I have seen someone's diagram, in this diagram he use a MPPT 75/10 to charge a 12V battery out of 24V bank.
But this 12V system and 24V system have a common negative.
This means means the INPUT and OUTPUT negative from MPPT are shorted.
Is it possible to use the MPPT 75/10 for DC to DC charger in this application?
Because the unanswerd answer from Boekel on febr 10, I send a email to Victron.
Here is the answer.
Hello
The mppt can not work as Dcdc converter with a common ground.
Best regards
Met vriendelijke groet
Johannes Boonstra
Sales Manager
It is possible to use it in that way, but like you say, the input is not isolated from the output - the negative is common.
Be aware that the MPPT will most likely run at full chat until the absorb Voltage is reached. If it's temperature goes too high then it might be a good idea to dial the charge current back a bit.
Thanks for your answer. Input and output don't need to be isolated.
But you are 100% sure, the MPPT will not burnout?
Without seeing the internal diagram I can not prove myself, thats why I ask.
In a normal PV situation, it is possible to put more PV array capacity than the MPPT can charge at. It will only take the amount of input power to reach the maximum output power.
The MPPT will limit the output current to 10A maximum. Like I said it might get hot when running at maximum power for extended periods of time (several hours). If this happens then it would be a good idea to reduce the maximum output power to maybe 8A.
The easiest way to blow up the controller is to put too much PV Voltage. You are putting 24V there from your 24V battery, so it is well below the 75V limit.
Can someone from Victron confirm what MPPT's can function as a DC-DC converter with a common ground? There is another recent topic about the same question.
I tried opening a 150/35 but I don't think I can open it without damaging.
If there is current measuring with a shunt on the negative side, then it is not possible to use as DC-DC converter if there is a common ground between input and output.
@mvader (Victron Energy Staff) / @Guy Stewart (Victron Energy Staff)
