We have an MPPT 100/30
at night it reports a zero or near zero battery voltage. This cannot be right as we still have power. During the day this reading is 13 to 14 volts.
Any idea what is happening?
asked
Battery voltage readings
The MPPT has no connection to the battery.
Check the wiring and the fuses.
I got exactly same issue on MPPT 100/10 module.
Replace the fuse and the batter voltage comes back :).
Thanks
Thanks Matthias. I will try to check those things. Where would the fuse be?
also I don’t understand where the reading of 13 volts during the day is coming from?
I don't know where you have installed the fuse. Normally the fuse should be as close as possible to the battery. Just follow the wires from the MPPT to the battery.
Durning the day the MPPT try to charge the battery and is producing the voltage.
Thanks Matthias. I have followed the wires and cannot see a fuse. I have tightened the battery connections and unclicked and clicked the cable joins.
Might the MPPT unit be defective? I have tried presets 1 and 2 and reset to defaults but still get the zero readings at night.
Can you measure the voltage at the MPPT and the battery with a multi-meter?
Hi Matthias. Unfortunately we don't have a multimeter with us.
Interestingly we disconnected the panels and then the batteries at the MPPT 100/30. We then connected just the batteries and the MPPT did not power up, nor is it possible to connect to it via Bluetooth.
As there is apparently no fuse between the batteries and the MPPT, might there be a fuse inside the MPPT which has blown? Is this replaceable?
These issues might have coincided with the first time we plugged in a shoreline supply since the MPPT was fitted. Could that have caused it to fuse?
Any further suggestions very gratefully received.
Thanks
Richard
There's more than likely an open or reversed polarity somewhere in the wiring between the MPPT and the battery. With sun on the panel, look at the battery CURRENT. If it's zero the positive or negative connection to the battery is open somewhere. You mentioned disconnecting and reconnecting the battery connections so that might be a place to start. You'll need a multimeter (available almost everywhere) to trace voltages and continuity.
If the battery polarity is or has been reversed, a non-replaceable internal fuse blows. You'll need to send the MPPT in for service.
The only way I can see shore power causing an MPPT failure would be extreme high battery voltage or possibly reversed polarity. But with a good battery it's unlikely a reverse voltage at the battery terminals could have been created by a charger.
There needs to be a fuse close to the battery to avoid fire should the wires to the MPPT short.
Not sure if there is an internal fuse but if there is one then it is not replaceable by the end user.
Can you try to connect something else to the battery wires of the MPPT (a 12V light bulb maybe) so you can check if there is 12V or not.
If there is 12V and the MPPT won't turn on there is an internal problem and you have to contact your dealer.
(a multi meter would be good to check the polarity)
Thanks both.
I was thinking that if the batteries are not connected the MPPT should be dead at night-time. From memory I do not think this is the case?
