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

Walt 05-22-2013 06:02 PM

Measuring the amperage supplied from a battery charger "may" be a bit more complex than simply using a DC amp meter as there is usually a large AC component involved in DC battery chargers. So perhaps this is a Peak current figure rather than an average current figure which the meter is measuring.

BobTurner 05-22-2013 06:57 PM

I think the charger is operating properly. Was it at 14.7 volts?
The charging curve you show is for a completely discharged battery. Since yours is only about half discharged, the charger sensed this and started in the middle of the 8 hour cycle - at 3 amps, half of 6.

Nevertheless, you might ask Odyssee why they recommend a 6 amp charger when they say a minimum of 6.4 amps is needed.

Brantel 05-22-2013 08:02 PM

Quote:

Originally Posted by BobTurner (Post 773149)
I think the charger is operating properly. Was it at 14.7 volts?
The charging curve you show is for a completely discharged battery. Since yours is only about half discharged, the charger sensed this and started in the middle of the 8 hour cycle - at 3 amps, half of 6.

Nevertheless, you might ask Odyssee why they recommend a 6 amp charger when they say a minimum of 6.4 amps is needed.

Nope,

The OCV at the start of the charge was ~12.1 volts.

Take another look at the charging curve. It is declaring the need for constant current of .4C10min which is 6.4 amps up to 4.7v. They call this the BULK CHARGE PHASE. Then the charger switches to the ABSORPTION PHASE.

The charger has LED's to tell you where it is in the cycle. I was also monitoring the battery voltage with a high quality volt meter. It was definitely in the BULK CHARGE PHASE....

I still say this charger is too small for the job or not working correctly. I am almost certain this is what killed my battery since I used the charger a bunch during my panel upgrade and during testing. The manual and technical literature warns many times to never perform the BULK CHARGE PHASE at less than .4C10min or it will damage the battery. Mine died in 6 months (with 3 of those months being panel upgrades and tests) so this seems like a good indication that something is wrong with the picture.

Brantel 05-22-2013 08:08 PM

Quote:

Originally Posted by Walt (Post 773138)
Measuring the amperage supplied from a battery charger "may" be a bit more complex than simply using a DC amp meter as there is usually a large AC component involved in DC battery chargers. So perhaps this is a Peak current figure rather than an average current figure which the meter is measuring.

Very true Walt. I imagine that the makers of this charger are just like the makers of cheap audio power amps. Most of them claim high power but it is in P2P instead of the real RMS rating. I imagine the same goes for this charger. However, the battery folks are clear that they must be charged with .4C10min amps and since the RMS current is what does the work, that's what we need to be seeing on the meter. I am using a true RMS meter.

I happen to have a digital O'scope I can put on the charger output to see what the true output is. It will be interesting to know for several reasons. I will post the results when I get a chance to test it.

Brantel 05-24-2013 07:22 AM

Quote:

Originally Posted by Brantel (Post 773165)
Very true Walt. I imagine that the makers of this charger are just like the makers of cheap audio power amps. Most of them claim high power but it is in P2P instead of the real RMS rating. I imagine the same goes for this charger. However, the battery folks are clear that they must be charged with .4C10min amps and since the RMS current is what does the work, that's what we need to be seeing on the meter. I am using a true RMS meter.

I happen to have a digital O'scope I can put on the charger output to see what the true output is. It will be interesting to know for several reasons. I will post the results when I get a chance to test it.

Quote:

Originally Posted by Walt (Post 773138)
Measuring the amperage supplied from a battery charger "may" be a bit more complex than simply using a DC amp meter as there is usually a large AC component involved in DC battery chargers. So perhaps this is a Peak current figure rather than an average current figure which the meter is measuring.

Walt,

I measured the output of the Ultimizer charger last night with a scope while performing some more test and it has a very stable DC output. Very little AC component and what is there is at a very high frequency. I opened the charger up and it has a switching type power supply not just a big transformer and a rectifier.

Brantel 05-24-2013 07:43 AM

I have an update:

I have been in contact with the folks at the Odyssey battery headquarters. They are very helpful folks. They have instructed batterymart.com to give me credit under warranty for the 6 month old battery.

They tell me that the primary reason for an Odyssey battery to have the symptoms that my 6 month old and 3 year old battery had was sulfation.

They also gave me a special procedure to follow to desulfate the battery if it can be saved. The prodedure is to discharge the battery at the 5hr rate maximum down to ~10v OCV. For the PC680, that is 3 amps max. And then to use the 6 amp Ultimizer to recharge the battery till it goes into trickle mode and to do this as many times as needed as long as the discharge time keeps taking longer than the last cycle.

I found my oldest battery (never threw it out) with a date code of July 09. It was replaced back in the fall of last year due to the same symptoms. I wanted to see if the special procedure could bring this thing back to life. So far I have completed 3 cycles on the battery. The first lasted about 5 minutes, the second almost 2 hours, and the third was well over 4 hours and tonight I plan to try another one. The bottom line is that this procedure seems to be working to revive this battery.

The only thing the support from Odyssey cannot explain is why these batteries are getting sulfated so quickly or at all in this application and with the continuous use of the Ultimizer charger.

I am a bunch more educated about these batteries now and I think the new one is going to last a long time even if I have to perform regular desulfating procedures on it. I still do not plan to keep it on the Ultimizer continuously.

larrynew 05-24-2013 08:28 AM

Quote:

Originally Posted by Brantel (Post 773537)
The prodedure is to discharge the battery at the 5hr rate maximum down to ~10v OCV. For the PC680, that is 3 amps max.

Brian - how do you do that? If it's as simple as leaving the master on overnight, I already know how. :o

Mike S 05-24-2013 09:45 AM

Quote:

Originally Posted by larrynew (Post 773559)
Brian - how do you do that? If it's as simple as leaving the master on overnight, I already know how. :o

You need to work it out with the formula for wattage, Watts=Volts x Amps.

A load of 36 watts should do just fine----------although as the voltage drops the amperage will go up slightly. I suspect probably a 12v light bulb rated at 30--35 W should do the job.

Brantel 05-24-2013 11:01 AM

Quote:

Originally Posted by larrynew (Post 773559)
Brian - how do you do that? If it's as simple as leaving the master on overnight, I already know how. :o

In the aircraft, I just turn stuff on till I get the current I want as measured by the VP-X Pro.

Out of the aircraft, I have an old car headlamp that I use for that purpose. Works great.

Sam Buchanan 05-24-2013 05:27 PM

Quote:

Originally Posted by Brantel (Post 773609)
In the aircraft, I just turn stuff on till I get the current I want as measured by the VP-X Pro.

Out of the aircraft, I have an old car headlamp that I use for that purpose. Works great.

Sure does sound complicated....why not just fly the battery?

Do the owners of the thousands of motorcycles and watercraft that use this battery obsess over this stuff? ;)


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