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Inverter question

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Old 12-18-2006, 07:20 PM
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Default Inverter question

I have been looking at used gensets to run an A/C unit and a TV/DVD unit for the kids - with not much luck. Portable Honda Generator is not an option I want to intertain.

This is the a/c unit I have been thinking about:

http://cgi.ebay.com/ebaymotors/boat-...QQcmdZViewItem
I believe these units are 'soft starts?'

and looking at the heavy equipment batterys shown here:

http://www.cat.com/cda/layout?m=37407&x=7
(weight ((with-in reason)) is not a real issue as this is going in a small daycruiser)

My question is,

How many batteries to run 3 - 4 hours?
What size inverter to cover my needs with no problems?
Does heat effect inverter performance - I question if inverter can be mounted in engine area or in cuddy.

Thanks
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Old 12-18-2006, 07:44 PM
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Default Re: Inverter question

RebarBox,

Batteries first. You'd be better off with multiple 6 volt golf cart batteries. I highly recommend the Trojan T-105 batteries for inverter use. They are rated at 120 amp hours and you will need to tie two together in series (+ to -) to make one twelve volt bank. To run your A/C, you're going to need at least 4 total if not more. 8 would be ideal but that is a lot of weight to carry around.

Inverter next. Stick with a high quality brand such as Xantrex or Trace (both made by Xantrex BTW along with some other brands.) For type of unit, try to stick with a pure sine-wave form inverter and stay away from modified sine wave or square wave inverters. They do not like to run sensitive or inductive loads very happily. Without knowing the specs for the A/C unit beyond 5.5 amps, I'd recommend at minimum a 2500 watt inverter.

You may also think about going with a 24 volt inverter instead of the more popular 12 volt. This will cut your amperage draw from your batteries in half. You will need to wire your batteries for 24 volt though which is not a big deal since you'll need multiple batteries anyway except that you'll need multiples that will work out to 24 volts.

The battery cables are very important too. Runs should be very heavy cable, minimum of 3/0 gauge - 4/0 is better, and be kept as short as possible. The inverter can be mounted in or out of the engine compartment. Ambient heat will affect output but the higher end units have cooling fans and larger heat sinks and are able to handle it. Mounting location should be determined by where your batteries will be mounted to keep cable runs absolutely as short as possible. Don't mount the batteries in your engine compartment and then run battery cables 25' to the inverter.

Good luck.

Last edited by DrNautica; 12-18-2006 at 07:48 PM.
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Old 12-18-2006, 08:02 PM
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Default Re: Inverter question

If you plan to install an inverter in an engine space it will need to be ignition-protected and have the appropriate UL or USCG ratings identifying it as such.
Inverters do create heat and you'll need to consider this when you look for a suitable installation position.
Yup, the golf cart batteries are the way to go. I agree with Dr. Nautica concerning the need for at least four of them. You'll probably need to upgrade to a higher-capacity alternator along with a battery isolator.
I run a 5000-watt inverter on my boat to support the A/C for short periods while I'm away from shore power. Currently I use four group 31 batteries wired in parallel but next season I'll switch to the T-105 batteries.
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Old 12-18-2006, 10:30 PM
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Default Re: Inverter question

If the ebay doesn't pan out, try WM. They are clearancing their Mermeid line at blow out prices. Myself and 3 buddies bought 4 units from them this fall. Plus they have a 5yr warrenty. The price does not include the install kit, but those are clearance priced too. Just a heads up.




http://www.westmarine.com/webapp/wcs...key=SiteSearch
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Old 12-18-2006, 11:19 PM
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Default Re: Inverter question

Quote:
Originally Posted by US1 Fountain
If the ebay doesn't pan out, try WM. They are clearancing their Mermeid line at blow out prices. Myself and 3 buddies bought 4 units from them this fall. Plus they have a 5yr warrenty. The price does not include the install kit, but those are clearance priced too. Just a heads up.




http://www.westmarine.com/webapp/wcs...key=SiteSearch
Do you know if they are soft start units?

Thanks for the input Doc. and Crazy.
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Old 12-19-2006, 12:04 AM
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Default Re: Inverter question

WHY NOT AN ENGINE DRIVEN AC?
http://www.nauticoolair.com/
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Old 12-19-2006, 12:06 AM
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Default Re: Inverter question

Not sure what that means.
Unless that is when the compressor has a couple second start up delay from when the fan and water pump turn on, then yes.
At least my 6500 R/C is.
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Old 03-22-2007, 09:17 PM
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Alright, I bought a new A/C unit - (6500 btu - cool only) with 7.5 amp draw continuous x 1.8 for start up draw plus 1 amp for pump.

I bought the Trojan T105 batteries - 4 for trail and will buy 2 additional if needed.

And went and bought a Xantrex Freedom 458 inverter/charger - 2000 watt cont., 5000 surge. But, I had told the guy from donrowe.com that I wanted a PURE sine wave and he must have missed that part cause I received this inverter and it's a MODIFIED sine wave.

According to a/c manufacture - a/c unit will work but might run 'slightly' hotter and not like long run times with modified in lieu of pure.

My intention is to power up a/c for 30 - 45 minutes to knock the heat down for my 2 year old to take a nap during the day.

So, what will happen if I install this modified sine wave inverter?

And, Doc., the number you gave me for PJ was not working...
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Old 03-24-2007, 09:04 AM
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Have you guys looked at the 12 volt AC units?
I saw one at the Washington DC boatshow. They are not cheap but it looks like might work.
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