Smart Battery Powered Circuit

[jtwrace]

I use a battery powered tube buffer. I would like to see if someone with much more knowledge than me is willing to take on this project.

What I would like is a circuit that will allow power from a DC battery and when the voltage hits a certain amount (say 10.0V) the battery charger will automatically start charging. Until then the charger is out of the circuit.

I use the US 800 CTek brand charger just in case anyone cares.

Any takers?

[Atilla]

A small sense circuit, with a relay to connect/disconnect the charger. That one shouldn't be a big issue, the problem is how to find out when to disconnect it.

There should be a battery charger controller that does all that however. I've seen quite a few, but since I never used any of them, I can't remember specific features or models. Any ideas?

[Lee Knatta]

Ok, you use a lead/acid battery.

Like Attila pointed out this shouldn't be too complicated to build or even be available ready made.

I remember I designed a very simple circuit for a similar application. In my case the voltage should me monitored and the PSU only switch on after the source voltage exceeded a certain value for some time and instantly turn off in case of power loss.

You need it work vice versa:
A circuits that activates the charger for the case the voltage is below a certain threshold for a certain time and turn off exceeding a certain voltage for a certain time. In this case sensing the charger current could make much more sense but the circuit doing this will be confused by the desulphation process since the current alternates all the time.
I had a look at the data sheet of the charger and suggest better not to use the amp while charging. Especially during the desulphation process the voltage will change very often what might be audible or even damaging to you amp circuit. I don't know the circuit. What is a tube buffer? I thought tubes work at several hundred Volt...?

Best Regards,
Lee

[Atilla]

Low-voltage tubes meant for car use maybe?

[jtwrace]

Originally Posted by Lee Knatta

Ok, you use a lead/acid battery.

Like Attila pointed out this shouldn't be too complicated to build or even be available ready made.

I remember I designed a very simple circuit for a similar application. In my case the voltage should me monitored and the PSU only switch on after the source voltage exceeded a certain value for some time and instantly turn off in case of power loss.

You need it work vice versa:
A circuits that activates the charger for the case the voltage is below a certain threshold for a certain time and turn off exceeding a certain voltage for a certain time. In this case sensing the charger current could make much more sense but the circuit doing this will be confused by the desulphation process since the current alternates all the time.
I had a look at the data sheet of the charger and suggest better not to use the amp while charging. Especially during the desulphation process the voltage will change very often what might be audible or even damaging to you amp circuit. I don't know the circuit. What is a tube buffer? I thought tubes work at several hundred Volt...?

Best Regards,
Lee

Lee

Here is my tube buffer: DODD AUDIO DIY

I'm asking more for someone to design the circuit. That's not my bag.

I currently leave the charger on the 12V battery now. Dodd says it's not an issue at all. So far so good. No issues.

[Lee Knatta]

Ok, I see. It's a preamp that uses tubes and has gain=1, right?

I wonder why it is battery powered. Since you leave the charger on all the time it isn't for mobile use, right?

I have no idea what the charger will do with the battery connected and power taken from the battery/charger.
It would be difficult for me to develop a circuit as described without the charger at hand.

Obviously it works well. Thus I wouldn't change it.

[jtwrace]

Originally Posted by Lee Knatta

Ok, I see. It's a preamp that uses tubes and has gain=1, right?

I wonder why it is battery powered. Since you leave the charger on all the time it isn't for mobile use, right?

I have no idea what the charger will do with the battery connected and power taken from the battery/charger.
It would be difficult for me to develop a circuit as described without the charger at hand.

Obviously it works well. Thus I wouldn't change it.

The buffer has NO GAIN.

Not for mobile use...for my 2 ch system.

I would just like to have a self contained unit for my AGM battery and charger that I don't have to worry about. I'm a bit over the top.

[richie00boy]

What you need is a comparator with hysteresis so that once it kicks in the cut-off threshold changes. Hope that helps trigger a design.

[nat8808]

Originally Posted by jtwrace

The buffer has NO GAIN.

Not for mobile use...for my 2 ch system.

I would just like to have a self contained unit for my AGM battery and charger that I don't have to worry about. I'm a bit over the top.

No gain is the same as saying Gain=1 .. i.e. the ratio between the input signal and the output signal is of 1:1 .

Just wanted to point out that Lee Knatta was correct in saying that.