Second battery question

[ralphl]

I'm splitting the power source on my 20' pontoon, leaving a stand alone starting battery for the motor and a second battery located in the console to handle the accessories. The accessory battery will be recharged from a solar panel while the motor battery will be recharged by the motor.

Two questions:

Should these two batteries share a common ground?

Will running a Humminbird 190C fishfinder rapidly drain the accessory battery?

Appreciate any and all advice - thanks in advance.

 

[Silvertip]

Re: Second battery question

Just curious how big the solar panel is. If it is about "half the size of the pontoon" it might actually be able to "charge" the accessory battery. What many people fail to realize is that 12 volt solar panels regardless of size will provide 12 volts output. Size however, is what determines the current or power output (amperage or watts). The small panels are simply not big enough to charge a battery (regardless what the package says). They are at best, battery maintainers. You would be better served by installing an ACR or dual battery switch.

The two batteries don't need a common ground but everything powered from each battery must be grounded to that battery.

 

[Skiwi]

Re: Second battery question

If your trying to charge the battery, I recommend your 12 volt solar panel delivers 5 watts or more and you live in a sunny climate.
I live in a high sunshine hours area and when I have used the lower watt rated ones they only have enough grunt maintain a charged battery, not lift a discharged one.

I now fully charge my batteries upon trip end with a mains charger and use the solar to maintain until the next trip, this appears to work for me.

I run my Hummingbird FF, Navman GPS, VHF and occasionally the stereo, for several hours off one cranking type battery from a single charge without problem. I am however switching to a deep-cycle to give me some "redundancy" for overnight trips etc.

*Note* My "12v" panel easily puts out 19v on a sunny day, so if your leaving it hooked up for extended periods, and your panel doesn't have one built in, it may pay to invest in a regulator.

 

[ralphl]

Re: Second battery question

The solar panel is 15 watts. It is located on the top of a very large dock box. It is all in a marina that has no power, so the only way to recharge the second battery is A. solar or B. crank a generator or C. try to make the 55 horse Suzuki charge a single, shared battery.

Drain on the accessory battery would be minimal except for the fish finder, very occasional docking and courtesy lights, and marine radio. The only real drain would be the fish finder and since I've never used one before, I don't know how big a power hog they are.

I've been using this same solar panel to recharge my trolling motor battery on a small fishing boat all summer long. It brings it from 50 percent to a bit over 90 percent with 12 hours of sun. The drain on this battery should be a lot less than what the trolling motor was pulling, so I'm comfortable that the 15 watt panel will keep it topped off and it should never get so totally exhausted that I won't be able to use the accessories.

Of course, I could go back to a single battery but my concern is that a problem with the accessories could get me stranded without enough power to start the motor.

I can isolate the grounds or combine them, just need to know if there is a plus or minus to either way.

 

[Robbabob]

Re: Second battery question

Not sure what your investment is at this point, but the ACR is the cat's meow

http://www.jamestowndistributors.co...le=Blue+Sea+Systems+CL-Series+BatteryLink+ACR

The system uses the starting battery to start the engine, both batteries are charged as long as they need it. With engine off, the starter battery is removed from the circuit is it drops to 12.7 or so volts... ensuring it is starter-ready when needed.

It will be my route when I'm ready to drop more $$$$ to replace my Perko manual switch.

I only pasted one example above, there are several manufacturers to choose from.

Good Luck and happy boating!

 

[Silvertip]

Re: Second battery question

Again -- all of the accessories you run off the accessory battery MUST have the ground wires from those accessories connected to the accessory battery ground. If you connect both battery negative posts together it doesn't matter where you ground the accessories as long as the ground point ends up at either battery. Current needs a complete path from battery POS to battery NEG.

 

[Boatist]

Re: Second battery question

15 watt solar panel is a 1.2 amp charger if the solar panel is pointed straight at a summer sun.
It will be much less when it is not pointed straight at the sun which is at least 23 hours a day if the panel does not track the sun.
Some panels will discharge the battery at night so make sure you get one with a diode to prevent discharge.

If I was going to try a solar panel I would get one with at least 50 watts and a voltage regulator and anti discharge diode.

I wish you Good Luck

 

[bruceb58]

Re: Second battery question

15 watt solar panel is a 1.2 amp charger

15 Watt panels are actually usually less than 1.2 amp because they are typically rated at their peak voltage which is normally 17V. Probably more like a 0.9 amp charger. I wouldn't expect a 15W charger to bring up a discharged battery unless it was left on there for a couple weeks.