[John 070]

I was monkeying around with Rheingold meaning in the car with laptop and ignition on, and lo and behold the battery icon comes up. I am distrustful of it, then again, like to test things out.

What did surprise me was that 18 hours on the battery tender, the light was still red, I expected it to be solid green, or flashing green, car was driven daily anyway for the last couple weeks.

Taking the tender off, the voltage was 12.75 and it passed a load test.

I still have my original BMW battery sitting on the garage floor, on a rubber mat to insulate it from the ground temp, and I tested that. 12.6! I likely hit it with the tender 2 wks ago.

Next time I probably will change the battery myself--at the 5 yr. mark I paid the dealer $280 to do it. Dunno if Rheingold can do AGM or not, but then again, if it's what the dealer uses, shouldn't it?

[robthewrench]

The question is how fast it drops to below 12.6. For a six cell lead acid battery, 12.6V is the fully charged value, but a cell will very low capacity left will cause the battery to drop below 12.6 quickly.

A reading of 12.2 volts is typically the amount for 50% of battery capacity depleted.

Different cars have different voltage sensitivities. Older cars would run at 12V. BMWs seem to be more sensitive than others and may start to show warnings and errors at just below 12.6V.

[John 070]

I would say the load test is meaningful. Imagine how many car batteries are thrown away by owners being "proactive," and there was some other circumstance that led them to believe they needed a new battery....

I found my answer we need ista p if we want to change from lead acid to AGM...ista d is to register only...