Hot restart issues.

A general rule of thumb: Every tenth of a volt is a 10% reduction is battery capacity. Pick a number for your fully charged lead/acid battery (not AGM, not LiFe, not Li-Ion, not etc.), say 12.8V. If you measure it next week and it shows 12.7V, that is a 10% reduction in capacity.

IF you started at a 12.8V number and you now measure 12.2V, that is .6V difference which translates to a 60% discharged battery.

A ways back in this thread, the battery voltage in this situation was said to be 12.2V. That is close enough to being 'dead' to not consider calling it anything else. Low. Ineffective. Wrong. Discharged.

...or...FIX IT.

Batteries and the systems they are used in CAN be a headache if you don't follow some basic rules. ...like, why fuss with a 12.2V measured system to try to 'start' ANYthing?

Realizing that what the battery 'reads' on its posts may well have not a thing to do with what the measurement is at the other end of the cable connection (maybe 1/2" away) is the sort of thing learned over time.

Whether the system is hot or cold isn't really the question if you are STARTING with a 12.2V source.

...and the measured charged FLOAT number of a lead/acid battery (say...maybe 13.2V) doesn't mean anything.

Don't lose sight of the 'rule of thumb' as stated above. One can find many lists/charts that show different numbers.


IF 'your mileage' does NOT ever vary, you probably are NOT normal.


Google's AI attempt at 'splaining the matter does say:

Lead-acid battery
A 12-volt lead-acid battery is 100% charged at 12.7 volts, 90% charged at 12.6 volts, 80% charged at 12.5 volts, and so on.



I have fussed with 'won't crank right and does NOT start...' complaints with other folks over email and the phone many times. I have asked repeatedly that the 'owner' check the battery terminals and connections. I have heard...repeatedly...'I checked that. It's all good.' But the problem persists, sometimes for MONTHS.

Finally I drive over to 'the place' 30 miles a way. I look at the battery cable/connection. I wiggle the cable and see the end wires (through the connector) move. I say, 'See that!?' I 'fix' that problem.

The engine cranks fine, starts fine, the problem has been, at least for the short term, resolved.

Trying to get an engine to run with a measured voltage of 12.2V is NO place to START. har har dee har