battery switch and charging

[rolrandy]

94 120 Johnson and I have a starting and a deep cycle battery on a battery switch
1-2-ALL and off
Is it bad to run the engine on ALL so both batteries will charge?
Or will this fry the regulator?
This is what I hear is it true

 

[rndn]

Re: battery switch and charging

I run a similar setup but find the deep cycle doesn'y always charge fully because it takes a lot of boating to charge it up. It won't hurt your boat but if you really want the deep cycle charged you should charge it at home unless you drive the boat for a couple of hours.

 

[angus63]

Re: battery switch and charging

Rule of thumb is not to charge different size/capacity batteries at the same time. A weak and strong parallel charge circuit may overcharge the strong battery causing boilover or plate warpage. Deep cycles like a long, slow charge anyway. A simple solar charger will keep the deep cycle happy. I use two dual purpose batteries (identical). Charge one on the way out and one on the way back. Always have the option to charge both if I need to.
Good luck

 

[rolrandy]

Re: battery switch and charging

I also have an onboard charger so when I get home I plug it up and charge
But I was just curious about while on the running on the water will it hurt to run with the switch in the all position deep cycle and starting battery on
Will it fry my rectifier?

 

[Vic.S]

Re: battery switch and charging

Will it fry my rectifier?

No but it would be better practice to charge the starter battery first then switch to the other one (via the "both" position on the switch) and charge that on its own. That way all the available charging current is going where you want it and by not having both batteries in parallel you do not run the risk of a defective battery pulling the other one down. If for example your deep cycle battery failed unexpectedly (They can and sometimes do) it might pull your starter battery down without you realising it leaving you with one dead battery and one flat one!

In inboard engine installations diode splitters or voltage sensitive relays (VSRs) are sometimes used to either chage both simultaneously or give the starter battery priority.

 

[tashasdaddy]

Re: battery switch and charging

you have to have the correct switch to change settings while the motor is running, you need a constant connection switch, inorder to change, the break switch will fry the rectifier, if changed while the motor is running. there are proper names for these switches, but they escape me at present.

 

[ezeke]

Re: battery switch and charging

"Make, then break". Don't ever trust the seller on these, verify yourself that both batteries are connected before switching to one or the other. The only 100% safe bet is to turn the motor off before switching.

 

[Silvertip]

Re: battery switch and charging

The term is "make-before-break" which refers to the internal connections on the switch. If a switch does not make the new connection before it breaks the existing connection, it creates a momentary open charging circuit which will bugger up the regulator. Chances are you have the correct switch. If one of the batteries is discharged far more than the other, then it would be best to set the switch to charge the most deeply discharged battery separtely. otherwise it won't do any damage if running on BOTH. An on-board charger for the troller is by far the best setup. plug in to shore power when you return to the dock.

 

[rolrandy]

Re: battery switch and charging

So do I need a voltage meter for both batteries??
to see where I am

 

[Boatist]

Re: battery switch and charging

Understand when you switch to all with a charged starting battery and a discharged and bigger trolling battery then the starting battery will start discharging into the trolling battery.
Since the trolling battery is usually bigger it can discharge the starting battery to the point you could not start the boat. If trolling motor should have a dead cell then it will surely discharge you starting battery.

If your motor alternator is 20 amps or more is should charge both batteries with most of the current going to the trolling motor battery. Also if the trolling motor battery is group 27 or bigger it will take at least 12 hours to fully recharge. If your alternator is smaller like and 8 amp I would not try and charge the trolling motor battery at all. Your alternator would be running at max output the whole time and could over heat.

If you have a dash volt meter then you can turn the switch and see the voltage of the battery you are switched to. Safer to turn the engine off before switching. If you have a good Make Before Break Switch then you can switch with the motor running but if you turn thru off you will need a new alternator.

 

[Vic.S]

Re: battery switch and charging

So do I need a voltage meter for both batteries??
to see where I am

Not necessarily. One meter with a three position switch so that you can select either battery or off would be sufficient. Even just a meter with no switching connected to the common terminal of your battery selector switch will be adequate to monitor the charging or show the state of charge of the battery in service.

Make sure you fit a fuse in the connection to the meter.

BTW your 1,2, both off switch is the type of switch commonly used for switching batteries. Make sure you always go via the "both" position if you change batteries while the engine is running. Its not so important if the engine is not running but it is usual to then switch via the "off" position

 

[yamamarinetech40]

Re: battery switch and charging

You shouldn't charge deep cycle batts with more that 10 amps ever....everybody knows this, but it won't hurt the rectifier or reg., it's eventually hurt the batts....you could put a seperate regulator down from swithc to deep cycles batts....

 

[Boatist]

Re: battery switch and charging

I think you should never charge with less than 10 amps. The damage done from being discharged is worse than any possible damage from a high amp charger. My current deep cycle is around 9 years old and it has been charged it whole life with a 65 amp alternator on my I/O engine. I bought it back when Costco was called Price Club and they sold Delco Voyager batteries. My dads trailer has been charged from his Chev truck's 100 amp alternator. Almost all camper and motor homes charge the deep cycle with the engines alternator while going down the road. Today the standard alternator is 100 amps or more. Charge it with a Smart charger or alternator with a voltage regulator and you will have no problems. Do not ever leave it discharged even over night if you want it to last.

 

[PondTunes]

Re: battery switch and charging

I always recommend to people when talking about dual battery setups to not try to charge 2 batteries at once with any outboard engine. You would be better off (as stated earlier) to charge your deep cycle with a shore charger once you get back from a day out.

Your outboard engine really isn't designed to recharge a dead battery as it doesn't have near the output of an automotive style alternator and it doesn't output at all during idle you've got to have the rpm's up before it even charges at all.... The easiest way to explain it is like this:

Say for example If you run a trolling motor, depth finder, bilge & lights and lets just say that that works out to 15 amps off of your battery per hour. A small outboard may have a 10 amp charging system (meaning it can put 10 amps back into a battery per hour) Thus it would take 1.5 hours at WOT to fully replace what you used. Charging systems on outboards vary a lot with 35 amp systems being available on newer, larger outboards so it is important to find out exactly what you are dealing with. Keep in mind if you happen to pick up a big group 27 battery with say 90 amp/hour reserve it would take even the 35 amp system about 2 1/2 hours at WOT to recharge it from a discharged state!!!

Thats burning alot of gasoline just to make your outboard charge up a battery... (which isn't at all what it's designed to do) The above setup was just strictly speaking of ONE battery if you had a starting battery + a deep cycle you would be looking at even longer to try to put charge back on the batteries.

The ALL setting in a 1-2-OFF-BOTH switch should really be reserved for Emergency use, being in the habit of switching to BOTH can very easily leave you with two dead batteries.

On normal use however your starting battery will be just fine cranking the boat then switching to battery #2 to keep it topped off or to run your loads (fish finder, radio, lights, trolling motor)

 

[azlakes]

Re: battery switch and charging

A small outboard may have a 10 amp charging system (meaning it can put 10 amps back into a battery per hour) Thus it would take 1.5 hours at WOT to fully replace what you used.

This true? I'm putting out about 13.7 volts at idle. Should voltage an amperage amplify as throttle increases? To what end?

 

[PondTunes]

Re: battery switch and charging

Outboard engines don't turn alternators, the battery charging voltage comes from the stator & rectifier. These are often unregulated and put out voltages & amperages that vary with engine speed.

According to my Johnson-evinrude Manual the V4/V6 engines are regulated with output amperages ranging from 10 amps to 35 amps. The higher amperages being available on the larger engines...

This means that your voltage should be regulated to a degree, the amperage however will probably still vary topping out at 10-35 amps near WOT.

 

[Boatist]

Re: battery switch and charging

Many outboards over 100 HP do have alternators, some belt driven. Most put out a good amount of power from 1000 rpms up.
A 35 amp alternator will not charge a discharged group 27 trolling motor battery in less than 10 HOURS. 35 Amp alternators or stators have voltages regulators set between 13.8 volts to 14.8 volts. Yes for 2 or 3 minutes battery may take 25 amps or so but by then the current will start to drop and will continue to drop until fully charged. After an hour most I have charged will be 10 amps or less. The more charge the battery is the slower it will charge and when Fully charged will drop to 0 amps.

My fishing partner I fish tournaments with has a group 27 battery. Often we prefish Saturday form sunrise to 1400. Get back home by 1600 and put on a 15 amp smart charger on right away. Battery is never fully charged by 0400 when we hook up to head to the tournament. That why always use two batteries on tourmament day.

 

[andy6374]

Re: battery switch and charging

The optimal setup would isolate the batteries during discharge and connect while charging. This is what you want

When the engine is started and the start battery reaches 13.7 volts, the VSR engages, allowing both batteries (start and house) to be charged simultaneously. When the voltage drops below 12.8 volts (like when the engine is stopped), the VSR disengages, separating the batteries.
This system eliminates the possibility of draining the wrong battery
and protects sensitive electronic equipment powered from the
house battery from harmful engine start up spikes.