BATTERY CHARGER: DUMB QUESTION OF THE DAY

Patrout

Those on-board battery chargers ... do they have to be plugged in to shore powere to charge my boat's batteries? Or do they charge the batteries when the motor is running? Crook

Thanks,
Pat

thataway · Posted: Tue Apr 08, 2008 11:31 pm Post subject:

The onboard chargers have to be plugged into 110 V AC --either shore power or a generator. The outboard engines have alternators or other forms of battery chargers, depending on the size of the motor. These are up to 45 amps. The factory chargers are 5 to 10 amps output.

nomadcruiser53 · Posted: Wed Apr 09, 2008 12:29 am Post subject:

You can also get the small solar panels that keep your batteries charged all the time. Pretty handy. Dave

Patrout · Posted: Wed Apr 09, 2008 2:34 am Post subject:

Bob and Dave,

Thanks, guys. That clears that one up.

Pat

matt_unique · Posted: Wed Apr 09, 2008 10:02 am Post subject: Charger

Keep in mind, you should test the system to be sure it works. My brand new Tomcat was wired wrong and the AC charger did not work. The dealer fixed the wiring and I verified it works now.

The only way to test is with a multimeter right on the batteries. Measure the voltage of your batteries without any charging, connect the shore power, flip the AC power switch, flip the switch for the AC charger, then test each battery to read the charge. It should obviously read higher than before you connected the shore power and flipped the switches to verify it is working correctly.

You should do the same to verify your battery charging from the engines. Never switch the battery selector switches with the engines running. Take a test read without engines running, start the engine, test the charge on the correct battery. Shut off engine, switch battery selector switch, and repeat test to make sure your engines can draw power from and thus return the charge once started.

Capital Sea · Posted: Wed Apr 09, 2008 2:00 pm Post subject:

thataway · Posted: Wed Apr 09, 2008 4:05 pm Post subject:

Basically, the alternator is an AC generator, which is pretty much unregulated. There are diodes in a rectifier which change the AC current DC current, and this goes to the battery, which is charged. If there is no battery (resistance) in the circuit, the diodes will be damaged by high voltage spikes. So, you either must have a "Make before Break" circuit--so that there is always the resistance of the batteries. Or you can have an alternator field current dissrupt switch, and that stops the production of the AC current--so no damage can occur to the battery. There must be a field current for an alternator to generate electricity.

Some battery switches have either "Make before break" or a field current disconnect. There is also a "Zap Stop" connector, which will prevent this damage as an add on to the alternator. All of these make it save to switch--but unless you know that these protections are present, there is the danger. You can check for the make before break with a digital volt Ohm meter. Many switches identify that they are safe.

Capital Sea · Posted: Wed Apr 09, 2008 4:12 pm Post subject:

Thanks. My system which switches on demand and can also be switched automatically has this safeguard built in. Your detailed response was much more informative.

C-Green · Posted: Wed Apr 09, 2008 4:32 pm Post subject:

So if I have this right, we need to protect the diodes. "Make before Break" refers to what? I assume "break" refers to breaking the contacts, thus disconnecting the battery or alternator, however you look at it; but what does the "make" refer to? If it's connecting (make) one battery before the other is disconnected (break), so there is always a load, how do you every get to "off"?

Jay

Jazzmanic · Posted: Wed Apr 09, 2008 5:44 pm Post subject:

Yeah, I'm kind of confused too. We have a Perko Switch with 1-ALL-2-OFF. How can I tell if I can change the switch while the engines are running? I don't think the switch is the "Field Disconnect" type. Does that mean I must turn off the engines before switching?

Also, I've read that I should be starting the motor with the switch in the 1 position. I've been starting in the ALL position and running the boat in ALL. If I were to start in 1 and don't have Field Disconnect, would that mean I would have to turn off the engine to switch it to ALL?

Sorry if it seems that I hijacked the thread but I think it's all related.

Peter

Capital Sea · Posted: Wed Apr 09, 2008 5:52 pm Post subject:

The issue is really one for the outboard right. If I were you, and had a shop you trust to do your work, as I do, then I would be asking them this question. With so many system options out there the only way to be sure your questions are answered in proper context with how your boat is set up is to explore the questions with one who knows your boat. IMO

Patrout · Posted: Wed Apr 09, 2008 6:20 pm Post subject:

Peter,
Not to worry about hijacking the thread. My basic question was answered and I learned quite a bit more than I expected by the other replies. This was a good one for me.
Pat

marvin4239 · Posted: Wed Apr 09, 2008 7:02 pm Post subject:

It hasn't been mentioned but I've been told that even if you have the make before break switch you should never turn the switch to off with the engine running. I think this can blow the diodes also.

thataway · Posted: Wed Apr 09, 2008 7:32 pm Post subject:

Yes, Make before Break, means that when the contact is moved to the next position (if it connects a battery--ie from 1 to 2 or 1 to ALL, OR ALL TO 1 ETC.) the circuit remains intact and there is always a battery present, thus the high voltage spikes will not damage the alternator diodes.

That is correct, you should never turn the switch to "Off" with the engine running.

You can check the continuity of the switch with no battery connected. Put the VOM on conductivity, and one of the leads on "1" and the other on "2", as you turn the switch between then the buzzer will sound momentary as you switch (and if you are on Ohms setting it will drop to less than one Ohm). This indicates that there is flow of current between the two terminals as you switch and it is briefly in "all" positon as you switch.

Starting and running on "All" is a good idea if you have fully charged batteries, and don't know about the switch. Just switch to the house bank (assuming this is "2") when you anchor or stop for any peroid--and save "1" for start, since there will be no power used and the starting battery will be fully charged. If you have a switch which will allow switching without damage, then you can start on 1, then switch to "all".
The beauty of the VSR is that they do this automatically--and let the starting battery charge before switching to "all"--

C-Green · Posted: Wed Apr 09, 2008 8:37 pm Post subject:

Got it. Thanks for the thorough explanation.

Jay