[Reyden]

 Сообщение от bosti :

You mean LiFePO4?

Yep.

 Сообщение от bosti :

So I often had to buy CR123 batteries to run instead of the 18650.

How many celsius degree outside when you use batteries in winter? That's an issue because it's not allowed to charge batteries when temperature below 0C. Good Li-ion or LiFePO4 are always better than cr123.

If you're interested read my old topic.
http://budgetlightforum.com...

[AEDe]

 Сообщение от bosti :

I often had to buy CR123 batteries to run instead of the 18650.

You can discharge 18650 as well as CR123. And you can not recharge 18650 as well as CR123 at very low temp. the price 2*cr123 is about price of good 18650. So where is the profit to use cr123?

[bosti]

 Сообщение от AEDe :

Where is the profit of cr123

Profit is that 100% charged CR123 I can find in shops, for 18650 I'm lucky if I find at all.
And sometimes I go for long times so I cannot bring a box of 18650 with me.
Also 18650 will self-discharge much more than CR123.

 Сообщение от Reyden :

How many celsius you can use in winter?

Sometimes up to -35 depending on where I am.

Regarding your panel charging sorry but I still cannot understand, how can panel output 5V (assuming) > 3.6V 18650 > 5V Buck > 3.6V? Cellphone be efficient?
More efficient is 5V (solar) > 3.6V? Cellphone...

Ok I probably misunderstood something because reading your page you have put much more thought in this than me

[AEDe]

 Сообщение от bosti :

CR123 I can find in shops, for 18650 I'm lucky if I find at all.

In Russia you have no chance to CR123 as well as 18650 far from big cities...

 Сообщение от bosti :

Also 18650 will self-discharge much more than CR123.

Is your go for years?

[bosti]

 Сообщение от AEDe :

In Russia you have no chance to CR123 as well as 18650 far from big cities...

That is good to know! I can find them here in europe.
Recharging in sub-zero temperatures is still a problem then, I will have to continue my research with thermo-electric charging, possibly a solution also to cold batteries.

 Сообщение от AEDe :

Is your go for years?

No but after several weeks they seem to loose power.

[Witchdoctor]

 Сообщение от bosti :

after several weeks they seem to loose power

Nope if you're using some quality cells like Samsung 18650-35E, Panasonic 18650GA, LG MJ1 and so on. Even several months is not an issue.

 Сообщение от bosti :

Recharging in sub-zero temperatures is still a problem then

Can't think of such a realistic case despite going outdoor in the cold pretty often. Were there is power for charging, it's usually at least above zero.

[bosti]

 Сообщение от Witchdoctor :

Even several months is not an issue.

I had my fenix cells and samsung 26F perform quite worse than the cr123, so it seemed to me.
Maybe I will try better cells and without pre-conceptions..

 Сообщение от Witchdoctor :

Can't think of such a realistic case despite going outdoor in the cold pretty often. Were there is power for charging, it's usually at least above zero.

Sometimes I am out several weeks in the cold without a >0 degrees shelter.
That is a reason I am interested in developing the seedback charger because the fire could can keep the cell warm.

[Reyden]

I would recommend you to read this topic about using Li-on in winter. There are lots of interesting tips.
https://forum.fonarevka.ru/...

 Сообщение от bosti :

Also 18650 will self-discharge much more than CR123.

Basicly self discharge is not an issue. Li-ion doesn't lose capacity at subzero temperature but available capacity is reduced. Restored while temperature is rising.

 Сообщение от bosti :

Sometimes up to -35 depending on where I am.

Try to find techniques how to charge li-ion safely on -35C. You can put the battery in your pocket closer to the body heat etc.

 Сообщение от bosti :

Regarding your panel charging sorry but I still cannot understand, how can panel output 5V (assuming) > 3.6V 18650 > 5V Buck > 3.6V? Cellphone be efficient?
More efficient is 5V (solar) > 3.6V? Cellphone...

Look, solar panel as well as seedback charger has its own efficiency depending on the load. Your charger can decrease efficiency of harvested power especially while changing weather conditions. That's why smart charger matters. As a rule cell phone loses in charging efficiency, it overloads the panel when there's not enough power to supply the load.

 Сообщение от bosti :

That is a reason I am interested in developing the seedback charger because the fire could can keep the cell warm.

https://www.amazon.com/Powe...

[bosti]

Interesting thread thank for pointing that out! Maybe mine was just pre-conception.
I think I will do some testing too now.
I have kept cells under my coat in the winter always warm and still found they lost charge quickly when exposed to cold in the flashlight, maybe just need to warm them up again..

 Сообщение от Reyden :

Try to find techniques how to charge li-ion safely on -35C. You can put the battery in your pocket closer to the body heat etc.

Yes with powerbank I charge at night inside the sleeping bag, but fire charging gives more possibilities, and if fire dies and cell gets cold, charging also stops. I will develop more after the summer when the need will arise, now the sun is shining
But I have much to study as I start to see it's not that obvious with charging.

Sadly I am at quite a low level in electronics, I can do little projects I have some tools but always following instructions, on my own I am often lost.
Hell I burnt my charging board of fenix hp25r with stupid self made adapter circuit contraption.

But thank you I appreciate very much all the very informative pages I can read here!

[Reyden]

 Сообщение от bosti :

But thank you I appreciate very much all the very informative pages I can read here!

Watch this video, I made it in a far 2016. There's the driver demonstration and translated description. I want to install it in Panda 3R for each led.

Прямая ссылка на видео YouTube

[bosti]

Yes I saw it, great project man I really really like it! I just wish I could be of help developing such things.
Sad truth is that I'm having trouble just with this simple stuff ;_;

[Reyden]

 Сообщение от bosti :

Sad truth is that I'm having trouble just with this simple stuff

What's the issue? Detailed description would have helped to understand what do you want to implement.

[bosti]

It's a dummy load to keep powerbank alive while draining low power, to power headlamp in low mode.
I built it but it does not keep alive, even changed resistor value to my powerbank but no.
I changed r1 to 28 because my battery needed that to keep alive. But still, it powers on if I insert it but then after 5 seconds it's off again.

And In the many time I unsolder-resolder I managed to mess it up and burn the flashlight board.

I don't really know what the problem is, now I should re-build it but breadboard-like because first time I went straight for the pcb being too sure of myself, which makes troubleshooting quite hard.

[Reyden]

 Сообщение от bosti :

It's a dummy load to keep powerbank alive while draining low power, to power headlamp in low mode.

Why your power bank is not able to handle light load and you need this scheme? I still don't understand the necessity of this. You was trying to charge flashlight, i got it.

[bosti]

Powerbank shuts off if current is less than ~150mAh.
So to use flashlight (and other electronics like a mini router for example) on low power mode I need higher load, this circuit is supposed to pulse a higher load to keep powerbank alive and not use much power in the process.

[Reyden]

bosti if I were you, I would make step up dc-dc converter and connect it directly to the power bank li-ion batteries. At low load currents the converter enters Power Save (PFM) mode to maintain a high efficiency, it can handle your load. Modern dc-dc converter will solve your issue, look at TPS61235 or TPS61032 etc. The solution that you offer is half measures.

[bosti]

 Сообщение от Reyden :

bosti if I were you, I would make step up dc-dc converter and connect it directly to the power bank li-ion batteries. At low load currents the converter enters Power Save (PFM) mode to maintain a high efficiency, it can handle your load. Modern dc-dc converter will solve your issue, look at TPS61235 or TPS61032 etc. The solution that you offer is half measures.

Thank you for the models! I surely will get into those.
But one problem is that I always need access directly to batteries, where not always the case.
With the dummyload I can just plug into any powerbank and immediately have low power, high efficiency does not matter so much in this case when draw is < 150 mAh on a 20000 mAh powerbank.

Oh but wait those converters say they support only one cell? Have you used for multiple?

[Reyden]

 Сообщение от bosti :

But one problem is that I always need access directly to batteries, where not always the case.

May be it's worth to replace your power bank to a new one that match light load requirements.

 Сообщение от bosti :

Oh but wait those converters say they support only one cell? Have you used for multiple?

It's for a single Li-ion or several in parallel.

[bosti]

 Сообщение от Reyden :

May be it's worth to replace your power bank to a new one that match light load requirements.

Yes that's the cleanest option, but since I already have 2 I wanted to get by by just buying a 555 chip

 Сообщение от Reyden :

It's for a single Li-ion or several in parallel.

That will come much useful I believe!

[Reyden]

bosti, I've never used such scheme before. Try to check all the components especially C1 - tantalum capacitor which has polarity.