Aritech CS350 alarm - Low battery warning - success

[netdudeuk]

Hi

I had this warning on the keypad LCD a while ago and replaced the lead acid battery with the same type.

However, the alert remained even after giving the system time to charge the new battery.

I don't see anything obviously wrong with it and I can't find any schematics online.

Any ideas please ?

Thanks

[JFJ]

One possibility is that the battery fuse (F1) might have blown. Supplying a constantly high charge current to the old, faltering, battery may have killed the fuse, or stressed it to the extent that the new battery's inrush current finished it off.

[netdudeuk]

Thanks.  I'm pretty sure that I've already checked the fuses but I'll double check.

[netdudeuk]

So it has thanks.

Here's the fuse (20mm) with this text on it.

T2AL250V

Is this the correct replacement part ?

https://www.maplin.co.uk/p/2a-time-delay-glass-20mm-fuse-10-pack-gl62s

Thanks

[netdudeuk]

I have a RC battery charger.

While I'm waiting for the fuses, I thought that I may as well start charging the replacement battery again, which is basically flat.

I've got about five hours before I would fit it into the panel.

Obviously we're talking 12 volts but what rate would you charge it at ?

I found an email that I sent to the seller of the replacement battery.  It said 'I have previously replaced the battery in our alarm a couple of times with no issues but I installed yours today and although everything looked ok initially and the Low Battery warning disappeared, the alarm sounded after about an hour and the keypad did not illuminate or respond to key presses.  I disconnected the new battery and reconnected the old one and someone was able to reset the alarm with the keypad. I don't know when the keypad started working again as I was nowhere near it when the code was entered.', if that gives any clues as to what originally happened ?

Thanks

[netdudeuk]

I have a RC battery charger.

While I'm waiting for the fuses, I thought that I may as well start charging the replacement battery again, which is basically flat.

I've got about five hours before I would fit it into the panel.

Obviously we're talking 12 volts but what rate would you charge it at ?

I found an email that I sent to the seller of the replacement battery.  It said 'I have previously replaced the battery in our alarm a couple of times with no issues but I installed yours today and although everything looked ok initially and the Low Battery warning disappeared, the alarm sounded after about an hour and the keypad did not illuminate or respond to key presses.  I disconnected the new battery and reconnected the old one and someone was able to reset the alarm with the keypad. I don't know when the keypad started working again as I was nowhere near it when the code was entered.', if that gives any clues as to what originally happened ?

Thanks

Ok, so I found the charging rate on the battery in the small print.

However, although the leads are not open circuit and the battery contacts are pretty clean, the charger gives me the CONNECTION BREAK error.

If it would help to have the battery with some charge in it before I fit into the panel and I cannot get the battery charger to work, I suppose that I could use my DP832.  However, I've seen plenty of people on here blowing up their PSUs (including the DP832) when attempting to charge batteries/

[JFJ]

Is this the correct replacement part ?

https://www.maplin.co.uk/p/2a-time-delay-glass-20mm-fuse-10-pack-gl62s

Yes, the Maplin fuse should be fine.

Obviously we're talking 12 volts but what rate would you charge it at ?

The recommended constant voltage for charging a sealed lead acid battery varies with temperature (and from manufacturer to manufacturer). At 20°C, the standby/float charge voltage should, typically, be 2.26V to 2.31V per cell or 13.56V to 13.86V for a 12V battery. To prevent battery damage during charging (e.g. from excessive gas production), the charge current should be limited to less than a quarter of the battery's capacity (Ah/4).

'I have previously replaced the battery in our alarm a couple of times with no issues but I installed yours today and although everything looked ok initially and the Low Battery warning disappeared, the alarm sounded after about an hour and the keypad did not illuminate or respond to key presses.  I disconnected the new battery and reconnected the old one and someone was able to reset the alarm with the keypad. I don't know when the keypad started working again as I was nowhere near it when the code was entered.', if that gives any clues as to what originally happened ?

Is there a date code on the battery?

If the new battery was old stock (left on the shelf for a long time without a top-up charge), lead sulphate crystals could have formed on its plates - acting as a barrier to recharging. Initially, that would cause the charge current to be very low and the charge voltage high. That would be perceived by the alarm's controller as a fully charged battery (hence, the warning disappeared). As the resistive sulphation layer broke down, the charge current would increase. Unless your alarm's controller has the means to limit that current, the flat battery might have drawn sufficient current to starve the keypad, and other parts of the alarm system, of power.

A battery that has suffered mild sulphation can, usually, be recovered by charging it at higher voltage for 12 hours - with the current limited to one tenth of the battery's capacity.

... I suppose that I could use my DP832.  However, I've seen plenty of people on here blowing up their PSUs (including the DP832) when attempting to charge batteries/

You could protect your power supply by fitting a diode in series with its output. The charge voltage would need to be increased by the magnitude of the diode's forward voltage drop.

[netdudeuk]

Thanks for the reply.

I have those fuses coming tonight.

So, I actually have two suitable batteries.  I've have had them both for three years.

One battery (Challenger AA61 - initial current <0.6A) has 090710S stamped on the top.

The other, an Ultra Max NP2.3-12 (initial current 0.35A), has 1205 stamped on the top.

Will the following process charge the Ultra Max NP2.3-12 battery without damaging either it or the PSU ?

On the Rigol DP832, enter 13.9V (which gives a no load 13.6V on the end of the diode with a DMM) on one of the outputs
On the Rigol DP832, enter 350mA for the same output
Connect a 1N5408 diode to the positive terminal of the PSU with the ring on the opposite end
Connect the end of the diode with the ring to the positive terminal of the battery
Connect the negative terminal of the PSU to the negative terminal of the battery
Switch on the PSU output
It would start off as CV.

Thanks again.

[JFJ]

Will the following process charge the Ultra Max NP2.3-12 battery without damaging either it or the PSU ?
...

Provided that the battery is in good condition, your setup should charge it without any problems.

As the capacity of the Ultra Max NP2.3-12 is 2.3Ah, the maximum charge current should be no more than 575mA (at 350mA, it will just take a little longer for the recharging to complete). If the battery is flat, your power supply will start off in constant current mode, and switch to constant voltage mode when the set 13.9V is reached. Once the charge current drops to under, say, 10mA, you could consider the battery to be charged, but it would do it no harm leave it on charge for longer.

If the battery has suffered sulphation while flat, then you may need to limit the current to 230mA, wind the voltage up to whatever level is necessary to achieve that current and charge it for 12 hours.

One advantage of using a regulated bench power supply to recharge batteries is that there shouldn't be any significant ripple on the output voltage. Thereby, avoiding the risk of overcharging the battery. When I recharge batteries that way, I usually switch the power supply output on before connecting the battery, and disconnect the battery before switching off. It's just as a bit of extra protection for the power supply (in case the diode failed as a short circuit). A sealed lead acid battery shouldn't leak any hydrogen or oxygen gas, so a small spark during connection isn't going to cause an explosion.

[netdudeuk]

Many thanks for the detailed reply.

Would it definitely be better to get the battery charged to some extent before putting it in the panel ?

[netdudeuk]

I kicked off the charging this morning.

A DMM across the battery shows 13.36 volts with the DP832 showing 13.795 volts.

However, the DP832 is in CV mode and only shows 1mV ?

[JFJ]

... with the DP832 showing 13.795 volts ... the DP832 is in CV mode and only shows 1mV ?

Should that read "only shows 1mA"?

If so, then the internal resistance resistance of the flat battery must be very high (probably because of sulphation), and you will need to drastically increase the BP832 output voltage, in order to force a reasonable charge current through the battery. The battery may, however, be beyond recovery.

[netdudeuk]

... with the DP832 showing 13.795 volts ... the DP832 is in CV mode and only shows 1mV ?

Should that read "only shows 1mA"?

If so, then the internal resistance resistance of the flat battery must be very high (probably because of sulphation), and you will need to drastically increase the BP832 output voltage, in order to force a reasonable charge current through the battery. The battery may, however, be beyond recovery.

Yes, mA, my mistake.

I think I'll pick up a new battery as both of them went the same way.

I really appreciate your help thanks.

Let's see what happens when I put in the new one tonight.

[netdudeuk]

I bought a new battery, removed the old one and then inserted a new fuse.

It worked as it should from them on.  Hopefully, a day and a half later, it should now be good for a while.

Many thanks to JFJ for his multiple detailed replies.