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-   -   What killed this PC680? (https://vansairforce.net/community/showthread.php?t=99810)

rv6ejguy 05-18-2013 09:46 AM

After 10 years on mine with some rather frequent bouts of inactivity, I decided to replace my 680 this annual with a new 680. Still seemed as strong as day one and passed the load test every year with flying colors. I'd put a 1 amp charger on it the first day of every month if it hadn't seen activity which I do with all my vehicle batteries getting stored for the winter. Haven't had any battery go bad for many years now- 3 cars, 1 bike, 2 airplanes.

The old 680 is now doing duty on our ignition coil test bench. I expect it will last many more years in that job.

Had nothing but great service from all my Odyssey batteries with no special chargers and maintenance.

Tom Martin 05-18-2013 11:49 AM

yes the Odyssey is a great battery and my experience echoes what others are saying. After five trouble free years in my rocket I put a new 680 in a year ago, just because; IFR, electronic ignition etc. The new battery is NOT as good as the one it replaced. Perhaps they are not all created equal. The post about the master solenoid "leaking" got my attention. I am going to test that unit, as it may explain some of the behavior I have been seeing.

bhester 05-18-2013 06:42 PM

Still Strong
 
Six years flying and one or two on before that. I've only trickled it a few time while doing instrument panel work, never overnight. I'm sure if you do the next one this way it will last the same way!

rapid_ascent 05-18-2013 07:19 PM

A battery charger can actually wear out a battery I've been told. This might sound strange, but if the charger is not designed to be continuously connected to the battery it is possible. I'm not an expert on batteries, but I have worked on UPS systems with people you are. I've been told that if the charger cycles too much or if there is too large of AC component on the charging voltage then that AC component effectively charges and discharges the battery when it is connected. This continuous cycling can reduce the life of the battery. The magnitude of the AC component and the length of time connected to the charger determine the impact. A low cost charger may work fine for charging up the battery, but it may not work well too to maintain a battery. I'm not sure if this is the cause of your problem, but its not something that would immediately come to mind to most people.

Omega232Devils 05-18-2013 07:23 PM

Battery Minder???
 
Hey Brian,
Sorry to hear about your battery issues. I keep mine on charge constantly, more out of habit than anything. Although, from posts in this thread it is not needed.

When I was shopping around for a charger I talked to the guys at BatteryMinder and they recommended the 2012-AGM charger. My concern was being able to leave the battery on the charger for months at a time, as I am often deployed and did not want to worry about damaging my battery while I was gone. The charger can be left on indefinitely without harm to the battery. Two years now without an issue.

You may want to give them a call, as they are familiar with AGM batteries and were extremely helpful. They may have some insight on your setup.

Dan

Bob Axsom 05-18-2013 09:35 PM

Could it be?
 
Batteries are a black art and the same manufacturer, part number, shape, size, and weight doesn't mean they are all the same. The one you have trouble with is probably just a bad battery because of some variation in the process or the materials. I worked at a battery company for seven months where many different kinds of batteries were manufactured. Surprise, apparently identical bateries are not all equal and sometimes you are going to get a dog that slipped through quality testing installed in your airplane. RTV (return to vendor) and hope for a failure analysis (good luck with that) and buy a replacement. Based on the strong support here the next one will probably be better.

Bob Axsom

N96TJ 05-18-2013 10:53 PM

Re: What killed this PC680?
 
I had a similar experience with the PC680 and the Odyssey Ultimizer 6amp charger. Now that I know what happened I think any SLA battery would do about the same thing.

My root problem was low voltage output from the (internally regulated) alternator. I typically saw 13.8v in flight. While this should be just enough to charge the battery, it is not enough to do the absorption phase of the charge. I thought this would be mitigated by using the Ultimizer charger between flights.

Long story here but what I eventually learned is that when you connect the 6amp Ultimizer to a "charged" battery it never instigates the absorption charge sequence. It goes straight to the "float charge" mode. After two years of this the battery gets sulfated (or something) and appears to lose most of its capacity.

For me the fix was to switch to an externally regulated alternator and to set the charge voltage at 14.8v measured at the battery terminals. I no longer use a charger between flights. I was also able to rejuvenate my PC680 with the process mentioned elsewhere in this thread, and get several more useful years from that battery.

The alternator voltage you are reporting is higher that mine was, but it sure sounds like the same problem I had.

Tom Johnson

Brantel 05-19-2013 05:55 AM

Quote:

Originally Posted by Bob Axsom (Post 772048)
Batteries are a black art and the same manufacturer, part number, shape, size, and weight doesn't mean they are all the same. The one you have trouble with is probably just a bad battery because of some variation in the process or the materials. I worked at a battery company for seven months where many different kinds of batteries were manufactured. Surprise, apparently identical bateries are not all equal and sometimes you are going to get a dog that slipped through quality testing installed in your airplane. RTV (return to vendor) and hope for a failure analysis (good luck with that) and buy a replacement. Based on the strong support here the next one will probably be better.

Bob Axsom

Bob,

You very well may be correct.

Brantel 05-22-2013 07:24 AM

Got the new battery in and decided to do some testing on the charger I have.

Here is what I use:



It is the smallest one that the Odyssey folks recommend for the PC680.

Here is a blurb from the battery manual that seems to be critical for long life. The Odyssey folks mention this many times in all of their literature so they must think it is important:



Here is the table they are referring to:



So 0.4 x 16 = 6.4 amps minimum...remember the recommended charger is only rated at 6 amps max.

Here is another chart they provide to let the end user know how the battery should be charged. Here we see the same requirement circled in Red for minimum charge current:



Note: The Odyssey Ultimizer chargers are suppose to comply with these recommendations....

Last evening I fired up the panel and accessories and sucked about 25 amps out of the battery for at least 20 minutes. Obviously the new battery has good capacity and I did not drain it below 12V during this test. The old one would have not ran more than a minute before dropping to < 9v.

So now I have a new battery @ about 40% state of charge to test the charger with according to this chart from the manual:



I connected the charger and started the charge cycle with a precision current meter inline and the 6 amp Ultimizer charger could only produce about 2.95 amps of current. This is less than half of the recommended minimum bulk charge current required by the owners manual of the battery. I found out later after talking to the Odyssey folks that this is normal depending on how deeply the battery was discharged.

I also found out that discharging at a high rate can lead to a false state of charge indication. They recommend that discharge test be conducted at a maximum 5 hour rate per this chart:



and to take it down to ~10V OCV to fully discharge the battery for testing.


Just an FYI....Not sure why but Odyssey has lowered the CCA rating of the PC680 battery. They went from 220 CCA's to 170 CCA's. Here is one of the original spec sheets:



Compare this Red star with the Blue one above...the Blue star rating is what is on the new battery. The older battery (6 months old) has the Red star rating. The PHCA, HCA and MCA ratings are also lower on the new battery and literature!

rv7boy 05-22-2013 02:25 PM

Excellent and informative post, Brian. The information in your post #39 should be a good reference post for future questions about the PC680 battery.


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