"ehsjr" <ehsjr@mverizon.net> wrote in message 
news:mr6cf6$j0u$1@news.eternal-september.org...
> On 8/20/2015 5:50 PM, Bill Bowden wrote:
>> My neighbor has a solar powered outdoor decoration light that cycles 
>> through
>> several colors but only runs for maybe an hour at night. It has a single
>> 1200 mAh 1.2 volt rechargeable battery and a couple small solar cells to
>> charge the battery. I measured the load current at 15 milliamps and the
>> charge current at only 1.3 milliamps so it appears the solar array is not
>> charging the battery sufficiently. She has another one of the same type 
>> that
>> runs all night so this one must have a problem. I have a few small solar
>> cell pieces where 4 in series charges the battery at around 70 milliamps 
>> but
>> I'm thinking that may overcharge the battery? I have some 3 inch square
>> cells that produce about 1 amp, but they are very hard to cut down to
>> smaller sizes.without breaking intp pieces. I tried an exacto knife and
>> managed to get 4 small pieces to do the job but I'm thinking they may 
>> still
>> be too large at 70 millamps. The circuit is all in one chip with the 
>> cells
>> and battery common to the positive side, and the negative side of the
>> battery and cells goes to 2 connections on the chip. The voltage drop 
>> from
>> cell to battery is about 200 millivolts while charging so it appears to 
>> work
>> like a blocking diode so the battery doesn't discharge into the solar 
>> cells.
>> There may be some sort of regulator that limits the battery charge but 
>> I'm
>> not sure. I guess I could just add a load resistor across the cells if
>> needed?
>
> 70 mA won't overcharge a 1200 mAh battery.  However, it might be
> more advantageous to fix the problem than to jury rig by adding
> more solar cells.  Always suspect the rechargeable battery
> first. You could swap the batteries between the good one and the
> bad one and test for several days, to see if the problem stays
> with the light or follows the battery.
>
> The 1.3 mA charging current is too low, so either the battery
> isn't drawing enough, the cell isn't producing enough or the
> circuit is not passing enough charging current.
>
> For a typical one-chip "garden light" schematic, google YX8018
>
> Ed
>

The battery is good and when fully charged powers the circuit for over 24 
hours. With a larger solar cell they wouldn't need to switch off the LEDs in 
the daytime. The charge current reads 70mA through the circuit, so it must 
also be good. That only leaves the cells themselves and I haven't any idea 
what's wrong with them. They would be difficult to remove and test. I'm 
going to enclose the additional cells in a small plastic box and run wires 
through a small hole in the fixture and attach the additional cells in 
parallel with the original. Doesn't look too professional so the neighbor 
will figure out a way to hide the box so it gets light and doesn't attract 
attention. She has about 50 of these things of different sizes and a bunch 
of statues in her yard, and a red Ferrari in the garage.




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On Fri, 21 Aug 2015 15:22:27 +1000, ehsjr <ehsjr@mverizon.net> wrote:

> On 8/20/2015 5:50 PM, Bill Bowden wrote:
>> My neighbor has a solar powered outdoor decoration light that cycles  
>> through
>> several colors but only runs for maybe an hour at night. It has a single
>> 1200 mAh 1.2 volt rechargeable battery and a couple small solar cells to
>> charge the battery. I measured the load current at 15 milliamps and the
>> charge current at only 1.3 milliamps so it appears the solar array is  
>> not
>> charging the battery sufficiently. She has another one of the same type  
>> that
>> runs all night so this one must have a problem. I have a few small solar
>> cell pieces where 4 in series charges the battery at around 70  
>> milliamps but
>> I'm thinking that may overcharge the battery? I have some 3 inch square
>> cells that produce about 1 amp, but they are very hard to cut down to
>> smaller sizes.without breaking intp pieces. I tried an exacto knife and
>> managed to get 4 small pieces to do the job but I'm thinking they may  
>> still
>> be too large at 70 millamps. The circuit is all in one chip with the  
>> cells
>> and battery common to the positive side, and the negative side of the
>> battery and cells goes to 2 connections on the chip. The voltage drop  
>> from
>> cell to battery is about 200 millivolts while charging so it appears to  
>> work
>> like a blocking diode so the battery doesn't discharge into the solar  
>> cells.
>> There may be some sort of regulator that limits the battery charge but  
>> I'm
>> not sure. I guess I could just add a load resistor across the cells if
>> needed?
>
> 70 mA won't overcharge a 1200 mAh battery.  However, it might be
> more advantageous to fix the problem than to jury rig by adding
> more solar cells.  Always suspect the rechargeable battery
> first. You could swap the batteries between the good one and the
> bad one and test for several days, to see if the problem stays
> with the light or follows the battery.
>
> The 1.3 mA charging current is too low, so either the battery
> isn't drawing enough, the cell isn't producing enough or the
> circuit is not passing enough charging current.
>
> For a typical one-chip "garden light" schematic, google YX8018
>
> Ed
>
>
>

YX8018 is possibly the worst chip ever made (at least the Chinese ones)

I bought 100 from AliExpress for about $5 (IIRC). 40% were DOA with  
various defects. Of the rest, using all variants of the circuits on the  
data sheets, with the recommended and also with superior components, the  
best efficiency was 30% (might have been low thirties). Yuk.

I don't remember all my test results but he might have a defective YX8018

On 8/20/2015 5:50 PM, Bill Bowden wrote:
> My neighbor has a solar powered outdoor decoration light that cycles through
> several colors but only runs for maybe an hour at night. It has a single
> 1200 mAh 1.2 volt rechargeable battery and a couple small solar cells to
> charge the battery. I measured the load current at 15 milliamps and the
> charge current at only 1.3 milliamps so it appears the solar array is not
> charging the battery sufficiently. She has another one of the same type that
> runs all night so this one must have a problem. I have a few small solar
> cell pieces where 4 in series charges the battery at around 70 milliamps but
> I'm thinking that may overcharge the battery? I have some 3 inch square
> cells that produce about 1 amp, but they are very hard to cut down to
> smaller sizes.without breaking intp pieces. I tried an exacto knife and
> managed to get 4 small pieces to do the job but I'm thinking they may still
> be too large at 70 millamps. The circuit is all in one chip with the cells
> and battery common to the positive side, and the negative side of the
> battery and cells goes to 2 connections on the chip. The voltage drop from
> cell to battery is about 200 millivolts while charging so it appears to work
> like a blocking diode so the battery doesn't discharge into the solar cells.
> There may be some sort of regulator that limits the battery charge but I'm
> not sure. I guess I could just add a load resistor across the cells if
> needed?

70 mA won't overcharge a 1200 mAh battery.  However, it might be
more advantageous to fix the problem than to jury rig by adding
more solar cells.  Always suspect the rechargeable battery
first. You could swap the batteries between the good one and the
bad one and test for several days, to see if the problem stays
with the light or follows the battery.

The 1.3 mA charging current is too low, so either the battery
isn't drawing enough, the cell isn't producing enough or the
circuit is not passing enough charging current.

For a typical one-chip "garden light" schematic, google YX8018

Ed

My neighbor has a solar powered outdoor decoration light that cycles through 
several colors but only runs for maybe an hour at night. It has a single 
1200 mAh 1.2 volt rechargeable battery and a couple small solar cells to 
charge the battery. I measured the load current at 15 milliamps and the 
charge current at only 1.3 milliamps so it appears the solar array is not 
charging the battery sufficiently. She has another one of the same type that 
runs all night so this one must have a problem. I have a few small solar 
cell pieces where 4 in series charges the battery at around 70 milliamps but 
I'm thinking that may overcharge the battery? I have some 3 inch square 
cells that produce about 1 amp, but they are very hard to cut down to 
smaller sizes.without breaking intp pieces. I tried an exacto knife and 
managed to get 4 small pieces to do the job but I'm thinking they may still 
be too large at 70 millamps. The circuit is all in one chip with the cells 
and battery common to the positive side, and the negative side of the 
battery and cells goes to 2 connections on the chip. The voltage drop from 
cell to battery is about 200 millivolts while charging so it appears to work 
like a blocking diode so the battery doesn't discharge into the solar cells. 
There may be some sort of regulator that limits the battery charge but I'm 
not sure. I guess I could just add a load resistor across the cells if 
needed?


  . 



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