Guru
Joined: 11/02/2018
Location: AustraliaPosts: 3318
| Posted: 11:18pm 02 Aug 2024 |
Some controllers will only produce their rated output voltage with a battery attached.
For a simple single charge rate unit the maximum battery voltage is usually about 13.6V to 13.9V. Below 13.5V won't charge it adequately. Above 14V will squeeze more charge in but if maintained for long periods may shorten the life of the battery.
A multi rate charger will vary the voltage depending on it's estimate of the state of charge of the battery.
To simulate a solar panel with a PSU put a high wattage resistor in series.
A suitable value would be the rated open circuit voltage of the intended panel divided by its rated short circuit current.
Rseries = Voc / Isc
Vary the PSU output from 0V to Voc while monitoring the battery voltage.
If you need to change the output voltage trace the circuit from the output to find the feedback voltage divider. Add a high value resistor across the upper leg to reduce the voltage or across the lower leg to increase it.