One common error i find is Users often try to charge their cordless tool battery right after they use it. If you use it professionally you probably put a lot of pressure on the tool and often this will make the battery very hot. there's nothing wrong with this type of usage as we all buy these tools for that specific reason! However, you may notice that you will get an error message when you try to charge it right after such use. The reason is the new chargers all detect hot batteries and will stop charging as this could cause damage to the charging system of the battery. ALWAYS wait til the battery cools down before charging. it doesn't have to be totally cold, just 'warm' is usually good enough. Most tool sets come with 2 batteries which is sufficient for most jobs so this shouldn't be a problem, however you may run across jobs where you may have to go thru 3 or more charges. if you need 3 charges, you can still have just 2 batteries. simply have both charged before starting your project. As soon as you feel the first battery losing power, take it off the tool and let it cool while you start with your second battery. A few minutes is all you need to cool the battery and then you can put it in the charger. The new Rapid charger DC18RA from Makita will only take about 30 minutes or less to fully charge your battery so you should be able to work continuously. Of course having 3 or more batteries available is the best option if you are worried about work interuption. Hope this was helpful and happy bidding!