The diode in series fools the charger, because the charger voltage sensing is tied to the output/charge cable at the charger.
When the he charger isn't charging
the diode is blocking, but as soon as the current
flows, and the diode is conducting, a reverse voltage at a lower then actual bat voltage is available from the bat.
So now the charger is in flat out mode exceeding its KVA, this will either lead to a burnt out charger or a fire. The diode will not live long either.
Originally Posted by goboatingnow
Simply putting a diode in series with the output of a battery charger merely causes a voltage drop it can never increase the voltage.
To increase the voltage the charger must have a way if sensing battery voltage at the battery terminals. That's find with a seperate sense line.
You can place the diode in that sense line , cathode towards the charger to fool the sense line sensing and hence raise the charger output.
Perhaps that's what you meant