by Bob Hammond » Mon Aug 24, 2020 12:25 pm
Some weeks ago, I theorized that a computer laptop charger could be used to power my trailer's devices and charge the battery on cloudy days when shorepower is available. Most people seemed to think that idea was 'out there'.
Well, I got around to connecting up the laptop charger to the PWM solar controller today, in place of the solar panel.
>>>>A word of caution here:
My solar controller is a PWM 'Moohoo' 30A brand. I can't say that it will work with other PWM chargers or with MPPT chargers. I was thinking that if I destroyed the charger or controller, that the charger would be no loss, and I was planning to upgrade the controller to a MPPT type anyway.
You're on your own about that.<<<<<
It works.
1. The no-load output voltage/amps of the laptop charger is 19.1 VDC (@ 3.4A), which is the same voltage as my 100W solar panel in full sunlight.
2. After connecting the charger in place of the solar panel, the solar controller reads the voltage from the laptop charger at 12.7V DC.
3. I turned on all the power consuming devices (lights, fans, USB) in the trailer with the exception of the CPAP machine, drawing about 23 watts.
4. The solar controller held the voltage at ~12.4VDC, supplying about 2.3A from the laptop charger, but not sending any current to the trailer battery (it's charged at ~13.3V).
5. At the connection of the laptop charger to the solar controller, the voltage oscillated between 12.9V and 11.4V
Since the trailer battery is charged at ~13.3V, the solar controller is not charging the trailer battery, but it is supplying current at 12.7V to all of devices that are drawing power. The next test, is to draw the trailer battery down to 12-12.4V, and then see if the laptop charger can charge the trailer battery through the solar controller.
So for today, I'll call this experiment a success. Instead of taking along a heavy/bulky full-sized auto battery charger in case of a cloudy day (and where shore power is available), I can charge the trailer battery or operate the trailers electrical accessories from the laptop charger. During times when the trailer is unused, I can use the laptop charger to keep the battery topped up.
Last edited by
Bob Hammond on Mon Aug 24, 2020 1:05 pm, edited 3 times in total.
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