Just wanted to share that these are great to have in your tow vehicle for security (safely jumpstarting your vehicle without needing a stranger's help) AND for providing a power source if needed. I bought a cheap 400amp peak power one on Amazon for $26.49 - it was an old model and they put them on discount. I actually bought 4 of them... I keep one in my Durango and have used it to jumpstart the V8 engine several times, along with several co-workers' V6 engines. I have also used it to charge up my cell phone, tablet, and/or kindle. I keep one in the clipper to use when camping to charge the electronic devices (I have a more expensive 800amp peak power one to jumpstart the clipper in there also). I have one in my FnR as a backup for the Durango one (use one for charging devices while camping and the other is ready for jumpstarting if needed). I gave one to a friend. They really work and hold their charge well. I usually charge them about every three months and right before a trip. Prices vary and there are many brands so I didn't link. If you find a good price, buy one for every vehicle plus your camper(s). Well worth it!