Wireless alarm - Batteries

[beatts]

Hi,

I have a wireless house alarm and decided to change the batteries this weekend as they need changing every two years apparantly.

However, the manual states the batteries should be Alkaline only as other high powered batteries can cause the alarm to malfunction.

Why is this the case. I have a mix of batteries in my garage, none are alkaline unfortunately they are all either Zinc Carbon or Zinc Chloride so I assume I cannot use these!

Surely voltage is voltage?

 

[JohnD]

zinc-carbon is a poor quality battery, and zinc-chloride is not much better. The capacity and stoirage life are poor. An alkaline cell is supposed to have 3 to 5 times more capacity.

however you can buy alkaline batts in quantity by reputable makes on Ebay. I bought a stock of Memorex batts at a very good price. Have a look.

 

[yaleguy3]

I buy AAA from Maplin and they work very well.

If its a Yale alarm then there a couple of a reasons not to use high power Alkaline or lithium batteries.

one reason is . . . if a normal battery lasts 2 yrs then a high power battery may last four. This is a long time for a battery to be in place and could lead to leakage and acid damage.

The other reason is the shape of the positive electrode end.
On some 'copper topped' or other high power batteries.

The electrodes (the raised bump) are slightly bigger in diameter in the batteries with the ability to produce more power.Presumably so they can transmit that high power in high drain scenarios with less resistance.

Unfortunately this can mean they do not fit the battery holder properly in the Yale sensor.

This can have two effects.

The first is that the circuit is not made and the sensor may be made inactive.... not what you want with a burglar alarm (always ensure you press the test/learn button after changing batteries to make sure the red led lights up and proves the sensor is working)

The second and potentially even more dangerous is that with a poor connection the resistance of the circuit is very high and this can lead to the batteries overheating and potentially exploding.

I had one sensor where the battery wasn't correctly installed during fitting and when I took it apart to resit the batteries they were really really hot , too hot to touch with your fingers.

You know the more I have learnt about the DIY system the more I am convinced in terms of system planning and installation that even they need someone experienced to install them. Even if its only to prevent a novice without training on a ladder with a drill.

 

[JohnD]

... with a poor connection the resistance of the circuit is very high and this can lead to the batteries overheating and potentially exploding....

with respect to your knowledge of alarms, but:

a high-resistance connection will lead to lower current flow, so will not cause overheating

Overheating might be caused by a short, or sometimes by putting one or more of the batteries in the wrong way round. In either case the device will not work.

 

[yaleguy3]

... with a poor connection the resistance of the circuit is very high and this can lead to the batteries overheating and potentially exploding....

with respect to your knowledge of alarms, but:

a high-resistance connection will lead to lower current flow, so will not cause overheating

Overheating might be caused by a short, or sometimes by putting one or more of the batteries in the wrong way round. In either case the device will not work.

The device was working so none of the batteries could have been the wrong way round or the circuit couldn't have been shorted.

A high resistance connection would lead to the creation of heat due to the friction of the electrons flowing through the 'bottleneck' while attempting to supply the required voltage.

I did learn reistance and heat in relation to circuit , socket and appliance testing with 17th ed testing equipment.

I am speaking from practical experience.
I suspect it won't be long before someone else more qualified than myself will point out that high resistance = heat.

 

[JohnD]

high resistance = low current

 

[ericmark]

Some systems cheat. The one I found to my cost is with camera flash guns where when they flash for a very short amount of time the short the battery. Use of batteries able to deliver high amps burns out the electronics. Not likely a problem with alarms but I have never reverse engineered one.

Rechargeable batteries have a lower voltage than non rechargeable so using them often triggers the low battery alarm.

Some batteries do explode this shows one that exploded inside my mouse.

Mouse 4

• ericmark
• 11 Dec 2009
• 5

As well as exploding the shelve live varies and of course one does not want a battery to leak.

As to heating up there are two reasons why a battery will heat up. One is drawing too much current. The other is a bad connection. Although to draw enough current from a battery for a bad connection to cause them to overheat it needs to be quite a high current draw anyway. With AA or AAA batteries it would need re-chargeable batteries to be able to draw enough current for a bad connection to cause it to heat up. Primary cells could not deliver enough energy has to be a secondary cell. As we get to D cell size then you could draw enough current but unless for very short time it would still discharge the battery too quickly.

For a battery to last 2 years if it was 1Ah then current draw is approx 0.06ma there is no way this can ever cause a contact to heat up.

The positive post size has been used by some manufactures to differentiate between standard and fast charge re-chargeables. Zinc carbon batteries often have a conducting side. but this is down to manufacture and unless it stated a manufactures part number one could never guarantee post sizes so unlikely this is a factor.

Likely hood of leaking could be why. Although to stipulate leak proof would seem better.

Where a high current for short time is used the internal resistance of the battery could mean cheaper batteries could not maintain the voltage.

But still think shelf life is likely the reason.

 

[yaleguy3]

Thank you for your technical input which does match my practical experience.
I am then at a loss as to how the batteries in the sensor heated up enough to be literally too hot to handle despite being fitted correctly and the sensor working normally ie no short circuit.

Would the fact that the batteries are in series meaning they are producing 4.5 volts for the circuit rather than 1.5 volts make a difference to their ability to overheat due to a poor contact in the circuit?
Some batteries do not work within the Yale sensors and this is down to the post size of the positive electrode.
I have never used rechargeable batteries due to their cost and undetermineable lifespan.

 

[ericmark]

Putting any batteries together will of course increase the heat they can produce. And where you are I seem to remember when in Hassi R'mel is warm anyway so it would not take much to get to a point where problems are found.

Any battery will tend to have a quicker chemical reaction as it warms up. For lead acid batteries we used a lower concentration of acid to compensate for this but with mass produced primary cells sold world wide this is not really possible.

It has been nearly 30 years since I was in Algeria but I expect you have to use locally made batteries Sona something if anything like when I was there? In which case I would just reduce to time used to one year instead of two.

It is of course easy in UK to say get the right battery but your not in UK. Even when you do buy batteries with a good name you have no idea if really made by the people on the label so if they physical fit then use but reduce time in device. Which in that heat would be good idea anyway.

I suppose if you need alarm you must be on coast as in the desert they seemed very trustworthy so maybe only 90 deg F but still quite hot.

Things must have changed as in my time no Maplin in Algeria. As to UK then can't see any reason not to use recommended batteries.

 

[yaleguy3]

My apologies I am not from Algeria it was just the first place I clicked at the top of the list.

But your insight into North Africa was great.
Had a holiday in Tunisia once . . . dodgy drivers , homicidal jellyfish and perverted locals.
never been back.