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Posted to uk.d-i-y
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Solar panel controller for nominal 5W panel - UnisolarSmartChargeFLX
On 11/05/2019 15:35, wrote:
On Saturday, 11 May 2019 13:26:44 UTC+1, David WE Roberts (Google)
wrote:
On Sat, 11 May 2019 13:22:21 +0100, Harry Bloomfield wrote:
David formulated on Saturday :
It claims that there is a blocking diode included to prevent
reverse current flow.
No, that simply means it will not discharge a battery, when it is
unable to charge it (in the dark).
Does this mean that I don't require a charge regulator?
You probably wouldn't need a charge regulator to use it to charge
a 12v car battery, its output is quite small at 0.30 amps.
For example, if I plug a USB 12V charge adaptor into the
supplied cigar lighter socket should that be all I need to
charge a power bank? Or, for that matter, a mobile phone?
A 12v to USB cigar lighter adaptor will include a 5v regulator.
Thanks.
The remaining question is "Is it safe to feed 16.5V into an
adapter?". I am assuming that it can cope with 14V+ as that is what
an alternator allegedly pushes out, and I assume that this gets as
far as the cigar lighter socket.
The nominal open circuit voltage will plummet as soon as any real power
is taken. The purpose of a charge controller is to maximise the power
delivered to the load and protect it from overcharging. But for a 40Ah
battery it will barely notice 300mA peak charge rate which is C/100.
Modern cars disconnect the cig lighter socket when the engine isn't
running, so that won't work. 5w is such a low charge rate that it can
be left on indefinitely, albeit not ideally.
It might well be broadly comparable with the average modern cars daily
discharge rate when averaged over 24 hours and UK weather. A lead acid
40Ah in good condition self discharge rate is around 1W or 5% lost
charge per month. Batteries that are on their last legs won't start a
car if it is left unused for more than a couple of weeks.
--
Regards,
Martin Brown
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