How to make a solar trickle charger?


Old 07-03-11, 09:39 AM
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How to make a solar trickle charger?


I currently have a GPS tracker (tk102) hardwired to a 12v 7ah battery and im trying to make a solar trickle charger that can be left attached to the bike 24/7,

Heres What i have so far:

TK102 GPS Tracker (Drains 0.05amps when its internal battery is fully charged)
12V 7Ah Sealed Lead-Acid Battery
12V 1.5W Solar Panel

Solar panel specs:
Open Circuit Voltage ( Voc ): 14 Volts
Maximum Power Voltage ( Vpm ): 12 Volts
Short Circuit Current ( Isc ): 132mA
Maximum Power Current ( Ipm ): 125mA
Power: 1.5W

What i need to know is do i need any kind of controller between the solar panel and battery to limit the charge or to prevent overcharge / discharge and if so is it something that can be made or bought?

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Old 07-03-11, 10:23 AM
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I think you will be fine without a controller with that small a panel, but others may say otherwise.
Old 07-03-11, 10:37 AM
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I am sure that you can buy a solar trickle charger to suit your usage. Google returned many results for 12V solar trickle chargers.
Old 07-03-11, 10:48 AM
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It would essentially be self regulating. As the battery voltage goes up to full charge, the current delivered would drop. The 132 ma short circuit current would be the absolute maximum when dumping current into zero volts. When the battery is at 12v the maximum panel output is 14v, thus you only have 2v capacity. Do they give a curve on the solar panel to tell you what it can deliver at different voltages?

Anyway, when the battery is fully charged it will be near 14v, thus the panel will not be able to add anything additional.


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