I was thinking of installing a 2nd battery in my 4runner for safety during off-road and freezing winter conditions (in case the main battery died). But it seems a portable jump starter could do the job. Some even have a built-in inverter (300W compared to 100W of the 2003 4runner) or a cheap air compressor, and are rechargable via both 12V dc and 110V ac.

Any idea how reliable these portable jump starters are? Would they jump-start in freezing conditions if the main battery died?

 

get a second battery....... those portable ones lose their charge after awhile and arent the greatest anyways as far as power goes... their rated # s dont live up to anywhere near close what they say they do.....

 

I've had a Schumacher Mighty Mite for years. Great product, works fine even after months of storage. Very compact, easy to charge, and has plenty of power.

http://www.batterychargers.com/detai...D120A&catid=13

In fact, I just bought another one yesterday for the '98 Taco. I will still get a dual battery setup at some point, but the portability of the Mighty Mite can't be beat.

 

Crawler is right on track with this one. While a dual battery system may be the ultimate in dependability, the portable units can be just what the doctor ordered. If you get the right portable unit, they hold a charge and are a heck of a lot easier to "install" than a second battery, isolator and wiring.

Many of us go for a dual battery system for a number of reasons, but a quality portable unit might be plenty for your uses.

 

I have both dual batteries and also carry a portable battery pack from time to time. I leave it plugged into a 12V socket and use it mainly for running accessories in camp to save wear and tear on the main batteries. It'll power my ARB fridge for over 24 hours. I've not used it for jump starts but I think it would help if needed. If it would not work directly, you could leave it connected for a while to help boost the main battery charge.