BF90 overcharging...

smokeonthewater

smokeonthewater

God
I know there are a couple of you guys on here that eat sleep and breathe out boards...

I have a 2001 Honda bf90 that has started overcharging the battery. I'm getting 16 volts while running. Of course my first thought is voltage regulator but are there any common things I should be checking before I get into it. FYI this is a freshwater boat and always garage kept.
I did just put a new battery in it but had the problem w the old one too.
 
I have zero knowledge of that outboard, but being a 4 stroke, does it have an alternator?

If so, is regulator separate or built in the alternator. We are very luck to have a very good shop here that still rebuilds alternators. Mercury has had an issue with the alternators on some of their motors. I am on my second and my buddy is on his third. Last time, he took his into the shop and they just installed a new regulator on his alternator.

Still ran about $125

If you have an alternator, maybe pull it off and take to a shop and see what they say

Sorry, can t help more
 
See, told you i had no clue

Hopefully one of the smart guys will know something

I do know Honda has some very good service manuals to help diagnose stuff, might be able to find them online
 
Put a good voltmeter on the battery to double check your readings. Check your battery connections, make sure they are clean. Load test and do a voltage drop test on your battery to make sure its OK. Check your battery cables, if you have a load tester, this is easy to do, if not, feel the battery cables from one end to the other, pay attention to where it goes thru the cowl. make sure you don't have any hard spots. Japanese electrical use very fine strand wire, it works great till it gets overloaded, corroded, or old. I replace Yamaha battery cables on a regular basis. Try using a set of battery jumper cables to add current carrying capability from eth engine to the battery and see if it makes a difference. Keep in mind, the regulators are fairly crude, they generally operate in an on and off mode, where as if it needs charging, it turns the charging coils on and it goes full voltage, if it doesn't need charging, it goes off, so its common to see big swings in voltage rather than variable output like an alternator would show.
 
Thx guys...
Spare I'm pretty confident in my connections and battery, but will double check just in case... I did remove the ground connections on the engine to inspect last night and not a hint of corrosion under em...
 
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Well connections were as I thought... perfect... no hard or crunchy spots in cables but noticed a couple wrinkles where they go through the cowl... not sure if that indicates an issue or not....
Did a load test using the trim pump.... after a few up/downs, voltage at bat during down stroke was 11.2v and voltage at engine end of cables was 11.0v....
0.2v drop through cables sounds excessive to me... what say you?
edit... measured load during down stroke is 36 amps


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Well I feel like a retard... I had compared dvom reading to gauge reading several times w the key on engine off and they were the same so I had it in my head that the gauge was good....
Doing some more testing today I had the engine running and checked between engine block and starter lug and to my surprise got 13.6v.... puzzled... tested at bat and again 13.6v.... a few more moments of haze and then w a big homer simpson DOH!.... clarity set in.... crawled under the dash and tested at the back of the gauge.... yeah.... 13.6v there too!!!

Dammit I KNOW better... worse yet Spare TOLD me better....

I swear I was smarter 20 yrs ago.... ugh
 
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smokeonthewater said:
Well I feel like a retard... I had compared dvom reading to gauge reading several times w the key on engine off and they were the same so I had it in my head that the gauge was good....
Doing some more testing today I had the engine running and checked between engine block and starter lug and to my surprise got 13.6v.... puzzled... tested at bat and again 13.6v.... a few more moments of haze and then w a big homer simpson DOH!.... clarity set in.... crawled under the dash and tested at the back of the gauge.... yeah.... 13.6v there too!!!

Dammit I KNOW better... worse yet Spare TOLD me better....

I swear I was smarter 20 yrs ago.... ugh
Click to expand...


You're fine. You simply had a senior moment. :you:
 
Smokeonthewater, believe me I am no expert by any means but I do have a outboard for a long time so I'm just giving you my advice and what I would do. The very first thing I would do is check the battery connections ( and you did that) second thing I would do is hook up a volt meter to the battery and run the engine even if you have to take her out with the volt meter hooked up and that's just to confirm that the readings on your dash are correct, if your multimeter is showing a better correct reading than its your dash meter than your done at this point if it's not your dash meter I would replace your voltage regulator, i have a Mercury and mine is on top but it's a two stroke You should change yours too I don't know where yours is bug I would change it. Hope this helps. The heavy hitters are going to reply hopefully soon but the problem I have with them is they do tell you how to fix it but sometimes I have no idea what there talking about But that's not there problem that's cause I'm ignorant about there solutions I don't know how to do it or don't have the tools that they say to use. I just read you have a second page and looks like you solved it talking about a senior moment just had 1
 
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