I have a honda 8-hp 4 stroke - it has a 5amp charger/alternator? - but I don't seem to be getting much charging to battery . How can I get a more powerful charging unit on the outboard ?
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Only can get watcha have
FHU: What makes you think you're not getting your 5 amps? I'll betcha it's because your batteries are pretty full. There's a thing called battery acceptance: when they're near full (up to 15 to 20%) they absorb, or "accept", less charging current. So, you may think your outboard's alternator isn't giving you the amps you thought you bought, but it could be your batteries, too. And amperage is usually rated at WOT.
FHU: What makes you think you're not getting your 5 amps? I'll betcha it's because your batteries are pretty full. There's a thing called battery acceptance: when they're near full (up to 15 to 20%) they absorb, or "accept", less charging current. So, you may think your outboard's alternator isn't giving you the amps you thought you bought, but it could be your batteries, too. And amperage is usually rated at WOT.
I replaced the cable and connectors on my Johnson 8 Hp 2 stroke. The wire that came with my outboard was smaller than #14, probably #16 wire and I had installed a cheap marine two prong plug and receptacle years ago for it on the inside transom. I knew that my battery wasn't getting charged due to a sloppy connection at the outlet and also the wire size. So what I did was replace the wire on the outboard with a #10 stranded copper duplex marine cable. I took the guts out of the receptacle and ran the duplex through the hole to a marine terminal strip that I installed just inside the lazarett on the bulkhead where I have another duplex coming from my battery and also terminating at this strip. I'm using a PC mouse pad as a cover for the term strip with STA-Con crimp connectors on all the conductors. I'm getting good voltage and current now, and I never have to charge my battery at the dock. Each year when I run the duplex wire through the outlet hole, I wrap a little tape around it so that it doesn't pull out. Then I apply some boat caulk on the other side to keep the water from going into the bilge. Having an 8" Beckson Deck Plate just under the outlet hole makes it easy to run the wire to termination strip and remove it each year.
Joe
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I'd point out that the engine won't generally be putting out a full five amps, unless you're running it pretty hard. If the outboard is running at lower rpms, the alternator output will be lower... 
FHU,
I have the same engine (well, at least same make, cycle and hp... mine is a BF8 A), and have a question about the plug you use. I want to use my outboard's charging system as well--did you get the 'special' plug from Honda that you need to add your own wire for, or did you get the whole cord with plug? I mistakenly bought the whole cord for the wrong engine, so have to get the plug.... Just curious about your setup, thanks!
I have the same engine (well, at least same make, cycle and hp... mine is a BF8 A), and have a question about the plug you use. I want to use my outboard's charging system as well--did you get the 'special' plug from Honda that you need to add your own wire for, or did you get the whole cord with plug? I mistakenly bought the whole cord for the wrong engine, so have to get the plug.... Just curious about your setup, thanks!
Are you sure the motor is charging? I have the same motor and have been told it's very easy to blow the regulator if it gets unplugged while running.
I probably have the same outboard (about 1990 Honda BF8). When I got the motor several years ago, the charging circuit did not work and the problem was a blown rectifier. I think it probably is fairly easy to blow the rectifier and you do this by disconnecting the outboard charging wire from the battery while the outboard is running. Note that you can run the outboard without it being connected to the battery OK (at least on this ouboard) and you can connect the outboard to the battery while its running - just dont disconnect while running.
Once I got my outboard rectifier fixed, it puts out about 2 to 3 amps at my normal "about 1/2 throttle" cruising speed. As far as I know, I have a functional "5 amp" charging circuit so as others have said, even when working, you dont get a whole lot of charging with typical sailboat use and probably need to have alternate ways to keep the battery charged.
Im not sure how you know if your charging is working on not - I have a current/charge monitor which makes is simple - but you could use a current meter (just dont let it get disconnected while running) to measure the current. You "may" be able to see a slight voltage rise in battery voltage when the outboard charger is running.
If your getting no charging from the outboard, first check your wiring between the outboard and the battery. Then make sure the fuse is good (FU in the schematic). If both of these dont result in charging current, you likely have a bad rectifier (shown as "SR" in the attached schematic) - likely caused by the charging system getting disconnected while the outboard was running.
One interesting note about the Honda charging system - there is NO regulator like you will find on a larger boat (also why I attached the schematic). Ie, the small outboard charging system gets no voltage feedback telling the charging system to back off current to the battery when the voltage gets near full (ie, about 13.5 volts). Ive measured mine putting out 18 volts into a load. You would have to try pretty hard but because there is no regulator, you could over charge the batteries and damage them. Im guessing the lack of regulator is common in under 10 hp (or low output current) outboards. Because the current is fairly low, I guess the manufacture didnt see the need to spend the money on a regulator.
Once I got my outboard rectifier fixed, it puts out about 2 to 3 amps at my normal "about 1/2 throttle" cruising speed. As far as I know, I have a functional "5 amp" charging circuit so as others have said, even when working, you dont get a whole lot of charging with typical sailboat use and probably need to have alternate ways to keep the battery charged.
Im not sure how you know if your charging is working on not - I have a current/charge monitor which makes is simple - but you could use a current meter (just dont let it get disconnected while running) to measure the current. You "may" be able to see a slight voltage rise in battery voltage when the outboard charger is running.
If your getting no charging from the outboard, first check your wiring between the outboard and the battery. Then make sure the fuse is good (FU in the schematic). If both of these dont result in charging current, you likely have a bad rectifier (shown as "SR" in the attached schematic) - likely caused by the charging system getting disconnected while the outboard was running.
One interesting note about the Honda charging system - there is NO regulator like you will find on a larger boat (also why I attached the schematic). Ie, the small outboard charging system gets no voltage feedback telling the charging system to back off current to the battery when the voltage gets near full (ie, about 13.5 volts). Ive measured mine putting out 18 volts into a load. You would have to try pretty hard but because there is no regulator, you could over charge the batteries and damage them. Im guessing the lack of regulator is common in under 10 hp (or low output current) outboards. Because the current is fairly low, I guess the manufacture didnt see the need to spend the money on a regulator.
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Sort of interesting and someone can correct me if wrong (could be...)
But based on the schematic I just previously posted, if the fuse fails while the engine is running, it is equivalent to disconnecting the outboard charging wires from the battery.
What happens is that the coil is "energiized" as the engine is running. When the battery load is disconnected, the current immediatly goes to zero and the energized coil creates a big voltage spike. This causes a reverse bias breakdown in the rectifier and damages it.
If the fuse were instead placed between the coil and the rectifier, the rectifier would be isolated from the coil if the fuse blew. The coil would still create a high voltage which might spark somewhere - but likely no damage. But with the fuse after the rectifier (like in the Honda schematic), seems to me the fuse blowing could also result in the rectifier getting damaged...
But based on the schematic I just previously posted, if the fuse fails while the engine is running, it is equivalent to disconnecting the outboard charging wires from the battery.
What happens is that the coil is "energiized" as the engine is running. When the battery load is disconnected, the current immediatly goes to zero and the energized coil creates a big voltage spike. This causes a reverse bias breakdown in the rectifier and damages it.
If the fuse were instead placed between the coil and the rectifier, the rectifier would be isolated from the coil if the fuse blew. The coil would still create a high voltage which might spark somewhere - but likely no damage. But with the fuse after the rectifier (like in the Honda schematic), seems to me the fuse blowing could also result in the rectifier getting damaged...
I'll apologize right up front for any questions tI ask hat are just stupid, but I'm having some trouble figuring out how best to connect my battery safely to my outboard alternator and how best to keep the battery charged. So please bear with me.
Here's my situation. I have a 1983 Oday 23, which I bought 3 years ago. It came with a group 24 deep cycle battery whose age and use I don't know. It also came with a 1983 Honda 7.5 outboard, which has run extremely well after some repairs. There was no alternator cord, and the PO did not seem to use the battery for much of anything. For the first season or so, neither did I. We'd turn on the cabin lights when we stayed overnight on the boat, which wasn't often, since we mostly daysailed. There's no shore power where we dock our boat (on Lake George), so every now and then I'd take the battery home and charge it.
Last summer I think I ruined the battery by not keeping it charged. Because we began to spend more overnights on the boat, I wanted to keep the battery in good condition and I finally got around to trying to learn more about how to do that. That's when I learned that I shouldn't allow the battery to discharge below 50% and that I should charge it after any significant use. I hadn't. By the end of the summer, the battery would no longer hold a charge.
So this year I bought a group 27 deep cycle battery, and I asked the mechanic at my marina to fashion an alternator cord, which he did. But my question now is whether I need to do more than simply connect the cord directly to the battery. As others have noted in this thread, my motor apparently puts out about 5 amps tops (according to the manual), so it's producing less than that under normal use (since I rarely run the engire at high RPMs). Do I need some sort of regulator or charge controller with this set-up? And I'm not even sure I should keep the wire plugged into the motor when I am starting it. Is that a safety issue? So what's the best way to connect the alternator to the battery. Joe's photos and description are helpful, but I'm not sure what his whole set-up looks like.
Finally, I'm considering buying a small solar panel to supply a trickle charge to the battery during the weekdays when we're not using the boat. I've been researching these systems and have a better idea what I need and what the considerations are than with the alternator. (I have a sizable solar electric system on my house, so I've learned something about how these systems work.) But my question is whether I need something to provide a trickle charge, since I don't use the battery much. I'm worried that the small alternator won't provide enough of a charge to replenish the battery.
Sorry for going on at length, but I've been reading all sorts of books, articles, and websites, and I'm only slightly less confused than before! Any advice would be most welcome.
Thanks.
Bob
Here's my situation. I have a 1983 Oday 23, which I bought 3 years ago. It came with a group 24 deep cycle battery whose age and use I don't know. It also came with a 1983 Honda 7.5 outboard, which has run extremely well after some repairs. There was no alternator cord, and the PO did not seem to use the battery for much of anything. For the first season or so, neither did I. We'd turn on the cabin lights when we stayed overnight on the boat, which wasn't often, since we mostly daysailed. There's no shore power where we dock our boat (on Lake George), so every now and then I'd take the battery home and charge it.
Last summer I think I ruined the battery by not keeping it charged. Because we began to spend more overnights on the boat, I wanted to keep the battery in good condition and I finally got around to trying to learn more about how to do that. That's when I learned that I shouldn't allow the battery to discharge below 50% and that I should charge it after any significant use. I hadn't. By the end of the summer, the battery would no longer hold a charge.
So this year I bought a group 27 deep cycle battery, and I asked the mechanic at my marina to fashion an alternator cord, which he did. But my question now is whether I need to do more than simply connect the cord directly to the battery. As others have noted in this thread, my motor apparently puts out about 5 amps tops (according to the manual), so it's producing less than that under normal use (since I rarely run the engire at high RPMs). Do I need some sort of regulator or charge controller with this set-up? And I'm not even sure I should keep the wire plugged into the motor when I am starting it. Is that a safety issue? So what's the best way to connect the alternator to the battery. Joe's photos and description are helpful, but I'm not sure what his whole set-up looks like.
Finally, I'm considering buying a small solar panel to supply a trickle charge to the battery during the weekdays when we're not using the boat. I've been researching these systems and have a better idea what I need and what the considerations are than with the alternator. (I have a sizable solar electric system on my house, so I've learned something about how these systems work.) But my question is whether I need something to provide a trickle charge, since I don't use the battery much. I'm worried that the small alternator won't provide enough of a charge to replenish the battery.
Sorry for going on at length, but I've been reading all sorts of books, articles, and websites, and I'm only slightly less confused than before! Any advice would be most welcome.
Thanks.
Bob
Bob—
I've got a pretty good primer on Solar Power on Boats on my blog that I'd recommend you read.
As for your alternator, you probably don't need a charge controller, since the output is relatively low...under five amps. A charge controller, like a FlexCharge NC25a might be a nice idea, since it will help keep the batteries in good condition, but it isn't necessary.
I've got a pretty good primer on Solar Power on Boats on my blog that I'd recommend you read.
As for your alternator, you probably don't need a charge controller, since the output is relatively low...under five amps. A charge controller, like a FlexCharge NC25a might be a nice idea, since it will help keep the batteries in good condition, but it isn't necessary.
electrical system design
I have a spread sheet that will help you compute all your loads, and size your storage and production.
william-roosa@us.army.mil for a copy
See you on the waters
I have a spread sheet that will help you compute all your loads, and size your storage and production.
william-roosa@us.army.mil for a copy
See you on the waters
SD, I've already read your primer. Extremely helpful! Thanks. I'm assuming that you think adding a solar panel for a trickle charge is a good idea for my set-up?
Bill, I'll email you. Thanks.
Bob
Bill, I'll email you. Thanks.
Bob
Follow-up to Alternator Question: Battery Monitor
Rereading this thread brought to mind another question: Is it worth installing a battery monitor in a system as simple as mine? I have been reading a lot about battery monitors and meters and have begun to understand some of the complexities of them, and I'm wondering if springing for something like the LinkLite monitor (http://www.xantrex.com/web/id/273/p/1/pt/5/product.asp) would be worth it in my case. A monitor like that one costs more than the new battery I just installed. Any thoughts?
Thanks again.
Bob
Rereading this thread brought to mind another question: Is it worth installing a battery monitor in a system as simple as mine? I have been reading a lot about battery monitors and meters and have begun to understand some of the complexities of them, and I'm wondering if springing for something like the LinkLite monitor (http://www.xantrex.com/web/id/273/p/1/pt/5/product.asp) would be worth it in my case. A monitor like that one costs more than the new battery I just installed. Any thoughts?
Thanks again.
Bob
I normally trailer sail my boat. I have one single battery bank (about 200 amp hours) that I can charge with either the old Honda BF8, a 6 amp battery maintainer, a 20 watt panel mounted on the boat boat and a plug for an 80 watt panel. The Solar panels use a single 10 amp PWM type charge controller. I have no battery switches - all the charging methods are always connected to the single battery as they are all current output with voltage monitoring. My loads are all low power - bunch of LED lights, stereo, DVD, low power inverters, AA battery charger. I have the linklite.
In my case, I dont NEED a battery monitor. I got by with volt meter fine for a couple of years. I probably did stress my batteries during this time mostly by not maintaining water level but also by undercharging.
However, I LOVE having the battery monitor!! It is a really fun thing to have on a boat and it no doubt will help you understand what your electrical system is doing and it will also generally allow you to keep your battery in better shape so it will last longer. Im comfortable with only one battery bank (no battery switches - makes things a lot simpler) partly because I can still run the boat if the battery dies (pull start outboard and self contained batteries on cell phone and hand held VHF) but its also partly because with the battery monitor, I have a very good idea what the single battery bank is doing.
Regarding the 8 hp outboard with no regulator, my normal use the outboard is to get in and out of the dock - no worry about the 2 to 3 amps it puts out during this time. Once a year, we do a big motoring trip to Lake Powell where the outboard is run a lot and without the regulator, this could over charge and damage the batteries. During this time, I will simply watch the battery monitor and when the batteries are full, I will disconnect the outboard charging from the battery (dont do this while the outboard is running).
Battery monitors are not necessary on a trailer sailboat - but its a great "toy" and will likely make your batteries last longer.
In my case, I dont NEED a battery monitor. I got by with volt meter fine for a couple of years. I probably did stress my batteries during this time mostly by not maintaining water level but also by undercharging.
However, I LOVE having the battery monitor!! It is a really fun thing to have on a boat and it no doubt will help you understand what your electrical system is doing and it will also generally allow you to keep your battery in better shape so it will last longer. Im comfortable with only one battery bank (no battery switches - makes things a lot simpler) partly because I can still run the boat if the battery dies (pull start outboard and self contained batteries on cell phone and hand held VHF) but its also partly because with the battery monitor, I have a very good idea what the single battery bank is doing.
Regarding the 8 hp outboard with no regulator, my normal use the outboard is to get in and out of the dock - no worry about the 2 to 3 amps it puts out during this time. Once a year, we do a big motoring trip to Lake Powell where the outboard is run a lot and without the regulator, this could over charge and damage the batteries. During this time, I will simply watch the battery monitor and when the batteries are full, I will disconnect the outboard charging from the battery (dont do this while the outboard is running).
Battery monitors are not necessary on a trailer sailboat - but its a great "toy" and will likely make your batteries last longer.
Actually, it is IMHO. A battery monitor will allow you to get a realistic idea of what your actual usage is, rather than having you estimating it...and estimating it is usually quite far off from the real numbers, often because you overlook small things, that add up quickly. By having a real idea of your actual usage—you have a much better chance of sizing your battery bank and charging systems to best suite your actual needs.
I would recommend going with the Victron BMV 600 instead of the Xantrex, as they actually make the LinkLite unit for Xantrex, and the Victron BMV 600 is a much better unit and only $10 or so more street retail ($195 vs. $185). The Xantrex draws more power 9 ma vs. 4 ma; has a lower supply voltage range 9-35 vdc vs. 9-90 vdc.; has less resolution on readings ±0.1 V or A vs. ± 0.01 V or A; etc.
Also, IIRC, the Victron comes with the wiring necessary for connecting the shunt to it, with the Xantrex, it is an option.
One reason to install a battery monitor is that it can often extend the life and usability of the batteries you have by allowing your to see how you're using them and whether your use and charging cycle is actually proper for the battery. If the use of one saves you from killing batteries prematurely, it can pretty readily pay for itself.
I would recommend going with the Victron BMV 600 instead of the Xantrex, as they actually make the LinkLite unit for Xantrex, and the Victron BMV 600 is a much better unit and only $10 or so more street retail ($195 vs. $185). The Xantrex draws more power 9 ma vs. 4 ma; has a lower supply voltage range 9-35 vdc vs. 9-90 vdc.; has less resolution on readings ±0.1 V or A vs. ± 0.01 V or A; etc.
Also, IIRC, the Victron comes with the wiring necessary for connecting the shunt to it, with the Xantrex, it is an option.
One reason to install a battery monitor is that it can often extend the life and usability of the batteries you have by allowing your to see how you're using them and whether your use and charging cycle is actually proper for the battery. If the use of one saves you from killing batteries prematurely, it can pretty readily pay for itself.
A battery monityor, just like a smart charger,
will extend the life of your batteries, because you'll finally know what's happening with and to them.
The cost of the monitor is one battery. One extra year on a battery bank you've broken even.
Why is there any question about this?
will extend the life of your batteries, because you'll finally know what's happening with and to them.
The cost of the monitor is one battery. One extra year on a battery bank you've broken even.
Why is there any question about this?
Thanks very much for this feedback, Walt and SD. Sometimes it really helps to ask when you really aren't sure (especially as a newbie), and this advice was just what I needed. (That's why, Stu.)
Bob
Bob
If your rectifier is fried, you could add an external rectifier. Even a cheap radio shack rectifier with a 400 volt PIV and a heat sink attached (really does not get that warm at 5 amps, but cheap insurance) will only set you back $10 or so. On my mid 80's vintage Honda, I unplugged the regulator, connected those two plugs together in the engine compartment, used the same wire and placed the rectifier between the engine and the battery. It can withstand the plug removal with engine running, although I wouldn't make a regular practice of it unless you install a capacitor and maybe a 15 volt zener diode to shunt away the spike. Just remember to have a dedicated connection, because attaching that wire directly to the battery will FRY the windings in the alternator and let out the magic smoke.
Godd Luck!
Godd Luck!
Flynfol, I actually did the same thing on my old Honda BF8 - bypassed the stock rectifier (probably would have been expensive and I dont like that its susceptable to being blown so easilly) and made an external rectifier which is mounted on a heat sink (some aluminum angle) in the Laz area of boat.
The bridge rectifier I picked up is 400 volt reverse voltage 35A forward current (MB354W - BP) and is maybe overkill - I think I paid less than $5 for it from Mouser. I also added a 100 uf 100 volt E cap accross the rectifier DC side and this is enough to "dampen" the alternator coil from producting a big damaging voltage spike when everything is disconnected from the battery. When I first put this in, I disconnected and connected the altenator wires from the battery over 100 times with the outboard running at various rpms (also watching with a scope) - didnt even come close to damaging anything.
The alternator output voltage when it has no battery load (ie, open circuit) can be fairly high - I think I saw over 40 volts (rectified with the cap). I dont think any sort of zener or transorb is necessary with the 100 uf cap but if you did put one in, It probably should be somewhere over 50 volts because you still want the system to work without the outboard connected to the battery. The problem then is that at 50 volts breakdown, it doesnt take much current to blow up the protection diode so you may have created a new problem. But its not needed regardless if the capacitor is large enough.
The bridge rectifier I picked up is 400 volt reverse voltage 35A forward current (MB354W - BP) and is maybe overkill - I think I paid less than $5 for it from Mouser. I also added a 100 uf 100 volt E cap accross the rectifier DC side and this is enough to "dampen" the alternator coil from producting a big damaging voltage spike when everything is disconnected from the battery. When I first put this in, I disconnected and connected the altenator wires from the battery over 100 times with the outboard running at various rpms (also watching with a scope) - didnt even come close to damaging anything.
The alternator output voltage when it has no battery load (ie, open circuit) can be fairly high - I think I saw over 40 volts (rectified with the cap). I dont think any sort of zener or transorb is necessary with the 100 uf cap but if you did put one in, It probably should be somewhere over 50 volts because you still want the system to work without the outboard connected to the battery. The problem then is that at 50 volts breakdown, it doesnt take much current to blow up the protection diode so you may have created a new problem. But its not needed regardless if the capacitor is large enough.
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