Mariner 150 chargin problem

I have a mid 80'2 mariner

I have a mid 80'2 mariner 150 - the charging system works fine at low to mid ranges but when I go to top end high speed for more than a few miles it kills the battery - all otehr speeds the charging system works fine - help

"J,

When you say that it ki

"J,

When you say that it kills the battery, do you mean that the battery actually goes dead, or do you notice a low ( or high ) reading on your voltmeter or ammeter?

Also, are you blowing any fuses?

The circuit that charges the battery is fairly simple. You will find two yellow wires from the stator to the rectifier. You should disconnect them and check the resistance across the two. Also check for a short to ground in each wire.

Reconnect the wires and run the engine. Check the voltage acrosss the two yellow wires with the voltmeter on AC volts. Check at various engine rpms.

Check the output from the rectifier, with the voltmeter on DC volts. Do this at various rpms also.

Let us know what you find out.

"

The battery actually goes dea

The battery actually goes deaad - well almost dead -

Oh here we go - checked the r

Oh here we go - checked the rectifier - From the positive terminal I could get no resistance to either of the field coil connections forward or reverse polarity - which I should get continuity to both with a reversed polarity check due to the rectifier being basically 4 diodes in series and parallel combined - correct?? Now from the ground I get (either conection reversed or forward polarity) Continuity from ground to terminal A (field coil) and nothing from terminal 2 (field coil) - If my prior AS degree in electronics engineering is correct - sounds like a bad rectifier to me.... I tested the stator and neither side is shorted to ground and the resistance across the coil is less than an ohm which is about right for a coil - how am I doing so far???

"J,

Sounds like at least a

"J,

Sounds like at least a bad rectifier.

"