Garden solar PSU simple project

[Davey Dorset]

Hi,
I have some solar light strings in the garden and the power supplies of them seem inadequate and was wondering about making a better solar PSU to run all 3.

The internal storage is 1.2v aa batteries 600mAH. What I'd like is to have one better solar panel charging up a couple of batteries in parallel that controlled the lot simultaneously and I'd like to use ready made circuit bits if poss.

I guess I'll need a solar panel, charging circuit, regulator and light sensor. Anyone able to point me in the right direction of kit to do this please?

Thanks

 

[audioguru]

"the power supplies of them seem inadequate".
Do you mean that the battery charge does not last long enough for the LED to light all night?
Do the solar panels charge the batteries all day in full sunlight?
Are the solar panels pointing at the sun?

I have many solar garden lights. They all use an IC inside that boosts the battery voltage to about 3.5V.
Old ones used small plastic covered solar panels and LDRs that got sunburned in 1 month then worked poorly.
New ones use a larger glass covered solar panel and no LDR.
Old and new ones use extremely poor quality Ni-CAD or Ni-MH batteries that I replaced with Name Brand Ni-MH batteries.

 

[Davey Dorset]

Hi, and thanks for the reply.

Yes - exactly. The lights don't last long and though the panels are next door to each other the performance is very different. They are brand new.

So the first thing I'll do is ditch the batteries for better Ni-MH ones. The existing ones are 600mAh - is putting a slightly higher capacity one in going to cause a problem?

The panels are currently in a flower bed that does get sun, but I'll extend the cables, put them higher and facing due south.

Cheers

 

[audioguru]

An AA Ni-MH battery rated for only 600mAh is mostly full of rice. I bet if you measure it then it produces only 300mAh or less. If the solar panel has a glass (not plastic) cover and measures about 45mm x 45mm (1.75" x 1.75") then better batteries will be fine.

I buy Energizer AA Ni-MH batteries that are made in Japan probably with Eneloop modern technology. They are 2300mAh and a charge lasts for 1 year like Eneloop batteries.

I found "a bargain" at Costco. 8 Duracell Ni-MH batteries plus a charger for less cost than for 8 Energizer batteries but no charger. But the batteries have a low mAh rating and they are made in China! They work poorly.

 

[rjenkinsgb]

The batteries in some cheap solar lights I had were pretty useless; I got some "pound shop" rechargeables (two for £1) and put those in, about ten years ago? They still work fine!

 

[audioguru]

A recent magazine tested Name Brand and cheapo store brand Ni-MH batteries and found that the cheap ones worked cheaply.

 

[rjenkinsgb]

They are good for what they are doing - I'm not using batteries that cost more than the lights! And they are still working a decade on; that's the only relevant factor in that application.

I'd never consider using the pound shop ones for anything important, though.

 

[audioguru]

When you buy a cheap solar garden light from a Name-Brand store then the extremely poor quality battery rusts away in one month but it has no cost. A name brand battery has a high capacity and a stainless steel or nickel-plated case that does not rust. Many cheap batteries leak.