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Old 09-19-2017, 01:20 PM
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AlexPeterson AlexPeterson is offline
 
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Default Melted backup battery

I put this on the long Oshkosh taxi thread, but had no replies. Here's what a 1.5 hour taxi in 80F weather can do to a backup AGM battery:



This battery is (was...) a Panasonic UP-RW1220P1. I had it mounted on forward side of firewall, left edge, below top motor mount attachment point. The non-bulged region is where the mount crossed it.

The main battery, an Odyssey PC680, is also forward of the firewall, lower right, but has no signs of stress. Odyssey recommended max operating temperature (meaning 100% of the time) is 113F. Undoubtedly this was exceeded, but the larger mass has a much longer time constant regarding heating up. Plus, the temp is a continuous operating max.

I'm moving the b/u battery back inside the plane (I moved it forward at the same time I moved the main battery last year). I'm going to place a few thermocouples up there as well, as I'm curious. I'll stick one on the main battery, covered with a patch of insulation. Maybe one somewhere near the cooling exit as well. I know others have taken some measurements (Dan H).
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  #2  
Old 09-19-2017, 01:27 PM
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The application guide for these Panasonic VRLA batteries includes this guidance:

Quote:
...temperature should not exceed 122°F (50°C) in order to prevent the deformation of resin materials which house the battery or deterioration of service life.
- Matt
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  #3  
Old 09-19-2017, 02:47 PM
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Carl Froehlich Carl Froehlich is offline
 
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I know a lot of Van's per plans builds have the battery on the engine side of the firewall - and I'm sure many are flying just fine. Here is example however of why I never mount any battery on the engine side of the firewall.

The RV-8A and RV-8 (180hp engine and Hartzell CS prop) have the batteries mounted just aft of the firewall on the floor (one PC-625 on each side). The RV-10 has both PC-625s mounted in the per plans spot after of the baggage compartment (stock mount slightly modified). All planes' W&B came out as good as you would want.

Carl
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Old 09-19-2017, 03:44 PM
gasman gasman is offline
 
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Quote:
Originally Posted by AlexPeterson View Post
I put this on the long Oshkosh taxi thread, but had no replies. Here's what a 1.5 hour taxi in 80F weather can do to a backup AGM battery:



This battery is (was...) a Panasonic UP-RW1220P1. I had it mounted on forward side of firewall, left edge, below top motor mount attachment point. The non-bulged region is where the mount crossed it.

The main battery, an Odyssey PC680, is also forward of the firewall, lower right, but has no signs of stress. Odyssey recommended max operating temperature (meaning 100% of the time) is 113F. Undoubtedly this was exceeded, but the larger mass has a much longer time constant regarding heating up. Plus, the temp is a continuous operating max.

I'm moving the b/u battery back inside the plane (I moved it forward at the same time I moved the main battery last year). I'm going to place a few thermocouples up there as well, as I'm curious. I'll stick one on the main battery, covered with a patch of insulation. Maybe one somewhere near the cooling exit as well. I know others have taken some measurements (Dan H).
Am I the only one that gets a - sign instead of the posted picture?????
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Old 09-19-2017, 03:52 PM
gasman gasman is offline
 
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That may have been the hottest place to locate a battery with the exhaust below and no way to move air out the top. The bottom battery at least has some air movement in it's area.
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  #6  
Old 09-19-2017, 06:08 PM
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Quote:
Originally Posted by gasman View Post
Am I the only one that gets a - sign instead of the posted picture?????
No. I don't see a picture either.
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  #7  
Old 09-19-2017, 08:58 PM
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Here's a direct link to the photo:

picture
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  #8  
Old 09-20-2017, 07:49 AM
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Default damage vs danger?

...so do you think there was a risk of fire, leakage ( AGM less acid) or other issues? Does it still make juice?
I've seen the Odyssey offered in a metal case, perhaps that should be standard for FWF.
My PC925 was mounted on the firewall near the oil cooler outlet, and on first flight the 'lid' warped from the heat, and all the little caps on the cells popped off! ( batt. mounted on it's side)
...so a new case/lid retainer was needed. 5 years later it seems fine.
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  #9  
Old 09-20-2017, 08:23 AM
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AlexPeterson AlexPeterson is offline
 
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The battery was still sealed, and was functioning (i.e., voltage was indicating full charge).

The metal jacket version is spec'd for a higher temp. From the manufacturer's site:

"Operating temperatures from -40°C (-40°F) to 45°C (113ºF), for models without a metal jacket, and from -40ºC (-40ºF) to 80ºC (176ºF) for models with a metal jacket."

Might be the appropriate one to get. It is slightly larger though:

PC 680MJ:
Length: 7.28"
Width: 3.13"
Height: 6.7125"

PC 680:
Length: 7.13"
Width: 3"
Height: 6.5"
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