Will both batteries charge?

[footbrake]

With the battery switch on "Both" will the running engine charge both batteries simultaneously? If yes then I suppose having the switch in either #1 or #2 will charge that particular battery selected.

 

[LippCJ7]

Re: Will both batteries charge?

With the battery switch on "Both" will the running engine charge both batteries simultaneously? If yes then I suppose having the switch in either #1 or #2 will charge that particular battery selected.

absolutely, on the nose.

 

[footbrake]

Re: Will both batteries charge?

Thank-you

 

[jhebert]

Re: Will both batteries charge?

With the battery switch on "Both" will the running engine charge both batteries simultaneously?

Not quite. The engine will supply charging current to the two batteries which are in parallel. Which battery will receive the charging current depends on the state of charge of the two batteries. If one battery is fully charged and the second battery almost completely discharged, then the charging current from the engine will tend to go to the discharged battery. Also, the charged battery will probably supply current to the discharged battery. This will continue until the two batteries have about the same state of charge. The charging current from the engine will then begin to charge them both, but the distribution of the charging current will again depend on the characteristics of the batteries.

 

[footbrake]

Re: Will both batteries charge?

Is it overworking the alternator trying to do both? Maybe I should charge #1 on the way out and #2 coming in. Also , can you leave the float chargers hooked to both batteries while it's at the dock ? I know they're not meant to charge the batteries, just maintain the charge.

 

[LippCJ7]

Re: Will both batteries charge?

what kind of motor?

 

[footbrake]

Re: Will both batteries charge?

It's a 2.5L,120 hp, OMC 4 cylinder

 

[emilsr]

Re: Will both batteries charge?

Is it overworking the alternator trying to do both? Maybe I should charge #1 on the way out and #2 coming in. Also , can you leave the float chargers hooked to both batteries while it's at the dock ? I know they're not meant to charge the batteries, just maintain the charge.

If single engine, it might. A 65 amp alternator will maintain or even slightly charge a single battery but not 2. Best thing is to invest in a charger and occasionally use that overnight to keep a full charge on them. They'll last longer this way too.

 

[Don S]

Re: Will both batteries charge?

A 65A alternator will charge and maintain 2 batteries with no problem. That is the typical size alternator for many IO's today. They even maintain more than 2 batteries without issues as long as one of them is not completely dead.
When you turn the battery switch to all or both, the batteries are then combined and in parallel and they equalize voltage between themselves. The alternator will then be charging both batteries until they are both fully charged.

 

[LippCJ7]

Re: Will both batteries charge?

ok after hours(ok maybe not hours) of research your alternator specs from 50-65 amps, as Don stated that is more then enough to keep both of your batteries fully charged no issue at all, the only thing you should be concerned with is the state of your batteries, I always like to tell folks at the beginning of the boating season to charge your batteries fully, then take them and have them load tested at the local auto parts store,this should give you a good idea as to the condition of your batteries, if you have time having the alternator tested is always a good idea as well same deal take it down to the local auto parts store and you will get a good idea of the alternators condition, niether of these tests cost you anything.

Remember you are talking about a lot of electricity so be careful batteries are fairly effective welders.

a decent 20-30 minute run with your battery select switch on both will charge your batteries nicely.

 

[Don S]

Re: Will both batteries charge?

a decent 20-30 minute run with your battery select switch on both will charge your batteries nicely.

A 30 minute run pumping out the full 65 amps output of the alternator will only put 32.5 amps hours back into the batteries.

A 65A alternator puts out 65 amps per hour.

A standard 27 case dual purpose battery has about 110 amp hours in it. Two batteries has 220 (Note, not all of those amp hours are usable.