Lead Acid Battery Voltage/ Current ripple?

[Hatimoooo]

Hello everyone!

I want to charge a Lead Acid Battery using an AC to DC converter.
I know the voltage ripple in the output AC/DC converter, but then I want to connect this converter to charge a battery using an inductor in order to filter even more.
The problem is that I can't calculate the voltage/current ripple after having the inductor connected.

The battery I am testing is a Yucel Y7-12, if that helps

Thanks a lot
Hatim

 

[betwixt]

Why do you need the inductor? The battery is almost totally immune to the effects of ripple and behaves like a very large value capacitor across the supply voltage anyway so ripple would be almost completely eliminated by it.

Brian.

 

[Genovator]

Inductor in series will help you in filtering high frequency noise. But to filter ripple, I think its better to use electrolytic capacitors in parallel. You will have a formula for calculating the resultant ripple after adding the capacitor....

dV= I/2fC

where dV is peak to peak ripple voltage,
I is load current, can be calculated by a multimeter
f is operating frequency
C is capacitor volume in Farads.

This way you can choose the best capacitor volume as per your need...

 

[Hatimoooo]

To betwixt:
I believe that what you wrote isn't a 100% right. I found already a model of a Lead Acid Battery somewhere else, but the capacitor is just a small part of it. The battery is mainly a Back EMF and some resistors and a capacitor. The ripple causes additional heat in the battery.

To Genovator:
Even if the voltage ripple is small, the current ripple can be very high because of the battery's behavior. That's why I'm using an inductor

PS: There are huge capacitors in the output of the AC/DC converter.

 

[treez]

The ripple causes additional heat in the battery

are you talking current or voltage ripple.
I am pretty sure that high frequency ripple current wont bother the lead acid battery.
Just make the acdc psu both current plus voltage regulated....then you can charge it constant current .........then do constant voltage at about 14V(?), then when the current tails off to 1% or whatever, then you do the constant trickle voltage.

 

[dick_freebird]

HF ripple may just pass through the plate stack and
put the heat on your source supply.

Many old-timey battery chargers are just a transformer
and half wave bridge rectifier. Major, low frequency
ripple there and not a problem (unless you boil it, which
is not about ripple).

 

[Hatimoooo]

Hello again
What I am talking about is low frequency ripple (150Hz). I believe it will be seen by the battery.
To treez:
If I have a voltage ripple, I should get a current ripple and vice versa. Am I wrong? So I'm talking about ripple (both of them because they are related)
To dick_freebird:
Thanks for the new info which makes me assured, I don't really have to be scared about the ripple then. But I think I need more infos about what you just said.

Thanks everyone for your answers. Hopefully the next answer will solve my problem.

 

[treez]

If I have a voltage ripple, I should get a current ripple and vice versa. Am I wrong?

...think of a buck converter, -the inductor is connected to the output voltage..........the output voltage has big caps and little volt ripple, but the buk inductor may have much ripple.
150hz ripple shouldn't be a problem for a battery

 

[FvM]

The problem is that I can't calculate the voltage/current ripple after having the inductor connected.

Apart from the point that a certain amount of current ripple isn't a problem for the battery, as said. You didn't tell anything about the power supply and it's output voltage ripple, so how should we help with the calculation?

How do you arrive at 150 Hz? Is ist a 3-phase half-wave rectifier? Any filter capacitors involved?

 

[Hatimoooo]

Hello again.
Yes FvM, I wrote before that there are huge caps in the output of the AC/DC converter.
The problem I am having is modeling the Lead Acid battery based on its datasheet, so that I can complete my filter calculations.
But from what everyone says, I shouldn't really worry a lot about it.
Thanks