Do these low voltage battery alarms work on Lead Acid

[TobyQuest]

Hi,

After having a flat leisure battery and recentlyreplacing the leisure battery and engine battery im anxious about over-discharging them.
I came across this neat gizmo today which is an screen that shows the voltage and has an alarm that you can set to go off when the battery is discharged to a certain level.
http://rover.ebay.com/rover/1/710-5...0001&campid=5338547443&icep_item=283708656975 Batery alarm gizmo

Not sure if the link will work but if you go on ebay and search "LED Low Voltage Alarm Buzzer Indicator Checker Lipo Battery Tester RC " you will find it.

Question is: is it suitable for lead acid batteries or only Lithium ones? If not,why not?

 

[tonyidle]

Only Lithium. Look at the voltage settings for the alarm.

 

[TobyQuest]

Yeah I saw the settings but I've seen a you tube video where a guy recommended using it for his Motorhome. He said wow it costing the 1 cell option rather than several smaller cells and it works.
Just personally unsure if the different battery chemistry affects this things ability to function properly

 

[Taran_Las]

Alarm set value range:OFF~2.7~3.8V

Not going to help much with Lead acid batteries.

 

[TobyQuest]

The gadget is used for hobbyists who have remote control helicopters, drones etc with multiple small battery cells. 5x2.7v is 13.5v.
It can be wired as a single cell rather than 5 smaller ones, so if the voltage is 13.5v and set to buzz the alarm at 12.2 it would be fine.

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[tonyidle]

The gadget is used for hobbyists who have remote control helicopters, drones etc with multiple small battery cells. 5x2.7v is 13.5v.
It can be wired as a single cell rather than 5 smaller ones, so if the voltage is 13.5v and set to buzz the alarm at 12.2 it would be fine.

That makes more sense - not immediately obvious from the description. There are however more obvious solutions - like this for example:

https://rover.ebay.com/rover/1/710-...0001&campid=5338547443&icep_item=401450840087

 

[Richard n Ann]

You could easily make a small alarm with a zenor diode or piezo sounder ?
Something like this...

Broken Link Removed

I could make it and send it you after the lock down ?

 

[Richard n Ann]

Or this one looks better, it will switch on and off cleaner.

IC 555 Low Battery Indicator Circuit – Homemade Circuit Projects

www.google.co.uk

Got some TS555s in stock ?

 

[TobyQuest]

Thanks for the info. I dont know anything baout electronics so ill give that a miss, but i have ordered one off that link.
It looks like maybe it doesnt get its power from the positive and nagative battery feed but instead from its own watch battery. Is that the case?
And presumably once it gets to a low voltage the alarm rings and continues to ring until it gets above that voltage so i think probably a switch will need to be added so i can turn it off once the alarm rings

 

[Richard n Ann]

Think I'll make one and see how well it works.
Got time on my hands for the next few weeks ?

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[thebriars]

Why go through all that faff when one of these simply plugs in, and tells you the actual voltage £3.58 inc postage:

https://www.ebay.co.uk/c/524745502

 

[Richard n Ann]

Much more satisfying to make one, it can have a piezo sounder for when you're not paying attention ?

 

[Richard n Ann]

Made this and it works OK, I've set it to come on at 11v but the blue component adjusts the set point.

Just a quick prototype...

 

[pappajohn]

Made this and it works OK, I've set it to come on at 11v but the blue component adjusts the set point.

Just a quick prototype...

View attachment 374059

You must have a surplus of veriboard.
Could have got all that on a quarter that size.

 

[Richard n Ann]

You must have a surplus of veriboard.
Could have got all that on a quarter that size.

Yes got loads ? that's just an off cut.

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[thebriars]

Much more satisfying to make one, it can have a piezo sounder for when you're not paying attention ?

When one did that for a living it loses much of the satisfaction.