D+ signal and installing aftermarket aux batt

[Kopiko]

Hello,

Currently, I'm working on installing an aftermarket auxiliary battery and inverter system into a 2019 Sprinter. I'm looking to for a D+ (or 15) connection somewhere in the vehicle to which I can connect a sort of 'D+ converter'. I have checked under the driver's seat for an EK1 terminal block (for D+, 15, and 30), but this vehicle hasn't been equipped with one. Is there any other terminal or circuit that i can use or tap into? Preferably somewhere in the driver's seat area.

The above mentioned 'D+ converter' senses whether or not the D+ has voltage on it (i.e. when the engine is running), and then activates an additional circuit that I can use for a run signal. I need this run signal to activate a specialized DC-DC converter/booster which charges the auxiliary battery from the starter battery and alternator.

Additionally, since today's vehicles come with a shunt on the starter battery minus terminal, (how) can I make sure that the system doesn't go mad when pulling some 40amps to charge the auxiliary battery? Any recommendations?

 

[autostaretx]

Some RV manufacturers put a "time delay" relay on one of the "ignition on" circuits, assuming that a minute or so after turning the key to "on", the engine will be running.

--dick

 

[Kevin.Hutch]

I would expect most DC-DC converters would have a low voltage sense on the input charge circuit making the converter act like a Voltage Sensing Relay to isolate any possibility of load on the start battery below a set input voltage, check the specs on your DC-DC converter.

 

[Eric Experience]

Kopiko
Your vehicle has the D+ terminal, you just have to look for it, it is in a 3 terminal block on a vertical panel near the hand break on RHD models. The D+ wire is blue with a yellow stripe.

 

[Kopiko]

I would expect most DC-DC converters would have a low voltage sense on the input charge circuit making the converter act like a Voltage Sensing Relay to isolate any possibility of load on the start battery below a set input voltage, check the specs on your DC-DC converter.

It does indeed have this feature, but i still need a run signal for the unit to switch on and start sensing.

 

[Kopiko]

Kopiko
Your vehicle has the D+ terminal, you just have to look for it, it is in a 3 terminal block on a vertical panel near the hand break on RHD models. The D+ wire is blue with a yellow stripe.

I suppose you mean this one. I've had a look, but it didn't have this terminal block unfortunately. I guess it's probably a factory option. Will see if I can find a blue with yellow wire?

 

[Eric Experience]

Kopiko.
We have just had a discussion about this terminal, Kieth posted a cct showing the terminal fed from fuse 15. Eric.

 

[FMMM]

Kopiko.
We have just had a discussion about this terminal, Kieth posted a cct showing the terminal fed from fuse 15. Eric.

Could you provide a link?

 

[autostaretx]

I suppose you mean this one. I've had a look, but it didn't have this terminal block unfortunately. I guess it's probably a factory option. Will see if I can find a blue with yellow wire?

If you submit your VIN to any of: https://www.datamb.com/ , https://www.lastvin.com/ , http://mbepc.net/f/vin/ http://mb.vin/
you can probably fetch a free copy of your "datacard" ... the options MB built into *your* Sprinter.
If your Sprinter is too new to have gotten into those databases (yet), ask at any MB parts desk for a copy (should be free).
Likewise a "private message" ("conversation" in forum-speak) to member @sailquik would get you one. Include VIN.

The terminal strip shows up as "EK1"

--dick

 

[FMMM]

If you submit your VIN to any of: https://www.datamb.com/ , https://www.lastvin.com/ , http://mbepc.net/f/vin/ http://mb.vin/
you can probably fetch a free copy of your "datacard" ... the options MB built into *your* Sprinter.
If your Sprinter is too new to have gotten into those databases (yet), ask at any MB parts desk for a copy (should be free).
Likewise a "private message" ("conversation" in forum-speak) to member @sailquik would get you one. Include VIN.

The terminal strip shows up as "EK1"

--dick

Thanks.
I may need that i.e. to connect to "EK1"/"D+" voltage sensing.
Went for a charger which has "Vibration sensor switch"* i.e. that's supposed to operate as an alterative to voltage sensing. There is an option to use voltage sensing, but easier to wire if the "Vibration sensor switch" works - I'm guessing there are other chargers which can operate without voltage sensing --- wondering why they don't just have an on/off switch!
*Sterling Power BB1240 Battery-To-Battery Charger - 12V/12V 40A

 

[autostaretx]

Voltage-sensing is quite common.
Usually the "trigger" voltage is 13.2 volts.
Below that, the charging system ceases operation.
Above that, it assumes that the alternator is producing charge and it starts charging the 2nd battery.

--dick