ANGST

I plan on getting the CTEK - 56-976 MXS 5.0 , connected to the 12v socket in the footwell .

Do I use AGM mode ?

CaymanMatt

No. AGM runs a higher voltage at times, and it's higher than your battery prefers. Run normal mode.
FWIW

Todd B

You're 718 has an AGM battery, use AGM mode when charging on the CTEK. Been using the CTEK in AGM mode since 2013 without issue.

CaymanMatt

Do searches for this question. You'll find AGM is not the correct setting. AGM is for power batteries, not really for automotive batteries.
YMMV, FWIW, MOO!

Todd B

Maybe you can post some links to your info.

If you talk to CTEK, they will tell you to use AGM mode, the charger that was sold as a Porsche charger used AGM mode. The AGM mode does charge at a higher rate at times, depending on the program and what the charger senses from the battery. The higher voltage is .3 volts. Porsche started using AGM batteries in the cars with the 991/981 series, because they implemented the auto start/stop.

When you say a power battery, I assume you are talking about UPS batteries?

AGM (Absorbed Glass Matt) battery

AGM batteries were first used to fill the void created by modern car demands and older flooded battery technology. They can deliver higher power output together with a longer cycle-life with the downside of being heavier and are more expensive (by a factor of between 1.5x to 2x). Because their performance can often be met by newer EFB batteries of cheaper construction, they are now more commonly found only in premium or commercial vehicles.

Their enhanced performance makes them suitable for use in cars with start stop engine technology, and some hybrid cars that use regenerative braking / passive bost..

Unique features:

• Glass matt separators
• recombinant lid technology
• higher pack pressures

confused66

I don't have the expertise of prior posters, but I've been using a "Battery Tender" brand on my Boxster for 15 years and never had any problems. Combined with fuel stabilizer, the car starts up easily every Spring (since I put it away as soon as they salt the rounds around here).

CaymanMatt

I searched for AGM 14.7 and found the following:
this is from my ctek 4.3 user manual:
"Normal" battery program 14-160Ah 14.4V/4.3A Use for WET batteries, Ca/Ca, MF, GEL batteries and many AGM batteries.
"Cold weather" battery program 14-160Ah 14.7V/4.3A Use for charging at low temperatures and power AGM batteries like Optima and Odyssey.

and from one of my posts on the 718 Forum:

(Edited to reformat a bit for clarity)
I just did a search from the PCA site since the Good to Know app doesn't have anything that's Good to Know regarding batteries. Here's what I found there. It's not necessarily 1:1 with our cars but I think it's applicable:
===========================
I have been in touch with Porsche NA and many dealerships and cannot get a straight answer. The question is: What type battery maintainer should be used on a Banner battery used in a 2016 GT4? This battery is a VRLA battery (listed right on the battery). Online information indicates VRLA batteries (Type of AGM battery) has a typical absorptive range from 14.2 to 14.5 volts.
...
I received a Porsche Bulletin No 1401 that stated " All 9x1 vehicles use AGM batteries. Any battery changer/power supply used must be set to this type battery. It is critical for AGM batteries that charging voltage not exceed 14.5 volts for more than very brief periods. I would interpret this as one should use a typical Lead Acid battery maintainer as it's absorptive phase is 14.5 volts.
===========================
For me this says Porsche does not want their batteries to be charged beyond 14.5V.
And from the manual for my MUS 4.3:

View attachment 29297
The cold weather program seems to be for low temperatures and for "Power" AGM batteries like storage batteries for solar arrays, etc.

I'm going to keep my maintainer on "Normal" mode from now on.
FWIW & MOO
==============
There is lots out there about this. As I stated above, I use and will continue to use Normal mode.

I hope this helps.

Todd B

Thanks, that helps!!

I had a odyssey battery in my race car and that's information I've based stuff on.

nineball

this is only my educated guess but they could be referring to deep cycle when they say "power". if you are really concerned you should take the guess work out of it and contact them to see exactly what they mean by "power". the only difference i can think of between the 3 versions of an optima are deep cycle or not, and they are all AGM. in the most broad sense of the word description - red - standard (cars/trucks); blue - deep cycle (boats); yellow - hybrid (cars/trucks/other).

fwiw i have been using the ctek charger on AGM since i got my CS in 03/17 and i'm still on the same battery with no issues i have also maintained multiple AGM batteries over the years with a battery tender jr. without issue in motorcycles, sea-doos, my '83 911, my CJ-7 and so on.

ldamelio

Same charger, another AGM vote. I researched extensively before buying/using.

ANGST

This thread doesn't make me feel bad about being confused

Are people using the footwell 12V socket ?

Also the Porsche maintainer ( CTEK rebranded ) does not have the AGM mode that is on the MXS5.0 , and seems to be recommended for the 718 platform with only having the "normal" mode.

CaymanMatt

Very interesting. Thanks for pointing that out.

nineball

i use the clips directly when i need to, like over the winter. eventually i'll install the ring terminals but i get distracted easily...

Todd B

I always use the 12v footwell socket and never have had an issue with my cars. You do need to be timely in getting things connected and powered, otherwise the car will time out the socket and turn it off. Park the car or turn on/off the ignition, plug in the charger, turn on the charger and lock the car. You can check the charger in 1/2 an hour to make sure it still sees the battery.

Old Guy

I have two Porsche-branded (CTEK) battery maintainers that I haven't used for about 2 years. Bought them about 3-4 years ago. We're now about to take a several week trip. One of the Porsche branded units simply doesn't work. Plugged it into the footwell charge port, then the wall socket...nothing. Yellow light comes on, but no response from the MODE button. Tried it on both of our Porsches. Nothing. I turned on the ignition because I needed to lower a window just a bit to get the wire thru. Does anyone else have experience with the Porsche unit failing??