Can i boost my solar ?

[Rufus2502]

I live off grid, have 500w of solar panels laid horizontal on my boats roof, naturally its not producing anything this time of year, my backup 5 kw Diesel generator is waiting for repair, i use a 30 amp digital charger with it but all I have working is a small 400 w petrol generator ( with AVR ) and it will not power that charger. However I have a 12 v DC -9 amp power supply sitting on a dusty shelf so I'm thinking can I connect that into my MPPT solar charge controller as a temporary charger ?



Can it be done with the solar panels still connected ?



Ower supply Amazon.com: Buying Choices: Symbol Technologies 50-14001-004, SYM04-1 Power Supply T96825 - https://www.amazon.com/gp/offer-listing/B06XHQ7Z87/ref=dp_olp_0?ie=UTF8&condition=all

 

[Zerax]

Assuming that your battery bank are at a nominal 12 V.... you'll need more than 12V to charge... but it may be that your 12 power supply will output more than 12V (13.8 is common). Also... on a boat, you'd normally have a 'charge bus bar' where all your various charging sources are connected to... that's where you should apply voltage... not to your MPPT controllers. Depending on the SOC of your batteries and their size... they may well draw more than the 9A available... and blow fuses... not an ideal solution !

 

[James]

30A x 12v is 360w
30A x 13.8v is 414w

these are nominal figures and do not take any losses into account.

assuming you have tried charging them all whilst linked together and the generator trips or bogs down,

try disconnecting one battery from the bank and connecting that to the charger on its own.
if that will charge then as it approaches 80% charge and the current starts to drop, connect the next battery in the bank and so on....
it might get you through.

as noted above, you are close to the max of generator output so just a small reduction in current might make it work, from there, you can start adding more batteries as the load decreases.
I am assuming that all batteries are near to 0% charged?