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Capacity check of pc680

PIN 37

Well Known Member
Can anyone tell me how to capacity check a PC680 battery? I have used a Concorde BC5000 battery cap checker but it gives results which are unlikely to be accurate since all the batteries I have tested using 16AH's as the setting show around 40% capacity and only 68% on a brand new battery.
Any ideas?
 
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Not enough data. Especially for those if us who don't have the Concorde cap checker.

You need to look at the load applied by the Concorde, then compare your results to the discharge curves on the PC680 spec sheet.

Remember, a 16AH SLA battery only has 16 AH of capacity when discharged at the '20 hour' rate of discharge (meaning that the 16 AH of capacity is spread over 20 hours of discharge).

Charlie
 
CBA IV

I used a CBA 4 from West Mountain Radio and a Win 7 laptop to check mine. You can set the test up however you want to do it. I chose a discharge rate that matches what I would be pulling from the battery with the alternator dead and everything shut down that I didn't need. In my case, that's about 4.5 amps. I ran the test down to 10.5 volts which is conservative considering that my electronic ignition claims to run down to 5 volts. It ran for 2.75 hours and delivered just over 12 ah. At a higher amp draw, you can probably count on fewer amp hours delivered.

Ed Holyoke


Can anyone tell me how to capacity check a PC680 battery? I have used a Concorde BC5000 battery cap checker but it gives results which are unlikely to be accurate since all the batteries I have tested using 16AH's as the setting show around 40% capacity and only 68% on a brad new battery.
Any ideas?
 
I used a CBA 4 from West Mountain Radio and a Win 7 laptop to check mine. You can set the test up however you want to do it. I chose a discharge rate that matches what I would be pulling from the battery with the alternator dead and everything shut down that I didn't need. In my case, that's about 4.5 amps. I ran the test down to 10.5 volts which is conservative considering that my electronic ignition claims to run down to 5 volts. It ran for 2.75 hours and delivered just over 12 ah. At a higher amp draw, you can probably count on fewer amp hours delivered.

Ed Holyoke

Most lead-based batteries have an inverse relationship between amp draw and ah capacity. The higher the draw the lower the ah capacity. This is why manufacturer list a 20 hour ah rating; It looks better. Good companies will also list a 1 hour ah rating to help the consumer better understand the range of capacity in different conditions.

Larry
 
Simple, and cheap.

Using the data sheet of the previous post -

Buy a 12 volt 50 watt bulb such as this one at Home Depot or your favorite hardware store -

http://www.homedepot.com/p/50-Watt-...oor-Dimmable-Floodlight-Bulb-419333/203001458

Use clip leads to connect the bulb to the charged battery and measure the battery voltage. Note the start time.

Wait until the battery voltage falls to 10 volts and note the time again.

A up-to-spec battery will last 3.5 hours per the data sheet. A shorter time is a loss of capacity.
 
When I was doing a lot of glider flying, it was important each season to start out with the firm knowledge of what the state of your ship's batteries were.

I found a test scheme by a fellow glider pilot out of Chicago to be cheap, accurate and effective and see no reason why it wouldn't work as easily on the PC-680 as it did the ones used in our gliders.

Two ways of getting to the test protocol, you can go here:

http://aviation.derosaweb.net

And scroll about 1/2 down the page to "Testing Batteries" or a direct link to the XL spreadsheet is found here:

http://aviation.derosaweb.net/batterytest/Battery_Testing_Template.xls
 
Thanks for you input folks, as usual a most helpful group. It would appear that our problem was that we were using 16ah as our base of testing (printed on the label of the battery ) instead of 12.3ah as on the graph of the 680 battery ( from Odyssey ) on one of the links suggested. Interestingly on another Odyssey publication ( googled) the rating for a PC680 battery for aviation use is quoted at 12.7ah, hmmm, a little confusing but we will test using both figures and see what we get. I wonder why the label on the top of the battery says 16ah :confused:
 
The AH rating (which is basically the total energy in the battery; not power) is at a discharge rate that runs the battery down over 20 hours. Higher discharge rates will result in being able to extract less total energy from the battery. Confusing, but that's the way it is. Look at the PC680 discharge curves, in the document linked earlier by another poster. 1st link I found that describes relationships of the various ratings:

https://www.batterystuff.com/kb/articles/battery-articles/battery-basics.html#4

Charlie
 
. I wonder why the label on the top of the battery says 16ah :confused:

Because its an industry standard and used for comparative purposes. Generally speaking, a 16 ah battery will deliver more energy in a similar current draw than a 14 ah battery. It's like listing a car's MPG. MPG is infinitely variable, but by comparing all cars against a common standard testing methodology, you can draw valuable comparison across different cars.

As you have learned, its not really meant to help you plan your available energy.

Larry
 
Time to Replace my PC680?

My PC680 let me down twice in the last two days. Engine usually starts fine with a couple blades. Now if it dosen't start after a couple blades the battery seems to give up. I charge it and then I get a to blade start again.

Info:
RV-8 with dual PMags, CS, rear mounted battery.
Skytec 149-NL starter.
Vans supplied starter solenoid.
Battery is 14 yr old, was used during construction and run down a least a half dozen times. has been good the last year flying.
Odyssey 12V 6a charger. Never use for trickle charging.
Voltage on D10 still shows 11.9 to 12v after start failure.
Local auto parts store load test: CCA 193a (170 rated). Voltage under load drops to 10.5V.

I have read thru a bunch of posts and will do more tonight. Just wondered if anyone can say if I need to replace the battery? I am on my way to ACS Canada neighbourhood tomorrow so it would be a good time to pick one up. Annual is due end of Feb. 70 Hr Tach Time so far. Please forgive me if the answer has already been posted.
 
My PC680 let me down twice in the last two days.

Battery is 14 yr old, was used during construction and run down a least a half dozen times.

Methinks you should count your blessings---------14 years might be a record.
 
I'd have to agree with Mike. But poor connections anywhere in the start circuit can lead to some seemingly inconsistent symptoms. You don't want to have the same problems after battery replacement.

Measure voltage *on the battery posts* (not the terminal ends, screws, etc) while it's failing to start the engine. If the voltage there is anything above the 8.5-9 volt range, you probably have a high resistance issue somewhere in the system. Even if the voltage is dropping lower than that, you could still have a high resistance issue that's limiting the charging system's ability to get adequate voltage/current into the battery. If it's not getting fully charged while flying, one start attempt might be all you get before capacity drops too low to spin the starter.

But you still should replace that battery....

Charlie
 
Thanks guys. I guess the PC680 doesn?t owe me much so I?ll replace it - lawn tractor needs a new battery anyway. I?ll also go thru the whole system at annual and make sure nothing else is causing a problem.
 
14 years - yeah, you made it about 9 years longer than you have any right to expect.
 
14 years - yeah, you made it about 9 years longer than you have any right to expect.

And been discharged fully and recharged a few times? Wow!

I just replace mine after about 2.5-3 years when I notice a bit of sluggishness on starts. It's one of the cheapest things on the plane to replace at, what, a hundred bucks? Not worth messing with.
 
And been discharged fully and recharged a few times? Wow!

I just replace mine after about 2.5-3 years when I notice a bit of sluggishness on starts. It's one of the cheapest things on the plane to replace at, what, a hundred bucks? Not worth messing with.

I don't know much about batteries, but I've been amazed at the 680's ability to recover after being fully discharged. Those things are tough.
 
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