Help needed: AA 1.5v Low battery detection circute

[fmark]

Help needed: AA 1.5v Low battery detection circute
Hello,

I'm looking for help with Low battery detection circute please.

I have some device (home automation RF trigger, Insteon TriggerLinc) that is using single AA 1.5v battery.

I'm using it as a water leak detektor. Unfortunately this device does not have low battery indicator of any kind. Therefore when battery dies it becomes useless (being hidden behind dishwasher machine).

So I thought to build a low battery detection circute that will monitor voltage of the battery and if it drops to lets say 1.0v, it will trigger the device (by shorting its terminals) and therefore drawing my attention.

I searched the web and found this ics: MAX9060, MAX9061 or MAX6433, MAX6434, MAX6435.

Unfortunately I know very little about electornics (though I can solder). Looking at the datasheet I can not figure out wich of the above ics I need. They differ by 'Reset out' option.

Could somebody please help me to pick right IC and create circute to implement the idea?

Thank you!
Mark

 

[MrAl]

Hi,

You might be able to use the 9062, 9063, or 9064, but it partly depends on what voltage you want to trip at.
So what voltage are you looking to trip at?

 

[fmark]

Hi,

You might be able to use the 9062, 9063, or 9064, but it partly depends on what voltage you want to trip at.
So what voltage are you looking to trip at?

Hi ! I'm looking to trip at 0.9-1.0 volt

 

[alec_t]

Perhaps this? No IC used. Vary R1 to set the trip point.

 

[fmark]

Perhaps this? No IC used. Vary R1 to set the trip point.

Thank you! I'll give it a try.
A few questions please:

1. How do I calculate R1 value for the trip point ?

2. Should I connect Out and Ground from your circuit directly to the terminals of the TriggerLinc (**broken link removed**) or I need to build some additional circuit for this ?

Thank you

 

[alec_t]

1) Not easy to calculate because of variations in transistor Vbe. Trip point depends on R1 and R3. Simulation shows that, with the values given, Q2 begins to turn on when battery voltage drops to 1V. Increasing R1 (or reducing R3) increases the turn-on trip voltage.
2) I don't know, because the internal circuit of the TriggerLinc (TL) is unknown. My circuit will only work if one of the TL sensor terminals is connected internally to TL battery negative (-). It needs three connections :- (i) from Bat to the TL battery positive (+), (ii) from Ground to - , and (iii) from Out to the TL sensor terminal which is NOT connected directly to + or -.
Using a multimeter, can you detect if either of the TL sensor terminals is directly connected to TL battery + or - (I would expect it to be connected to one or the other. If it's connected to + then we can modify the circuit to cope.)?

 

[fmark]

1) Not easy to calculate because of variations in transistor Vbe. Trip point depends on R1 and R3. Simulation shows that, with the values given, Q2 begins to turn on when battery voltage drops to 1V. Increasing R1 (or reducing R3) increases the turn-on trip voltage.
2) I don't know, because the internal circuit of the TriggerLinc (TL) is unknown. My circuit will only work if one of the TL sensor terminals is connected internally to TL battery negative (-). It needs three connections :- (i) from Bat to the TL battery positive (+), (ii) from Ground to - , and (iii) from Out to the TL sensor terminal which is NOT connected directly to + or -.
Using a multimeter, can you detect if either of the TL sensor terminals is directly connected to TL battery + or - (I would expect it to be connected to one or the other. If it's connected to + then we can modify the circuit to cope.)?

Unfortunately I'm away from home now and can not test TriggerLinc with a multimeter. I'll do it when I return home .

Thank you again.

 

[alec_t]

Here's a revised schematic showing two versions. Version A is usable if one of the sensor wires connects to Bat- ; Version B if it connects to Bat+.
Note that R1 and R3 of my previous schematic have been replaced by a trimpot for setting the trip-point.

 

[colin55]

Turning the pots will blow up the transistor.

 

[colin55]

Use the principle of this circuit to produce a tone in a piezo diaphragm.
Remove the LED. Change 1u to 10n and put piezo diaphragm across the 33R. Use 1v5 supply
**broken link removed**

 

[fmark]

Use the principle of this circuit to produce a tone in a piezo diaphragm.
Remove the LED. Change 1u to 10n and put piezo diaphragm across the 33R. Use 1v5 supply
**broken link removed**

Thanks ! Do you mean that piezo diaphragm will make loud sound to notify me about low battery ? I'm actually looking for different notification option.
When I'm away from home, I want to be notified about water leakage. I have controller (ISY99) that monitors ToogleLinc terminals. If it gets triggered, my controller will send me an email.
In other words I'm looking for a solution that will 'close' terminals of ToggleLinc when battery is getting low or when water leak is detected.

 

[alec_t]

Turning the pots will blow up the transistor.

Colin is right. My bad. I should have included a 100k resistor between Bat+ and the top of Pot1 in Version A, and between Bat- and the bottom of Pot2 in Version B.

 

[harold777]

All good intentons, but I thought the available supply was one cell, ~1.5v?
OP really needs to define the options avaialable. . . a simple solution is probably the best - have you considered using a rechargeable battery and one of those plug-top PSU's - a simple current limiting Res would make this into a float charger, so there should be no issue with battery going low. You could charge several batteries (eg AA, or AAA) so there would be enough supply to operate a beeper. (But note Rechargeables are lower voltage, like 1.2 each). Ideally the cells should be soldered in series .. . .since bad-contacts are very likely in the rear of a kitchen appliance . . . and ideally the thing should be in a waterproof box.
Also I note you are seeking alkaline cct, yet suggest 1v as the cutoff . . . I think this is too low.

Frankly, for OP with limited electronics ability - it's such a minefield - Are you sure you can't buy this already made?

 

[fmark]

Hi! I did consider more simple solution like building 1.5v power supply. But with limited space behind dishwasher I don't have room for water insulated box etc.
So I'm trying to stay wireless.

That's true, my electrictronics abilities are limited. However I do like to solder and schematics created by alec_t and colin55 seems simple to me. Thanks

 

[colin55]

Replace the 33R with 10mH choke for loud output

 

[harold777]

I sense a nasty gooey mess with this one . . OP want to detect water leaks but won't waterproof the detector . . . Arrgh!

 

[ericgibbs]

I'm using it as a water leak detektor. Unfortunately this device does not have low battery indicator of any kind. Therefore when battery dies it becomes useless (being hidden behind dishwasher machine).

So I thought to build a low battery detection circute that will monitor voltage of the battery and if it drops to lets say 1.0v, it will trigger the device (by shorting its terminals) and therefore drawing my attention.

hi fmark,
What you are asking for, if I understand correctly, is a leak detector for a one of specific problem.?

Why not just fix the problem that could cause the leak.?

E.

 

[fmark]

hi fmark,
What you are asking for, if I understand correctly, is a leak detector for a one of specific problem.?

Why not just fix the problem that could cause the leak.?

E.

Thanks for your questions. Leak detector is needed for early prevention of a bigger water damage. I have leak detectors in bathrooms, laundry room and kitchen.
If leak is detected and I'm away from home, I can call and ask my neighbor to come to my house and shut the main valve.

I guess similar question would be : Why to have security system against fire/burglary ? Wouldn't it be easier to fix it ?

 

[4pyros]

Smoke detectors go on top. Leak detectors go on the bottom. Would not one at the low point be enough?

 

[ericgibbs]

Thanks for your questions. Leak detector is needed for early prevention of a bigger water damage. I have leak detectors in bathrooms, laundry room and kitchen.
If leak is detected and I'm away from home, I can call and ask my neighbor to come to my house and shut the main valve.

I guess similar question would be : Why to have security system against fire/burglary ? Wouldn't it be easier to fix it ?

hi Mark,
In your previous posts you have only referred to one device a 'dish washer', not the full house.

A security system is to prevent burglaries, a leak detector 'battery failure detector' will not prevent leaks, so I think your comparison is unfair.

Have you already had water leakage problems.??