Battery charging...

merttan · #1 (**permalink**) 06-17-2008

As far as I know, my outboard motor is seized and there is a good possibility for me to buy a new one instead of trying to repair the old SOB...
Obviously the outboards with alternators are rather more expensive and I don't have shore power connection to charge the battery...
I was wondering if I could keep the battery charged with a solar charger and still get out of the marina with the puller style outboard?
I read through all the solar charger threads and some web research on it, yet couldn't come to a conclusion...

I'm thinking about a 10W panel...

My expected power loads are:
Mounted vhf with PA (1 to 5amps) (10amphr/day max. expected)
Nav lights (6amps) (20amphrs/day max)
Interior lights (8amps)(10 amphrs/day max)
Depth finder (1amp) (10 amphrs/day max)
50amphrs max use... My previous motor had a 12A alternator which served me without any battery problems when I combined sailing with motoring to recharge the battery over weekend trips...
My battery is 100amphour...

I mostly day sail but now and then we go for a 2 day/3night sailing to the block island or long island...

What are your comments?

sailingdog · #2 (**permalink**) 06-17-2008

Merttan-

A 10 Watt panel isn't going to do the job. A 10 Watt panel generates less than 1 Amp. 10 Watts/14.4 Volts = .69 Amps. That means the panel, will on average, add 3.47 Amp-hours to your battery over a day. The self-discharge rate of a wet-cell battery can be as great as 1% per day...which means you're only getting a net charge of 2.47 amp-hours per day. You're planning on using up to 50 amp-hours per trip... See a problem?

Panels below 60 Watts are generally considered maintenance panels, in that they will keep the batteries from discharging, but not much more than that.

You'll probably want at least an 80 Watt panel, which would give you about 25 amp-hours per day, and would re-charge your battery, instead of just maintaining it. You'll probably need a charge controller with an 80 Watt panel.

Quote:

Originally Posted by merttan

As far as I know, my outboard motor is seized and there is a good possibility for me to buy a new one instead of trying to repair the old SOB...
Obviously the outboards with alternators are rather more expensive and I don't have shore power connection to charge the battery...
I was wondering if I could keep the battery charged with a solar charger and still get out of the marina with the puller style outboard?
I read through all the solar charger threads and some web research on it, yet couldn't come to a conclusion...

I'm thinking about a 10W panel...

My expected power loads are:
Mounted vhf with PA (1 to 5amps) (10amphr/day max. expected)
Nav lights (6amps) (20amphrs/day max)
Interior lights (8amps)(10 amphrs/day max)
Depth finder (1amp) (10 amphrs/day max)
50amphrs max use... My previous motor had a 12A alternator which served me without any battery problems when I combined sailing with motoring to recharge the battery over weekend trips...
My battery is 100amphour...

I mostly day sail but now and then we go for a 2 day/3night sailing to the block island or long island...

What are your comments?

JimsCAL · #3 (**permalink**) 06-17-2008

A large solar panel is going to cost you far more than the extra cost of the alternator version of the outboard. That said, it looks to me like your electrical usage estimate is very high. You can get by on a small fraction of that. The electronics estimates seem very high and remember you will only use the navigation lights when sailing after dark. I cruised for several years on a Pearson 26 with an outboard that didn't have an alternator. By being careful with cabin lights at night, using a battery powered anchor light, etc., I could get a full charge on the Group 24 battery to easily last a week. I would carry a portable charger to top off if I stayed in a slip. Unlike an inboard, you don't need a topped off battery to start the engine. That said, life was much easier once I replaced that engine with one with an alternator.

BarryL · #4 (**permalink**) 06-17-2008

Hello,

That solar panel would be fine for your day sails. The VHF draws almost nothing in receive mode, and you don't run lights during the day. The only real draw is the depthfinder and it's minimal.

The problem is your night sailing. Running the nav lights and interior lights will draw more amps than your solar charger would put back.

If you really want to get an OB without an alternator, I would bring / buy a cheap automotive battery charger. Start with your charged battery (from the solar panel), sail to block, enjoy the trip. Before you leave to return home make sure you use the automotive charger to fully charge the battery before you leave and you'll be fine.

My first boat was a Catalina 22. The OB did not have an alternator, the boat was on a mooring. I used the same solar panel as you. I had no problem for the season I used the boat. I mostly day sailed but did do a few night sails with lights, etc.

Barry

negrini · #5 (**permalink**) 06-17-2008

If your amps eating balance prove correct, I think Barry is too optimistic. SD did a rasonable explanation, but higher wattage pannels on your boat size simply is not practical. Good sense says keep a small maintenance pannel, but go for a charger OB. I had my Honda BF 100 generating 6A on our O'Day 23 for many years trouble free operation.

camaraderie · #6 (**permalink**) 06-17-2008

I'd get one of these:
Cheap Portable Generator | Buy Portable Generator | Best Portable Generator | Discount Briggs & Stratton Portable Generator - Eastern Tools & Equipment 1,200 Watt 2 HP 2-Cycle Gas Powered Portable Generator (Non-CARB Compliant) #TG1200

At $150 bucks...you will always have power and the ability to charge your battery.

sailingdog · #7 (**permalink**) 06-17-2008

Of course, the main advantage of the solar panel is that it can charge the batteries without using fuel and is quiet and basically set and forget.

It also doesn't present the risk of CO poisoning or make any noise.

Rockter · #8 (**permalink**) 06-17-2008

Oh I wish I had American prices.
That really is very cheap... like £75.... and 1200 W.
Do they make a diesel version?

camaraderie · #9 (**permalink**) 06-17-2008

Sorry Rock...the portable diesels are all over $1k and the smallest are in the 2.5kw range here.

merttan · #10 (**permalink**) 06-18-2008

My power consumption estimates are maximum on worst case scenario... I usually stay around 15-20Amphrs/day under normal circumstances. That being; no fog, no night sailing, no sleep overs on mooring or anchor, etc.

I can see the obvious problem about underpowered solar units... So a new OB with alternator seems to be the better choice...

Cam; is that genny you show reliable? I don't want to waste 150bucks on a madeinchina POS aka use me twice and I'll die

I found a Honda gen unit, really small and portable. About 600$. It has about 80dB noise level and 1 gallon gas tank... However, my concern is where to keep it in the boat? I don't think they are really mean to be used in marine environments where it's moist all times if not wet...

80W solar panel is a bit awkard on a 22 footer boat, wouldn't you agree?

I have a back-up power pack, which has a DC battery and AC convertor installed on it... It worked fine when I needed to jump the battery, but I don't know if I could charge the boat's battery with it, since the power pack's internal battery is smaller than the boat's group 24...

I think I'd need to cough up the money and get an OB w/ alternator...
The new OB's alternator is rated 6A, my old one's was 12A... That's a big drop :?