mercury 40hp no batt needed?

[domains]

Can i run my motor without over charging system , i want less weight no batt cables .its electric start will it charge no probs diconnected ?

 

[Texasmark]

Re: mercury 40hp no batt needed?

Unless your engine has a magneto (electromagnet and a rotating magnet) you need your battery to run your ignition.

Now, if you are asking the question as to whether or not you will hurt your engine's alternator by not having a battery attached to the output the answer is probably not if you don't allow the leads to short out. The voltage will be somewhat higher than normal, but since we are talking about a 12v system, even if it doubled (which it won't) the voltage isn't that high for modern insulating materials.

Mark

 

[domains]

Re: mercury 40hp no batt needed?

Cool thanks ...i was wondering if it would burn plugs or whatnot ..its a stator charging system not points .i know it starts with harness disconnected .

 

[j_martin]

Re: mercury 40hp no batt needed?

No battery installed could cause the peak inverse voltage on the bridge rectifier to go over spec. The spec on a mercury diode is a mystery, but obviously too low. If you replace the diode with a 400 volt unit, you will have no problem. If your motor actually has a voltage regulator on it, you will probably kill it with no battery.

Below is a picture of a rectifier. If your unit has an aluminum box with 4 or 5 wires coming out of it, it's a voltage regulator.

hope it helps
John

 

[domains]

Re: mercury 40hp no batt needed?

1976 mercury 402 40hp ..motor is in a garage 30miles away ..going there tonight il check ..where would i buy a 400 diode and do they cost much...i can hookup batt if to expensive ,just i wanted less weight on boat.

 

[Laddies]

Re: mercury 40hp no batt needed?

On your 402 simply remove the 2 yellow leads from the rectifier and tape the ends off separately and you will have no problems both the manual and electric start us the same stator and switch box as replacements neither use any battery voltage to run the ignition system

 

[domains]

Re: mercury 40hp no batt needed?

Cool thanks ....one wire goes to the solenoid and other goes to wire harness. il tape them both thanks.

 

[Laddies]

Re: mercury 40hp no batt needed?

Those are not the 2 wires I was talking about the is a rectifier on your engine with 2 wire coming from under the flywheel those are the 2 yellows you need to disconnect and tape

 

[domains]

Re: mercury 40hp no batt needed?

aaaa ok my stator only has a red and black wire ...i seen the yellow ones before on other motors ...so i'm set to go then?

 

[Laddies]

Re: mercury 40hp no batt needed?

If your stator is a early replacement stator for a manual start engine it wouldn't have the 2 yellow wires or if the electric starter was a add on kit from Mercury it never had a charging system on it so your still alright, you just don't have the alternator wire to tape. If you decide to remove the starter for weight be sure to tape any removed wire ends.

 

[domains]

Re: mercury 40hp no batt needed?

Cool thanks for all your replys...kinda new at this . fathers a auto machanic helps me but even hes not to sure when it comes to boat motors .