Voltmeter, Alternator, and a Battery

Hello... I have a 99 SN with the PCM 285 hp engine. I noticed on its maiden voyage this year my voltmeter was indicating 12 volt. Prior to installing I kept it on a battery tender in the basement. Much to my surprise when I installed it the perfect pass just sat there and beeped. I called them on the phone and he told me that it was because I didn’t have enough voltage... so I checked condition and charged it with regular battery charger...it stopped beeping.

While on the lake I noticed 12 volts on the gage... I came home and put on the tender. Went to check it before I took it out and only 10 volts. Battery was a 2018 series 65 from Walmart and who knows how old the alternator was so I replaced it. I also wanted to replace the impeller and belts too, so I used it as an excuse to update these components as well. Glad I did the impeller was bad...royal pain in the butt but glad I did it Got it all put back together Started her up and only got 10 to 11 volts on the meter, but the pump worked well and belts were nice and quiet!

I looked in PCM Manual trouble shooting Section and it said bad battery could cause this problem as well as the alternator.

Here are my questions as it is a new to me boat 2 years ago:

1). I can’t find a series 65 marine battery, I’m sure a car battery is not designed for this, My compartment says series 48 or 41. I can’t find one. What size marine grade battery fits in there?

2) I listen to the radio while resting that’s all, starting battery or dual purpose?

3). Do alternators of that year have built in voltage regulators, or do I have to check that too?


Thanks... hope to find a battery and test this out...battery voltage gauge is only 2 years old.

Thanks,

Otto

Chris,
Good move on looking for a new battery since I question it's condition and here's why. I'm not a believer of battery "maintainers" due to my experience with them. Back in the Y2K scare days I installed a whole house generator and since it did not have a on board charger, I installed a maintainer. Less than 2 years later the battery failed. Then two more battery failures at about the same 2 year time period each. So, I installed another brand of maintainer. Same thing and three more batteries. After the approximate 12 years, I asked at Napa what they thought was going on and the reply was the maintainers are boiling the life out of batteries and I wasn't the only one that it was happening too. Now, I have NEVER used any type of maintainer on ANY of my boats over winter layup and have NEVER had a problem. I put the boats up for the winter with a fully charged battery and come spring they crank up the engines just fine. The battery in my X55 that I just cranked up is 8 years old, made it through 7 winters and cranks the 312 great. Also, why are you storing your battery in the basement? For the warmth? Do you take your car battery in every night when it gets cold? Get your battery load tested and I'd say there's a good chance it's not in the best shape. You should also get the alternator checked too since I suspect it too.

As mentioned by Jim, I agree that an automotive STARTING battery is your best choice for your application.

Thanks, I was able to find a group 48 battery (that is what the decal in my compartment calls for) at advanced auto for 25% off so I jumped at it. I will hook it up and give you an update.

I was trying to do a good thing with those tenders...it follows my saying that no good deed goes unpunished! I always go the extra mile with maintenance because I don't want to be one of those guys! I appreciate you sharing the battery tender story....

Hopefully that will be the problem...Its a good thing as I needed a new impeller and now I have a record of hours on the parts....

I will let you know!~

Otto

Check the voltage at the battery with the engine running using a VOM (volt Ohm meter). It should be around 14.

Chris,
Get some voltage readings with a VOM. Don't just use the volt meter in the dash. Start at the battery and then move forward to the dash. Clean all your connections as you go. It sounds like your loosing the volts someplace but the readings will tell.

When you check for voltage loss, have the circuit under load.

If a connection, wire, switch, or breaker is corroded & has resistance, the loss is magnified under load.

Battery maintainer is a generic word..
BATTERY TENDER is the brand you want to use. Made by DELTRAN CORP.   They are guaranteed of 10 years. I use them on all of my toys with no problems ever. Never cooked a battery.   Many cheap brands out there that do not monitor the battery condition and tend to fry the battery. They cost more but again you get what you pay for.

I got a battery tender generic brand at harbor freight and it keeps my Acura fully charged every winter for the 3 months I’m in CO skiing. The Acura has the technology package that drains the battery after 6 weeks being laid up. No complaints from me. I don’t put one on the Nautique or pontoon though, just a 10 amp charge overnight and I’m good to go.

Otto Throttle wrote: battery terminals 12.67 volts back of voltmeter 10.6 volts. that was static....when I get home I will fire it up and take some actual running readings!

2 volts with no load is excessive. With a load the drop will be more.

8122pbrainard wrote: Chris, Get some voltage readings with a VOM. Don't just use the volt meter in the dash. Start at the battery and then move forward to the dash. Clean all your connections as you go. It sounds like your loosing the volts someplace but the readings will tell.

I'd say your alternator isn't working based on your voltage readings.

It looks like a Mando and it's replacing your original Mando

Your measurement of no voltage differential between the alternator output and the battery positive is telling you the alternator isn't doing any charging since the battery voltage is about 12.2 and isn't up around 14 volts which it would be if the alternator was charging.

You mention that the excitation wire is hooked up, check the voltage where it hooks to the alternator. It should be the same as battery voltage If it's zero, it means the alternator isn't getting any excitation and that's why it's not charging.

The jumper between the S terminal and the output should be like you have it. It provides output voltage to the voltage sensing network in the alternator. Some setups use a separate wire but don't worry about that........you have it right.

Bring it to an auto parts store and they'll most likely tell you "it's not working"   

There is the breaker on the back of the motor....how can I check to see if the is bad?

Here's a TRB wiring diagram that's representative of what you have.

If the breaker on the back of the engine was tripped you'd have power to nothing at the dash and the boat wouldn't start or even turn over.

Rule that one out   

Ok here is what I did......

Put new alternator back on....

Chased orange wire back to the solenoid...

Made sure the plug was tight by wiggling it...

Hooked up battery for a run...

Started motor....

Checked power at terminal of battery 13.6 volts off of meter

Checked power off of alternator 13.6 volts off of meter (off the orange wire and grounded to the block)

Voltage off battery gage about 1/2 volt low of the multimeter.

Could it be this was the problem???????? Really??

Someone suggested taking the plug apart and putting some dielectric grease on the posts.....


I have a test run tomorrow on the lake....

What do you think... did I find the problem? Should I use the grease?

Electrical work... as confusing and sometimes as dangerous as a woman!

I wouldn't bother with Keno's test

It would show about 13.6 volts at the Exc terminal and just tell you that the alternator is now charging which you already know.

If you're talking about the 8 plug connector being the thing to take apart and grease...........watch yourself, it can be a simple straightforward job or it can be like dealing with a gang of 8 angry women.   

Probably the best thing is to take it apart and clean and grease all the connections but i've had them apart and found ugly terminals that are ready to fall apart due to corrosion.

I'd still pull it apart though so you know what you have, otherwise it'll turn around and bite you with electrical issues when you least expect it.

If you wiggled a different plug, do the same thing, pull it apart and grease it like someone suggested.

And.............you may now be the owner of a perfectly good spare alternator .

If that's the case, I'll go back to disagreeing with Pete and say don't return the new one, having spare parts on the shelf is a good thing.

I think we can say "Good job Otto"    .............and enjoy the 4th.

Water tested and all is normal! Even the voltage drop between the battery and the dash volt meter is rectified. I attribute the voltage drop to the resistance caused by times effect of oxidation on the plug. The plug popped apart easily and every contact cleaned and greased I look forward to many hours of fun!

Though I replaced the alternator when I didn't need to, I have a spare. BUT if it wasn't for taking that off, I would not have checked the impeller (and replaced) or changed the fully belts. So I am thankful for that. Even with the frustrations I have learned through this forum about how to trouble shoot more effectively. Thank you everyone for putting your input it my thread; I appreciate it!

I have one question though...I seem to idle a little faster going up and down the river...could it be because the voltage is flowing better to the engine electronics?

Happy 4th!   I hope all of yours is filled with internal combustion power!

Otto