One neat gadget that has come down in price is a battery conductance tester. An actual load test is still the best way to test a car battery, but it requires charging before and sfter the test. Conductance testers convert the batterys own DC voltage into an AC signal and tests the health of the battery. Therefore (in theory) it doesn’t need to be fully charged, but will determine a defective battery. Sometimes a “bad” battery will test OK, but generally they are accurate and if it condemns a battery it is almost certainly bad. If you’ve had to warranty a battery, this is what they most likely used, a handheld conductance tester.
While I “know” a proper jump start should not hurt anything… I would be hesitant to provide a jump start, just based on the potential, however remote, expense and headache electrical problems can cause, the scope and number of sensitive computer gee-gaws and low current devices…
Better to test their battery first - with a conductance tester - and then if the battery is OK, just dead, proceed from there. Even then, a jump pack would be a better choice - no connection to my vehicle would be reauired, therefore no risk.
This is why we carry the base level AAA and towing insurance with our car insurer. The AAA will get me a tow truck in most places, and a few miles of towing. It also has the advantage of covering any car I happen to be near (It covers ME, not my car).
Towing insurance, at a few $/6 months, lets me call any towing company I want, and get reimbursed by the insurer. I have a friend who’s husband runs a towing company. Apparently what AAA pays for a tow is less than what I generally pay, so when it’s crazy busy out (think ice storm or -40 degrees), the AAA calls tend to sink to the bottom of the pile. Towing insurance has the benefit of going with my car, and not with me. So I can lend my car and if my friend needs a tow, it’s still covered.
Update: I shouldn’t have been so cocky about needing jumper cables for myself very often because I did yesterday far from home and in terrible weather. I somehow managed to leave my lights on during an event that lasted a few hours. When I got back to a mostly empty parking lot, my battery was as dead as Michael Jackson. However, there was an SUV idling menacingly not that far away. I whipped out my jumper cables and marched right up to ask for help.
Of course he helped me with no threat of rape or murder. I was on my way less than 5 minutes later. I can’t see a reason why everyone should not have them and learn how to use them. I could have waited an hour or two in the freezing dark for AAA to show up but I didn’t need to because I had my own cables.
I have long carried jumper cables (good ones, 25 feet of 2 gauge copper with 2-way clamps). Also a portable compressor, toolkit, blanket, flares and fire extinguisher. Also spare bulbs, tire valves and caps, hanger iron, duct tape, WD-40, and a multimeter. Add to that the winter supplement of tow cable, folding shovel, snow brush and ice scraper. Haven’t used the cables in about a decade now, but they are there. Have never used any of it except a bulb or two and the snow brush on either of my current vehicles.