Nexus 7 charges via regular micro USB and the charger is a 2A charger. If you lose your the OEM charger, it seems that you have to buy a new one. Don't worry. There are some compatible chargers woking really well at exactly the same rate.
The compatible chargers list for Nexus 7
* The blackberry playbook 1.8a charger.
* HP TouchPad charger
* Samsung Galaxy Tab 2 7.0 Charger.
* Galaxy SII do the job quickly and well.
* A Motorola wall charger plugged in the wa
The iPad 2's, Blackberry phone's and Philips universal charger are not working for that.