Battery for Solar Water feature

Korkyb

Hi all

i I have bought a 2nd hand water feature which came with a pump and solar panel.

The pump works when the panel is in direct sunlight but stops when it is not.

It’s has a battery backup but it doesn’t charge not seem to be functioning at all in spite of the panel being outside for a few sunny days.

So I’m thinking

a/ the batteries are goosed.
or
b/ the panel isn’t charging the batteries.
or
c/ the batteries are being charged but are not powering the pump.

How do I figure out what my problem is before splashing out more cash?

If it is just the battery that needs replacing could I use a bigger battery (perhaps externally to the panel) - what battery would I need?

If not where would I source a replacement for the current one 4 x 18650 (2x2) 7.4v 29.6wh.

There are no details on the pump or panel about power requirements or output!

Thanks for any advice.

twopenny

What's the name of the solar water fountain?
Even a photo.

Have you checked the connections for soil, moisture and are they fitting well?

I don't have back up battery but when mine failed I was able to find the problem on YouTube and it was surprisingly easy to fix.
They tend to be simple.

Korkyb

Here are pics of the solar panel and battery.

Korkyb

I think believe the water feature and the solar panel / pump were bought separately & the panel / pump were not cheap.

All connections seem to be dry & working.

Korkyb

The pump is working fine when the panel is in direct sunlight and also when I attach a mains adapter to the solar panel “charger” port.

I’m not even sure if the mains adapter is the correct output for the panel (it’s from my WiFi booster) & can’t have permanent mains to the water pump due to the water features position.

I did try leaving the mains adapter plugged in to see if it would charge the batteries but no success…

QrizB

That battery is from 2017, so is eight years old which is pretty ancient (it's broadly the same sort of battery you used to get in a laptop, before they all went ultra skinny). Do you have a multimeter? Can you check its voltage?

You can get an equivalent battery from eg. AliExpress for a reasonable price, or from somewhere more reputable for a less reasonable one

Something like this (an example not a recommendation):

https://www.aliexpress.com/item/1005008942497255.html

TELLIT01

As the solar panel is supplying power to the pump, and the pump works, it really does indicate pretty strongly that the problem is with the battery.

WIAWSNB

That's a decent unit right enough, Korky.
Do you have a digital multimeter? They cost peanuts, and are the most useful tool - worth it.
Placed across the battery terminals on the PCB, with the panel aimed at the sun, you'd soon know if it was receiving a charging voltage.
It's quite possible a battery or two have failed, but I'd still expect a little bit of grunt from them, after a good while of charging in full sun. But, hey.

Each 18650 battery is, I understand, ~3.7V, so that would explain the overall 7.4V - a pair of batteries in series, and then connected in parallel with another pair to double the storage capacity.

That suggests it would really need at least two batteries to have completely failed - one in each series stack - for the whole battery pack to be kaput.

So, whether it's the batteries remains an unknown.

Personally I would buy a digi multi first, and go from there.  

As to your other Q - can you increase the storage capacity, if you do need to replace your 18650's? You will find these batteries in various 'capacities', with your current pack being 4Ah in total (2 x 2Ah). Good chance you can find a pack with a larger overall capacity - that's the easiest way. Bear in mind it'll be limited by the charging capacity of the solar panel, so you'll only likely have a larger battery fully charged up at the height of Summer :-)

Anyhoo, check whether your battery pack is actually receiving a charging voltage first - ie, a multimeter - and we'll go from there :-) 

molerat

It is a standard off the shelf battery pack / connector so easy to find.  As above you need a multimeter to check the voltage at the battery connector is around 8.5v for it to charge successfully.

Grenage

As TELLIT01 says, if it works when the sun is out, it must be the batteries.

WIAWSNB

Or a connection in between.

How annoying would it be to replace the battery pack to find no change?