one battery enough?

[John]

I have a starting battery for my outboard. My question is will that battery be allright if I use it to power my lights too? How long can I use it this way before it will no longer start my moter? I don't have anything else to power up, just the nav lights.The battery is new/fully charged.Thanks John

 

[Trevor]

Really depends

Hi John -Does your outboard have an alternator? Do you have shorepower for use when you are at a dock (with a charger)? I would think using just running lights and maybe a depth sounder/knotmeter would last you quite a while, but that depends again on what type of battery you have. Deep cycle batteries are better for house loads, while starting batteries (such as those in cars) have higher cranking amp ratings but aren't suited to long term draws. Perhaps others with similar boats will offer their experiences here.Best,Trevor

 

[Dan]

How many amps?

How large is your starting battery? How often and how long do you run the nav lights? A deep cycle battery is best for the nav lights, and other low-draw items. I use a small solar panel to keep my deep cycle topped off, and have only had to charge it with shore power once in five years.

 

[John]

more info 2nd question

I have a new 500 amp starting battery. NOT a deep cycle. My boat is on a mooring. I will use the lights for 3 or 4 hours at a time.I'm not sure if my outboard recharges, I think it does.Its a '99 15HP merc., have to check the book.If I buy a solar panel do I have to have a regulator so I don't overcharge?

 

[Dan]

Solar

My panel delivers 11 watts at peak output, which is only about .8 amp. If you left it charging for a long period of time without ever discharging, then you might worry about overcharging. I doubt you will have that problem. Regulators become important as the amps go up. Locating the panel where it is out of the way and in good sun is the biggest problem. Mine is a flexible number from Unisolar, and somewhat portable. It came equipped with an in-line fuse. I believe the difference between using a "starting" battery vs. deep cycle would be negligible in this situation.I use a pull start on my outboard, so I only have the deep cycle (105 amps). About once a week, I might stay overnight in a cove. I run my nav lights, my interior lights, and a a/c boombox from a 140 watt inverter (not all night, of course). On these overnight jaunts, I might use 20 amps, so to recover that, I need about four good sunny days for the panel (.8 amp x 6 hours sun x 4 days = 19+ amps). If I'm sailing by day and running the stereo, there is basically no loss from the battery. If LED nav lights ever get cheap, I could cut the draw significantly and get much more out of my battery. Incandescent lights are huge wasters of energy.Hope this helps.

 

[John]

Thanks

Thanks for the info.