Arlo battery charger dead?
I'm pretty sure my Arlo battery charger has stopped working, even though it's LED does come on green. When I measure the voltage on the plug, I get near zero volts, though I expect around 12.
Could anyone with the Arlo battery charger just measure this (without the battery attached, of course)?
The long story of this is that the motors became intermittent, I started to investigate, found the 12V SLA batteries were only 5.8 volts. Plugged in the charger, found it odd that the LED stayed green. Then measured the charger.
So I think the battery charger has gone dead, which is why my SLA batteries aren't at voltage.
buddy
Could anyone with the Arlo battery charger just measure this (without the battery attached, of course)?
The long story of this is that the motors became intermittent, I started to investigate, found the 12V SLA batteries were only 5.8 volts. Plugged in the charger, found it odd that the LED stayed green. Then measured the charger.
So I think the battery charger has gone dead, which is why my SLA batteries aren't at voltage.
buddy
Comments
I asked Parallax support this question, and got a good reply from Chris Savage:
I believe the way this charger works the batteries cannot fall below a certain voltage or the charger will not engage.
I have experienced this before myself on a battery that was older and had discharged down below minimum safe level for an SLA battery.
I verified this by using a different charger to bring the batteries up to about 11 volts, then I tried the arlo battery charger again. It seems to work fine, the LED is red, and the batteries are charging.
Now if I could figure out why they discharged in the first place...
Apologies for missing this post earlier. Once the battery gets below the safe minimum voltage for the SLA battery the charger won't detect it and so it won't charge. Unfortunately these chargers indicate a green light with no connection so it can be difficult to see that there is an issue when this happens.
Another possible option for monitoring the battery voltage would be to use one of the many inexpensive voltmeters available on ebay and other places.
Here's one for $1.90 from ElectroDragon.
You could probably find a similar meter on ebay with free shipping.
You wouldn't want to leave the meter connected all the time since it will slowly drain the battery. I suppose using a voltage divider with an ADC would also slowly drain a battery but depending on the resistor values used, the current might be low enough, you wouldn't need to worry about draining the battery with the resistors.
Of course if you monitored the voltage from a location after the power switch, these concerns about the voltage monitor/meter draining the battery are unfounded.
Probably?
12V SLA batteries are made by stringing together six 2V cells. If one or two of the cells have gone bad, you might get a temporary full charge, but it doesn't last long. I've encountered a number of poorly made imported batteries that had this problem.
Both batteries are newly purchased and only used for a month. I'm pretty sure I now know how the batteries got so far discharged, which caused all this. I'm hoping that this one-time deep deep discharge for only a few days, can be recovered from by resuming good charging practices.
The deep discharge happened while I was trying (foolishly, I now believe) to use the 12V SLA's to keep my laptop charged, so I could run the laptop more than it's paltry 90 minutes of battery time. I was using a DC-DC supply to go from 12V to 19V to the laptop. Anyway, I don't do that anymore, I'm planning to buy a better laptop, and that's a topic for a different thread.
Back to the arlo charger, it got quite warm when the batteries were charging on it, too warm to comfortable hold. I put the charger on a pyrex dish, put a thermometer on it, and it measured about 118 degrees F at the max. (I actually measured it every 15 minutes, and got a nice curve. Could probably put a thermistor on it and determine where it is in the charging cycle!)
Until you get that new laptop you can use the battery from an 18V cordless drill (if you have one) to extend the laptop run time. With a fully charged laptop and drill battery I can usually get a full 8 hour day's work done. It's also an added incentive to buy a cordless drill if you don't already have one. Darn handy thing to have.