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You can do a "quick and dirty" rough estimate of the condition of your battery. It's not the same as a load tester (which simulates the cranking while testing the battery), but it will be a clue, and it's almost as good as a hydrometer to determine if you have one or more bad cells:
After the car has been running a while (maybe a half-hour if it's really cold) with no loads (headlights, rear window defroster, etc. all off), turn off the engine and let it sit a few hours (for the plates to equilibrate).
Then take the caps off the cells, and put the probes of your DVOM across successive pairs: first, the negative terminal and the first cell's electrolyte (just dip the probe in the acid solution), and write the voltage. Then from that same cell's solution to the next cell's; and so on until you get to the voltage from the last cell to the positive terminal. Normal voltage should be about 2.1 volts across each of the six cells.
In addition to individual variation among the cells, total voltage (pos to neg terminals) across a healthy (fully charged) battery at rest should be 12.6 volts; at a mere 12.1 volts, your battery has only 25% of a full charge, and at 11.9 volts, consider the battery dead.
This technique will probably reveal one or more cells that are considerably lower in voltage than the others -- not a good sign, and a reason to replace the battery.
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