Adding 2nd fuel gauge to a sender

[nfluester]

We have the standard volvo (VDO I guess) gauge and sender on our KAD44'S and I'd like to get the tank levels onto the NMEA backbone.

There are lots of NMEA devices but how does one wire an additional sender in as I assume they are resistive and adding a second gauge will mess up the resistance.

Is there a splitter box I need to get or am I worrying about nothing and I can just tap into the sender or gauge in parallel?

 

[harvey38]

I'm confused by your question but here is my input -

Why do you need to install another sender?

Use the sender/s you currently have and convert the resistive load into an NMEA sentence using one of the many converters available.

 

[nfluester]

It maybe a non issue but I was under the impression that if I wired in another gauge all be it a NMEA convertor the resistance would change.

Am I talking rubbish can I just wire it in parallel to the sender or the gauge?

 

[harvey38]

You don't wire it in parallel, at least not my unit, I took a feed from both contacts on the back of the gauge and into the Albacombi unit and hey presto, NMEA 2K out of the other end

 

[nfluester]

Thanks I'll give it a try ?

 

[harvey38]

Thanks I'll give it a try ?

The Alba Combi, and others, just read the input voltage/resistance and convert it to 2 N2K, they don't add to the resistance already being read by the gauge. If you are going down the converter route, ensure you know what you are buying. There are plenty on the market, I went with Alba Combi as it is multi input and they provide a Web based calibration tool to ensure the output readings are accurate and can be adjusted to deal with non linear inputs. If you are only looking to just put fuel quantity onto the N2K backbone, you should be able to use some of the less complex, and cheaper units out there but, it does get quite addictive. I'm planning on full engine parameters, fuel, grey, black water quantities etc.

 

[colhel]

The Alba Combi, and others, just read the input voltage/resistance and convert it to 2 N2K, they don't add to the resistance already being read by the gauge. If you are going down the converter route, ensure you know what you are buying. There are plenty on the market, I went with Alba Combi as it is multi input and they provide a Web based calibration tool to ensure the output readings are accurate and can be adjusted to deal with non linear inputs. If you are only looking to just put fuel quantity onto the N2K backbone, you should be able to use some of the less complex, and cheaper units out there but, it does get quite addictive. I'm planning on full engine parameters, fuel, grey, black water quantities etc.

Sounds like an interesting project. The fuel gauge on our tamd41a is rather like motorbike one, ie it shows when it's full and empty but for the bit in-between you have to rely on guesswork. Will you get improved accuracy? We have a Garmin MFD that can show fuel and water levels but not presently used.

 

[harvey38]

As for accuracy, that depends on many factors such as tank size ie are they big enough for the engine capacity and being emptied quickly, what type of sender is installed, shape of tank so if an upside down triangle tank so shows full for a while then quickly drops.

If you are concerned about accuracy then you will only have an inaccurate digital fuel gauge. Research the above and if you do have an odd shape tank then the Alba Combi can set up a nonlinear curve to allow accordingly.

 

[petem]

What are the alternatives to AlbaCombi?

 

[harvey38]

What are the alternatives to AlbaCombi?

Quite a few, Google NMEA 2000 converters.

 

[fred247]

we've just fitted an Actiscence EMU I -oil pressure, temp, tacho, fuel. feeds just taken off the back of the gauges. if common ground, only needs one unit for both engines
needs calibration