Classic Over Voltage Set Point

[zoneblue]

Guys you may recall that i also have confirmed the same rare classic output reading anomaly previously, if you need me to to find the threads holler. I dont recall seeing it occur for a while but ive probably not been so studious.

I always noticed it as a output current discrepancy of a couple amps, that came then cleared next day, never thought to study the voltage implications of it though.

Edit:
heres the post, graph shows the phenomenon clear as day
http://kb1uas.com/mnsforum/index.php?topic=1959.msg18186#msg18186

[Wxboy]

As a refresher this happened late in the day when the Classic was outputting more power than it was reporting.  Eventually the batteries would be in absorb taking only about 70 watts or less with no load.  The controller was outputting the 70 watts or less but showing zero on the screen.  This condition would send the batteries up and up and even the max. voltage set point would not stop it.  2 of my batteries started bubbling internally and then gassed and now their capacity is much lower than the other 6 batteries and they can't be used in the bank anymore.

So how did you establish there was power , the 70watts, going to the bank?
Was that from the WBjr screen which shows actual battery current or maybe a DC clamp ammeter on the main battery cable?
The zero power just shows there was no power being provided by the Classic BUT if the WBjr shows amps flowing into the battery then something else is likely providing that power  OR  if the WBjr is connected wrong way around then the 70watts could be the base (tare or minimum) load.

dgd

dgd, the power out was confirmed by a clamp meter and the power was coming from the Classic. 

[dgd]

After reading ZB's previous posts on this issue this seems to be an issue, maybe with just some Classics 

70 watts  output into a fully charged bank after Absorb completed for 48v battery bank, thats about 1.25Amps @ 56v
I'm surprised that would be sufficent to take an AGM bank  voltage high enough to cause battery destruction due to gassing/venting. Perhaps so if the bank capacity was quite small hence allowing the bank voltage to rise fairly rapidly
And that would only be for a few hours while PVs were illuminated each day then just the tare load of the Classic overnight (and any other connected loads) would soon reduce the bank voltage.

I checked through 6months+ of 10 minute logs I have for two RE systems with Classic 150s, 24v and 48v
AGM banks and thankfully found no real evidence of this behaviour. Or if there was then its likely insignificant and lost in the Amps reported for Classic output, WBjr battery current and tare/running current used by loads.

dgd

[zoneblue]

Its actually quite hard to spot. What you are looking for is when the positive WbJr current exceeds the classic output current. In order for that to stand out you need either no loads or fixed loads. Or if it happens during bulk on  a nice day. But i only ever saw that once, usually it was in abosrb that it does it. Personally ive only noticed it a half dozen times.

[boB]

Its actually quite hard to spot. What you are looking for is when the positive WbJr current exceeds the classic output current. In order for that to stand out you need either no loads or fixed loads. Or if it happens during bulk on  a nice day. But i only ever saw that once, usually it was in abosrb that it does it. Personally ive only noticed it a half dozen times.

Was there possibly a semi-heavy DC load that suddenly turned off during Absorb ?

boB

[Wxboy]

[/quote]

Was there possibly a semi-heavy DC load that suddenly turned off during Absorb ?

boB
[/quote]

Not in my case.