Unusual voltmeter readings on the console

M

matt_unique

New member
My port side usually charges at about 15 and my starboard side at about 14.

The other day I fired up the engines and noticed my port side at idle was 14 and the starboard side was about 12.5. I ran the rmp's up a bit on the starboard engine and the charging jumped right up to 14.

I know the engines are usually not charging very much at idle but it was an unusual reading. I usually get about 14 on both sides as soon as the engines are running. I will monitor it again this weekend.

Ideas?

I can certainly test the bats sans engines running then with engines running to verify exact charging rates.

Thanks
 
Captains Cat":vgh7io7j said:
I would guess that the 12.5 v batt was kinda low and when it's fully charged, will read as it did before at idle too.

Charlie
Click to expand...

I was thinking about that....though I did charge all bats to full before splashing. Maybe it needs a few good runs. I will monitor closely.

Thanks Charlie.
 
If a slight increase in RPM caused the CHARGING VOLTAGE to jump up then the problem is in that alternator/regulator, not the battery... With the battery showing 12.5 the real question is why didn't the regulator command the alternator to charge - like the other engine did?
Best look to your belts, clean, grease, and re-tighten all cables and clamps and posts... And if it doesn't show a reasonable charge voltage at idle RPM of at least 13, then have the alternator tested at the nearest Pep Boys, Sears, etc..

Now, charging voltage is separate from resting battery voltage...
At rest, a fully charged 12V lead-acid battery will read 12.7 volts...
12.5 volts is 80-85% of full charge - which is what yours showed...
Your battery may, or may not, be going bad... But first you have to fix the alternator so it works properly, then give the battery an equalizing charge and finally do a load test on it... Every boater should have a battery load tester, if not on the boat, at least have one available...
 
denny-o":bx48gtth said:
And if it doesn't show a reasonable charge voltage at idle RPM of at least 13, then have the alternator tested at the nearest Pep Boys, Sears, etc..
Click to expand...

LOL. I've not yet found a Pep Boys, Sears, or any general automotive place that can effectively or willingly test the output of an outboard motor alternator. Methinks you forgot that all C-Dorys are outboard powered.

Good info though.

Don
 
Matt, was this a digital volt meter, or analogue? At low RPM, the "alternators" on the Suzuki' (and most outboards) will put out very little voltage or amperage, and if the idle was low this is not unusual. The fact that it jumped up, means that the "alternator" is OK.

Agree, you do need to check out that battery by load testing it. Is is possible that the batteries were deeply discharged during the winter? I had several of my original batteries fail--and it was when a friend borrowed my boat--and I suspect that the batteries were deeply discharged.
 
I charged all three batteries before winter storage. I stored them inside in a room that does not fall below 60. For spring prep I filled them all with distilled water and threw them on the trickle charger. Each battery read fully charged the moment I connected the charger.

I did notice, however, that one of my battery "cylinders" was very low on water. Perhaps that bat is not at 100%.

Today when I fired her up (idle) port side immediately read 14 volts and starboard read 13 but climbed to 14. My gauges are analog Suzuki gauges. The starboard alternator is charging both the house and starboard start battery. When running at cruise power my port side read 15 volts and starboard was just over 14. (This has always been the case - I assumed it was due to the fact that the starboard alternator is providing juice to two bats).

I could use a multimeter or check the gauges on the starboard side while firing her up on just one battery. Perhaps I will read a difference and determine if one of the bats is low on charge.

I made a good two hour cruise today.
 
Have your tried to swap the leads to the gauges behind the panel?
The idea would be to ID inaccuracies of the individual gauges and eliminate "apparent" inequalities between the batteries.
Or swap the start batteries and confirm that the indicated values follow the individual batteries.

Paul Priest
Sequim
J.C.Lately
 
Well today I had a chance to look into this a bit more. All 3 bats read 12.65 to 12.7 volts with the multimeter.

When I fire up the starboard engine it does not matter what bat I use (start/house/both) it reads 12.5 volts after start then slowly climbs to just over 14. Port side immediately reads 14 volts when it starts and climbs to 15.

When I use the starboard start bat to start the port engine, it immediately reads 14 then climbs to 15.

So...I know the issue is with my starboard engine. I will check with a few dealers tomorrow to see if this is some kind of voltage regulator/alternator issue with my starboard engine. The starboard engine has always charged at just over 14 and the port engine has always charged at 15. I always assumed this slight reduction in charge was a function of the fact that the starboard engine is always charging two bats. It does maintain just over 14 when running and of course 60 seconds after starting.
 
Well I checked with the service departments at two Suzuki dealerships up this way. Both said the readings were within normal operating parameters.

Port engine - shoots right up to 14 and climbs to 15 after about a minute.
Starboard engine - initially starts at about 12.75 then climbs to 14.2 after about a minute and remains there.

So...unless I get new information I will just watch it and proceed as usual.

Thanks for the suggestions.
 
I agree--watch it. I suspect it is the difference in the charging circuits--do you have a VSR? This could account for part of it. The bottom line is that it is charging properly.
 
thataway":1qjycmtd said:
I agree--watch it. I suspect it is the difference in the charging circuits--do you have a VSR? This could account for part of it. The bottom line is that it is charging properly.
Click to expand...

Hi Bob,
I do not have a VSR in my system.

As long as she charges over 14 I think I'm good.

Thanks again.
 
I have three deep cycle bat's aboard Napoleon. Last weekend after a 40 min run I had to start my engines a few times in a short period of time. On the 2nd or third start my port side went dead. I did not get the usual diagnostic engine alarms when I turned the port key, everything pegged (1st thought is short when this happens), and of course the engine would not turn over. I switched the port bat switch to another bat and she fired right up.

I did not have time to diagnose last weekend. Tomorrow I will check again, then also take some readings with a multimeter on the bat. I'm thinking possible short on the wires leading to the port bat, or perhaps the switch in position 1, or bad bat. The bat would still be under warranty (interstate). Any other ideas?

Thanks
 
That battery is either not charging, and or is a bad battery. The batteries my Tom Cat came with only lasted a little over 2 years. (They may have been abused by someone I loaned the boat to--and were dead when I got back to my house--with the explaination "the port engine is hard to start"....Nothing wrong with the engine.
 
thataway":2rruqju0 said:
That battery is either not charging, and or is a bad battery. The batteries my Tom Cat came with only lasted a little over 2 years. (They may have been abused by someone I loaned the boat to--and were dead when I got back to my house--with the explaination "the port engine is hard to start"....Nothing wrong with the engine.
Click to expand...

Thanks Bob.
My voltmeters indicate a charge when the engine is running. Likewise when I switched the port bat switch to draw from the starboard start switch she read over 14v charging. (I switched my starboard bat to draw from the house bat).

The interstate marine/rv bats come with a 12 month full replacement and 30 month prorated replacement.
 
Well I tested the port bat again today and no luck. As I began to remove it I discovered the wing nuts were loose. I tightened them down and she ran perfect...duh....well problem solved! Before heading out today I made sure the rest of them were good and snug.
 
Ah--you should have told us you use wing nuts! They are not the best solution, even though many of us use them. I have switched over to regular nuts with lock washers. If you use wing nuts, use vise grips to get them really tight. Nylox nuts are not the solution because heat may melt the nylon. You might also consider an non corrosive grease on the nuts.
 
I used pliers to snug them all down. Lesson learned should I encounter the same behavior again.

When you turn the key and your gauges peg it means there is a short, in this case the short was right at the bat terminals. I had the right diagnosis but never thought to check the tightness of the terminals until I went to remove it.
 
matt_unique":qw209lmn said:
I used pliers to snug them all down. Lesson learned should I encounter the same behavior again.

When you turn the key and your gauges peg it means there is a short, in this case the short was right at the bat terminals. I had the right diagnosis but never thought to check the tightness of the terminals until I went to remove it.
Click to expand...

Matt, wht do you mean when you say "short"? That usually means that something is leaking to ground, not a loose connection. Am I misunderstanding something?

Charlie
 
Captains Cat":acai8gcx said:
matt_unique":acai8gcx said:
I used pliers to snug them all down. Lesson learned should I encounter the same behavior again.

When you turn the key and your gauges peg it means there is a short, in this case the short was right at the bat terminals. I had the right diagnosis but never thought to check the tightness of the terminals until I went to remove it.
Click to expand...

Matt, wht do you mean when you say "short"? That usually means that something is leaking to ground, not a loose connection. Am I misunderstanding something?

Charlie
Click to expand...

Well the behavior was the same, turn key and gauges pegged full down. Perhaps one cable had enough contact while the other did not. I tested a few seconds later and this time I had the usual engine diagnostic alarm but no turnover, etc. all kinds of weird behavior. Once I snugged them down all was well.
 
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