question

stoduk avatar image
stoduk asked

How to change MPPT from 12V to 24V

We've got a 12v system currently, with one 12V battery, an MPPT 75/15 charge controller and a Phoenix 12/500 inverter. We want to increase the storage capacity by adding a second battery - and plan to put the two batteries in series to make it 24V.

The inverter will need to be replaced, as it is 12V only, but the charge controller seems happy being 12V or 24V.

However, the manual for the charge controller suggests that the voltage setting is fixed the first time the unit is powered on :(. We don't have either a USB or bluetooth cable to program the controller.


Questions:

- is there a way to reset the charge controller so we can connect it to 24V and it will redo the initial scan?


- if not, does anyone know any friendly dealer or similar near Hertfordshire who would be able to lend us the cable (or let us take the charge controller to them to reprogram)?


TIA,

Anthony

MPPT Controllers
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3 Answers
Mike Dorsett avatar image
Mike Dorsett answered ·

This should be automatic according to the instructions for an older MPPT 100/50.

"When the 24V battery is reconnected later in the day the system voltage is restored to 24V after 10 seconds if the battery voltage exceeds 17.5V.

Also: the controller can be reset by shorting the output (NOT with a battery connected!) and applying a voltage >7V to the input (with a small power supply or small solar panel).

Elsewise, this can be set over the VE-direct connection.

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stoduk avatar image stoduk commented ·

Thanks - the manual for 75/15 claims this: "The controller will automatically adjust itself to a 12V or a 24V system one time only. If a different system voltage is required at a later stage, it must be changed manually, for example with the Bluetooth app, see section 1.8."

I guess I was hoping somebody had figured out a way to do the equivalent of a factory reset so this autodetection will be repeated. I suspect I'm being blindly optimistic! Having to pay £30 for a glorified USB/TTL cable is a pain when we have such a limited budget, but it might be unavoidable.

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ddickov avatar image
ddickov answered ·

If you have a phone and the Bluetooth app you can change the system voltage with victron connect on android or Apple it won’t find a Bluetooth connection on the laptop with victron for windows hope this helps a bit, mppt voltage is selectable in the app

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ddickov avatar image
ddickov answered ·

Bluetooth adaptor should be cheaper to buy thanks david

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