Charging two batteries at once?

[FastOrange]

Will this harm a 70hs rude? Should I use an isolator or dual solenoid? I don't want to drain my starter battery with 400 watts of stereo when I'm trolling with the kicker for 3+ hours.

 

[F_R]

Re: Charging two batteries at once?

You want a dual battery switch. You know, the one with the lever to select 1, 2, or Both.

 

[rustyscrew]

Re: Charging two batteries at once?

Alternatively, you can buy a battery combiner for about 50 bucks. It is a voltage relay switch that combines the batteries when it senses higher (charging) voltage to the starter battery. I have found they can be tempermental, but I may have had a bad one. They are good if you don't want to remember to isolate the batteries when you aren't running. If you are doing day trips, you may just want the switch and keep them isolated all of the time (unless you need a jump from the auxillary) and just charge the battery during storage.

Anyone else have an opinion?

I actually just picked up a perko switch (cheap at a garage sale) and I am considering switching out the combiner.

 

[Solittle]

Re: Charging two batteries at once?

A switch that has "1", "2", and "Both" is the way to go. I use "Both" for starting my twins then switch to "1" or "2" on the way out and to the other on the way back. That should keep both batteries at a relatively close charge level. What you don't want is to have one battery fully charged and the other fully discharged with the switch on "Both". They will both seek the same level of charge with a possible result of the fully charged battery being drained by the other. If both get low enough in this process you won't have enough juice in either to start.

 

[FastOrange]

Re: Charging two batteries at once?

Can I run a dual solenoid that constantly charges two batteries but only draws from one to start and the other "auxillary" battery can be used for the stereo, electric motor, etc.?

 

[reload]

Re: Charging two batteries at once?

It would seen that you could put a diode of sufficent size in series with the charge wire to both batteries (two diodes). Connect load from one battery to stereo and the other to the starting system. This would eliminate the draining of one battery to try to charge the other (seeking same level). What I don't know is if the charging system will handle both batteries being charged at the same time. I still think the 1,2,both switch is the way to go.