Alternator output

[cddetelich]

Engine is a 1990 175 Johnson. I use very little electricity while using boat-at most fishfinder and running lights-voltmeter reads 12.5 before starting, right after starting voltmeter reads 14, maybe 13.5 if both of the above are on. After half a season (3 months) battery was still low-I took it out to recharge and noticed motor turned over faster than ever-seems like alternator is not putting out enough to recharge after starting? Battery is one year old, starting/deep cycle combo.

 

[F_R]

Re: Alternator output

Why do you feel it is low? 14-14.5 volts after it runs awhile is excellent. A tad lower with some accessories on. Most regulated systems are set at around 14.5 volts depending on temp etc. Unregulated systems often go up to 16 or so, but then people start fretting and worrying about possibly cooking their battery.

 

[jtexas]

Re: Alternator output

12.5 volts is only about 75% of full charge...so sounds like you finish with more than you start out with...sounds like a good alternator to me. When you started out with it fully charged, how was it at the end?

Battery will self-discharge, also you may have a parasitic load if you keep it in the boat between times. Testing with a hydrometer will reveal if you have a cell going bad.