Portable Jump Starter

The gadgets with the AGM batteries are great, except that people don't check them on a regular basis and so they are dead when they are most needed.

Just get a good set of 30 foot #4 jumper cables.

--scott

Yep, stay away from cheap cables. 16' has always been long enough for me. Shorter cables, more volts. How many times have you seen people stand around for a long time waiting for the dead battery to juice up, and they give up simply because of bad connections? You have to hear the load happen on the charging car before you have a good connection, so the connectors are important too, especially the side post connectors. Seems the alternator load will drop the idle RPM on the charging car 100-200 rpm, so it's pretty noticeable even with no alternator whine.. I know you know this, but others might not. Amazon has reviews of these portable jumpers, so I'd look there. My first thought was why would anybody want one. I haven't even used jumper cables in maybe 5-6 years. But reading some reviews I see the portable chargers come in real handy for car lot owners, construction equipment owners, farmers, etc. Might be useful to boaters too. .

I have not had good luck starting using those jump starters. It does work well starting my riding mower. The advantage of using another vehicle, it starts to charge the dead battery, reducing transfer amperage. Required.

Greg

The jump boxes CAN work, if you get a big one and you keep it charged all the time. It's a useful thing to have, say if you work security on a large facility and often need to help people get their car started. But if it is something you use every once in a while, forget it.

Also... avoid Chinese AGM batteries. Look for ones made in Japan or Vietnam.

--scott

"#4" is the important part of that post. Don't use cables that are too light, I've seen lots of 8AWG or lighter cables on the market, they're pretty useless.

I agree, jump boxes are nice for a garage, but on the road jumper cables are lighter and always work.

nate

The thing that kills you when you are jumping a car is any resistance in the jumper cable circuit. Main source of resistance is where the wire is crimped to the clamp and where the clamp grabs the battery terminal.

Doing a quick calculation of the difference between using a #8 jumper

12 foot long and a #4 12 foot long and assuming the current draw is 150 amps, the difference in voltage drop in the actual wire is 0.66 volts. The resistance in the #8 wire for the 12 feet is less then 0.008 ohms. A poor quality crimp on a cheap set is undoubtedly much more than that and I think it's the main source of the problems with cheap cables I have found that cables work a lot better if you solder the wires to the clamps instead of just relying on the crimp. Esp with the cheapies because the metal they use is usually fairly soft which means the crimp doesn't have very much clamping force. I've not had any problems jumping cars with the cheap cables that I've soldered. Thicker wires are better, no doubt there, but big wires with lousy crimps are probably worse than cheap ones with soldered crimps.

we use them to pull vehicles from the parking lot into the shop. As for the brand? It's whatever our parts house had on sale the month the last one died. If for personal use, I'd use Amazon too.

GW