No. This mod ONLY stops the PJ from turning the power system off when ever it gets nearly charged from an external pwm or mppt controller charging the batteries.
It does not have any effect on the charging of the batteries by whatever method you choose.... and it will render the internal charging by the pj itself as dumb, not intelligent.
If you use the PJ as a charger, this is not for you. ( and it would not have caused any trouble anyway without the mod)
If you are charging from some other source ( what I thought you did ) it will have no effect on charging, but will stop the annoying OV shut down.... I note that the latest board I bought has no bad effects at this time, and requires no fix... good to see.
If you explain exactly what and how your charging with, we can help.
From your comments thus far, I suspect it is using a grid connect inverter, reverse charging.
This brings it's own set of problems to deal with, and the PJ has no part in this.... ie you don't want the PJ to turn off... just to turn off the grid tie inverter.
So the zenner stops the PJ from turning off under any circumstances... what we need for uninterrupted power, but we must control the over voltage some other way.
If using a grid tie, then you need a voltage switch to shut the grid tie off when V= whatever you are comfortable with... 29v@7 amps perhaps.... but you can't expect the PJ to do this for you.... even a windmill style dump load wold be fine.
As a generality, the grid tie will shut off from over voltage AC when the batteries can take no more, and shut themselves down. For flooded cells this can work ok. This is because when the batteries can take no more heavy current, the power from the grid tie must go somewhere..... so it pushes up the AC voltage... and when it gets to ( whatever your design rules say), it will shut off... primitive but works with properly programmed and islanded inverters. The european ones fail this regularly, so are probably going to cause problems, the chinese ones seem to follow the rules more carefully.. SMA will cause all sorts of problems in this way..
So your best to make up your own OV switch, that interrupts the grid tie by battery voltage relay ( op amp and a relay).... or a very large dump load.
Before it sounds like you were relying on the pj turning off.... which is a no no.... if your relying on it to drive the house at all.... so you don't want to be doing it that way .
If you don't care if it turns off, then remove the zenner.... then the PJ will act as a voltage switch... but it will be useless as a steady load provider.... always something.... but it is not PJ's problem really, and needs another solution from the start.
It is interesting that the PJ could still see the 31v as too high, but now does not act on that information... interesting... maybe you could use that as the voltage switch signal?
... ie any time it beeps, shut down grid tie relay.... ...... not so silly now I think about it,,,,
........oztules