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Old 26-01-2015, 16:45   #16
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Re: Two fried laptops later.

Originally Posted by Errantries View Post
We have a Cobra CPI 2575 that uses a modified sine wave ........... we are only getting 100 volts out of the outlet.
Laptops and other electronics can be sensitive to modified sine wave, let alone low voltage. We have 2 laptops aboard and the power supply for one buzzes and gets hot when running on the main inverter (modified sine wave).

I solved it by buying a small 150W sine wave inverter for electronics only.

Whatever the case, 100 volts suggests a faulty inverter.

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Old 26-01-2015, 17:19   #17
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Re: Two fried laptops later.

The fact you've had many electrical failures hints at a persistent but intermittent problem.

I'd suggest you have a qualified marine electrician help you out.

Otherwise log your AC feed and add or remove loads and devices until you find the culprit.

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Old 26-01-2015, 18:17   #18
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Re: Two fried laptops later.

Originally Posted by leftbrainstuff View Post
The fact you've had many electrical failures hints at a persistent but intermittent problem.

I'd suggest you have a qualified marine electrician help you out.

Otherwise log your AC feed and add or remove loads and devices until you find the culprit.

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That is what I was thinking too.

To the OP:

Thanks for providing the info on location and weather etc.

Though I am no electrical engineer this looks like a case where deduction is important.
"When you have eliminated the impossible, whatever remains, however improbable, must be the truth." -- Sherlock Holmes
This topic interests me as I recently replaced my PC laptop (that died) with a Macbook Pro, and I would hate to lose my new mac (and iPad or other devices) to some kind of electrical gremlin on a boat.

Good luck.
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Old 26-01-2015, 19:52   #19
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Re: Two fried laptops later.

I'm leaning to the same. There's something in our electrical system that's causing spikes... we just need to figure out where they are coming from. The iPhone battery "exploded" in my SIL's words (after she had flown back home), but she left that thing plugged in all the time, like we all used to do before moving on a boat, I guess. Had it plugged in a USB outlet wired to the 12v DC system. The cords just stopped working after being plugged in the same outlets- hard to tell when that happened.

I did some research on the Cobra inverter, and I'm hearing that it's normal to get a slightly lower voltage reading from these devices than expected, so I'm hesitant to say that it's faulty.

I'm not really sure how to "see" when these spikes occur, as I'm not sure if my multimeter will detect them. I doubt that my multimeter is RMS capable. Will any multimeter do the trick for me, or do I need something fancy? To be honest, we are really only using the 110 inverter to charge our laptops. Every once in a while we'll use it for a sewing project, but that's it. No microwave, coffee maker, or other kitchen do-dads. Our power tools run on a different inverter running 220.

Anyone got a phone number for a solid marine electrician in Cartagena, Colombia? What about in Colon, Panama?

Right.... You guys are my Obi Wan. My only hope.

Thanks again for your input. I'll definitely report back on any findings. Feel free to keep throwing me a bone or two.
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Old 26-01-2015, 20:16   #20
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Two fried laptops later.

Is your surge protector really a surge protector or is it a mere power strip? Also it may not be any good if paired with a portable inverter such as the one you have. Surge protectors work by sending the voltage spike to the grounding wire and then to ground Your inverter is grounded to??
An MSW inverter will read lower voltage with most multimeters...your Cobra probably is putting out 110.
If you look at Apple forums you will see that MSW inverters tend to fry Apple products. I do not know why, but you are not alone.

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Old 26-01-2015, 20:50   #21
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Re: Two fried laptops later.

YOu didn't explicitly say... so I am going to ask... are you in a marina? Are you plugged in?
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Old 26-01-2015, 20:54   #22
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Re: Two fried laptops later.

While you should be able charge your laptops and run your equipment from your inverter, it sounds as if you are dealing with a problem that will be hard to fix on the Internet.

Harmonics issues involving inverters can do a lot of damage, including causing fires.

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Old 26-01-2015, 22:08   #23
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Re: Two fried laptops later.

Originally Posted by a64pilot View Post
...I'd say get a DC to DC convertor, a car charger to charge your laptops...
Me too.
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Old 26-01-2015, 23:04   #24
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Re: Two fried laptops later.

The reason you measure 100V out of the inverter is because it is a modified sinewave inverter. Unless you have a true RMS meter (most cheap meters are not true RMS) it will read low because the peak of the output is not 170V like a true sine wave. In fact, the inverter output isn't a sine wave at all. It's actually a type of pulse that goes positive, then to zero, then negative and repeats 60 times per second. (I assume you have a 60Hz inverter). If you are looking for spikes then look no further than your inverter. It makes fast rising pulses all the time. It's a shame that these companies get away with using the term modified sinewave when the output has no resemblance to a sine wave at all.

Surge suppressors from Home Depot will do nothing to help. In fact, they may make things worse. I would eliminate all that stuff.

I don't wish this to sound cruel but you have a 2,500W inverter that sells on Amazon for less than $200. It is not possible to build a high quality inverter at that price per watt. You might consider getting a much smaller inverter (say 600W) pure sine wave and try that. Defender sells the Go Power! GP-SW600 Power Inverter pure sine inverter priced at about $300 in the US. In Columbia I don't know what is available. If you find something there post the model here and we can check to see what its specifications are.
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Old 26-01-2015, 23:45   #25
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Re: Two fried laptops later.

Backing up a bit...

What EXACTLY do you mean by fried?

And how EXACTLY do you know?

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Old 27-01-2015, 00:08   #26
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Re: Two fried laptops later.

If both laptops were plugged into the same power brick at the time they fried, then I would suspect the brick as the defective unit. If the MSW inverter were indeed screwing anything up, it would screw up the power brick.

I'd recommend a DC to DC converter to run any future MacBooks just for the sake of energy efficiency. It's slightly more efficient than converting 12vdc to 110vac then converting 110vac down to 19vdc or whatever Macs use.

If you're really serious about monitoring your AC voltage, they sell some data logging DMMs on Ebay for a reasonable price.
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Old 27-01-2015, 00:40   #27
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Re: Two fried laptops later.

Originally Posted by Errantries View Post
We've also fried several iPod/iPhone charging cables (just won't work anymore) while charging DC straight from the battery, and my sister-in-law's iPhone battery fried also after charging from the DC side.
These failures have nothing to do with the inverter, whether sine wave, square wave, or a triceratops wiggle. They do sound like high humidity failures,
and perhaps that is the charging brick problem, and it has put out 110vac to the laptop instead of 18vdc, which would kill the laptop.
I would not test the charging brick with another laptop after it killed two already.
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Old 27-01-2015, 04:07   #28
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Re: Two fried laptops later.

I read all this with interest as I recently fried my cordless drill charger on the boat.

I have a decent sine wave inverter, and it has run everything I have plugged into it so far, but the other day I had left the master switch off, I plugged in the drill charger, nothing happened, I went "doh!" and switched the master 12V switch on, at which point the inverter fired up and nuked the drill charger, with the classic fried capacitor smell I have grown to know if not love.

So, I have learned to make sure nothing is plugged into the inverter as it is switched on, perhaps this situation occurred to the OP?

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Old 27-01-2015, 04:31   #29
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Re: Two fried laptops later.

Hi folks,

Thanks for the advice... here's a few answers to you questions.

dohenyboy: We bought both a surge protector bar and a voltage regulator. The voltage regulator claims to keep the voltage in a certain spectrum, protecting against spikes. I'll have to take a look at how it detoured the voltage spikes and where the grounding is. This was just a temporary solution... not something that we thought we'd use permanently on the boat. Just a safeguard (we thought) while we find the reason for the voltage spikes.

zboss: We are anchored outside the marina. Not tied up and not plugged into shore power.

The_Alpine: We took both computers to the mac store here, they were opened up, and I was told that the motherboards were dead (on both) due to surges in voltage.

socaldmax: The laptops were damaged while using two different charging bricks. And (for better or worse), I tested the second charger with my buddy's computer (after the second laptop fried), and it's working just fine.

Yes, the DC to DC option is a good work around, and we have a few chargers like this on board. But, we are seeing electronics failures while plugged into both DC and the 110 AC inverter. I think, stupidly, when we saw electronics being damaged by our system, we thought using the 110 AC would be safer since the voltage from the battery was being converted through the inverter. I'm realizing now that this wasn't a good call. But, I'd like to get to the heart of the issue and make sure my system isn't killing all my electronics.

The options here regarding MSW versus PSW are similar to what I'm finding online. While the MSW are cheaper and a PSW is definitely better, I'm finding a lot out there that says the MSW shouldn't completely damage my logic board. Shouldn't is the key word I guess.

It's also possible that the DC charging problems could have a different root from the AC charging problems. Maybe the cords and the iPhone died due to overcharging or humidity, but the laptops died due to my MSW inverter. I can't kill anymore computers, so I'll start with getting a new inverter (we've got some guests coming soon that can bring it from the states), and we'll look for a marine electrician in Panama. We inherited the old inverter from the previous owner.

Another interesting thought I had last night... both laptops died in similar circumstances. They were being charged from the inverter, and while being plugged in, I had attempted to turn them on. With the first laptop, the battery was drained, so it was plugged in, left to charge a bit, then attempted to be turned on (but wouldn't). With the second laptop, some settings were changed and I needed to do a restart. Laptop was being charged from the inverter, it was powered down, but then wouldn't power back up. I wonder if the powering on is when the damaged occurred, or could it just be when you see the symptom present itself of logic board damage?

Thanks again gents.
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Old 27-01-2015, 04:57   #30
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Re: Two fried laptops later.

There is no way I can think of that a motherboard would fry without the charging brick also being fried. The brick does voltage conversion and isolation, but it is easily damaged by modified sine wave inverters. DC voltage coming from the brick is also further regulated on the main board. I'm with others who recommend a pure sine wave inverter for electrics.

You didn't specifically state the modes of computer failure. Condensing atmosphere, bad power, vibration or shock, and heat are the leading causes of computer failure. Were your computers sitting on top of charts or papers or fabric that might have blocked the bottom ventilation?

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