrmarshall22]

[thataway]

I assume that you checked the voltage with a digital volt meter.
Consider that each engine is only capable of putting out 22 amps (current engines--not positive about the 2006 model). That 22 amps is at something over 2000 RPM (again not sure of the curve on that outboard)--but at idle the charging current will be very low).

A fully charged battery at rest will read about 12.6 to 12.7. When you start each engine you draw down some of the capacity of each battery.

The assumption that because you have greater demands that the alternator would be charging more is false. Your voltage will be lower because you have more current draw--the alternator is only capable of so much--22 amps max--and that will be at high RPM.

At low RPM, you will probably not be running a lot of electronics, in that the alternator may not keep up with Radar, VHF lights, stereo, GPS Fishfinder etc. Having the Wallas off a different battery than the electronics and majority of draw sounds like a good idea, since you need good battery voltage to start the Wallas stove.

You can measure the alternator output with an ammeter (most Digital volt/amp meters will only measure current up to 10 amps, but it is easy to buy a 20 or 50 amp meter if you wish. (A shunt is usually used with a 50 amp meter, since you don't want to run all of the current thru the gauge.

You can also measure what the current draw is of each appliance on the boat (including electronics).

Do you have a shore side battery charger? It is easy to damage batteries in even a year.