Sender: <marv@lancaironline.net>
To: lml@lancaironline.net
Date: Wed, 28 Feb 2007 00:44:03 -0500
Message-ID: <redirect-1873024@logan.com>
From: "Tom Gourley" <tom.gourley@verizon.net>
Subject: Re: [LML] Re: Reiff Airplane Preheat Systems (TSIO550)
Reply-to: "Tom Gourley" <tom.gourley@verizon.net>
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References: <list-1871638@logan.com>

Based on what I saw on Reiff's website their preheat system runs from AC so 
to power it from a battery you'd need a power inverter.  There are all sorts 
of modified sine wave inverters (I don't think you'd need a pure sine wave 
inverter for this) for under $100 that can handle just a 200W sump heater or 
a full 800W Reiff system.  Let's say you opt for the 200W sump heater. 
According to Reiff's site that will take 9 qts of oil from 22F to 87F in 
about 3 hours (your results may vary).  If you're using a 12V battery (ok, 
it's not exactly 12V but let's use that as nominal) it would require about 
16.7A to deliver 200W.  However, inverters aren't 100% efficient.  A decent 
one should be close to 90% which means the battery would have to deliver a 
little over 220W, or about 18.5A.  If you put a timer on the system so that 
it came on 3 hours before you arrived you'd need a 12V battery with a rating 
of over 55 A-hrs.  Something like an Interstate UBIGJOE (seriously, that's 
what it says on their website), which is an industrial deep cycle battery, 
might handle it, but it weighs 80 lbs.  There are batteries with more 
capacity but typically they're even heavier.  If you decide to try this 
route find a battery with a Reserve Capacity rating of more than 3 hours 
(180 min) at a current drain of more than 18.5 A.  Don't go by the amp-hr 
rating.  For example the UBIGJOE is rated at 107 A-hrs so you might think it 
should last for nearly 6 hours at 18.5 A.  Not the case.  The amp hour 
rating is if the battery is discharged over a 20 hour period.  The RC rating 
at 25A is 185 min, about 70% of what you'd expect just using the A-hr 
rating.

Powering the 800W Reiff system would take a lot of battery.  I didn't see 
one on Interstate's site that would handle it.  Of course you could alway 
use multiple batteries. (How's your back?)

If you only live a mile from the airport maybe you should consider a long 
extension cord :)

Tom Gourley