Voltage regulator for FF

[Skidz]

Hey folks,

I just got a HB 898si, that I'm using on a boat with a 2000 25 hp Johnson OB. This engine does not have voltage regulator.

On my old fish finder, when running at WOT near the top of the rpm range, it would say 'voltage high'. I don't want that to be an issue with the new HB, and I have heard that a regulator will solve this issue, capping at about 13 volts.

Has anyone heard of this, or know what I need to purchase to keep my new unit from getting fried?

Thanks,
Skidz

 

[jhebert]

Re: Voltage regulator for FF

It is common that on outboard motors with an unregulated charging circuit the output voltage will become rather high when the motor is running at higher engine speeds. The concept of the unregulated charging circuit is for the battery to provide most of the voltage regulation by absorbing the charging current and holding down the voltage. However, if the battery is fully charged, its terminal voltage will rise above the usual 12.9-volts of a fully charged battery, and the battery terminal voltage may be as high as 15-volts or more.

If you have sensitive and expensive electronic devices connected to the battery when its terminal voltage is raised to 15-volts are more, these devices may begin to complain about the high voltage. I don't know anything about your specific device, but if it is complaining about its input voltage being too high, you probably should take some step to remedy the problem.

The best remedy would be to add a voltage regulator to the charging circuit of the outboard motor. This will also help with battery charging. Batteries which are left on charge with a charging voltage of more than about 14.5-volts will tend to boil off their electrolyte, causing harm to the battery.

If you want to leave the motor unregulated, you will have to find some sort of external voltage regulator for the electronics. I don't have any specific recommendation for you.

 

[John_S]

Re: Voltage regulator for FF

I don't know if the HB will shutdown before damage occurs. On that HB unit you can enable the main display to show voltage. Normally, you won't see that high of voltage. When you do see it rising and above 14V, turn on some other accesories such as lights, live-well, pump, etc.

I would think an output regulator that feeds the battery and all equipment would be a better solution. Expensive? Large heat-sink? Not efficient?

With an inline regulator, what happens when the motor is shut off, and back on battery power? Is there a voltage drop across the regulator? or is it really a converter?

 

[jtexas]

Re: Voltage regulator for FF

I'd be real suprised to find a new FF that doesn't have over- or under-volt protection.

A voltage regulator chip like the 7812 (couple bucks at radio shack) would work, but it would drop 2 volts any time the input voltage is below 14; since your cranking batt ought never to get below 12 point something, you'd be good to go long as the minimum FF voltage is at least 10. Wouldn't need a heatsink unless you're drawing 2 amps or more; most FF draw way less than an amp.

But I bet your new HB input voltage range is 10-18, maybe even 10-20 anyway.

 

[John_S]

Re: Voltage regulator for FF

You are probably right about the protection. While I have tested the low voltage, I have never shut it down from high voltage. I have seen the same warning message though. The warning threasholds are adjustable. I am not sure of the amp draw. I think those size units recommend 3 amp fuses. They power an external gps receiver plus they can power other accessories. If going with that regulator, a heat sink might be worth it.