johnson 90 hp, losing battery charge

hey i have got a 90 hp johnson outboard motor and i take it out and it lasts for about an hour then it loses charg, any help would be appreciated cheers troy

Re: johnson 90 hp, losing battery charge

99% bad recitfier, but have battery load tested at the auto parts store (free) before ordering recifier.

Re: johnson 90 hp, losing battery charge

If the battery holds its charge when off the boat then it is not likely to be the battery that's at fault.

As TD says the rectifier could well be the trouble.
If you have the simple round rectifier as used on models without power tilt and trim you can test it as described on the Engine FAQs board, but if you are using a digital meter use it on the "Diode test" range as they don't always work for testing diodes on the resistance ranges.

If you have a rectifier regulator I don't know how to test those easily.

Before ordering a rectifier I would either test it or carry out some current measurements with an ammeter to see if the battery is in fact being discharged through it. If it runs the battery flat in an hour you are looking for a fair old current, more than the top range of most multimeters, unless you have a very small capacity battery.