Lighting on PWM load output

Julian-Indaiatuba · Dec 16, 2020

Hi, newbie here I´m afraid.
I have set up a small off grid system at home, just to deal with some power outages we have here, so we can keep the TV, Internet and fans running.
I have an Epever 60A charge controller, hooked up to my solar panels, and six 115 Amp batteries connected in series and parallel for a 24V system.
The charge controller has a DC load output to which I have connected seven 24V-7W LED lights, which light up when it gets dark and turn off at midnight.
I was told by a friend that so many light could harm the charge controller. I´d never heard that before, so I thought I´d ask here.
Any thoughts would be more than welcome.
Thank you.

snoobler · Dec 16, 2020

7 * 7W = 49W
49W/24V = 2.04A

Your friend likely read something somewhere and misinterpreted it or just likes messing with your head.

Your charge controller load output has a current rating. If you don't exceed it, you're good. If it doesn't have one, I would assume it's the same as the charge rating, i.e., 60A.

Julian-Indaiatuba · Dec 16, 2020

snoobler said:
7 * 7W = 49W
49W/24V = 2.04A

Your friend likely read something somewhere and misinterpreted it or just likes messing with your head.

Your charge controller load output has a current rating. If you don't exceed it, you're good.

Thank you very much for your quick reply.
Unfortunately I can´t find anything in the extremely thin manual about the output current rating.
I presume just over 2A won´t be much of a problem then?
Thank again!

snoobler · Dec 16, 2020

I revised my post after you quoted me. In that case, I would assume 60A. Using a thin wire gauge would impose a lower current limit.

I can't imagine 2A being an issue unless you used absurdly thin wire.

Factory400 · Dec 16, 2020

PWM units can and will conduct EMI through the cables that can interfere with other connected electronics. I deal with this kind of thing in the design lab all the time.

In real life, it is exceedingly unlikely the PWM would get passed the ability for the charge controller to reject this noise. Even if it did, it is double exceedingly unlikely to have a significant impact on it's operation - much less damage.

With ultra-cheap lights and ultra-cheap charge controllers that do not conform to any standards - it is technically possible.

It is worth noting the the internal controls of the charge controller are extremely sensistive - working at micro-volt level signals. Microvolts are like feathers in a tornado and it is up to the manufacturer to isolate those signals from the external electrical tornados.

Julian-Indaiatuba · Dec 16, 2020

snoobler said:
I revised my post after you quoted me. In that case, I would assume 60A. Using a thin wire gauge would impose a lower current limit.

I can't imagine 2A being an issue unless you used absurdly thin wire.

Again, thanks for your reply. I used normal wire that would normally be used for wiring in homes.
it doesn´t get warm or anything, so I presume it´s OK.

Julian-Indaiatuba · Dec 16, 2020

Factory400 said:
PWM units can and will conduct EMI through the cables that can interfere with other connected electronics. I deal with this kind of thing in the design lab all the time.

In real life, it is exceedingly unlikely the PWM would get passed the ability for the charge controller to reject this noise. Even if it did, it is double exceedingly unlikely to have a significant impact on it's operation - much less damage.

With ultra-cheap lights and ultra-cheap charge controllers that do not conform to any standards - it is technically possible.

It is worth noting the the internal controls of the charge controller are extremely sensistive - working at micro-volt level signals. Microvolts are like feathers in a tornado and it is up to the manufacturer to isolate those signals from the external electrical tornados.

Thank you for your answer. I´m afraid my knowledge is lacking a bit as to understand everything you wrote.
My PWM definitely isn´t the best, but also not the worst, so I presume it has the basic standards and protections.
My lights are good quality ones, and I always try and wire things one or two gauges more than is needed. Just as an extra safety.

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