# [sdiy] I’m Looking for a simple circuit that simulates this type of battery (12V 9AH)

Jean-Pierre Desrochers jpdesroc at oricom.ca
Mon Jul 3 01:03:15 CEST 2023

```Just put a big power resistor or rheostat in parallel with the bench power supply. This load will act to sink the current from the charger and stop it driving up the terminal voltage of the power

supply. Using a bench power supply to model a battery will fail without this parallel resistance to absorb the power because the power supply can't absorb energy itself. At a pinch something

like a car headlight bulb will probably suffice as the load if you haven't got a suitable rheostat at hand and don't want to test with an actual real battery!

I thought about doing that but was hesitating ..  I’ll give it a try !

I'm guessing you just want to check the charging current sourced by the charger for various different "battery" terminal voltages?

I  want to check the ‘threshold’ voltage from where the charger will START charging (around 10V I guess – Zener D6)
and the battery voltage that will signal the END of charging (around 13.6V or more I guess – Zeners D7+D8).

A battery voltage of around 10VDC or less will keep the charger from charging the battery.

That’s what I’ll test..

De : Richie Burnett <rburnett at richieburnett.co.uk>
Envoyé : 2 juillet 2023 17:36
À : Synth-diy at synth-diy.org; Jean-Pierre Desrochers <jpdesroc at oricom.ca>
Objet : RE: [sdiy] I’m Looking for a simple circuit that simulates this type of battery (12V 9AH)

Just put a big power resistor or rheostat in parallel with the bench power supply. This load will act to sink the current from the charger and stop it driving up the terminal voltage of the power supply. Using a bench power supply to model a battery will fail without this parallel resistance to absorb the power because the power supply can't absorb energy itself. At a pinch something like a car headlight bulb will probably suffice as the load if you haven't got a suitable rheostat at hand and don't want to test with an actual real battery!

I'm guessing you just want to check the charging current sourced by the charger for various different "battery" terminal voltages?

-Richie,

---- Jean-Pierre Desrochers wrote ----

Hi list,

I have a battery charger circuit that I need to fix and do some tests on..

It is supplied from a 15VDC (22VDC actually) at 1.2amp and its job
is to charge a 12VDC 9AH battery for a small CRATE TAXI TX-50D portable guitar amplifier.

Its battery is done with a very high ESR value.. No recharging possible.

Now before I go buy a new one I’m Looking  for a simple circuit that simulates this type of battery (12V 9AH)

And will be connected to the battery terminals of my charger..

Any clue what this circuit would look like ?

Here is my charger schematic section :

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