Is there another problem besides a weak battery?

Probably just the battery. You can take the battery to Walmart auto center or any auto parts store and they will test it for you free.

it should have jump started ,, but if you have cheap jump start cables your dont really know how to do it . often it doesnt work. But if it started for you last week and not now . it is most likely the battery.

Never hurts to remove the battery cable connection at batt if they look corroded and clean them then put them back on.

not saying your son in law doesnt know how jump start , but a lot of people really dont know how to do it , especially with cheap jumper cables . and the side terminals on today's batteries makes it even more difficult to get a good connection. .

if the batt is 3 or 4 years old , if it started last week , a new batt would prob solve your problems .

But if you can borrow a battery charger from a friend and charge the battey , then you would know for sure.

One thing i do when looking at old car battery is this .

If you look at the smooth sides of the battery . the 2 sides on the ends of the battery. They should be flat . if they are bulged out , even just the slightest little bit . Then the battery has " sulfated " . and it no good.

I would suspect it is the battery. It could also be the alternator or the starter but you can take the battery out and run it to the auto parts store and they will check it for free so I'd start with that. Cold weather is murder on an old, weak battery.

The only way to tell is with a voltmeter.

Harbor Freight sells them for $3.

First take the battery out and charge it over night.

It should then read 12.5 volts.

Then while cranking, it should drop down to about 10 volts.

If it drops to 9 or less, there is a problem with either the battery, starter, or binding engine.

If when you stop cranking, it comes back up to 12, then it is not the battery, but the starter or binding engine.

Starters get less efficient when the brushed wear out or short the commutator.

Thick cold oil or water frozen in the water pump can cause the engine to bind.

If the battery does not come back up to 12, then replace the battery.

But also clean the terminals and grease them to prevent corrosion.