As suggested, why charge batteries when you're driving in round in a car with an Alternator on?
I assume you've seen this-
As others have said, you need to be careful how you charge and discharge such devices.
Do you have any details on the gloves? How does the temperature selector work on them?
If they last 1.5H hours and the battery is rated at 16.28Wh, it suggests they pull 10.8W on full power, which translates into 1.5A.
So throw the batteries and run the gloves direct of the 12V in the car!
Hence you need a circuit with an 8V regulator running off a 12V ignition feed that's good for 5A.
Try this fella-
https://uk.farnell.com/seagate/ip3r18k05/ic-v-reg-5-0v-18k05-to-3-2/dp/1202002?st=voltage regulator 8v 5a
It will need a heat sink and mounting in a box etc. You'll need suitable connectors/leads to wire up to your gloves too. I'd suggest they connect to the base of your jacket and run down the sleeves to each glove (Like a toddlers mittens).