UKC

We have a set of solar powered LED fairy lights around the patio in the garden.

These work by charging a standard NiMH AA battery during daylight and have a light sensor to automatically switch on when it gets dark enough.

Once on, they run for a set amount of time - 6 hours, I think. If the rechargable battery doesn't get enough charge (not enough sun during the day), there is a backup non-rechargable AA in there (which seems to have gone flat - no surprise, given it's winter).

So, to get to the point, I'm wondering about jigging the wiring to add another rechargeable battery in parallel with the first. I think there's room in the case to do that*, but will the solar panel be able to charge both? I think it will in strong sunlight, but not sure it will at this time of year, which sort of defeats the point.

* I could always ditch the backup AA and use that space and just disconnect those wires.

Thoughts?

If you out them in seies it won't charge and in parallel you will get the same amount of charge so (assuming the existing battery never gets full as it is now). Seems to me that the designers have given this some thought and just changing the battery when it warms up will be best.

On the other hand if you are going to hack the system raise your ambitions. Maybe you can get it to emote and thereby bring even more love and happiness to you garden..

Replace the installed rechargeable battery with a less crap one. It will be a crap one, almost guaranteed.
That alone will help. Then upgrade the solar panel so you can fill it.
Then realise you've spent way more than these things are worth, and scratch build your own much better one for not much more money with a TP4056 and LiPO

Wire the system to a really, really small exercise bike with a Dynamo and get those pesky fairies to peddle some power.  

Yes - good point.

Would if I had the time!

The trouble with these things is that they are built to an absolute bare minimum cost. So the NiMh battery will be dirt, it's worthwhile replacing this. But the solar panel will also be specified to just about charge the rubbish battery in summer, so your one decent battery will never get a full charge, let alone two of them. So you need to replace the panel, and by now you are at the point where you might as well build a decent one from scratch.

Edit: I've just noticed that longsufferingrope holder said exactly the same thing this morning. I could have just said +1