Voltage rises to 17v for a minute..

Hi all.

Yesterday i saw my voltage on the gauge and on my garmin gps showed 17.2v it stayed like that for a minute or two and went back to 14 again. Then it happed a copule of times again. No effect on the engine or any electrical parts. The rpm was between 1000 and 2500 no changes of voltage with increasing/decreasing rpm..

Is that a new regulator or alternator?

Thanks.

More information is required. What motor is this? Outboard or inboard? Model?

Oh sorry. Its a 1996 115 hp mercury 2 stroke outboard

What kind of batteries do you use? Not a strong charging system on that engine and flooded wet cell batteries are best. Deep cycle or AGM batteries stress the charging system too much. Mercury put out a service bulletin about this.

make sure the wires on the voltage regulator are all tightly connected and not chafed or melted. Follow the yellow wire from the voltage regulator and inspect it closely.

look at the switch box too and make sure connections are tight and no melted wires anywhere.

Thanks. I have looked at all the cables they seem fine. This is the battery I use.

What are the consequences if the issue remains?

CaptainJS said:

Thanks. I have looked at all the cables they seem fine. This is the battery I use.

What are the consequences if the issue remains?

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Check the water in the battery. Top off with distilled water only.

The consequences are your engine will catch on fire. Don’t cheap out if the voltage is correct. Go through it thoroughly and spent the money on the improved voltage regulator.

Understand that this engine was engineered to run off a starting battery. Multiple batteries which only like to accept slow charging /accessories will push the charging system to meltdown.


The new regulator is better. Some use the Yamaha regulator but the voltage regulator is a maintenance item under improper/heavy load.

Understand, neglect and cheeping out will result in meltdown/potential fire!

Ok many thanks for the feedback. I would like to exchange it for a new one but which? I guess if i exchange it for an original one thw issue will be the same?

I dlnt understand how it could run off a starting battery? There is no pull cord to start it (and good luck doing that with a 115 hp)...

The old part will be superseded by the newer one. Just take it off and go through every connection. If you buy a new one count the wires on it, six right?

Look under the top of the cowling, is there an emergency pull cord? I’m not sure how high the emergency start goes but I know the 75-90 ELPTO have one attached to the top of the cowling.

Also, if you do pull start it with a dead or no battery there is a procedure by outlined in the manual to disconnect something with the voltage regulator. I have never had to do it and pull start. Read the manual. Call Mercury and ask, if you need clarification on the superseded part to get the latest version.

I have the 1996 135, one step up from the one you have. For me, there are two voltage regulars attached to the block behind the plate at the back of the outboard that holds the coils.

Item number 7 if you need a picture of what to look for. www.marineengine.com will give you the parts diagram if you enter your serial number. From there, go to ignition coil / voltage regulators sub section, find it in the list. The website gives you the original part number and all subsequent. I would go with the newest Mercury/Quicksilver on the compatible list or the CDI brand regulator. You don't have to buy from there, search for that part number if you like. I typically buy from them if I looked up the part number and price with them is comparable to other retailers. Note that some of the newer VRs no longer use/need the black wire to ground at the top of the block. Also, to inspect the VR and wires, I needed to remove the metal plate holding the coils. Don't by the unbranded regulators on ebay! also make sure if it did not come with the thermal paste, you pick some up for the install.

Plenty of YouTube videos on how to test a voltage regulator.

When I had a VR loss, the damage to the VR was obvious due to melted wires and melting of the plastic face of the VR. Hard to see the damage without removing that mounting plate. The wires are routed through a sleeve up to the point they are joined to the VR leads.

FYI, I have the 135, and do have an emergency start pull cord that came in the original owner package.