From March, 2010
ET312 Battery Care Tips
I received an email from a customer today asking some questions about his new ET312, specifically why the battery level seems to fluctuate suddenly when the AC adapter is connected, and why the charge level seemed so low when he first turned it on.
The battery level displayed can be a little confusing. Here’s how it works.
When plugged into the AC adapter, the battery level displayed is higher since it sees the charging voltage being delivered to the battery via the charging circuit. It’s normal for the displayed value to increase to 99% as soon as the adapter is connected, but this isn’t really displaying an accurate battery charge level. In order to sense the battery voltage, the AC adapter needs to be disconnected before the ET312 is powered on. [Future idea: Maybe there should be a way of disabling the battery charging circuit during power-up in order to get a more accurate display of the battery level, with or without the charger being connected. Noted.]
The percent charge is also an approximate figure. It’s normal for our units to ship with a battery that is 50% – 75% or more charged when you first turn it on. For best results, connect it to the AC adapter and let it charge overnight to stabilize the battery level. Then make sure it gets connected to the charger at least once a month — or just leave it connected all the time. It won’t hurt the battery.
Don’t forget about the ET312 for 6 months and then expect the battery to have any life left in it. It will slowly discharge by itself so charging it routinely is the best course.