BF 5A charging issue....how does the voltage rectifier/regulator work

Installed a BF5a charging kit in a 2004 four stroke five horse Honda. I am getting a voltage reading off the battery of...non running engine=12.95 volts and running= 13.04 volts ???....question is ...does the regulator auto sense for charging voltage?......I read off one of the pick up coils an AC signal of 10.4 V at idle RPM and up to 14.0V at higher RPM going into the Rec/Reg....is this anywhere correct?....I finally placed the battery under load, turned on all the lights radios and such and the battery voltage dropped to 12.4 volts. I then fired up the BF5a and at idle it climbed to 12.6 volts and then with an increase of RPMs it climbed to 12.8 volts ....does this sound anywhere correct?...man, has this been a real head scratcher. I thought that the voltage would have been over 13 volts always...If anyone has any idea if this is running right or not please let me know.

Re: BF 5A charging issue....how does the voltage rectifier/regulator work

One other thing....I questioned the regulator and ordered another one. I replaced the original one and it made no difference.....geeezzz

Re: BF 5A charging issue....how does the voltage rectifier/regulator work

How many amps is it now rated for? I'm guessing not many, and max output is at higher RPMs ...

Re: BF 5A charging issue....how does the voltage rectifier/regulator work

Hey Outsider and thanks for the reply.....the charger kit is rated at 3.75 amps I believe. It sure would help if the kit came with documentation stating parameters. The result is not what I was expecting but maybe it is the norm. On a fully charged battery the current should be low so does that mean the voltage regulator also drops the charging voltage?...I guess that if it was constantly over 13 volts it may boil the battery...documentation from Honda sure would help....tnx

Re: BF 5A charging issue....how does the voltage rectifier/regulator work

Most older small OB charging systems are unregulated. Pretty crude. The manufacturers feel that 3 or 4 amps isn't going to boil the battery too badly. Tohatsu is a notable exception, in that their modern rectifiers are regulated. Regardless, the output on those small units is puny, and will not supply much charging. Might keep up with a VHF radio, but not much else. Basically, the fact that you get a voltage increase at higher RPMs indicates that you are charging.

Re: BF 5A charging issue....how does the voltage rectifier/regulator work

Hi Paul and thanks for your reply. It sure is disappointing to spend a few hundred dollars expecting to not having to worry about a flat battery only to find out that your investment can't keep up to your expectations. That is my biggest beef with companies like Honda. They do not produce much info to accompany their product and if there is a problem you are directed to contact your local dealer. Then when you contact the dealer they can't offer you any more information than what you already know. Data sheets or access to the charging kit operating specs would be very benificial, someone had to design this kit and kept records. It just ticks me off that the support locally to me is not that great. I had to order the Kit from the U.S.A. as it was not available here in Canada according to the local dealer.Isn't that great support..haha .....tnx

Re: BF 5A charging issue....how does the voltage rectifier/regulator work

You need to understand that the alternator on any small OB of any make and any vintage will be puny. It's a matter of how much horsepower is required to operate the alternator. For example, a car alternator can easily use more than the entire 5 hp of your motor. The small charging systems will keep a good battery topped-up, but can't charge at the amperage needed to power most onboard loads. That said, they might offset using LED running lights, or a little sounder use. Any amps-in will help. The larger OB's generally have very robust charging systems, as they have the HP to drive them.

Dunno about parts availability for Honda in Canada. I do know that Canadian Tohatsu/Nissan dealers have full access to all parts for their products.

Even the [relatively] new Tohatsu/Nissan 6 hp sail-pro charging system (also available for the 4/5/6 hp non-sail versions) is only 5 amps (60 watts), although it is well-regulated to help prevent boiling of the battery.