Rookie Dual Battery Question

[alex37]

I just bought a 1999 Regal. It has the dual battery with the switch. Should I alternate batteries each time I take it out?

 

[Mnemonic]

Re: Rookie Dual Battery Question

No need. Run it on the All setting so both batteries are charged. Only reason you'd need to switch is if you anchored up and you were listening to a stereo on battery 1 for 7 hours, you might not have enough cranking amps to start on battery 1. You would switch over to battery 2 and start on that.<br /><br />PS - Unless you have a "Make before break" type battry switch, DONT switch the setting when the motor is running!

 

[KRS]

Re: Rookie Dual Battery Question

If you go out infrequently, then you probably need to be removing the batteries and storing them in a safe place, with an overnight charge once a month.

 

[QC]

Re: Rookie Dual Battery Question

Here's what I do because I have no idea what my kids might do with a switch or something if we are sitting on the beach. I always start the day on ALL. Then on my first stop for the day (after a good chance to charge them both) I switch to the one corresonding with the date. i.e. #1 for odd dates and #2 for even dates. Then if somebody (or me) leaves something on or we listen to the stereo for a long time, I always have a fresh battery for starting.

 

[travism]

Re: Rookie Dual Battery Question

Are the two batteries the same? If not, you might get different responses. Some boats, like mine, have a starting battery and a house deep cycle battery. Starting batteries are made for lots of amps for a short spurt, like starting the engine (duh). Deep cycle batteries are made for low amp output for longer periods of time, like using lights and the radio while overnighting on the hook.<br /><br />I start the engine on the starting battery, then switch it to "all" to charge both batteries while the engine is running. I have a make before break switch so that's okay. And when we anchor, especially overnight, I switch it to the house battery. I repeat the process when we get going again. If stopping and starting a lot like during watersports I'll just leave it on the starting battery.<br /><br />So in short, I say it depends on your battery setup and how long you will be at anchor. You can just keep in on "all" or "both" position if you have two starting batteries and don't anchor for too long.

 

[QC]

Re: Rookie Dual Battery Question

I agree with travism. My system noted above is for two of the same. Mine are both starting batteries.

 

[BUBBLES II]

Re: Rookie Dual Battery Question

I'm no expert. I have recently been told that in the "all" position the battery with the least resistance (the one that is most charged) will be the only battery charged. (Not sure if terminology is correct.) Select either 1 or 2 and both will be charged, one after the other. This kinda makes sense, in my case. At the slip, I left the switch on all, and with the bilge pump kicking on for two weeks, both batteries were drained barely enough to require a jump. When started, I left the switch on all. The motor ran all day, five hours. I thought I was charging both batteries. However, only the one that had more oomph in the beginning was charged. The other was still reading the same, 6v, on guage, at the end of the day. I'm winging it with the dual batteries. Please, explain the make or break switch.

 

[Silvertip]

Re: Rookie Dual Battery Question

In the BOTH position, both batteries will charge. However, if batteries of two different brands, sizes, age, and/or capacity are used in parallel charging problems can be encountered. Depending on the capacity of your engines alternator, 5 hours may not have even begun to fully charge even one battery. If the switch is in the BAT 1 position, only that battery will charge. Same in BAT 2. OFF turns everything off. The bilge pump however, should be connected directly to to prevent the boat from sinking if its tends to take on water. Make-before-break switches are designed so the switch connects to the next circuit before it disconnects from the other. For example, if you had the switch set to BOTH and were moving it to "1", the connection to "1" would occur before the connection to "2" was disconnected. This feature is extremely important since charging system damage can occur if the battery load is removed for even an instant. Therefore a switch that does not have this capability should never be switched with the engine running.

 

[BUBBLES II]

Re: Rookie Dual Battery Question

Yes, the bilge pump is directly wired to one battery. Thanks for your answer, Upinsmoke. I understand now.

 

[imported_Curmudgeon]

Re: Rookie Dual Battery Question

USCG just spent a bunch of tax payer money looking for a missing boat off CHS; they were found 2 days later. They ran their switch on "both", the motor alternator quit, both batteries went dead, the motor wouldn't start ... and the VHF wouldn't work. Routinely using "both" invites a surprize ending to your day.

 

[caplbi]

Re: Rookie Dual Battery Question

running the switch on the all/both selection is a sure fire way to burn up the alternator,I know because I did the same.Bought a new alt.from a marine rebuilder and was told never run on the all and never change selections while engine is running. Hope this helps.

 

[alex37]

Re: Rookie Dual Battery Question

This has all been very helpful. Thanks.

 

[Silvertip]

Re: Rookie Dual Battery Question

Old C -- If that scenario happened like you said, (the alternator quit), and the switch was is BOTH, It was the fault of the operator, not the switch. Alternators fail. The voltmeter should have told him/her that. At that point you immediately go to "power conserve" mode by switching to one battery or the other and turning off all unecessary electrics. With all the electrics on a bigger boat it does not take long to drain two batteries -- especially if one is weaker than the other. You implied it was the switches fault. I need to disagree with the BOTH setting causing alternator damage. If the battery switch is properly wired and with BOTH selected, the alternator does not know and could care less if its output is going to one battery or two. Why? -- because electrically, two batteries in parallel is simply one bigger battery to the alternator. In comparison, its like having a motorcycle battery in the system or an automotive starting battery. The alternator doesn't care. As I pointed out earlier, if one of the two batteries is bad (such as a bad cell or internal short), yes, charging problems could arise, but that can happen if you don't even have a battery switch. Or how about the operator that thinks, my BAT #1 is low I better switch to it for the run back to port. That battery is bad so an alternator could very likely hatch. It simply makes no difference what setting is used if there is an electrical problem on the vessel. Besides, an alternator failure can occur and suck a battery dry in short and it does not have to be the fault of the battery (or batteries). If the BOTH position was a problem, switch manufacturers would not be permitted to have the provision for safety reasons. It simply amazes me how little people know about the vessels and features they stake their lives on when going on the water. Especially offshore.