What type of power adapter/converter do I need when I'm in Israel?

You need to look at your charger in question—if it says “Input 100–240Vac 50/60Hz” you’re good to go.

If it says “Input 120Vac 60Hz” you may need a different charger or an actual adapter.

If your adapter is good with it, all you need is a plug adapter. I play it safe and always take a 220–110 adapter. Also watch some countries run on 50Hz, which plays havoc with some equipment.

Israel is 220/50, like most of Europe. You’ll need a voltage adapter unless your device has a switch or a label rating it for dual voltage.

http://www.israel-travel-tips.com/en/147/Israel%20Travel/Communication/Electricity%20and%20Telephone

For something as simple as battery charging, a cheap adapter will do. If you have a piece of sensitive electronic equipment, you might go with a more expensive converter that uses a transformer instead of a triac.