Battery Charge -Mercury outboard

[waterline]

I have a new Mercury 4HP 4-stroke Sailpower outboard that has a built in alternator/charger. I was simply going to extend the cable to the battery on my boat (pos and neg), with an inline connector if I need to remove the engine or break the circuit. Can anyone tell me if I leave the wires disconnected at the engine, will this do any harm to the charger/alternator in the engine?
There is absolutely no mention of the charging unit in the handbook.

 

[jollyjacktar]

Figure it out. You are running it now without a battery in the circuit or it appears that the manual lets you do this. No harm? Ergo put a battery in the circuit via the + and - connections. Most likely will be charging on the magnetto circuit at about 3 amps max. You may need to rectify this current, although the +,- terminals would indicate that there is a built in rectifier, otherwise a heavy duty, with heat sink, simple diode on one of the lines [bridge rectifier better] will sort this out. Might be a good idea to check things out with an AVO meter or such like just to make sure charge circuit works and is DC and/or else even put a light globe in the circuit [without the battery being coinnected] to see if it works. If all else fails check the www. etc thinghy.

 

[chriscallender]

I have a 7.5HP Mercury Sailpower of approx 1984 vintage. I am nearly sure that the manual says that it is OK to run without the engine connected to a battery for emergency use but that it is not recommended for long term use. I'll dig out the manual tonight and see if I can confirm this. But not sure if the charging circuit will be the same for a new engine as an old one anyway

 

[rex_seadog]

I have a 1999 Mariner 8HP Sailmate (identical, I understand, to the Mercury Sailpower) and on a previous boat had a 1996 Mariner 4HP Sailmate, both being rectified but not regulated. According to my dealer there is no problem connecting to a battery as you describe. However they strongly recommend having a switch in the +ve lead (as I have) so that it can be isolated when the engine is not in use. They say it should come to no harm if left isolated (or totally disconnected) when the engine is in use but E P Barrus (the Mariner/ Mercury distributor) recommend that this should only be done for short periods. (I sometimes to forget to switch on the isolator in the +ve lead and so far I have had no problems).
Although not regulated they do not seem to think there will be any problem in overcharging the battery.