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Old 20-08-2011, 07:26   #16
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Re: Damage to Alternator ?

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Originally Posted by fairbank56 View Post
Just proved myself wrong about this with some test's in the shop. While the spikes produced from both the motor coils and solenoid coils are much higher on the motor side and solenoid side, there is also a significant spike produced on the other side of the switches (solenoid contactor and start button/switch) i.e., the side that may have other electrical/electronic devices on them. The reason being is that it takes a finite amount of time for the switch contacts to actually fully open. During this time, when the magnetic fields are collapsing, there is resistance between the switch contacts as they are opening that the spike makes it across. This is what causes arcing and pitting of the switch contacts. This all happens in an instant but I can see it causing problems to sensitive loads. Typically, power feed to the engine wiring harness and the engine gauge panel comes directly off of the starter solenoid battery terminal.
Cool post. Glad you took the trouble to test your earlier assertion and honestly report the results. And kudos to btrayfors for being right.
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Old 20-08-2011, 07:39   #17
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Re: Damage to Alternator ?

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Electronic devices are usually internally fused with very low amp fuses and I have never had a problem with them blowing. If a voltage spike of 200v were to get into radar, etc., I would think it would build up enough amperage to blow them??
That would depend on the type of fuse, but generally I don't think a fuse would be fast enough to blow unless the spike had a significant duration. Most boat's electronics should be designed to block spikes with internal voltage snubbers. You can also add an external voltage snubber to provide additional protection.
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Old 20-08-2011, 08:34   #18
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Re: Damage to Alternator ?

The voltage spikes are of extremely brief duration and would not likely blow any fuses. We recently had a "Navy 44" at USNA get hit by lightning that took out a lot of the electronics. It took out various individual components in the M504, M802, AT-140, B&G H3000 and Furuno NavNet without blowing any fuses. I got everything repaired except for the NavNet. It was beyond economical repair as several IC's had holes blown in them! Internal and external fuses all intact.

I think the problem of spikes from the starter and solenoid not usually causing any problems is because the large spike (200-400v) is not on that side of the solenoid contacts that is connected to your equipment. The spikes on that side are much lower and the equipment can handle it. That said, voltage spikes and electrostatic discharges can degrade electronic components (xistors, diodes, ic's etc.) without initially causing any problems noticeable to the user. The MTBF (mean time between failure) of the equipment may be reduced, i.e. it may fail sooner because of it being repeatedly hit by these spikes. This is why we tech's must wear ground straps when troubleshooting circuit boards as just the static buildup on our skin can damage these components.

Best to follows Bills advice and try to keep your starting/engine circuits separate from your house system.

Eric
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Old 20-08-2011, 09:11   #19
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Re: Damage to Alternator ?

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Originally Posted by fairbank56 View Post
...... The spikes on that side are much lower and the equipment can handle it. That said, voltage spikes and electrostatic discharges can degrade electronic components (xistors, diodes, ic's etc.) without initially causing any problems noticeable to the user. The MTBF (mean time between failure) of the equipment may be reduced, i.e. it may fail sooner because of it being repeatedly hit by these spikes. This is why we tech's must wear ground straps when troubleshooting circuit boards as just the static buildup on our skin can damage these components.

Best to follows Bills advice and try to keep your starting/engine circuits separate from your house system.

Eric
Eric,

Yes, exactly. While it's unlikely that fuses will blow in most instances, it's also quite likely that some damage will occur to sensitive solid-state components, and this damage is cumulative over time As you said, it may well affect the MTBF of the equipment, even if the problem isn't visible to the user immediately.

Thanks for doing the bench tests Eric. I haven't had the time to do them to try to measure the magnitude and duration of the voltage spikes. This might be a good thing for someone to do, i.e., measure the voltage spikes on both sides of the contactor on various common starters, as well as on common frig compressors, e.g., the Danfoss BD-35.

Bottom line: I think it's a very good idea to separate the engine start circuit from the house batteries and other loads, particularly the electronics. Then, let an EchoCharge or DuoCharge or similar voltage follower device take care of maintaining the start battery. Here, again, the choice of device is potentially important. I don't like isolators or combiners for reasons earlier stated, irrespective of manufacturer's claims.

BTW, I just finished doing this for a customer yesterday, along with several other electrical upgrades. The case was a little unusual, in that the house batteries are located some 22' one-way wire run from the house batteries. I put the EchoCharge near the house batteries, extending its positive and negative wires 6' using AWG8/2 duplex boat wire directly to the house batteries, and 22' of AWG6 battery cable from the EchoCharge to the start battery. I believed it necessary to use such large wire to keep the voltage drop to a minimum (less than 3% @ 15A, and less than 1% at 5A). On startup, the system seems to be working well, and adequate voltage is getting to the start battery to maintain it in a fully-charged state.

Bill
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Old 21-08-2011, 12:27   #20
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Re: Damage to Alternator ?

Perhaps I should start a separate thread for this, and moderators are welcome to do so. I mentioned above that I had a fried alternator. In disassembling it (an LR155-20, 55a. Hitachi) and following Yanmar's service manual test procedures, I discovered that 2 of the three diodes are good. One is burnt out. The brush assembly, windings, and armature all test out fine. The regulator looks ok. In searching around the internet, I can't find any info. on how to obtain a matching diode. It has a blue base and one thin blue stripe. There are so many different types of diodes, I can't really i.d. this one with confidence. Would like to hear from the electronics gurus here about how to match this diode with a replacement. This alternator should be repairable for about $1.00 but obviously suppliers would rather I buy the whole $100.00 diode plate unit. It looks a simple matter to solder in a new diode if I can find a matching replacement.
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Old 21-08-2011, 14:26   #21
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Re: Damage to Alternator ?

The alternator has 9 diodes. 6 rectifier diodes for the main output and 3 smaller ones known as the "diode trio" that provides output to the "L" terminal for operation of the indicator lamp on the engine panel. Sounds like you have only checked the diode trio.

Eric
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Old 21-08-2011, 15:24   #22
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Re: Damage to Alternator ?

smurphny,

I went through this a couple of weeks ago in Panama City after absent-mindedly turning the switch off before pulling the fuel shutoff.

I have the same alternator as well and began researching a self done repair.

I learned in an age of global manufacturing a new aftermarket (not rebuilt) alternator is available in 55 amp and 80 amp versions for your application. At the price of less than one hundred dollars, to boot.

Being open minded, financially strapped, and not believing the most expensive option is always the best option; I chose to upgrade to a new 80 amp aftermarket alternator.

Wilson rebuilds the original Hitachi's and sells this same alternator for over four hundred dollars, but they are known to be high priced, yet were the only option available I could find locally.

I know what some would think of my choice, so maybe they will spare me the platitudes.

At any rate, I thought my experience worth mentioning.

An example.

NEW Aftermarket Hitachi: Marine Alternator &amp YANMAR
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Old 21-08-2011, 17:32   #23
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Re: Damage to Alternator ?

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smurphny,

I went through this a couple of weeks ago in Panama City after absent-mindedly turning the switch off before pulling the fuel shutoff.

I have the same alternator as well and began researching a self done repair.

I learned in an age of global manufacturing a new aftermarket (not rebuilt) alternator is available in 55 amp and 80 amp versions for your application. At the price of less than one hundred dollars, to boot.

Being open minded, financially strapped, and not believing the most expensive option is always the best option; I chose to upgrade to a new 80 amp aftermarket alternator.

Wilson rebuilds the original Hitachi's and sells this same alternator for over four hundred dollars, but they are known to be high priced, yet were the only option available I could find locally.

I know what some would think of my choice, so maybe they will spare me the platitudes.

At any rate, I thought my experience worth mentioning.

An example.

NEW Aftermarket Hitachi: Marine Alternator &amp YANMAR
Thanks Four Winds. That's an even better deal than the backup (installed when I fried the original) I got from Spider Marine: http://www.spidermarine.com/showitem.aspx?&id=100438&name=100%25%20NEW%20Hitac hi%20%2012%20Volt%2055%20Amp%20Alternator. Am trying to fix the original or will have to get another to use as the backup. Spider also has a 100a Delco that they say is directly swappable without any modifications.

Fairbank56, If I can find the last 6 diodes, will check them too. The service manual does not have a good physical description of where to test them. If they're in the regulator (sealed) unit there's no way to get at them. Even if I can't fix this thing, it's been interesting dissecting it.
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Old 21-08-2011, 19:17   #24
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Re: Damage to Alternator ?

I see you are aware of these options. I should have guessed that to be so.

Actually I have the Spider Marine model now. Just happened to click on a different bookmark from my searching when I posted earlier. I found it the day after I ordered from Spider Marine as I was still searching just in case the order had a problem.

One day I'll have a backup. Only takes a few minutes to swap one out.
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Old 22-08-2011, 07:18   #25
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Re: Damage to Alternator ?

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I see you are aware of these options. I should have guessed that to be so.

Actually I have the Spider Marine model now. Just happened to click on a different bookmark from my searching when I posted earlier. I found it the day after I ordered from Spider Marine as I was still searching just in case the order had a problem.

One day I'll have a backup. Only takes a few minutes to swap one out.
Alternators seem to be a high-malfunction item so decided to keep a spare. Still no luck on finding just the diodes. There are some automotive LR series alternators with VERY similar looking diode plates. They, of course, are 20 bucks as opposed to 90+ bucks for the marine part through Yanmar. I may just order one and try it out to see if one works. Just kills me to pay through the nose for the same thing with a "marine" label.
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Old 22-08-2011, 08:11   #26
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Re: Damage to Alternator ?

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I'm seeing around 100-200 volts on the starter motor itself and double that on the solenoid. On the battery terminal side of the solenoid where your other loads may be connected, I'm seeing around 20-50 volts. It's difficult to get an accurate reading as the scope probe is also picking up spikes just being in the vicinity of the starter without being connected to anything.

Eric
With the battery bank acting as a "filter" I have not been able to measure a spike that could do much damage on the panel side of the battery. It is important to not "tap into" or use the starter cable or solenoid feed as a direct feed to instruments or electronics but I do see it done.

Have you guys been able to measure the spike after the battery?

BTW our own boat suffered a lightning strike last summer and not one fuse was blown. Nearly every electronic device on the boat was toast except for a few of pumps of which two have since succumbed.

We even lost multiple devices that were not plugged into anything a Garmin 176 GPS, the ACR Epirb, magellan HH GPS, iPod, laptop, and HH VHF. The Magellan was even wrapped in tin foil and then in a Ziplock bag with desiccant and stowed in Pellican case for ditch purposes, fried.....

Lightning does funny things. The only device still working after the strike are the fresh water pump and the fuel polishing pump and starter motor.
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Old 22-08-2011, 08:23   #27
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Re: Damage to Alternator ?

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With the battery bank acting as a "filter" I have not been able to measure a spike that could do much damage on the panel side of the battery ...
A battery (bank) is an excellent buffer.
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Old 22-08-2011, 10:12   #28
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Re: Damage to Alternator ?

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With the battery bank acting as a "filter" I have not been able to measure a spike that could do much damage on the panel side of the battery. It is important to not "tap into" or use the starter cable or solenoid feed as a direct feed to instruments or electronics but I do see it done.
My test setup in the shop was the starter locked in a vise, 3' #4 cables directly to Lifeline GPL-24 80ah battery. 20-50v spikes were measured directly at the battery terminal.

Yanmar 4JH series factory engine wiring harness taps off the solenoid battery terminal for power to the gauge panel, starter slave relay, stop relay, intake heater relay and alternator main output.

Eric
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Old 22-08-2011, 10:18   #29
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Re: Damage to Alternator ?

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My test setup in the shop was the starter locked in a vise, 3' #4 cables directly to Lifeline GPL-24 80ah battery. 20-50v spikes were measured directly at the battery terminal.

Yanmar 4JH series factory engine wiring harness taps off the solenoid battery terminal for power to the gauge panel, starter slave relay, stop relay, intake heater relay and alternator main output.

Eric
Eric,

Very interesting. Just curious but was the starter grounded to the battery making a circuit or was it just grounded to something on the test bench? I have not tested this on a bench myself but have in the field and have not been able to discern any spikes when the ships panel is wired to and from the battery and not tapping into the negative or positives coming from the engine or batt switch.
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Old 22-08-2011, 10:26   #30
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Re: Damage to Alternator ?

"Fairbank56, If I can find the last 6 diodes, will check them too. The service manual does not have a good physical description of where to test them. If they're in the regulator (sealed) unit there's no way to get at them. Even if I can't fix this thing, it's been interesting dissecting it. "
I dont know this alternator, so bear with me if I'm all wet, but arent these 6 diodes the big ones on the back of the case.. possible pressed in..?
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