Trickle charge on Mercedes G63 AMG

[oilboy123]

I have a vehicle that my niece is leaving at my my house for a month or so. So I'm thinking how to not get punished for doing a good deed......
I think this vehicle has the main battery under the rear seat?
I wanted to put my Noco 1 amp charger on it. I see two terminals on the passenger side under the hood. One appears to be hot. But when I put my multimeter on them I got no reading? I did get a reading on one while putting the other lead on an engine ground. Can I charge on that hot lead?

I can't find reliable info on this vehicle online. Not like my Focus...... ha ha. Thanks for any thoughts, or ridicule......

 

[dishdude]

Locate the battery and put the trickle charger directly on it.

 

[GON]

The positive terminal is under a red cover close to the passenger side firewall on top of the engine bay on a G 63.

Many Mercedes with the battery under the seat are not very feasible for a trickle charger without a lot of intensive work. Finally, your MB more likely than not has two batteries, one for engine start, and the other small battery to maintain vehicle's programming if main battery is removed. You only need to be concerned with trickle charging the primary battery.

You can see the large red cover on the passenger side of the firewall in the below picture.

Finally, you are doing your niece a disservice by not driving her AMG at least once a week-on a long road trip-keeping the G wagon's mechanics always moving.

 

[Astro14]

I’m with @GON - drive it once a week.

My Mercedes are happy when driven constantly. They like to run.

Parking them for a month is asking for trouble, even with a trickle charger.

 

[andrew_j]

My friend/mechanic has this wagon. It sits in winter months for a month or so no trickle charge. Does it have a drain issue?

 

[Astro14]

My friend/mechanic has this wagon. It sits in winter months for a month or so no trickle charge. Does it have a drain issue?

A lot of modern Mercedes have a heavy quiescent load - meaning, that all of the computers are running even when the car is “off”.

Many of them have two batteries - one small battery under the hood, for starting the engine, and a larger “consumer” battery, elsewhere to power all of those consumers of electricity.

My wife’s SL600 has an H8 AGM in the trunk as a consumer battery. It’s a beast, and yes, it can got a month without being run, and if the consumer battery gets low, the battery management module will shut off the consumer battery and preserve the starting battery. The car will start, but it will be unhappy for a while until the consumer battery gets back up to reasonable voltage. Sometimes, resets on various systems are needed if the consumer battery went flat.

So, for a month? I would just drive it, at least once, halfway through.

The other consideration is the brakes - high iron, great performance, but they rust easily - by keeping the rust down, you avoid weird pad/rotor wear, and on this car, pads/rotors are a very expensive proposition.

Finally, air suspension, or hydraulic suspension, will bleed down over a month. Usually not a problem, but I would prefer to avoid that settling.

So, seriously, unless you have it in a garage and on a battery maintainer, just drive it.

 

[gman2304]

just drive it.

This

 

[eljefino]

If I had a vehicle that awesome in my care I'd feel nervous driving it, just like OP. Maybe I'd take it up and down the driveway to scrape the rust off the brakes, and keep the tires from flat spotting.

The underhood jump point is usually convenient to a fusebox or power distribution center; its use as a jump point is secondary. Still a great place to trickle charge, and still a great idea to do on a car with all its electric "stuff."

 

[JeffKeryk]

We leave a car at our Petaluma home for months on end. I used a NOCO 1A on the RX450h connected to the jump point under the hood. Battery is in the rear. Battery died. So now I use a larger Battery Tender connected directly to the battery.

So far so good.

 

[loneryder]

The positive terminal is under a red cover close to the passenger side firewall on top of the engine bay on a G 63.

Many Mercedes with the battery under the seat are not very feasible for a trickle charger without a lot of intensive work. Finally, your MB more likely than not has two batteries, one for engine start, and the other small battery to maintain vehicle's programming if main battery is removed. You only need to be concerned with trickle charging the primary battery.

You can see the large red cover on the passenger side of the firewall in the below picture.

Finally, you are doing your niece a disservice by not driving her AMG at least once a week-on a long road trip-keeping the G wagon's mechanics always moving.

View attachment 283745

The ground post is to the left of the coolant bottle in front of the red sliding cover. Don't use a trickle charger. Use a battery maintainer and it will be fine.

 

[loneryder]

A lot of modern Mercedes have a heavy quiescent load - meaning, that all of the computers are running even when the car is “off”.

Many of them have two batteries - one small battery under the hood, for starting the engine, and a larger “consumer” battery, elsewhere to power all of those consumers of electricity.

My wife’s SL600 has an H8 AGM in the trunk as a consumer battery. It’s a beast, and yes, it can got a month without being run, and if the consumer battery gets low, the battery management module will shut off the consumer battery and preserve the starting battery. The car will start, but it will be unhappy for a while until the consumer battery gets back up to reasonable voltage. Sometimes, resets on various systems are needed if the consumer battery went flat.

So, for a month? I would just drive it, at least once, halfway through.

The other consideration is the brakes - high iron, great performance, but they rust easily - by keeping the rust down, you avoid weird pad/rotor wear, and on this car, pads/rotors are a very expensive proposition.

Finally, air suspension, or hydraulic suspension, will bleed down over a month. Usually not a problem, but I would prefer to avoid that settling.

So, seriously, unless you have it in a garage and on a battery maintainer, just drive it.

Yes and when the battery gets weak from that constant load, it will set codes that have nothing to do with the battery. Very confusing to new MB owners. I learned this the hard way.
Agreed...just drive it a couple of times.

 

[barryh]

When you throw in the fact that modern cars rarely finish a journey with a fully charged battery because of the smart alternator, I wouldn't dream of letting one sit for month without driving it or a top up charge. My Last MB would sit at the airport for a week but even that made me nervous and want to carry a booster pack. My W204 had the red slider +ve connection mentioned above and a brass earth post nearby. I don't think you can do any harm with trickle charger as MB usually state that charging with the battery connected to the car is OK up to 14.8 volts. I would charge it after a week of sitting and it always needed it.

The electrical demand and complexity is the worst aspect of modern cars in my book and 2 batteries is an admission of a design failure. I really dislike the fact that I can't open a car door while it's in the garage without triggering a substantial draw on the battery. And the worst is they don't always go to sleep properly, I had a couple of episodes where the battery went flat in 2 days for no obvious reason. The cure that worked for me was to disconnect the battery overnight, although that brings it's own issues so it's a last resort. Several times I'd go in garage to find parking lights on one side illuminated even though they weren't switched on. Turning the lights on and off again would reset it. Must have been a faulty SAM module - modern cars are not confidence inspiring on the electrical side.

 

[goblin]

Never, EVER charge a German vehicle that has dedicated posts under the hood by connecting directly to the battery posts, UNLESS the battery is otherwise disconnected from the vehicle.

If you want to trickle-charge it - charge at the posts under the hood and call it a day.

 

[OVERKILL]

Never, EVER charge a German vehicle that has dedicated posts under the hood by connecting directly to the battery posts, UNLESS the battery is otherwise disconnected from the vehicle.

If you want to trickle-charge it - charge at the posts under the hood and call it a day.

This is a new one to me. This is exactly how I charged my M5, which had the battery in the floor of the trunk, every winter. My Jeep has the battery under the passenger seat, so the jump posts under the hood are far more accessible, but that was not the case with the bimmer.

IIRC, the cables from the battery on the M5 to the jump posts were just heavy extensions, I can't see how connecting a charger to them, or to the posts directly makes a difference here? But I'm interested in hearing the reasoning.

 

[goblin]

This is a new one to me. This is exactly how I charged my M5, which had the battery in the floor of the trunk, every winter. My Jeep has the battery under the passenger seat, so the jump posts under the hood are far more accessible, but that was not the case with the bimmer.

IIRC, the cables from the battery on the M5 to the jump posts were just heavy extensions, I can't see how connecting a charger to them, or to the posts directly makes a difference here? But I'm interested in hearing the reasoning.

Not sure what year your M5 was. If you had an E39, chances are it was ok.
I'm talking about most BMWs after 2002, or whenever they started using the IBS sensor on the battery terminal. Then everyone started using similar stuff.
The story goes the car is better off when you charge through the IBS, so it can control things. Charging at the battery's poles bypasses it. Which won't damage the battery, but might damage car electronics.

You won't automatically damage the car if you charge directly at the poles, but there's a real risk. So if you have to do that - disconnect the car's cables first.

Which, in itself, is a whole different adventure, as a BMW has to go to sleep gracefully before you disconnect, which is a whole thing.

I put "German" together, as they all use such a system nowadays, one way or the other.

 

[BHopkins]

Never, EVER charge a German vehicle that has dedicated posts under the hood by connecting directly to the battery posts, UNLESS the battery is otherwise disconnected from the vehicle.

If you want to trickle-charge it - charge at the posts under the hood and call it a day.

I have always done battery maintenance on my E350 by connecting directly to the battery, instead of using the convenience posts. Rarely have I disconnected the battery before charging. Been doing it for all of the 6 years that I have owned her. Never had a problem.

My understanding is that the battery connections are there for convenience, because batteries in most MB cars can be inconvenient to get to.

 

[oilboy123]

I mis stated trickle charger. But I will be maintaining batt with a Noco 1 amp. The thing sounds like it needs a tune up when I start it cold. It has 40,000 miles. This G63 needs some love. But I will not be doing that work for her. I just want to keep the batt up. I might replace the strut on it, but that is it.

When I started it up, it showed 1/8 tank of fuel, and low coolant. Also the LR tire has age cracks, and the 4 tires have 3 different datecodes. When I lifted the heavy hood it had a support strut that was blown out. So I had to retrieved a piece of support wood. Connecting to the underhood positive post will charge both batts? The challenge is finding a good ground. The second post next to the positive post at the underhood jump post is not a negative? I watched a video of a guy jumping a G550, it had a negative post on the fender well.

That is a lot of motor in the engine bay...500+ hp V-8 Jeez. They also can have a V-12? Speedo says 180mph. The thing has the shape of a short wheelbase Jeep. I'm not sure how a brick can go 180mph.

I don't want to drive it because of liability, very low gas, and crappy tires. I put it in my backyard because I was afraid of vandals/thieves/hotwire happening. We live near a casino. The cops here say that a lot of people go down our private road to do drugs after gambling. I have had people cut my old trucks fuel fill hose twice to siphon gas.

I tried put it into 4 wheel drive to get it around my property. But it seems like I need a PHD just to enable it. I tried putting it in neutral then hit 4 wheel drive. But the button would not light up. When I looked into the manual it said the trans must be in neutral, and the vehicle rolling........ jeez....... I tried that and no dice. My 2012 F150 4x4 is simple in comparison. This vehicle also has another 3 switches on the dash for engaging wheel configurations.

 

[OVERKILL]

Not sure what year your M5 was. If you had an E39, chances are it was ok.
I'm talking about most BMWs after 2002, or whenever they started using the IBS sensor on the battery terminal. Then everyone started using similar stuff.
The story goes the car is better off when you charge through the IBS, so it can control things. Charging at the battery's poles bypasses it. Which won't damage the battery, but might damage car electronics.

You won't automatically damage the car if you charge directly at the poles, but there's a real risk. So if you have to do that - disconnect the car's cables first.

Which, in itself, is a whole different adventure, as a BMW has to go to sleep gracefully before you disconnect, which is a whole thing.

I put "German" together, as they all use such a system nowadays, one way or the other.

Yeah, it was an E39, think the last year was 2003.

I can't see how a low output maintenance charger could damage the car's electronics, given these same electronics are hooked up to something (the battery) that can deliver hundreds of amps instantly. I know BMW has that "battery programming" thing, if you replace the battery as part of the IBS or BMS, but that was of course post-E39.

My Jeep is on a platform shared with Mercedes (hence the battery beneath the passenger seat).

I could see if BMW has something that isolates the jump terminals from the electronics to prevent damage when you are either providing or receiving a jump, but I can't see how that would be at all relevant with a low output maintenance charger?

 

[Chris142]

The connection under the hood is the jump start terminal . You can put your charger there and there is a ground terminal near it.

 

[edyvw]

This is a new one to me. This is exactly how I charged my M5, which had the battery in the floor of the trunk, every winter. My Jeep has the battery under the passenger seat, so the jump posts under the hood are far more accessible, but that was not the case with the bimmer.

IIRC, the cables from the battery on the M5 to the jump posts were just heavy extensions, I can't see how connecting a charger to them, or to the posts directly makes a difference here? But I'm interested in hearing the reasoning.

You had E39. After 2004 and all BUS designs, absolutely on ports; otherwise, your FRM might get fried. Actually, no E60,90 etc. should be used to jump start anyone. When someone asks me to jump start them, I will go get Tiguan or a Toyota.