Hello There !
Sorry for this question that was probably answered many time before but I can’t seem to find them in the search.
For a DIY fence electrifier, I have on hand a 12V/5Amps PWM and a 12V/120W solar panel. Provided that the voltage ranges match, is there any risk at potentially forcing more amps than the controller can handle ? Or is the extra power just lost ? I am charging a 35Ah Gel battery.
Many thanks,
R.
Hard to say for sure without info on the PWM. Likely it will be fine and limit the output to 5 amps. Consult your owners manual to be sure. Or just buy an inexpensive 10 amp controller and get all the advantages of your 120 watt panel. You can probably pick one up for 30.00 or less. A Victron Blue Solar 75/10 MPPT retails for under 50.00. For 10.00 more the Smartsolar MPPT gives you bluetooth.
A 12V gel battery will top out at 14.4 to 14.7V while charging so the “12V” solar panel needs to actually put around 16V to 18V into the pwm to get the job done. There will be a label somewhere on the back of the panel . I suggest to do a check on this before spending anything on other components.
@jamesv is technically correct. But I have never encountered a “12V” panel that actually only puts out 12V. The 12V designation is nominal. It likely puts out at least 18V.
If the Battery is low and the sun comes on full to generate the possible 10A from the module, then this can overheat the 5A PWM. However, if charge conditions are such that the charge current never exceeds 5A you will be fine. Overheating will lead to the PWM switching fet melting, going short and consequential loss of regulation. PWM controllers are not internally limited like the MPPT controllers that Victron makes.
Thanks, yes it’s a victron bluesolar PWM.
Yes sorry was maybe not clear. It does provide the voltage for charging a 12V battey.
That sounds like I should use another controller 
Hello Sean,
Thanks for your answer. About the risk of damaging the controller, it seems like you disagree with Mike higher up, who says the controller could be damaged.
I will check the setting about the battry type though, I did not think about that.
Cheers,
R.
@Raven Just stick to the specification sheet. The 10A model would have been better use of resources and power is never lost as it is ONLY produced to serve a load. If the PWM can only charge at 5A that is all it will produce. It is also important to take into account that LA batteries will typically be charged at between 10-20% of the battery rating as a rough guide so the 5A is probably just fine but check the battery manufacturer’s specifications. https://www.victronenergy.com/upload/documents/Manual-BlueSolar-PWM-Charge-Controller-LCD&USB-12V-24V-30A-&-48V-10A-20A-30A-EN-NL-FR-DE-ES-SE-IT.pdf
