Hey everyone! I'm a bit of a newbie when it comes to solar, but I've been trying to educate myself and troubleshoot an issue I'm facing. I initially set up a **flooded lead-acid battery** to run a small load (a ham radio) using a **370W solar panel** I got for free, despite it being cracked. It's rated at **44.76V open-circuit (Voc)**, and I connected it to a **cheap PWM charge controller**.
After plugging everything in and setting the battery type to Flooded, I was shocked when the controller started showing **19+V** once the sun came out. I measured the battery terminals with a multimeter and, to my surprise, that voltage was reaching the battery. I thought there was an issue with the controller and didn't want to risk damaging my radio, so I decided to upgrade my setup.
I got a **better Bluetooth solar controller** and a **12Ah LiFePOâ‚„ battery**, thinking the BMS would help manage the voltage. However, after connecting everything, I got a shocking **37V reading at the battery** and an error popped up in the app.
I also tested it with a smaller portable solar panel, and it still showed **19V at the terminals**. It's leaving me puzzled:
- Are both charge controllers just defective? They're rated for 50V.
- Shouldn't they regulate the voltage to protect the battery and load?
- Why is the **Voc** going straight to the battery and load output?
Any insights would be appreciated, as I feel there's something fundamental I'm not grasping or I might just have bad luck with these controllers.
3 Answers
From what you’ve described, both your prior and current controllers might not be totally functioning as they should. The initial PWM could have failed and be bypassing regulation completely, sending full solar input to the battery. For your second situation, are you sure your LiFePO₄ battery was activated before use? They sometimes can get switched off, leading to odd behavior.
And as for your wiring, I recommend double-checking everything. If the wiring isn't up to par or incorrectly set up, it can lead to erroneous readings at the terminals. A picture of your configuration could help clarify the situation.
Overall, I’d suggest testing with a known good setup to determine whether the issue lies in the controllers or your configuration.
Honestly, it sounds to me like an MPPT charger would be much more suitable for your setup than a PWM. PWM needs the voltage to match the batteries better, but MPPT can handle higher voltages and give you the right output.
That said, if your portable panel is also reaching 19V at the terminals, it’s best to avoid your radio until you get the right setup confirmed.
Also, as for your concern about finding lower Voc panels, it's normal to see higher voltages, but proper voltage regulation is key to keeping your devices safe. Have you considered looking into brands or models like Victron for a solid MPPT option? They tend to offer good voltage regulation!
First off, PWM controllers can have issues when paired with panels that have a significantly higher voltage than the battery. They're designed to pulse down higher voltages, so if you're using a panel rated at 37V, it may not handle it well.
Secondly, it sounds like your MPPT (if that’s what the newer controller is) should regulate the output properly, converting the voltage while maintaining adequate current. Just make sure you know the specs of all the components you're using.
Lastly, it’s definitely not uncommon for cheap PWM controllers to have problems. If you suspect both controllers are faulty, it might be worth checking everything again, especially the connections and whether you activated your LiFePO₄ properly before use. If you've swapped components around and still get high voltage at the terminals, there might be a deeper issue with your setup.
I’d also check the connections to ensure the battery is connected first. If you accidentally hooked up the panel without connecting the battery properly, that could lead to some serious overvoltage combined with poor controller regulation. Just something to consider!