Battery monitor for portable amps etc.

[setmenu]

I thought this might be useful for those who rely on battery power.
The circuit is based around the LM3914N-1 10 LED bar-graph driver.

RV2 is used to set the lowest voltage that LED 1 is illuminated at.
RV1 is used to set the highest voltage that LED 10 is illuminated at.

Setting the range requires on first deciding the pack voltage to be used and
then studying the discharge curves of the cell to be used and deciding on
which voltage range will give the most useful scale.
I am using Nimh cells made by Sanyo, graphs can be found for them on their web site.
Unless one decides to plot ones own graph under the intended load, some
guess work is required as the Sanyo curves tend to be for higher loads than
would be used for our devices.
The curve appears to flatten out with a later steeper drop off when lightly loaded.
For my own 9.6v packs I have chosen a range of approx 9.9v-10.26v.
This should be OK.

Have fun

Setmenu

 

[Nisbeth]

Whoa, that's a very compact layout

Nice job!

/U.

 

[leftbldg]

Nice. How do you plan to enclose it? Is that a momentary switch on the backside?

 

[setmenu]

Thanks,
They are designed as in line units with the supply leads.
I am still waiting for some clear heatshrink tubing, but the part complete pics should give the idea.
The switch is a momentary action type, just needs a quick press to determine battery state.
Nice and visible day and night

Cheers

Setmenu

 

[setmenu]

Finished!


Setmenu