Battery Tender

German1967 · 02-18-2021, 05:52 PM

Quote:

Originally Posted by albertw

Quote:

Originally Posted by jv92red

From my understanding, normal will work just fine but in AGM mode these batteries can take a higher charge rate than normal lead acid batteries so if your in a hurry to top it off then use AGM mode, otherwise normal will work just fine too. But again, i set it to car/AGM mode and let her sleep.

This might be true, but the more important difference is the charging voltage. Standard on my Ctek is 14.4 volts and AGM is 14.7. Float is a lot lower (13.8?). This matches my understanding - to reach full charge an AGM needs 14.7 volts. There is some disagreement (on aviation forums, because many aviation voltage regulators are adjustable) on whether the charger in a vehicle should be set at 14.7 for AGM, as that might be hard on the battery once it is fully charged.

Once it is fully charged it falls back to float voltage (13.6). Hence, I don't think there is an issue. Further, if there were a higher failure rate of AGM batteries charged via CTEK AGM setting we would have heard about it.

albertw · 02-18-2021, 06:17 PM

Quote:

Originally Posted by German1967

Once it is fully charged it falls back to float voltage (13.6). Hence, I don't think there is an issue. Further, if there were a higher failure rate of AGM batteries charged via CTEK AGM setting we would have heard about it.

I didn't say there was an issue for cars. I just wanted to head off someone saying their car puts out 14.4 volts when the engine is revved, so how can 14.7 from a charger be safe.