Mercedes Battery Isolator Switch

[Ntrepid]

So I know that disconnecting the battery on our cars has some minor inconveniences tied to them (i.e. resetting the clock) while on newer cars, more things like radio presets may be lost.

As I understand it, MB ships cars to the US with a battery isolator switch which is removed prior to delivery (maybe at port of entry). So I was thinking about finding one online (maybe even a Hella who makes them for MB).

Any thoughts as to specs I should consider (Amps in particular) as well as if there is anything I am missing. What I am trying to do is take my car off of a tender through the season it won’t be driven which should help with desulfation (I think).

Here is an example unit:

HELLA 002843011 2843 Series 100A Rating Battery Master Switch

Amazon.com: HELLA 002843011 2843 Series 100A Rating Battery Master Switch: Automotive

Robert

 

[gsxr]

Robert, is your idea to leave the battery in the car but disconnected, and not plugged into a tender? That would probably be OK for short term (couple of months) but much longer and a tender would still be recommended, if you want to prolong battery life.

For desulfation, get a maintainer that offers full-time desulfation, like PulseTech or Battery MINDer. Or, get a permanent-mount desfulation unit (PowerPulse) and use any standard maintainer.

 

[Ntrepid]

Dave -

Absolutely. Just want to go through the winter months. I have the cars on a battery tender and this switch would interrupt that as well. When the circuit is closed, the tending would continue.

My concern is that is listed above is rated at 100A (assuming sustained) but the cranking amperage is several hundred amps.


Robert

 

[gerryvz]

Robert, for the past three-plus winters I have had Laura's 4Runner on said type of switch underhood. It works perfectly fine. The truck sits outdoors in my driveway and perhaps gets driven once every week or two weeks -- mainly as a Lab(rador) Cab for going on dog outings and such.

Her 4Runner has a parasitic draw (it's a faulty interior accessory computer, as diagnosed by the stealership, that they want $1,200 for and must be programmed to the vehicle by the stealer), so that after about 4-5 days, it draws down the battery. I installed the switch underhood and it works super well. The only PITA is that I have to raise the hood and switch it on when we want to drive the truck.

I have no qualms about leaving the battery connected underhood (with the isolation switch installed). I have NEVER had any issue with the battery discharging with the switch disconnecting it. The longest I have left the truck without driving it is perhaps six weeks. The battery is going on 4 years now (three Maryland winters) and it's going strong !!

That Hella switch looks very similar to the ones that MB used for transatlantic transit that, as you mentioned, they removed at the port of entry (much of the East Coast, this would have been the Port of Baltimore).

I have never used a Battery Tender with the truck with this switch installed. Just connect the switch and go. Driving the truck charges up the battery. I have never looked at amperage specs, to be honest, so am not of much help there. But I've also never considered it an issue.

I say go for it !!

Cheers,
Gerry

 

[DerFuror]

For years I've successfully used this type of battery isolator switch on several vehicles in conjunction with a permanently mounted pigtail connection for my battery tender. With this configuration, the green knob disconnects the battery power from the car, yet allows the battery to maintain charging, obviating parasitic draw situations. The knob can also be removed, providing a degree of theft-deterrence.

 

[MB V8]

GVZ or DerFuror......names of or links to your battery isolator switches? Thanks

 

[gerryvz]

The Hella one mentioned above is my go-to.

 

[MB V8]

Okay thanks

 

[LWB250]

So I know that disconnecting the battery on our cars has some minor inconveniences tied to them (i.e. resetting the clock) while on newer cars, more things like radio presets may be lost.

As I understand it, MB ships cars to the US with a battery isolator switch which is removed prior to delivery (maybe at port of entry). So I was thinking about finding one online (maybe even a Hella who makes them for MB).

Any thoughts as to specs I should consider (Amps in particular) as well as if there is anything I am missing. What I am trying to do is take my car off of a tender through the season it won’t be driven which should help with desulfation (I think).

Here is an example unit:

HELLA 002843011 2843 Series 100A Rating Battery Master Switch Amazon.com: HELLA 002843011 2843 Series 100A Rating Battery Master Switch: Automotive


Robert

Just out of curiosity, has anyone ever seen one of the Mercedes battery disconnects? I'm assuming they must recycle them, considering they're used on every car they ship out of the country I presume. I would think they would be pretty simple and inexpensive, like the ones you have the knob that just screws down a contact onto a flat terminal.

Dan

 

[Ntrepid]

Here are some part numbers I found for them.:

• A0005454908
• A0005459708

Can's seem to locate them on MBOEMparts.com


Robert

 

[LWB250]

Hmm. I may have to challenge my parts guy. However, as they remove these at the port of entry, it's unlikely he's ever seen one or even knows what they are.

I'll ask him next time I talk to him.

Dan

 

[gsxr]

Just curious, what is the reasoning behind the disconnect, if a battery maintainer is connected? I like the idea of everything in the car staying at 13v in storage. If there's no maintainer, I understand disconnecting if parked more than a few weeks.

 

[northNH]

I’ve used the brass green-knobed shutoff as shown on many cars over many years.

Big plus is the simple ability to electrically disconnect/reconnect the entire car from the battery, instantly if in a panic or slowly as part of a more measured diagnostic or healing procedure.

Bought my first one from a J.C. Whitney catalogue back when they were touting their brand new no charge 800 phone number on the cover...

 

[Ntrepid]

Just curious, what is the reasoning behind the disconnect, if a battery maintainer is connected? I like the idea of everything in the car staying at 13v in storage. If there's no maintainer, I understand disconnecting if parked more than a few weeks.

I'm guessing if you have a parasitic drain that you can maintain the battery while in storage versus continually maintaining it.


Robert

 

[gerryvz]

The only downside I have when I reconnect Laura's 4Runner to start it up, is that it doesn't remember the radio stations, nor the HVAC settings (it resets them to a default setting of no fan and 75F temp). Oh yeah, and the digital clock has to be reset. Just used her 4Runner on Tuesday after it was sitting for more than a month, disconnected. No worries at all.

 

[gsxr]

While I'm not familiar with the Yoda, on a 124 chassis, why not fix the cause of parasitic drain if it's pulling the battery down in less than a month or two? Or let the maintainer compensate for a very small drain.

If the vehicle in question is parked far from an electrical power source to connect a maintainer, that I understand. But if there's an outlet within ~30' or so, I'd just leave the batter+maintainer connected normally. I use a 25' extension on a coupe of cars.

 

[gerryvz]

While I'm not familiar with the Yoda, on a 124 chassis, why not fix the cause of parasitic drain if it's pulling the battery down in less than a month or two?

Ummm...because I'm allergic to paying the local Toyota "stealer" $2K (parts and labor) to replace and program a new interior convenience computer. Per my earlier post:

Her 4Runner has a parasitic draw (it's a faulty interior accessory computer, as diagnosed by the stealership, that they want $1,200 for and must be programmed to the vehicle by the stealer), so that after about 4-5 days, it draws down the battery.

 

[gsxr]

Um. I said, "...on a 124 chassis...". Usually not that hard to chase down drains on the 124.

Not wanting to pay the toy Yoda stealer just means you are cheap, Honch...

 

[DerFuror]

A startling thread I read on 500Ecstacy (back in the very early days of my 500E ownership) about a potential electrical fire issue provided further impetus for my use of the isolator switch on my 500E. My car usually goes into hibernation (sometimes for months unattended) from November to May once Winter starts to show its ugly mug. The isolator switch assuaged my concerns by helping ensure the safety of my investment until more info was obtained on the hazard issue. The contents of & around my garage were way too much to risk.

Also, we had several 1950s - 60s British roadsters over the years. No locks. Positive earth wiring. Lucas' reputation. The green knob switch worked well from both an anti-theft & potential electrical fire-during-storage standpoint.

 

[cossie]

Reviving this thread... any consensus re: the best battery kill switch to use for our cars? I'll be needing it in all my cars that are rarely use.

Just want to share my traumatic experience today.
My W210 with M112 burned down while the car was parked for 2 days almost burning down the house too. The key was inside the house, no accessories left on, no battery tender attached. Based on the CCTV footage, smoke started coming out of the grille and hood gaps, 5 minutes later the whole front end was in flames.

Same thing happened to my W202 with M111 5 years ago. It was just parked when it burned down.

Both incidents happend in different places.

 

[cossie]

What are your thoughts on this type of cut off switch? Do you think it will fit in our 036?

 

[gerryvz]

What are your thoughts on this type of cut of switch? Do you think it will fit in our 036?

That is exactly the type of switch that I have been using since 2016 in my wife's Toyota 4Runner. I don't know whether it would fit the 036 or not, but I don't think so given the tight room in that battery compartment. I would recommend the "green wheel" type that the Derf illustrates in his post. Easy enough to untwist the thumbwheel, or even remove it. And still keep a trickle charger attached to the battery to keep it maintained over the winter.

One note with that "knife" type of switch, is that the copper knife and hinge area DO get surface-oxidized periodically, and once or twice per year require taking some steel wool or fine sandpaper to remove the thin surface schmutz to restore proper contact. It's just polishing the surface to make good contact. The knife part and the "receiver" parts for the knife blade.

 

[cossie]

Thanks @gerryvz! Just ordered a couple of those green terminals.

Is it safe for the modules if the battery is frequently cut-off?

 

[gerryvz]

Not having power won't hurt the modules in any way.

 

[LWB250]

Thanks @gerryvz! Just ordered a couple of those green terminals.

Is it safe for the modules if the battery is frequently cut-off?

You'll just lose the clock settings. Everything else should be fine. Even your radio settings will be intact.

Dan

 

[JC220]

For years I've successfully used this type of battery isolator switch on several vehicles in conjunction with a permanently mounted pigtail connection for my battery tender. With this configuration, the green knob disconnects the battery power from the car, yet allows the battery to maintain charging, obviating parasitic draw situations. The knob can also be removed, providing a degree of theft-deterrence.

View attachment 102719

View attachment 102720

Thanks for this, it is a good idea and my current setup of too many cars and no time means several of them do sit draining batteries on a constant basis.

I do need to sort out outside sockets for trickle chargers etc but I think these green items requiring no tools to disconnect are a good idea and I just mail ordered 4x of them to see how they work out.

My 600etc drains a battery completely every month or so and I have to open the boot to charge it anyway. So I could disconnect the good fully charged battery in the first instance and no different when I go back to the car except next time it will be a fully or still decent charge battery ready to go.

 

[gsxr]

Anyone have a link to their preferred GreenKnobs™? I still plan on keeping my stored cars on maintainers, but the shutoff is a nice idea for safety / fire prevention.

 

[nocfn]

Napaonline.com has them for less than 20 usd

 

[JC220]

Napaonline.com has them for less than 20 usd

I bought 4 of them on ebay UK for £19.80 including postage

 

[JC220]

Just a note on these green battery cut off jobbies:



The whole car will be running through a single M8 stud. That is the design of these. There is a full insulator between the terminals to allow the stud to quickly turn off the car at a half turn etc.

I wasn't fully aware of that. I think for a 4 cylinder car this is OK.

But for 6, 8 or 12 cylinder S classes etc, no way. It will have an impact on the starter juice or even at risk of a melt down with the power going through it IMO.

 

[DerFuror]

We know what the E500E electrical power requirements can be. My 500E has been using the same GreenKnob isolator for the past 13 years. Zero issues.

I somewhat recently took advantage of a stretch of unseasonably fine weather to do some driving & to relocate the 500E to a less active garage before the Hinterlands' eventual blanketing of snow & roadsalt. Driving was as fun as ever. It's all settled in now until next driving season. Car covered, Battery Tender plugged in, GreenKnob isolating the fully charged battery from the car. All good.

 

[nocfn]

Good to see. Writing by Derf - I feared you may have expired….

 

[northNH]

Just a note on these green battery cut off jobbies:

View attachment 156827

The whole car will be running through a single M8 stud. That is the design of these. There is a full insulator between the terminals to allow the stud to quickly turn off the car at a half turn etc.

I wasnt fully aware of that. I think for a 4 cylinder car this is OK.

But for 6, 8 or 12 cylinder S classes etc, no way. It will have an impact on the starter juice or even at risk of a melt down with the power going through it IMO.

Perhaps of interest…
Stumbled on one of these NOS/NIB on a hard-to-see high cluttered shelf.
Specs state “Rated 125A continuous, 500A surge”.