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Date: Fri, 04 Aug 2006 17:49:53 -0400
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From: Tom Thibault <tthibaultsprint@earthlink.net>
Reply-To: Tom Thibault <tthibaultsprint@earthlink.net>
Subject:  [LML] Re: LR3C Regulator
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Chris,

In general you are right.  I looked for the document you showed and found the new version of it.  It is the Operator's Manual, DWG 5-0164.  It has the same chart and essentially the same words.

The thing for us that matters is the operating temperature of the battery in flight.  Those of us that have cabin mounted batteries should likely be operating in the 50-90 degrees F range.  For that case, the voltage should be 14.0 to 14.2 per Concorde direction.  In my case, the battery is on the engine side of the firewall at a much higher (currently unknown) temp.  In that case, the voltage should be set at less than 13.75.  I will be lowering mine to 13.6 most pronto until I get some of those temperature tapes so that I can find out the real temperature.

Finally, the above is only about the battery operating temperature, not the LR3C temperature or mounting location.

I verified all the above with an extremely helpful and friendly Concorde battery engineer on the phone just now.


Tom Thibault

Tom, et al 
In another Concorde document they provide a chart showing charge voltage as a function of battery temperature.  The 14.1 V really only applies at 25 degC.  I can't figure out why they don't qualify the 14.1V in the reference you cite, as well as others, with a temperature value.  This could really affect batteries installed in engine compartments. 
 
Leighton,
-another possibility.
Have you checked your charge voltage with a calibrated voltmeter?  I found my Electronics International voltmeter to read low by 0.2V and the JPI EDM low by 0.1 V  -both leading to higher than intended charge voltages initially.  I had adjusted the voltage according to the EI.  I too fried an early battery during a summer of instrument approaches while charging at what was really 14.3V with OATs of 100 degF.  -felt like 120 degF inside.
Chris