Battery charger - power supply issue affecting ADC

[Acetronics2]

I'm searching for this ELEKTOR info - but seems to be available only for members... Still looking for it.


I assume it will be better to use a MOSFET, no?

Hi, Roger

Here : http://www.elektor.fr/magazines/2001...1).65895.lynkx

a P mosfet will be easy to use ... a N Mosfet a bit harder ...

But there's some more investigation to do with your circuit before throwing it to the wastebox ...

Alain

[Ioannis]

I repeat again that, your final design might look like a Linear Power Supply.

As such, a NPN pass transistor is the usual choice. The transistor acts like a voltage follower, so whatever voltage is present at the base, that voltage-0,7 is presented at the emitter, with current amplification of course.

Ioannis

[Acetronics2]

Hi, Ioannis

just have a look to the NS Datasheet of the LM 350 page 10 ... there is a very simple Pb batt charger design ... easily usable with the 317 or 338 ( Paper datasheets included it in the 1982 Databook release ...).
fits the I - V charging method ... Roger looks for ...

But do not tell Roger ... he is a friend ...

Alain

[Ioannis]

Hi Alain. Between us, yes there is a simple charger and many more everywhere!

But Roger is looking for something to be controlled by his darling PIC. So, I can understand him trying to emulate a pot with an electronic pot. But this is not going to work as he is expecting... But don't tell him either! He is a friend and might be hurt!

Ioannis

[Acetronics2]

Hi, Ioannis

Let's be honest ... It CAN work ...

but it will ever be for his own pleasure ... and impossible to sell .

the BTI CCS 9620 SL is the living proof it can work ... It's a dedicated Pic !!! ( probably 16HV xxx )


Always the same : Amateur or pro ... solutions are not the same !!!

Alain

[Ioannis]

I agree Alain. I usually think on terms of reliable commercial product, that is well in the middle of the specs.

It can work with little tricks and magic, but I won't trust it. Especially with the lead batteries!

On the other hand the idea of the linear power supply is so simple... And prooved reliable.

The Pic will only have to create the Vref and then a comparator will adjust the base voltage of the pass transistor. Thats it!

Ioannis

[Acetronics2]

He,he

You just forgot the Battery tempco compensation ...

( -20 mv/ cell / deg C ... to be verified ! )

seriously ... a High end Lead Acid Charger is a piece of cake !!!

Alain