A.M.

Found a metal lug in the trunk to clamp to. had to go looking for it...everything in there seems like plastic.

Critter

Follow the neg cable from the battery to the chassis

Max.H

The negative cable goes to a box with a connector on it. Are you sure it's ok to the connect that source? I was hesitant because it has that black box with a electrical connector.

To avoid risk I attached the black clamp from the trickle charger to that bolt you see. But, unsure if that's a good enough ground.. It looks ok because it connect the chassis.

Is that ok?

A.M.

exactly where I connected it. No issues.

Max.H

Nice, thank you!

What was your before charge and after charge voltage? Car off and car on. if you don't mind me asking.

cetialpha5

I don't think you really understand what wind chill really means. It's a number that refers to what it feels like to humans if the wind wasn't blowing. If it's 20 degrees out with a -20 wind chill, the temperature of the battery is still 20 degrees, not -20. To bare exposed human skin, it would feel like -20, but not to inanimate objects like a car battery.

Just google wind chill or read the wiki which says "The effect of wind chill is to increase the rate of heat loss and reduce any warmer objects to the ambient temperature more quickly. It cannot, however, reduce the temperature of these objects below the ambient temperature, no matter how great the wind velocity."

The risk in running an ancient battery is that the car won't start. That's what it's needed for. When the car is running, you can have a dead battery and as long as the alternator is working, the car will still run.

Critter

Thank you for the insight, any automotive questions I will forward to you, this way I can rid myself of any engineering/automotive knowledge so I have room for video game strategy.

Max.H

I got my 1.5 amp battery tender all hooked up last night. And it went green 3 hours later and stayed green this morning. I checked voltage while still connected and the voltage shows 12 volts. Not what I was hoping for as that is pretty much what I began with before. Wanted to see it charge for longer period of time also. Wanted to see higher then 12 volts cold, car not running.

It's says its charged green light and i suppose just mantaining it. I will leave it on another day and see what happens.

Critter

Either your meter is wrong or the battery is bad.
Take it to autozone or similar place and have them load test the battery. Voltage should be above 12.7V minimum

Max.H

Ok will do, But, the voltage meter is right from the AMG screen. It's accurate.

The car sat for awhile and hasn't been started often. I'm thinking the battery is going bad. I was hoping to get a little more life from maintaining the battery with the battery tender.

Above 12.7 minimum with the car off sounds too high. I think its suppose to be 12.6 and below. When car is on it should be 14.2 range. No higher

Either way I will go have it load tested and go from there. Thank you!

cetialpha5

I don't think he understands batteries that much. My degree is in electrical engineering. 12.7 volts is basically a fully charged new battery at 78 degrees Fahrenheit. When the car is on, you always have a higher voltage than the battery so that current can flow into the battery to recharge it. If the battery were at 14.2, the charging system wouldn't be charging the battery. If you do a search for a state of charge chart, 12 volts is about 40-50% charged, however those charts assume a battery that hasn't had a load on it for a few hours. When reading it on the car, it has a load on it and the temperature at this time of year is typically lower so the state of charge might actually be higher than what's stated in the chart. A lower state of charge means that you just don't have the amp hours in the battery that it's rated for, but if the rest of the system is fine, you might be able to get away with it for a while. Just don't make it a habit of sitting in the car with the radio and lights on and the seat warmer on for several minutes before starting the car. You might end up draining the battery to the point where it won't start the car.

06E55BEAST

Sorry to bump this thread, but the white "low battery, convenience options not available" still comes on periodically. I had the battery control module replaced a few months ago. the aux battery was replaced last year, not sure what else could it be? the main battery?

Toadster

that was my issue, swapped in a new battery and life is good now

check your battery voltage:

put key in the ignition, turn to stop #1
push the odometer reset button 3 times, it will bring up battery voltage (mine was 11.6)
turn the key to #2 position (not start) so all accessories turn on (my voltage dropped to 11.3)

a good battery will register 12.6-12.7 on key #1 and ~12.3-12.4 on #2

0-60inAMG

Hey Toadster, there are many of you like Shardel etc that have been a great help on mbworld site, thanks for that.
I was occassionlly getting conv functions uavail and mybattery would go down to 11.6v after a while.
I just swapped my 6 yr old battery for a new one and got the battery sign with visit workshop esp warning (it wasn't red on the dash). 1 malfunction same as last time I charged the old battery.
So I shut the car off turned it on and off a couple times and no warning & no malfunction.
Did you have that as well after swapping batteries?

Toadster

no i had no issues after replacing the main battery - how old is your AUX battery? (the one under the air vent under the hood?)

0-60inAMG

good point, the aux bat is over 4 yrs old

Toadster

they're < $70 - check the parts thread, that battery works great

0-60inAMG

thanks again, that parts list is awesome, use it all the time........cheers

A.M.

Well, as many of you stated....sheeees dead. I have no plans on driving it for a month or so. Should I trickle charge her until then? or just let it be.

Toadster

not sure if trickle charging would help - not sure if it's even recommended if the battery is too low...

others may have input

cetialpha5

You have a 6/2amp charger right? Did you charge the aux battery also? Deep discharges aren't good for the battery and reduces battery life. Did you buy a new battery? You might also want to consider getting a battery disconnect switch so you don't kill it while it's sitting for long periods.

A.M.

Ive been hooked up to the trickle charger at 2 amps for almost 40 hours now, still has not went into maintenance mode. Seems a little long no? All functions have returned, the rear end is back up, no msgs in cluster.

About charging the AUX battery, I read somewhere that whilst charging the main battery the AUX also gets charged and once the car turns over the alternator takes care of the rest?

Is that information wrong? If the AUX was dead and the main charged wouldn't I get a msg in the cluster?

Critter

Save yourself from getting Carpel Tunnel writing about your batteries, just go buy a new main and a new aux and enjoy 5-7 years of no issue.
Resurrecting a dead battery is okay if you are going to use it to power a 1980 car radio for a few days, you cannot expect it to power your car without causing damage to other components.

A.M.

New batteries are deffenitely on the purchase list come Mid april. Im just curious more then anything else. Information on this subject is so scattered and conflicting you don't know which direction to take.

But like you said, the easiest way to go is change the batteries and see what happens next.

Critter

How old are the batteries?