Just a quick update on the Arlec Garden Spotlight ( SKU: LVS020). After removing the solar panel from the spotlight, I disconnected the wires from the main YX8018 board ( with wire cutters ;-) ) . This spotlight also uses the basic driver circuit that many of the cheaper garden lights use. Compared to them, the battery is a bit bigger, and so is the LED, but the general charging method and LED powering is the same. 

The sun was out, so some quick tests. The 75x60mm solar cell stats are:

Open Circuit voltage: 6.8V

Short circuit current: 94mA

With 11 cells in series, that breaks down around .62V per cell open circuit. According to Wikipedia, the maximum power point is approx 75-80% of the open circuit voltage. The panel will be around 5.44v based on this approximation.

In terms of chargers, I bought a few to try:

CN3065 Based: https://www.aliexpress.com/item/32918308318.html

CN3971 Based: https://www.aliexpress.com/item/4000309853682.html

and https://www.aliexpress.com/item/32978847396.html

MCP73871 Based: https://www.aliexpress.com/item/32779475903.html

TP4056 Based: https://www.aliexpress.com/item/1005001621934354.html

A nice variety!! Some are linear and some are switch-mode. They all should work with the solar panel in the spotlight, although some have preset MPPT points, so some mods are required if 5.4V is the max power point. The CN3971 boards come default set to 6V, or selectable 6/9/12/18v, but the chip itself is rated from 4.5V and up to 28V.

One problem with the battery in the Solar light is that it doesn't have any protection. If it's discharged too much, the battery will stop working and not be able to be charged any more. Only the TP4056-based charger has built-in protection. Fortunately, one of my previous purchases from Aliexpress was a number of small pack-protection PCBs, so I can easily wire one of these in and utilise one of the other charger modules.

That's it for now. I'll update more once I've done some wiring!!