Motorola Bag Phone Batteries

Howdy:

I have some Motorola bag phone batteries, that I would like to recharge
thru my vehicle's cigar lighter, while on the road. The batteries I have
are SNN 4298 A -1 (sealed lead acid).

Making an adapter with a voltmeter (and ohmmeter if necessary) and
enclosing same in a covered battery box, is no problem.

What I need to know, is the charging times for the batteries, when
they're at various states-of-charge (or discharge, if you will).

IOW: X-number of hours for a battery discharged down to 11V; X-number of
hours for a battery discharged to 11.5 V, etc, when hooked up to the
vehicle's 12V 60A alternator.

I would really appreciate any comments and advice from readers who have
charged the same, or similar batteries, in this manner.

Thanks,
TD