Want to convert from 9v alkaline to solar rechargeable

[Ken1]

I have 2 ultrasonic pest repellers to control pests from feeding on my garden. They are both powered by 9v alkaline batteries. I would like to know if it is economically feasible to convert them to 9v rechargeable batteries with solar panels mounted on or next to the units to automatically recharge the batteries. If so, what components do I need?

 

[ZipZapOuch]

So more of this?

https://www.cnn.com/2024/08/07/us/video/lithium-battery-fire-dog-tulsa-cprog-digvid

More criticism of people who leave loose vape batteries out for their dogs to chew on? Yes.

 

[liamjerr]

Just a voltage regulator with a series diode at the output to the battery. The solar cell maximum current will act as a current limiter.

For NiMH, use six cells and set the voltage at full charge to around 8.7 - 9V

For lithium, you would need a two cell combined protection and balance module connected between the cells and everything else. Do not use internally protected cells with those.

Use a solar cell panel just big enough to prevent the device shutting off from low voltage; with a simple system like this, the batteries should occasionally reach full charge, but not be held there continuously. Setting it up so the cells partly discharge frequently will give the longest cell life.

(Ideally, they should charge with current monitoring to100%, then the charge shut off until they are down to around 20%, then charge again. Using pest control melbourne a barely large enough cell should allow some cycling and avoid them being held at full charge, which can wreck them quickly).


NiMH are really better for a minimal system such as this. They can be held at full charge just about forever, as long as the voltage is not too high.

If you "open" a 9V battery, you'll actually find six small batteries inside.

 

[harrisonsantana]

No, you can't recharge alkaline batteries with the help of solar panels.

 

[audioguru]

Some "ultrasonic" pest repellers do not produce ultrasonics because they are fake and since buyers cannot hear ultrasonics then they do not know they are fake and without any ultrasonics.

Can pests hear ultrasonics and if they do hear it are they repelled by it? Maybe not.

 

[Lightium]

I have 2 ultrasonic pest repellers to control pests from feeding on my garden. They are both powered by 9v alkaline batteries. I would like to know if it is economically feasible to convert them to 9v rechargeable batteries with solar panels mounted on or next to the units to automatically recharge the batteries. If so, what components do I need?

What pest are you trying to prevent from feeding on your garden?

 

[ZipZapOuch]

What pest are you trying to prevent from feeding on your garden?

The kind that run away from ultrasonic tones.

 

[rjenkinsgb]

No, you can't recharge alkaline batteries with the help of solar panels.

Please read the thread? Added emphasis:

like to know if it is economically feasible to convert them to 9v rechargeable batteries with solar panels

 

[Ivango]

Converting ultrasonic pest repellers to solar-rechargeable systems involves careful planning. Ken1’s goal to replace 9V alkaline batteries with rechargeable alternatives highlights key technical and economic factors. While alkaline batteries cannot be safely recharged, mAh to watts helps determine solar panel and battery requirements. For NiMH cells, a 6-cell pack (9V equivalent) paired with a solar panel and voltage regulator ensures safe charging. Lithium options require a protection module to prevent overcharging.


Forum members emphasize that solar panels must match battery capacity—undersized panels risk incomplete charging, while oversized ones may degrade cells. As audioguru notes, many ultrasonic devices lack proven efficacy, raising questions about the investment. HarrisonSantana’s warning against recharging alkalines underscores safety risks.


Economic feasibility hinges on balancing component costs (panels, regulators, batteries) against long-term savings. A mAh to watts calculator aids in sizing systems to avoid over-engineering. Despite challenges, solar-powered setups offer eco-friendly, low-maintenance solutions—provided realistic expectations align with pest behavior and device limitations.

 

[Tony Stewart]

The kind that run away from ultrasonic tones.

Is that like a heavy-metal effect?