12v Battery Voltage too High

[Adamlukegilbert]

I am connecting a new 12v leisure battery to a new Sunix solar controller. The controller flashes a warning and displays 12.6v, so it seems to be too high. How would I reduce the voltage?

Previously I used a Buck converter to step the voltage down from an 18v drill battery, but the solar would not charge this setup.

Total beginner, any help would be great.

 

[Bud Martin]

Can we get more info about the 'Sunix' solar charge controller and also how you hook up the Buck converter to the charge controller?

 

[Adamlukegilbert]

Bud,

Thanks for the reply. The charge controller is a simple product from eBay. I'm not sure what other information is relevant. Picture attached.

The buck converter was just inserted into the circuit, positive to positive, negative to negative. I'm very much the beginner! I could share photos if it helps understand the issue.

 

[Forbisher]

Bud,

Thanks for the reply. The charge controller is a simple product from eBay. I'm not sure what other information is relevant. Picture attached.

The buck converter was just inserted into the circuit, positive to positive, negative to negative. I'm very much the beginner! I could share photos if it helps understand the issue.

View attachment 43919

How about a link to the sales page.
The SCC is a PWM that is Li compatible.
Were you using the buck comverter when getting 12.6V?

What chemistry is your leisure battery?
How many watts of panels do you have?

 

[Adamlukegilbert]

Link to SCC here:
https://www.ebay.co.uk/itm/174633248068

I was not using the Buck when getting 12.6V warning. I only used the Buck to test the SCC with an 18V Li battery, but the SCC did not indicate any charging. I assume a 12V battery should not get a warning of above 12.6V.

The battery is calcium lead alloy, link here:
https://www.ebay.co.uk/itm/Deep-Cyc...e=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2649

The single panel is 235W, but it was not connected when getting this warning.

Does that help?

 

[JeepDaddy]

12.6 volts is the standard fully charged voltage for a 12 volt lead-acid battery. That's not the issue. What is the warning message that the SCC is giving? 12.6v is not an error message.

 

[Adamlukegilbert]

I seem to have fixed this by discharging the battery for a little while to reduce the voltage. Now the SCC is able to be powered, and the solar can start charging. This suggests to me the SCC will never let the battery get over 12.6v which could be a problem for a deep cycle battery, but at least I can start using it.

Thanks for your help!

 

[Jordi]

The problem you have here is that you bought the wrong controller for the battery you have. Your battery apparently has an out-of-range charging profile that surpasses the maximal voltage the controller can offer. Over 12,6V the controllers shuts-off charging to protect the battery; I guess because lead acid batteries can be damaged when charged over that 12,6V.

From here onwards, insecure of what I say as I am noobish:

Using a stepdown buck alone in combination with the controller won't help you to charge the battery because it reduces the output voltage of the battery to say 12,2V but it only allows current to flow in discharge direction: battery to controller. So no charging possible.

What you can do is connect the feed (solar panel) to a step-down buck from feed to battery at almost full charge voltage (13V?) and connect the battery to a step-down buck from battery to load at the voltage you require. This because the bucks have a single-flow direction and can not transfer charge from source to load in absence of feed. So basically you don't use the controller anymore. The second buck is optional in case the load is an inverter that has a voltage range as input (eg. 10-15V)

Last option is that you test (maybe somebody can say it already) If when the over voltage is reached, via the spontaneous decrease of voltage (connect load), the controller can restart charging functions or requires a manual reset. Then you can use the controller to charge the battery at eg. 70%, moment at which charging will finish. So eventually the system works well, but the battery has a lower capacity.

Some cheap PWM controllers require you to disconnect and reconnect the battery when a protection jumps.