battery tender

[steve shea]

Do Sonnenschein gel batteries require a special maintainer or will my Interstate 12V lead acid maintainer be ok? It has a maximum output of 12V and shuts off to float when at full charge,1.5 amp I think.

[davep]

That does not sound correct. The nominal voltage of a fully charged battery is about 12.8 V. To charge such a battery requires an output near 13.8 or 14 volts; the normal output of an alternator at driving RPM's. Full charge is normally determined by the voltage, not a current.

[NorthernThrux]

Nope. Too low. Even 12 is too low. A fully charged battery is 12.8 V or so. You need an AGM maintainer. It will go higher in voltage for short periods of time (14.7 or so) and then ramp down voltage and trickle charge on a cycle (i.e. not continuously). Just invest in a CTEK or something equivalent. Cheap insurance. Much cheaper than a new battery. I use one on my 911 and also the same one my Macan (which is also an AGM battery) because most of my drives in the winter are short and electricity intense (lights, heated wheel, heated seats, rear defrost etc) and the CTEK tops up the battery once a week.

The Macan is 5.5 years old and the battery still load tests at 96% capacity.

Ravi

[steve shea]

Which model CTEK? I just switched from Lead acid to Sonnens But wont be driving the car till spring.

[NorthernThrux]

I have a CTEK MUS 4.3. I've had it for at least 8 or 9 years so it may not be made any more. But any charger which has a specific AGM mode would be fine. On mine, the snowflake symbol mode is the AGM mode.

EDIT: I see it is still available. But so are many others.

[steve shea]

Thanks Ravi!

[raspritz]

I have used El Cheapo $20 battery maintainers from wherever for years, all different sorts of 12v batteries. No problems ever.

[66S]

Newer Ctek chargers go through cycles including one to renovate older batteries, I just got a 4.3A polar version.

[66DC]

I'm using an AGM-specific BatteryMINDer for my AGM battery. 8+ years later it's still cranking strong.

[911GP]

I have a CTEK MUS 4.3. I've had it for at least 8 or 9 years so it may not be made any more. But any charger which has a specific AGM mode would be fine. On mine, the snowflake symbol mode is the AGM mode.

EDIT: I see it is still available. But so are many others.

I have a CTEK MXS 5.0 and the instructions state that normal battery program (the car symbol) should be used for Gel batteries. The AGM option is for "AGM batteries like Optima and Odyssey".