Very quick question regarding electronics (charging a battery)

[Rich1988]

Hi, as title just a quick question regarding electronics, I have two small solar panels (1 x 1.5 watt and 1 x 4.5 watt panels) and I just want to keep a 7ah battery topped up, together they should produce around 500mah.

My question is, I have a dual cigar socket which I am wiring to the battery, into this dual socket I will plug both solar panels, to my mind this should just give the standard 12volts and charge the battery but I just wanted to check if anyone else can see any issues with this?

Cheers

 

[SGCWill]

You need the battery voltage + 10% to charge it.

Also need diodes to stop discharge when the sun isn't shining I think.

Better use google for diy solar panel chargers, but most involve voltage regulator ic's

 

[Rich1988]

You need the battery voltage + 10% to charge it.

Also need diodes to stop discharge when the sun isn't shining I think.

Better use google for diy solar panel chargers, but most involve voltage regulator ic's

Sorry I should mention that these panels are designed to charge 12 volt batteries and have an output (disconnected) of around 17 volts, they also have diodes built in to prevent reverse charging

What I was checking is that connecting them in that way wont cause any issues, I.E 2 x 12v charging sources connected to the battery. I cant see why It would as it should still be 12volts total?

 

[SGCWill]

It'll be in parallel, so should still work and I don't really think you'll have to worry about overcharge with the low power panels.

Personally, I'd be more comfortable building a little circuit to stop it charging once the battery reaches the right voltage. Don't shout at me if it catches fire though!

 

[Rich1988]

haha I will be keeping an eye on it! it is just for a camping trip and I have a 9.6 watt led light set up that it is powering, (working on roughly 5 hours of functional light from it) and the panels are just to recoup during the day some of the energy used at night.

 

[AshD93]

You're making the assumption that both panels output the exact same voltage though which they never will.

 

[Rroff]

Some kind of charging circuit with overcharge protection should be in there really also blocking diodes (often but not always found on panels now) are pretty important.

For simplicity you really want panels that are closer matched ratings wise even though you'll rarely get identical output even then.

 

[Rich1988]

off load the two panels connected were outputting 18.9v, which is a reasonable output at rest, as far as overcharging protection do you mean for the battery? as It will be only connected for a maximum of 10 hours before being used again