Can I get away with a cheap inverter?

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sully75

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Jan 6, 2014
89
Pearson Triton Cambridge
I have a very simple electrical system on my boat, no outboard, 1 100w panel, a Genasun controller and 2 agm batteries.

The only thing I'd think about using an inverter for would be the occasional friends laptop (mine are on 12v chargers) and my random orbital sander (a cheap Makita, for the record).

I noticed Maine Sail has a cheap cobra inverter in one of his articles:
http://www.pbase.com/mainecruising/ipad_charge_

Could I get away with this 800w inverter for my purposes? Will my head explode? Will all my metal parts of my boat disolve?
http://www.amazon.com/Cobra-CPI-880...qid=1401539572&sr=8-1&keywords=cobra+inverter

BTW I've asked about 12 questions here recently and gotten great information, much appreciated. Thanks
Paul
 
Maine Sail

Maine Sail

.
Feb 6, 1998
11,709
Canadian Sailcraft 36T Casco Bay, ME
sully75 said:
I have a very simple electrical system on my boat, no outboard, 1 100w panel, a Genasun controller and 2 agm batteries.

The only thing I'd think about using an inverter for would be the occasional friends laptop (mine are on 12v chargers) and my random orbital sander (a cheap Makita, for the record).

I noticed Maine Sail has a cheap cobra inverter in one of his articles:
http://www.pbase.com/mainecruising/ipad_charge_

Could I get away with this 800w inverter for my purposes? Will my head explode? Will all my metal parts of my boat disolve?
http://www.amazon.com/Cobra-CPI-880...qid=1401539572&sr=8-1&keywords=cobra+inverter

BTW I've asked about 12 questions here recently and gotten great information, much appreciated. Thanks
Paul
Click to expand
Not an issue unless you try and tie it into the ships AC system. Keep the 120V side of it free from the ships AC system and you will be fine. That Cobra I use is there to simply provide "load" for battery capacity testing and such, though I have used it for charging an iPad. It is pretty dirty power.

For a RO sander you may want to find an inexpensive pure sine inverter such as the Xantrex ProWatt SW.. Motors and more specifically battery chargers for drills, cameras etc. really don't like dirty inverter power and the cheaper the inverter usually means the dirtier the power. I have used some inverters that my drill or MultiMaster won't even start up on unless I can rotate the motor a bit. I also destroyed about 4 very expensive DeWalt batteries using a cheap inverter before I realized the dirty power was causing the charger issue...

I am usually not a big fan of "X" brand but the Xantrex ProWatt SW are priced well for pure sine and work pretty well....

ProWatt SW Sailboatowners.com

Since the ProWatt came out a bunch of other inexpensive "pure sine" inverters have hit the market...
 
S

sully75

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Jan 6, 2014
89
Pearson Triton Cambridge
Unfortunately the ProWatt ends up being "major money" while I can kind of justify the Cobra as "petty cash". I'll have to see how the funds add up at the end of this refit. Might just have to do without it for the summer then.

Really only need it for the sander, so I can probably make due without it. I wish there was a cordless RO sander by Ryobi but their little cordless sander looks pretty dinky.
 
S

sully75

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Jan 6, 2014
89
Pearson Triton Cambridge
whoops. I guess Ryobi does have a cordless sander. Probably not great but I'll give it a try.
 
I

IStream

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Nov 14, 2013
200
Catalina 50 Seattle
sully75 said:
whoops. I guess Ryobi does have a cordless sander. Probably not great but I'll give it a try.
Click to expand
I'd save your money for the ProSine. No sense wasting money on a crappy tool, no matter how cheap.
 
S

sully75

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Jan 6, 2014
89
Pearson Triton Cambridge
I ended up getting a very clean looking Prowatt SW600 used off ebay.

I'm wondering what I should use for the ground? I don't have an inboard. My keel is more or less encapsulated (I could drill through a lot of fiberglass to sink a bolt in it, I guess...)

Would I install a grounding plate? Not sure what else to ground it to.

Thanks!
Paul
 
Stu Jackson

Stu Jackson

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Feb 26, 2004
23,047
Catalina 34 224 Maple Bay, BC, Canada
Ground

sully75 said:
I'm wondering what I should use for the ground? I don't have an inboard. My keel is more or less encapsulated (I could drill through a lot of fiberglass to sink a bolt in it, I guess...)

Would I install a grounding plate? Not sure what else to ground it to.
Click to expand
Paul,

Your ground is the negative post of you battery bank. Don't mess with the keel or anything else. Buy Charlie Wing's Boat Electric book.
 
S

sully75

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Jan 6, 2014
89
Pearson Triton Cambridge
wait a sec...so the negative terminal AND the ground are both going to go to the negative terminal on the battery?

I thought the ground was to give the GFI something to ground to?
 
Stu Jackson

Stu Jackson

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Feb 26, 2004
23,047
Catalina 34 224 Maple Bay, BC, Canada
sully75 said:
1. wait a sec...so the negative terminal AND the ground are both going to go to the negative terminal on the battery?

2. I thought the ground was to give the GFI something to ground to?
Click to expand
1. The negative of the battery IS the ground for the DC system.

2. GFI is AC.

Two different electrical parts of the systems. Don't mix 'em.

Really, if you're asking this, you should buy the book.

Good luck.
 
M

mitiempo

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Sep 28, 2008
922
Canadian Sailcraft CS27 Victoria B.C.
sully75 said:
wait a sec...so the negative terminal AND the ground are both going to go to the negative terminal on the battery?

I thought the ground was to give the GFI something to ground to?
Click to expand
The chassis ground goes to the battery negative post or negative bus as Stu said. It should be no more than one wire size smaller than the other DC cabling feeding the inverter - preferably the same size. It is for a DC fault and has to be large enough to carry the full input current of the inverter.
 
S

sully75

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Jan 6, 2014
89
Pearson Triton Cambridge
Ok I thought it was for the AC fault from the converted AC current. You are sure about this?
 
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