Battery Check

[Scuba 1004]

How do I check that the engine is charging the battery,also could you tell me the correct size battery for my engine, Yamaha 90hp outboard 1999
6H2-86
Normal Power 441kw

 

[Silvertip]

Re: Battery Check

You need a voltmeter to test alternator output voltage. Connect the meter to the battery and start the engine. The voltage may read about 12.6 at idle but it should rise to 13.5 - 14.5 volts or so at 1500 - 2000 rpm. If it stays at or below 12.6 the charging system is not working. There is no maximum size battery required for your engine. You can only go too small. I tend to recommend a 500 CCA marine starting battery. The cost and physical size doesn't change much so you may as well install a battery with more capacity. Gives you that much more reserve cranking power.

 

[rodbolt]

Re: Battery Check

minimum battery size is 380 cold cranking amps, I am with silvertip though, on a battery bigger is better. no sense in starting out with the minimum.
I use 1000 CCA on all my stuff.