when using different makes of drill chargers, I've notice that inverter power needed is often much greater with some of the chargers hummm?

[irishjohn]

I ran into a bit of a power problem once using a sine wave inverter on a Makita and also a Milwaukee drill charger.
The Makita charger power info said 60-watts input even though I knew it didn't factor in peak power.
it would trip the overload of my AIMS 180-Watt inverter.
OK....So I bought a 350-Watt sine wave inverter which also tripped!
OK, I then went for the "550-Watt all-wheel-drive with power take off winch with the 50-caliber Browning machine gun" thinking that would for sure power it......Nope....it tripped it only it took 8-seconds to do it.
Ahhh but my old faithful 1000-Watt sine wave worked just fine.
but when I went to charge my new brushless Milwaukee drill it works just fine on my hundred and 80 watt sine wave inverter!
Just thought it would give some of you out there a pause before you buy your next cordless drill.
by the way, I build portable solar/lithium ion power packs for a few doctors who work at Doctors Without Borders.
One of the doctors is the one that gave me that problem as he needed to use some rechargeable power tools!
John

 

[Diysolar123]

many of the battery chargers have a large capacitive load.. in other words for a very short time, they are a short circuit (a capacitive reactance of 0)!!
ok, not exactly zero, its basically the supply voltage/(wire resistance+cap ESR) ; and the wire resistance is probably milliohms.
So its 60watts input over a second, and a thousand watts for a 0.01 seconds hehe
This is why inverters should be precharged before you connect your battery bank, caps are shorts until they charge up a bit.