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Post by thespianator on Sept 21, 2016 13:37:45 GMT -5
Greetings, I have a small 7.5 watt portable Coleman folding panel that has the option to run a 5V USB or a 12V auto-like socket. I'd like to connect it to a spare battery charger that I have, but I don't know where to make the connection to a 12V plug. Unfortunately no schematic. I've attached pics of the PCB for the battery charger. I'm guessing that the connection should be at the three pins just below the point marked "SECONDARY". Is that correct? If so, how do I tell which of the 3 pins to connect to? Thanks for any help with this! |
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Post by barclay66 on Sept 22, 2016 2:21:06 GMT -5
Hi,
You can connect the positive lead to the point with the marking 'Vout' and the negative one to 'GND1' (visible on the third picture). Use these points for measurement if You want to make sure that the voltage You're feeding matches the one generated by the onboard power supply. Avoid contact with any surface at the primary side!
Regards,
barclay66
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Post by thespianator on Sept 22, 2016 14:19:02 GMT -5
Thanks! I guess I should have looked for that. Would you recommend that I test both the AC generated voltage and then the voltage as supplied by the solar panel? Also, if I just put leads on those two points you mentioned and run them to a power socket, could I then use this charger either as solar or as AC (provided I put a protective insulating sleeve on the connector)?  |
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Post by barclay66 on Sept 23, 2016 2:05:59 GMT -5
Would you recommend that I test both the AC generated voltage and then the voltage as supplied by the solar panel? Yes. The voltage that You'll be feeding from an external source (solar panel) shouldn't be higher than the AC generated voltage (+/- 2 Volts should be OK though). Otherwise the charging circuit and/or the batteries You're charging may be damaged. The charging circuit has been designed having the properties of the AC power supply in mind. Also, if I just put leads on those two points you mentioned and run them to a power socket, could I then use this charger either as solar or as AC (provided I put a protective insulating sleeve on the connector) Yes. Please have in mind that this power socket will carry the AC generated voltage as long as the charger is connected to AC. Never connect the external source to it as long as it is connected to AC! Just one more thing: The AC power supply has some kind of feedback voltage regulator function (visible through the optocoupler designated 'PC1'). If this regulation circuit should work as part of the charging principle (see this article: www.radio-electronics.com/info/power-management/battery-technology/nimh-nickel-metal-hydride-charging.php), feeding an external constant voltage won't work as the charger then is designed for managing the AC generated voltage according to the charging status, thus making it variable. You should be able to identify this situation by measuring the voltage between 'Vout' and 'GND1' without batteries inserted, with an empty battery inserted and with a fully charged battery inserted. If the measured voltage varies more than 1-2 Volts between the different scenarios then feeding an external voltage won't work... Regards, barclay66 |
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