Inverter with Transfer Switch

I put in a Cobra 800 watt unit last year. I screwed it into the top of the battery holder and tied it down with the strap. Hard wired it directly to the battery and ran a plug out of the inverter and wire off it to an outlet that I put in my locker right inside the cabin and used it for charging cellphones and running fans, blenders and tv's. Never had an issue with it all season. (use a GFI outlet for added safety) and remeber to turn the unit off when not in use. Good luck WAKEUpII
p.s. bought it from amazon for about $40.00
 
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You've got to be kidding me....

Is that you Kearney? I know that's you... no one could come up with that stupid of a suggestion.
 
wakeup 19 said:
I put in a Cobra 800 watt unit last year. I screwed it into the top of the battery holder and tied it down with the strap. Hard wired it directly to the battery and ran a plug out of the inverter and wire off it to an outlet that I put in my locker right inside the cabin and used it for charging cellphones and running fans, blenders and tv's. Never had an issue with it all season. (use a GFI outlet for added safety) and remeber to turn the unit off when not in use. Good luck WAKEUpII
p.s. bought it from amazon for about $40.00
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That could be dangerous if the battery is in the engine bay. If so, much safer to hard wire to the battery with proper fuse/breaker to some place outside the engine bay for the inverter mounting.
 
wingless said:
The Xantrex has 88% peak efficiency versus the ~60% efficiency in my example.
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wingless said:
That 88% peak efficiency would be at maximum load (8.3A AC / 1,000W) and less at lower loads, like the 130W max of your LCD.
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mawyatt said:
Actually peak % occures below max load and in most all inverters/converters is not that strong a function of load down to ~0.2 rated or lower load. % is controlled by many factors including switching MOSFET Ron losses, actually switching losses, transformer/inductor losses and control electronics.
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That does not comport w/ my experience. But, this is easy to measure once the device is on-hand, measuring power in and power out, then calculating the ratio.


wingless said:
Remember, these things suck when they fail, 'cause all that power goes through one small part. That is, lots of smoke and flame until the conduction path has vaporized during failure.
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mawyatt said:
The more modern designs employ integrated electronics (IC chips) and vastly improved switching devices (MOSFET) to yield highly efficient reliable inverters that have built in protection modes (over/under voltage, over temp, overload and so on). However they can and will fail especially in very hot environments, remember heat is the enemy of all electronics.
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Maybe I’m jaded from having seen too many fried inverters, but I wouldn’t want one on my boat after seeing extended-duration open flames from a failing inverter.

But, go for it! It’ll probably be fine. Please report if otherwise.
 
wingless said:
That does not comport w/ my experience. But, this is easy to measure once the device is on-hand, measuring power in and power out, then calculating the ratio.


Maybe I’m jaded from having seen too many fried inverters, but I wouldn’t want one on my boat after seeing extended-duration open flames from a failing inverter.

But, go for it! It’ll probably be fine. Please report if otherwise.
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Just go to any source that has a graph of eff. vs. output power, most peak near 35 to 50% max power. This eff. peak is relatively modest, usually only a few percent above 10% or 100% rated load eff. To measure eff., one will need a true RMS reading voltmeter and ampmeter, the typical DVM most of us have will not give the proper reading. A Fluke 87 is a good meter for this (I have one but it's in my lab somewhere at work, I have a Fluke 77 on the boat which is your typical DVM, plenty good enough for troubleshooting though).

The reason the eff. is relatively flat with a slight peak about midstream is the losses are a combination of switching losses, switching device series loss, magnetic losses and support electronics power. The switching losses vary slightly with load, the switching device series loss is directly proportional to load, the magnetic losses are a combo of fixed and proportional to load and support electronics are a constant loss (power drain). As the load increases the load sensitive losses increase, however the fixed losses are now averaged over a larger output power and have less influence thus tend to cancel some of the load sensitive losses effect. All in all this plays out as a relatively flat eff. vs. load effect which makes calculating expected battery life at various loads a little easier.

As far as relibility goes the older designs tended to have problems, especially when bipolar switching transistors were employed. Most modern designs utilize complex ICs that have many built-in protection/safety features and use MOSFETs for the switching devices which all boils down to a more reliable, lower cost solution.

These inverters are a good example of how ICs (Intergrated Circuits) are improving the overall product with lower cost, better reliability and performance. The cost of developing these ICs is enormous (in the Millions of $!!) which we call Non-Recurring-Engineering or NRE, however the recurring cost is very low because the ICs are batch processed on 8" or 12" silicon wafers which may yield 10,000 chips!

Generally a application specific IC (ASIC) is not justified unless the quanity is well into the millions of chips, otherwise the amoritized NRE cost per chip is too high. This is where we as boaters benefit because of other applications that have the volume to justify the developement of ASIC which then can be adapted for our use.

Anyway hope this helps and gives a view into the IC world where I live.
 
I'm one of those geeks too. I design FPGAs and ASICS for the largest North American wireless network equipement manufactures. That is untill my job is moved to China later this year. :smt100
 
Westie said:
I'm one of those geeks too. I design FPGAs and ASICS for the largest North American wireless network equipement manufactures. That is untill my job is moved to China later this year. :smt100
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Good company!! I've been involved with all sorts of electronics and developed an RFIC ASIC technology in 90 that's carried us forward to today.
 
Four Suns said:
Geek
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That personal attribute was intentionally selected to be the driving force in my character. During religious classes I heard that “the geek shall inherit the Earth.” It sounded good to me.

It wasn’t ‘till much later that I found I’ve been suffering hearing problems. I’ve been diagnosed w/ CHW, but I’ve decided to avoid treatment.
 
wingless said:
That personal attribute was intentionally selected to be the driving force in my character. During religious classes I heard that “the geek shall inherit the Earth.” It sounded good to me.

It wasn’t ‘till much later that I found I’ve been suffering hearing problems. I’ve been diagnosed w/ CHW, but I’ve decided to avoid treatment.
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Good one, that's funny!! Gates and Allen must have attended the same religious class!!
 
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