I got one of these probably 5 years ago.
http://www.pricefalls.com/product/Ryobi-P131-18v-In-Vehicle-Dual-Chemistry-One-Battery-Charger-number-140126001/6813241?utm_source=GoogleShopping&utm_medium=cpc&utm_term=PLA-SC&utm_content=73605900511&utm_campaign=Charges back up my batteries when no elect at house, (which was Maybe 2 times in last 10 years). Charges in my 01 Dodge alright and pretty quick. Less than an hour to work at time. Charge one going to work and one coming home.
I do like that flashlight that uses those batteries and have a had a hard time buying it separate.
Was thinking about "jerry rigging" so LED could fit in. Would last long time. Regular flashlight lamp last about 2 3/4 hours wonder how long LED would last?
We don't take it camping with us but what do you folks use it for camping?