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Electronics => Repair => Topic started by: msknight on November 16, 2019, 04:24:24 pm

Title: Simple charge 6V bat from solar
Post by: msknight on November 16, 2019, 04:24:24 pm
OK ... I'm a beginner attempting to repair an outdoor battery powered, solar charged LED light.

The original PIR sensor went west (along with the external power switch... that's non-responsive too.) ... however I've currently jerry rigged it on the bench with a new 12v DC PIR sensor which appears to have built in ambient light sensing (which it looks like the original one didn't... or was driven to the board) as the original had five cables to the board and this only has three.

Anyway... despite the battery being a 6v M6-4.0 (4Ah) ... I hooked everything together directly.... and it all works!!!

Now... my problem is that I need to hook the solar panel up to charge the battery, and I'm clueless.  Underneath my little worktop bulb, it appears to be putting out 9vDC... so I'm presuming that this will output more when it's in good daylight.

The power from the solar comes in via the black two strand cable at the bottom, and I've currently left that soldered to the circuit board, because I haven't got a clue where I'm going after this point. - There is a red and black going from the circuit board in the direction of the battery, but this is going to a separate 12v dc input jack and isn't connected to the battery.

How best should I hook the DC in from the panel to charge the battery please?

(and how the heck do spiders manage to get inside these units? I found four small deadies in here.)
Title: Re: Simple charge 6V bat from solar
Post by: pcmad on November 18, 2019, 02:52:00 pm
have you tested it with is external power to work out on the pir will work on 6  to 9 v

also why cant you put the wirer back where they came from


have you work out the pollity on the wire of the pannel

you last pic the left circle looks to be ground you the check this  by conternewanty by the header on the board marked gnd
Title: Re: Simple charge 6V bat from solar
Post by: msknight on November 18, 2019, 05:05:50 pm
Yes, I've tested it with the PIR and LED connected to the battery and turned the dials so it would trigger... and it worked when I move my hand in front of it. This was by direct connections and not including the board at all.

The original PIR had five wires that went into the board. Three went into the socket marked "GND Time 3.6v" and two went into S3 marked "REY PIR" ... so the PIR I bought isn't a direct replacement.

You're correct. The one on the edge of the board is ground.

I know enough that I can't connect the solar panel directly to the battery as I presumably have to prevent overcharging, but I believe I have two choices...

1) Construct a different charging circuit to connect the panel to the battery and ditch the current circuit board

2) Tap into the board at the correct places to deliver the controlled charging current to the battery.

I'm not sure that I can do this while the PIR is also connected directly to the battery terminals at the same time. But if I can't then I'm going to have to work out a way to connect the three-wire PIR into the existing circuit somehow... something I'm not sure will work.
Title: Re: Simple charge 6V bat from solar
Post by: pcmad on November 19, 2019, 02:35:22 am
what is the battary type if its lead or nicad or nimh there fine being over charged just put a Schottky diode just after the solar panel will stop dmaged to the panel and battary discharge

lithium it will depend if the battary got protection on it or not  and what kind

Title: Re: Simple charge 6V bat from solar
Post by: msknight on November 19, 2019, 05:10:18 pm
Looks like it's lead acid...

Title: Re: Simple charge 6V bat from solar
Post by: pcmad on November 19, 2019, 06:12:00 pm
yep lead acid just put a Schottky diode just after the solar panel will stop dmaged to the panel and battary discharge
Title: Re: Simple charge 6V bat from solar
Post by: tautech on November 22, 2019, 08:02:02 am
Looks like it's lead acid...
Yep, SLA.
You don't want to drain it flat repeatedly as it will shorten its life dramatically.
Ideally you want to manage its DOD (depth of discharge) and charge to near its max cyclic voltage.
A battery supervisor management IC can look after all of the above.

Or you could just wing it with a carefully selected zener diode with double the wattage rating of that of the PV panel.
Zeners do have leakage below of what they're rated for and you need to take that into account when selecting one especially if you want to get near to max charge of the battery.
If the PIR and LED draw is low then you'll have some wriggle room.  ;)