Tapping into MB factory installed aux battery

Legwound

Member
Hey All

Another dumb question.

I've got the factory installed auxillary battery under the drivers seat and cut off relay E36.

I also have the ED5 programable special module. I really don't know what this enables me to do but I beleive it is where I should be tapping into for additional loads I'm about to describe. Is this the correct place to tap in?

As far as loads I'll be running, I'll be adding load in stages. For starters a small inverter (insert inverter suggestions here). From what I've read jusing a few small inverters rather than a single large one is more efficient and this will be my strategy for growth/expansion.

I'll run a computer from it for starters, 15" laptop for a few hours of entertainment at night with the wife and a few hours work during the day.

I'm in the midst of getting my MB installed booster heater converted to run when engine is off. I'm thinking it's be good to power the unit from the auxillary to preserve my starting battery. I'm assuming once I get that sorted I'll be running it overnight with similar draw as an Espar Hydronic D5 for say 8 hours.

I'll be adding a battery monitor to get a sense of my typical draw and will add components one at a time.

In the near future I'll add a fridge, and some additional interior lighting.

I may also add an Espar airtronic D2 if required (I'm in Canada)

I'm thinking I'll eventually run a 20 - 27" tv and sound system from the computer when I have the interior fully sorted. The sound system won't be very exotic, just adequate to hear the programming when it's raining on the roof. I'll be adding a kitchen/sink so pumping water will happen as well.

I think eventually I'll add solar charging capacity once I get a handle on my needs. That and potentially a second battery if required.

That's my anticipated load for now.

So where's the best place to tap in for this Sprinter novice?
 
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Mrdi

Active member
You are posting on the NCV3 arena.
The OEM NCV3 aux batteries are under the hood.
The starter battery is under the drivers side floorboards.
The MB suggested connection to the OEM Aux. battery is under the drivers seat.
Might help if you posted your year and model.:thumbup:
 

sailquik

Well-known member
For your computer, I'd suggest finding the input voltage an purchasing a 12v to XXvdc step up power supply.
Much easier on the battery, not inverter scream when the voltage to the inverter drops when you shut off the engine.
Just seems to me that boosting 12vdc up to around 16-19 vdc is a whole lot more efficient that powering an inverter, that
converts 12 vdc to 110VAC then using the computer's power supply to drop the 110VAC back down to 16-19 VDC that the
computer needs.
I have a power supply for each of my computers, and I will never go back to an inverter to power anything that can run off
DC power.
I've been getting these high reliability/low noise power supplies from Power Stream.... just determine what your computer needs,
and then purchase the correct Power Stream adapter and you will have reliable power for your computer with the engine on and the
alternator charging, as well as with the engine off, using the main battery (or Aux. Battery if you have one) as a power source.
http://www.powerstream.com/ADC.htm
Roger
 

Legwound

Member
You are posting on the NCV3 arena.
The OEM NCV3 aux batteries are under the hood.
The starter battery is under the drivers side floorboards.
The MB suggested connection to the OEM Aux. battery is under the drivers seat.
Might help if you posted your year and model.:thumbup:
good points. I tend to overlook the obvious....

2010 144 low roof.

I do have a battery under the hood which I assumed was the starting battery. learned something already!

I'll look for the connection point. I have to pull the seat to install my tow brake controller shortly anyway.
 

Legwound

Member
For your computer, I'd suggest finding the input voltage an purchasing a 12v to XXvdc step up power supply.
Much easier on the battery, not inverter scream when the voltage to the inverter drops when you shut off the engine.
Just seems to me that boosting 12vdc up to around 16-19 vdc is a whole lot more efficient that powering an inverter, that
converts 12 vdc to 110VAC then using the computer's power supply to drop the 110VAC back down to 16-19 VDC that the
computer needs.
I have a power supply for each of my computers, and I will never go back to an inverter to power anything that can run off
DC power.
I've been getting these high reliability/low noise power supplies from Power Stream.... just determine what your computer needs,
and then purchase the correct Power Stream adapter and you will have reliable power for your computer with the engine on and the
alternator charging, as well as with the engine off, using the main battery (or Aux. Battery if you have one) as a power source.
http://www.powerstream.com/ADC.htm
Roger

good info, I had always thought the inverter route was the long way around for these devices. I assume that charging my and my wife's phone by this route will be better also.

thanks
 

Mrdi

Active member
Connect to OEM Aux. Battery at this copper fuse, lower nut.(see pic)
Fuse as soon as possible after the connection.
You will find this fuse under the drivers seat, port, aft.
It has a plastic cover. (not shown)
Info and pic from MB Up-fitters document.
Don't forget to dis-connect the Aux. Batt. negative terminal
when playing up-fitter in this area.
 

Attachments

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sailquik

Well-known member
Legwound,
Does your 2010 144" wb Sprinter have the factory installed trailer towing package?
If so, no need to remove the drivers seat (I did that once....not doing it again unless absolutely necessary)
to install your trailer electronic brake controller.
Pull the plastic cover off (where you have access to all the fuses under the driver seat) on the LH side of the
drivers seat box and take a flashlight and look around on the bottom of the seat box area.
You will find a light green 4 pin connector that is already attached to the trailer wiring adapter on the top
middle rail of the under the seat electronics package.
Do search on "green connector" for a lot more info...photos ...everything you need.
You will have to buy the mating connector + 4 pins from a Mercedes Sprinter dealer, but it's a very straight
forward task once you have the parts and have located the factory installed connector.
The part numbers for the mating green connector and 2 sets of pins (one larger AWG than
the other) are:
Connector: 039-545-35-38 (my cost $2.24)
4 Pins: 046-545-40-28 (my cost $2.59 ea=$10.36)
4 Pins: 035-545-74-28 (my cost $2.41 ea= 9.64)
If you have any trouble getting these parts, let me know and I can give you a POC at
Sun Motor Cars Mercedes in Mechanicsburg, PA that can order them for you.

If you don't have the factory installed trailer wiring harness....good luck.
I'd suggest having a dealer install the complete harness to avoid many issues.
Check out this link:
http://groups.yahoo.com/group/sprintervan/photos/album/1508017253/pic/list
Roger
 
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Amboman

New member
From what I've read using a few small inverters rather than a single large one is more efficient and this will be my strategy for growth/expansion.
This strategy needs revision (as a few is more than three) and that is just misguided.
 

Legwound

Member
Yes I do have the factory harness. I have a swivel seat base and have had the seat off previously so i know what you mean, it's a bit of a bear. I ordered the connector and pins today, they'll be in tomorrow. I also have a Tekonsha P3 on the way.

I'll be putting in a battery monitor also (brand/model to be determined) which will require me to get the seat off so i'll tackle a few items at once.

Legwound,
Does your 2010 144" wb Sprinter have the factory installed trailer towing package?
If so, no need to remove the drivers seat (I did that once....not doing it again unless absolutely necessary)
to install your trailer electronic brake controller.
Pull the plastic cover off (where you have access to all the fuses under the driver seat) on the LH side of the
drivers seat box and take a flashlight and look around on the bottom of the seat box area.
You will find a light green 4 pin connector that is already attached to the trailer wiring adapter on the top
middle rail of the under the seat electronics package.
Do search on "green connector" for a lot more info...photos ...everything you need.
You will have to buy the mating connector + 4 pins from a Mercedes Sprinter dealer, but it's a very straight
forward task once you have the parts and have located the factory installed connector.
The part numbers for the mating green connector and 2 sets of pins (one larger AWG than
the other) are:
Connector: 039-545-35-38 (my cost $2.24)
4 Pins: 046-545-40-28 (my cost $2.59 ea=$10.36)
4 Pins: 035-545-74-28 (my cost $2.41 ea= 9.64)
If you have any trouble getting these parts, let me know and I can give you a POC at
Sun Motor Cars Mercedes in Mechanicsburg, PA that can order them for you.

If you don't have the factory installed trailer wiring harness....good luck.
I'd suggest having a dealer install the complete harness to avoid many issues.
Check out this link:
http://groups.yahoo.com/group/sprintervan/photos/album/1508017253/pic/list
Roger
 
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Legwound

Member
This strategy needs revision (as a few is more than three) and that is just misguided.
I got my several small inverter advice from the link in the conversion forum

https://sprinter-source.com/forums/showthread.php?t=14341

Post number 3, top link to handybobsolar. His lengthy article suggests smaller inverters over a single large inverter. According to Bob, all the inverters have a draw, even when not feeding a device, and larger inverters have higher idle draw.

I'm thinking of 2-3 for my purposes, starting with a small one and adding as needed. I'd only turn on what I need to avoid drain. I'm not an expert and am only repeating what I've read elsewhere so it could be a flawed strategy. More research.

I am very open to inverter advice as to sizing and brand/models
 
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WPJ

New member
I could see the draw to this as well.

1for tv and electronics,
1f fridge pump
1 for,x.....

Each one with a dedicated cut,off switch. You can run,much smaller wire to each one and save on the large costly runs or wire.
 

NBB

Well-known member
Connect to OEM Aux. Battery at this copper fuse, lower nut.(see pic)
Fuse as soon as possible after the connection.
You will find this fuse under the drivers seat, port, aft.
It has a plastic cover. (not shown)
Info and pic from MB Up-fitters document.
Don't forget to dis-connect the Aux. Batt. negative terminal
when playing up-fitter in this area.
WARNING!!

THAT IS NOT A FUSE!!

If it was, it would be a few kilo-amps, at least.

You can buy a fuse to fit into that spot.

See "My Climbing Rig", near the end.
 

autostaretx

Erratic Member
THAT IS NOT A FUSE!!
I agree... it looks like the shunt for a current meter (such as a battery monitor would use to measure the current in/out of the battery).

The way those things work is that it's a carefully calibrated piece of copper, with a known (very low) resistance. Perhaps 0.001 ohm.
As (let's say) 100 amps flows through ta chunk of copper, there will be a voltage drop across it of 0.1 volts.
A sensitive voltmeter could then tell you (by seeing that tenth of a volt) that you were, indeed, drawing 100 amps.
Or, if the alternator was running (without any loads), it could also tell you how much current was crammed back into the battery.
(assuming the alternator/isolator also had to feed through that chunk of copper to reach the battery).

--dick
 

NBB

Well-known member
I agree... it looks like the shunt for a current meter
No, it's not a shunt, either. It's a cheap piece of copper meant to be removed and replaced by an actual fuse. There are not any systems out there that place the shunt on the positive battery lead, anyway.
 

Vanwoman

New member
This is a very helpful thread. Many thanks. Where do you hook up the negative or ground lead from an inverter if you tap in the positive under the seat?
 

autostaretx

Erratic Member
The PSM is for loads that use the starter battery (and/or the normal vehicle electrics).
There may well be signals you want to access (such as "engine running"), but the actual *load* for the auxiliary battery would not attach to the PSM.

In the T1N, there were *no* MB "load-side" connections on the Aux Batt... you were expected to add your own.
The attached extract from a 2007 NCV3 wiring diagram suggests that there's an "External Fuse 2" with an "uncommitted" red wire attached (lower right corner).
Look for the connection *to* "External Fuse 2" on the isolator relay.

2007aux.jpg


--dick
 
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Mrdi

Active member
This is a very helpful thread. Many thanks. Where do you hook up the negative or ground lead from an inverter if you tap in the positive under the seat?
There are a couple of grounds under the seat as well.
Look towards the front under the seat and you will see them bolted to the floor
See #7 on page 3 on the previous posting pdf.
 
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