Outboard charging

Is that a nominal 12v or really 12v? Cos if the latter, I don't think it will charge a battery however long you leave it. There needs to be a bit of extra "pressure" to push the leccy in.

Pete
 
In lieu of an answer from any experts:

I hope I'm correct in remembering that I = P/V. In other words 60W / 12V = 5 Amps. I expect that is at full pelt too. So if you have a, for example, 70Ah Battery which was half flat you would need to motor at full throttle for 7 Hours.

In other words your alternator is not very powerful.

Having said that it's similar on my 9.9HP and it seems to be sufficient to put back in what was taken by starting a number of times (locks on the river) plus the occasional charging of a lap top etc.
 
dylanwinter said:
I have bought one of these

http://www.tohatsu.com/outboards/6_4st_spec.html

the spec says that it produces 40w 5Amps 12volts

is that full blatt

half blatt

is that sort of charging power any good

how long would I have to run the engine and at what revs would I have to run the engine to top up a 50 per cent discharged car battery

Dylan
Click to expand...

Thats is maximum output. You will probably have to run at close to full revs to get 5 amps.

BUT is it DC for battery charging or will you have to add a rectifier/ battery charging kit? **


In theory a half charged car battery .... 70Ah??? .. will need 35Ah to recahrge it so that is 5 amps for 7 hours. In practice it will take longer, a good deal longer perhaps if you do not run the engine at high revs.


The electrical output from small outboard engines is poor. If you need good charging you need an inboard engine with a proper alternator.

You can but try it and see what sort of revs you need to get a decent current output.

** if its the sail drive model it should be DC .. I think... but the manual will tell you.
 
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O/B charging

Well it sounds like you have bought it with the battery charging so next step is to find out exactly what it will do for you. fit a cheap amp meter into the charge circuit or use your multimeter.
Certainly the older o/bs had an alternator built in to the flywheel as an option. This is actually another 1 or2 coils mounted under the flywheel next to the coils that generate power and timing for ignition. The field is provided by permanent magnets in the rotating flywheel. This means that there is inherently no way to control the output.
This produces AC at a voltage dependent on speed. On the old Johnson it seems to be rated and designed for driving nav lights on AC without a battery so not too much voltage as to blow the globes at full speed and not so little as to make the globes too dim. When you add a bridge rectifier to this the AC is converted to DC the problem being that the DC might be OK to power lights or even depth sounder but not enough to charge a battery. Further the voltage is dependent also on the current draw so the result is for the Johnson barely .3 amp into the battery (reasonably charged).
I did make a new rectifier pack of 6 diodes using schotky diodes and these improved the charge current to near 1 amp at reasonable cruise revs. The schotky diodes have a much lower forward volt drop than the usual silicon diodes ir .25 versus .7 for silicon. There are always 2 didoes in series for the bridge rectifier so that is a voltage loss reduced from 1.4 down to .5. That additional voltage is vital for battery charging to get the current in. This is what I used but current rating is a bit low.
http://www.altronics.com.au/index.asp?area=item&id=Z0042
So if battery were flat or you had a load on the battery at the same time you might get more current out of the alternator into the system.
What you really need is an MPPT regulator as used for solar panels which hopefully can squeeze all the power out of the alternator at a lower voltage and up convert it to what is needed to charge the battery.
However you might still not get much so a solar panel might be your best bet. Or a small generator and charger.
I would suggest knowing your requirements that a largish battery might be a viable way to go. This will get more charge out of the alternator but mostly will bring you power from a shore charging beginning.
good luck olewill
 
Notwithstanding these clever suggestions to improve performance , a word of reassurance.
On my last 5hp 2str mariner I had a charging coil fitted and it replenished a 70a/h leisure battery for quite a few years, cruising and living aboard , so I think the charging regimen is actually ok through the standard rectifier . But as KTL film corp is heavily invested in charging camera batteries, possibly from a cigar lighter type charge, who knows without measuring the actual boat battery voltage after one or more hours charging/engine running at sensible revs?
Dylan I also fitted the charging coil to your favourite English winged outboard and surprisingly that worked quite well too through same 70a/h battery do these things to work.
My last boa had a 10hp e/start saildrive Suzuki and the charging was excellent, I believe the key thing is you bought a saildrive unit, didn't you?
 
dylanwinter said:
I have bought one of these

http://www.tohatsu.com/outboards/6_4st_spec.html

the spec says that it produces 40w 5Amps 12volts

is that full blatt

half blatt

is that sort of charging power any good

how long would I have to run the engine and at what revs would I have to run the engine to top up a 50 per cent discharged car battery

Dylan
Click to expand...

My homework said it was more Harrell that it was worth, then there are plenty of Martins round here so it was no bother to spend a night to top up.

Will be interested in how you get on with connections, that was the final straw for me, just not designed to be disconnected when leaving boat.

I also found the engine would not lock straight ahead, I tied the tiller.
 
Dylan,

modern saildrive outboards like yours actually have upgraded charging coils compared to the 3 amp of standard outboard coils.

It will be useful, but not enough to keep the battery /ies topped up for your purposes, you'll need a good solar panel too.

I expect you know modern solar panels - the thin Solarex, Sunware etc type - are moderately flexible, so can fit cambered decks.

Seateach are good for solar panels, but not batteries; that's a job for a little internet research.

I imagine you'll also need a battery monitor; I'm not impressed with my NASA BM-1, though others seem to like it; seems you get what you pay for, and this will be an important 'guage' for you.

I have a lot of electrics on my boat inc radar - bought and fitted in the knowledge I can only run it in short bursts, but modern radar with short warm-up times and standby allow one to do that.

I rely on the 30w solar panel with a good 100A/H battery and rarely bother plugging in the mariner 5hp 2 stroke charger unless on a long motor in calms using the autohelm, but in your case it would be worth disciplining yourself to plug it in every time the engine is run.

One little advantage with charging coils is that they can run the boat electrics even if the battery has completely caved in.
 
Dylan

Unless you plan to use your engine a lot, Solar panels will probably help more than anything. On the old boat the charging coil provided just enough to power the fan to suck all the exhaust fumes out of the well, to keep the engine running sweetly :(

I had two 10 watt panels with a charge controller which had the battery fully charged every time we went out. While they didn't match the drain of chart plotter, vhf etc, we NEVER had a flat battery even after a full days sail with everything on, including the tiller pilot.

Even though the new boat has two battery banks and a proper alternator charger, I am planning to fit around 20W+ of solar to top up and float charge while not aboard.

Regards

Ian
 
EdBeynon has exactly the same engine as you on his Hurley 22. I'm sure he will be along before long. These engines designed for sale boats have the extra bits needed to make a proper charging capability, i.e. regulator and rectifier. Connect them straight up.

I have a similar output from my Yamaha 9.9 o/b. In addition I have a 30W flexible solar panel which sees light of day when away for more than a weekend. I use my power for all normal instruments, an autopilot most of the time, chart plotter, VHF, Navtext, LED navlights, LED inerior lights and netbook on and off when needed, and a CF18 compressor coolbox running constantly. I have never run out of power yet. When I start the engine the voltage goes up to maximum 14.4 usually within half an hour. I never run the engine more than half revs. It seems to charge at tickover quite well too.

This is my solar panel...

http://www.marlec.co.uk/products/photovoltaic-panels-solar-pv-panels/spectraflex32/

It may be less efficient than the best crystalline ones, but it is little affected by shadows, it's light, bendy, tough and can be thrown around happily. Not cheap unfortunately.
 
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excellent

AngusMcDoon said:
EdBeynon has exactly the same engine as you on his Hurley 22. I'm sure he will be along before long. These engines designed for sale boats have the extra bits needed to make a proper charging capability, i.e. regulator and rectifier. Connect them straight up.

I have a similar output from my Yamaha 9.9 o/b. In addition I have a 30W flexible solar panel which sees light of day when away for more than a weekend. I use my power for all normal instruments, an autopilot most of the time, chart plotter, VHF, Navtext, LED navlights, LED inerior lights and netbook on and off when needed, and a CF18 compressor coolbox running constantly. I have never run out of power yet. When I start the engine the voltage goes up to maximum 14.4 usually within half an hour. I never run the engine more than half revs. It seems to charge at tickover quite well too.

This is my solar panel...

http://www.marlec.co.uk/products/photovoltaic-panels-solar-pv-panels/spectraflex32/

It may be less efficient than the best crystalline ones, but it is little affected by shadows, it's light, bendy, tough and can be thrown around happily. Not cheap unfortunately.
Click to expand...


my plan is to see how I get on with the ooutboard

maybe buy a solar panel I can leave set out in the cockpit

D
 
I may be wrong but I go on the assumption that it's sufficient to stop the battery draining with lights, radio, tiller pilot etc and any excess that adds to the battery is a bonus rather than hoping it will charge. That said, LM lives in a marina so gets a proper charge regularly anyway.
 
I have a tohatsu 8HP 4-stroke. According to my battery monitor it charges at about 4.5- 5 amps at 14.4v regardless of whether I am in idle or flat out so must be regulated in some way. I use it for about 45 mins on any trip in any one day to get in and out of moorings.

That plus a 10w solar panel has never left me short of power but then the probably not consuming more than 10 A/h per day. LED lights have significantly reduced my power consumption.
 
I had same engine as you (Mariner version) on a Hunter Horizon 23, battery was an 85 amp/hour leisure battery. I would say I used the engine more than the average person would as I sail in a very tidal area where one's sailing is controlled by narrow access windows to ports and anchorages and you can't be late getting in - so on goes the engine. My electrics were just lights, instruments & radio/CD and the engine just about kept the battery charged. Having been following KTL I would say you'll use the engine less than I did and you also have your cameras to charge, so I think the outboard alone may prove insufficient and may need supplementing with a solar panel as already suggested. I don't think there's anything to be gained from putting some form of regulator on the alternator output, the power just isn't being generated.
 
Dylan, you will find out when you use it, but my view is that it will be inadequate for your needs - the laptop & cameras etc use a lot of power, that will not be adequate, even if you motor all day.

An inboard alternater throws out up to 60A to a flat battery, your O/B will not even be close to that. 5A at best is about 8% of a proper alternator. As others say, it would be fine for someone with led lights, occasional VHF use, no electronics & a manual water pump, but your camera batteries & laptop are surprisingly power hungry. My little netbook is 2A consumption alone.
 
JimC said:
I had same engine as you (Mariner version) on a Hunter Horizon 23, battery was an 85 amp/hour leisure battery. I would say I used the engine more than the average person would as I sail in a very tidal area where one's sailing is controlled by narrow access windows to ports and anchorages and you can't be late getting in - so on goes the engine. My electrics were just lights, instruments & radio/CD and the engine just about kept the battery charged. Having been following KTL I would say you'll use the engine less than I did and you also have your cameras to charge, so I think the outboard alone may prove insufficient and may need supplementing with a solar panel as already suggested. I don't think there's anything to be gained from putting some form of regulator on the alternator output, the power just isn't being generated.
Click to expand...

Large outboard with more powerful " alternators" usually have a regulator.

Some of the smaller outboards now also have regulators but not really necessary.

No regulator on my 6 Hp Evinrude. Absolutely not necessry in fact have had to fit a solar panel to avoid having to take the battery home periodically for charging.
 
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