Best Battery Jump Box
 

Since I am having undiagnosed battery drain, I want to have a jumper box on hand for emergencies. I need a good dependable box for a 750 CA / 590 CCA EverStart Battery from Walmart. The battery is 4 months old. Also, 240 station wagon-1992, in southern New England-Do you think the battery I have is big enough? Should I have more cold cranking amps for the 4 cyl? Could the brand of battery I have not be a good one? All advice will be greatly appreciated.

there's a specific battery type that properly clamps into a volvo... I've generally gotten Interstate somethign-or-the-other. these have a flange on the base that locks down with the stock clamps.... ah, its a MT-47, Automotive / Truck Batteries - Mega-Tron 47 Automotive Battery 75 months 590 CCA

I dunno anything about walmart house brand batteries, but most car batteries are made by just a couple companies like Johnson Controls and Interstate.

your drain is probably that crappy walmart battery........

I just realized the OP is asking for a JUMPER box, not battery recommendations. shoot, get any sort of cheap plastic battery box, and some jumper cables. done. my amatuer astronomer friends will strap a battery box onto a lightweight hand truck, and use that to carry a bigass marine/rv battery to run their telescope equipment all night in the field.

Dying battery sounds like a bad diode in the alternator or an abused battery. Best jump box ever is the M46 manual trann'y. Now on a more serious note, I would find out if the battery drains while sitting (meaning a constant draw on the power while the engine is off) or while running (meaning that the charging system is not doing it's job). One last thing, there's a protective belly pan on the bottom side of that car that's supposed to keep crap from getting up into the front of the engine. If that's missing junk can get in you alternator especially since it's mounted so low on the 240's.

indeed, that pan is not only important to keep dirt out of the engine, it also hugely improves the airflow on the radiator. well worth replacing if its missing.

a decent battery, when its fully charged but hasn't been on a charger for a few hours (this includes the alternator running... when a battery is first disconnected from a charge voltage it holds a 'surface charge' that causes too high of a reading), should measure just under 13V. a mostly discharged battery is about 12V, and anything under 12V is deeply discharged. These voltages are somewhat temperature dependent, the 'standard' voltages are at 70F or there abouts, if its freezing cold, it will be considerably lower.

When the battery is charged and the car is running, it should be almost 14V (or about 1V higher than the batteries idle state). it might take a slight boost above idle to achieve the full charge voltage.

cheap battery load test if you don't have a load tester or want to take it to a garage for a electrical test... charge the battery, let it sit an hour, measure the voltage and turn on the headlights (headlights, running lights, engine on but not running is a total of about a 12-15 amp load), and measure the voltage at intervals, writing down the elapsed time and voltage to 0.1V accuracy... It will probably immediately drop like 0.5-0.7V as soon as you turn things on.... a good battery should drop less than 0.1V every 10 minutes or so. if it drops a lot faster, the battery is toast. stop the test before you get to 11.6V or so. my kinda old battery started at 12.5V (off overnight, that reading is lower than I'd like to see), and 11.85V with the car on, then dropped to 11.81V (-0.04V) in 10min. and 11.79V in another 10, I shut if off at that point, and it recovered to 12.2V within a couple minutes (which tells me this battery is kinda weak, but serviceable)