Why not - Convert your mains LED floodlights to solar? (actually there are several reasons not to, but I did it anyway).

[Muhendis]

1 minute ago, Crossy said:

It's the terminal name of the XY-MOS module, it's not actually PWMing.

Well at least it's not in Mandarin

[maxpower]

6 hours ago, Crossy said:

Current draw with an LM358 is about 1mA at 12V supply to just under 2mA with the lights on (most of the extra is lighting the LED). Not sure if it's really worth going to an ultra low-power device.

 

Voltage comparison jobs like this are best served by a dedicated comparator like the LM393 with unused input pins of a dual device tied to ground.

 

Only one mosfet is required (the status led is wasting energy). Voltage can be applied directly through the 100R charge limit resistor, without the 10k.

For anyone with experience, cheap microcontrollers which spend most of the time sleeping are the best choice for these tasks. 

[Muhendis]

R9 (10K) looks a bit big. I don't know what the  MOSFET gate-gnd capacitance is but I would think it would turn on a bit slow with a 10k series drive impedance. The LM358 has a minimum current capability of 20mA but a large signal rise time of 10uS so maybe there is a case for doing away with R9. You have a tube full of 358's so it won't hurt too much if frequent switching overtaxes one.

[Crossy]

Yeah, the 10k for R9 was chosen really to keep the LED current down (it has 1k on the module), if it were a PWM driver I'd be looking at something smaller. But since it switches once each way every 24 hours I doubt the limited slew rate at the gate is going to cause problems. EDIT the D4184 has an input capacitance of 1500pF so 3000pF for two = 3nF. Time constant with 10k = 30us, I'm not going to worry.

 

As noted earlier it's a 358 'coz I had them, a dedicated comparator would likely be better but the op-amp does the job just fine.

 

Two MOSFETs 'coz the module has them, one would be just fine.

 

LED is there again because it was on the module and it lights up as a handy debugging aid.

 

Use a microcontroller, nah, not for a one or two off hobby project, making loads commercially and needing to minimise hardware costs then why not indeed.

 

As noted earlier my grounding is strictly bipolar (no, not THAT bipolar, the other one!!) and I moved out of the design world before power MOS devices became a thing, hence my using a ready made module, guaranteed to work. 

[Crossy]

9 hours ago, Muhendis said:

Well at least it's not in Mandarin

 

Ah, you bought some of those too ...

 

[Muhendis]

1 hour ago, Crossy said:

I moved out of the design world before power MOS devices became a thing

Ah yes. Those wonderful days of thermionic FET's. Did you know that the Will's fag factory in Bristol was heated by the mainframe computer that took up an entire floor

and a girl was gainfully employed testing said fets in an AVO valve tester. I nicked a few of the failures to make a high quality amp which saw good use in my jazz entertainment attempts.

Sorry. Back to the topic.........????

[Crossy]

2 minutes ago, Muhendis said:

Will's fag factory

 

Careful, our friends from across the pond will be having palpatations over a "fag factory"!

 

[Muhendis]

4 hours ago, maxpower said:

best served by a dedicated comparator like the LM393

With an added NPN to zap the fet gate.

[Muhendis]

2 minutes ago, Crossy said:

 

Careful, our friends from across the pond will be having palpatations over a "fag factory"!

 

Not a big problem. They can't spell palpitations either and a fag is a public school junior.

[Crossy]

11 minutes ago, Muhendis said:

Not a big problem. They can't spell palpitations either and a fag is a public school junior.

 

Important note for non-brits, a Public School is actually a private school, public (non-private) schools are called grammar or high schools.

 

As one of the last to take and pass the "Eleven Plus" I'm a grammar school boy complete with all the quirks to go with it. I took (and passed) "O" level Divinity (bible studies) purely because it meant I didn''t have to do double sport in the healthy sleet.

 

I got a taste for electronics from our (long passed ???? ) physics teacher "Jack" Roberts who endeared himself to all by falling down the stairs and breaking his leg during the "speed of light" experiment.

[Crossy]

15 minutes ago, Muhendis said:

With an added NPN to zap the fet gate.

 

Open collector output here we come!

[Muhendis]

16 minutes ago, Crossy said:

As one of the last to take and pass the "Eleven Plus"

Yer nearly old like me

[Tronx]

Well you are right about the LM358, during day, you will get the free power, and during night with the LED on, the 0.5mA will not matter at all. They sell the LM358 by kg on Ali.

What do you have to control battery charge and discharge level? Or is this part still operational from the Lamp?

[Crossy]

1 hour ago, Tronx said:

What do you have to control battery charge and discharge level?

 

The pack has a cheap (90 Baht) 30A BMS 

https://www.lazada.co.th/products/i2294264016-s7728105060.html

which prevents over-discharge, charge voltage is limited by the MPPT (set a bit below the BMS charge cut off level).

[Rampant Rabbit]

The sensors  on  all of  mine tend to disintegrate  from the uv off the sun, the plastic  literally shreds  to dust or the sensor  sensitivity fails  totally. Global  house  currently  have some good  20w  Philips  ones for  sale at just 200 baht with sensor which is very cheap as they were originally  500 baht,  I  bought a load for spares.

[Muhendis]

12 hours ago, Muhendis said:

With an added NPN to zap the fet gate.

Oops! PNP

[Crossy]

8 minutes ago, Muhendis said:

Oops! PNP

 

Put it down to age ???? 

 

Actually, in this case the op-amp with a totem-pole (is it still PC to call it that) output that can push/pull equally in either direction scores over the open-collector comparator.

 

Anyway, what we have works very nicely, I don't really see any need to develop it further. Maybe for the next light set (other side of the house).

[Muhendis]

1 hour ago, Crossy said:

Put it down to age ???? 

Spot on............????

[Tronx]

On 5/17/2021 at 8:50 AM, maxpower said:

 

Voltage comparison jobs like this are best served by a dedicated comparator like the LM393 with unused input pins of a dual device tied to ground.

 

...

For anyone with experience, cheap microcontrollers which spend most of the time sleeping are the best choice for these tasks. 

Good point to mention the floating inputs, that can save some current.

 

Your second statement about the microcontroller does not hold in may 2021 anymore. Prices have skyrocketed. An attiny13 costs now over 70 cents. Tiny45 over 1€. These prices will trigger fakes to be produced and sold on Aliexpress.

[maxpower]

1 hour ago, Tronx said:

Your second statement about the microcontroller does not hold in may 2021 anymore. Prices have skyrocketed. An attiny13 costs now over 70 cents. Tiny45 over 1€. These prices will trigger fakes to be produced and sold on Aliexpress.

 

Now that's funny!

 

Last time I looked we were down to 4 Cents for 6 legs 8-Bit 16MHz at our local Shenzhen market. 

 

Back to the hobby market...

 

Battery + panel voltage monitoring and direct FET drive on a $1:20 device that for most of the time consumes less than 1mA, and there's even space left over for a PWM charge controller. It's a no brainer even for a novice Arduino hobbyist.

 

Anyway just a suggestion for the more daring, now back to the world of open collectors and stuff.
 

 

[Tronx]

Well, we are talking about hobby stuff. These exotic chinese controllers are for the Chinese and their cheap electronics products. No support, no community, in the best case a chinese data sheet.

And even they do not use controllers, but they build  little comparator type chips like on the balancer/charge controller shown by crossy.  It's only a shame that they are not configurable like stuff from Texas Instruments.

You cannot set a lower full charge voltage, nor a higher low voltage cut off (or it is not documented). I can upload the data sheets if anyone is interested.  Their chips protect the batteries to some extend, but always too close to the edge, reducing life time.  Still these balancer boards  are great, only 8yA current consumption when idle.

[maxpower]

On 5/19/2021 at 10:21 PM, Tronx said:

Well, we are talking about hobby stuff. These exotic chinese controllers are for the Chinese and their cheap electronics products. No support, no community, in the best case a chinese data sheet.

 

Which for some hobbyists includes using well documented cheap Chinese microcontrollers. 

 

On 5/19/2021 at 10:21 PM, Tronx said:

And even they do not use controllers, but they build  little comparator type chips like on the balancer/charge controller shown by crossy.  It's only a shame that they are not configurable like stuff from Texas Instruments.

 

Companies like BYD Hycon HM-Semi manufacture charge control devices with a wide range of pre set parameters and tolerance. The aim is to keep external component count to a minimum and limit production line testing.

 

Those wanting fully adjustable BMS systems or devices should go out of the bargain basement and up to the next floor.
 

 

On 5/19/2021 at 10:21 PM, Tronx said:

You cannot set a lower full charge voltage, nor a higher low voltage cut off (or it is not documented). I can upload the data sheets if anyone is interested.  Their chips protect the batteries to some extend, but always too close to the edge, reducing life time.

 

BMS of the type shown are safety protection devices not continuous charge limit controllers. Those with balance features offer a method to dump cell excess at a set voltage. The balance process revolves around charge controller voltage and the point where absorption is low.

 

 

Reminder

This topic is about converting existing 220V LED lights to solar. Its an idea that on paper looks simple but in practice not always easy to find an efficient reliable solution. 

 

This is why we often find a set of reasonably well matched components and a simple control processor inside cheap Chinese solar lights.

 

Back to the hobby market ..

 

 

 

 

 

 

[Crossy]

So the final version of the Mk-1 in a box and on the wall.

 

 

 

It's not perfectly optimised but in reality does it need to be as a one-off?

 

The panel is a bit over-sized, it recharges after a full night of light by about 2.30PM, actually that's great as the panel gets shaded about then anyway.

The pack is also over-sized, the BMS never cuts off on low voltage even if the previous day was a bit dull (the initial 4S3P pack did). It's also in a shaded area so hopefully the cells will have a decent life.

 

So, since I still have a couple of floodlights that are looking sorry for themselves, I'm going to build another for the other side of the house ???? 

 

[Crossy]

If anyone is considering doing a similar system with small lighting heads these chaps look interesting and at the price have to be worth a look.

https://www.lazada.co.th/products/i1797896080-s5318412627.html

Same size as my modified mains units.

I'll order a couple to see what's what.

EDIT Sorry there were only 3 in stock, I bought them. There are other sellers with similar items.

 

[rumak]

I tried using  GOOGLE TRANSLATE  to understand what you are saying :

 

Google message said "  SORRY,  language not found " 

 

as Charlie might say...." oh dear ! "

[Muhendis]

1 hour ago, Crossy said:

If anyone is considering doing a similar system with small lighting heads these chaps look interesting and at the price have to be worth a look.

https://www.lazada.co.th/products/i1797896080-s5318412627.html

Same size as my modified mains units.

I'll order a couple to see what's what.

EDIT Sorry there were only 3 in stock, I bought them. There are other sellers with similar items.

 

I bought some 30W versions of these and found they were running off a 36v power supply which is totally incompatible with any of my on the shelf bits and pieces. With a bit of judicious snipping I have managed to make four 10W LED modules fit. When I get all the rest of the bits I will need I can run them at 24v and perhaps a little less out of consideration for the heat sink.

[Crossy]

17 minutes ago, Muhendis said:

I bought some 30W versions of these and found they were running off a 36v power supply which is totally incompatible with any of my on the shelf bits and pieces. With a bit of judicious snipping I have managed to make four 10W LED modules fit. When I get all the rest of the bits I will need I can run them at 24v and perhaps a little less out of consideration for the heat sink.

 

You might find these chaps useful.

https://www.lazada.co.th/products/i405736555-s787436625.html

Boost Converter DC to DC 10-32V to 12-35V Step Up.

[Muhendis]

3 hours ago, Crossy said:

 

You might find these chaps useful.

https://www.lazada.co.th/products/i405736555-s787436625.html

Boost Converter DC to DC 10-32V to 12-35V Step Up.

Yes they would be fine but they don't have cc/cv settings. My design uses two for each light. One high/normal power and the other at reduced power. switching between them is done by an IR proximity detector. The dc-dc converters are good for up to 5A and voltage up to 36v. Heat sink is recommended above 50W. At 62 Baht each, it's worth finding out if it does what it says.

[Tronx]

There are different types, some have CC.  This one is up to 50V.

[Tronx]

On 5/23/2021 at 5:58 AM, maxpower said:

 

Which for some hobbyists includes using well documented cheap Chinese microcontrollers. 

...

 

Reminder

This topic is about converting existing 220V LED lights to solar. Its an idea that on paper looks simple but in practice not always easy to find an efficient reliable solution. 

 

This is why we often find a set of reasonably well matched components and a simple control processor inside cheap Chinese solar lights.

 

Back to the hobby market ..

 

 

 

 

 

 

I've opened another thread  not to spam this one here too much. The question is: Which chinese controller would be suitable for hobbyists where we can save a few cent, but still get the quality we expect from "western" products.

Crossy's balancer  seems to be his only protection against over-discharge and over-charge. I agree that this is only a balancer, but it has features for battery protection. I'm using the same, but have not tested it's low voltage shut off, because these LiFePo4 are precious here in Europe, not 1$ like in Thailand. Therefore I put a ICL7665 circuit between battery and load and solar, which switches load off when all cells are at 3.0V or solar off at 3.55V.

Saying that you need to pay "a much better" charge controller is ok for big 100Ah cells, which cost a lot - and draws a few 10 mA quiescent current too. But here we need a cheap solution for 10 or 20 solar lights.

Can you propose a few reliable chinese microcontrollers, or clones with a reasonable price?