View Full Version : 12V accessory power behind the bulkhead

09-25-2010, 09:01 PM
I bought a 12V extension cord for power in my cargo area, that way I can charge my cordless tools in the back, and try and keep some of the mess out of the cab. Turns out the extension I bought must be too light of a wire gauge, and will not correctly charge the batteries due to a low voltage condition.

Here is the extension that did not work http://www.amazon.com/gp/product/B000Z0HVHA/ref=oss_product

I would like to make a new one up with 16GA. lamp cord, and hard wire it to the 12V power supply with a fuse, where is a good source to tap 12V on the NCV3, under the drivers seat would be the most convenient.


Altered Sprinter
09-26-2010, 02:10 AM
The particular 12v cord your showed should work,if you tested the connections for powering up an accessory.
The basic 12v units will charge power tools but are non fused,
Higher quality units are earthed with both positive and negative.
Specifications (http://www.projecta.com.au/documents/item/120)
Second variant will handle charging of most batteries [not all] however it has an automatic cut off in the event of mains start battery going below minimum voltage.
Specifications (http://www.projecta.com.au/documents/item/123)
Most power tools require a small 600w inverter for a decent controlled battery charge to protect the electronics of the power tool,as an inverter has auto cut out to protect electrical items on over charge or spiking of power fluctuations.

15A to 30A 4mm single core will do the job.
H/D 12 v points can be run from mains starts deep cycle batteries with H/D wiring and auto cut offs with fuses. where multiple outlets can being incorporated from 5w to 20w outlets. for fridges 800w jugs whatever,.
Batteries are fully monitored for voltage whilst in a non start operating mode.
separate monitors are active on aux and mains start batteries whilst in operational mode. to visually see battery voltage draw temperature of battery and alternator charge. Direct tapping from live ign from under the seat can be achieved if you tap into the mains direct,before a fused line.
It requires a minimum 40 amp relay plus inline fusing for an additional extension voltage line.

09-26-2010, 03:06 AM
How many volts do you -need- for your charging? ...and how much current?

With the engine running above 1500 rpm, the Sprinter is still only going to be providing about 14.3 volts

Be sure to post a review of the RoadPro on Amazon, but i'd guess (since they don't say) that it's probably 18 gauge.
Going from 18 to 16 gauge lowers the ohms per foot by about 1/3rd, and increases the current-carrying area by 1/3rd.
Your NCV3 may have a "accessory tap point" under the driver's seat (many do).
It's a small block with two or three unused screw (or bolt) points, one "always on", one "on when running"

It's option "EK1", and the description from the "options" manual says:
Details & Technology
The terminal strip is mounted on the inner side of the driverís seat base. If comprises three connections:
Terminal 1: D 12 V/10 A (120 W)
Terminal 2: 30 12 V/25 A (300 W)
Terminal 3: 15 12 V/15 A (180 W)
Here's a photo:26537

good luck hunting

09-26-2010, 12:10 PM
I am charging with the key off, batteries charge just fine with out the extension. I don't want to use an extension cord, because I charge my blue tooth in the cab, and that means more plugging in and out for power to the rear. Is that picture under seat for NCV3 vans, or T1N? Are they all the same? I will check the wattage of my battery charger.


09-26-2010, 02:27 PM
That picture was taken from the 2010 NAFTA NCV3 Options "Bible" (the entire document is posted somewhere in this forum)
(your original question said "NCV3", so i tried to be germane)


09-28-2010, 08:07 PM
Thanks for the help, center terminal was the only one that was live full time. I built a custom battery pack holder while I was at it. 12V accessory power is just below the red charger.


09-28-2010, 08:25 PM
The 2010 Options List (bible?) is attached to this posting: http://sprinter-source.com/forum/showthread.php?p=84016

It's in NCV3 Database under the subject title: Option Codes, but it really should be changed to Sprinter 2010 Option Codes.