What size wires

[Daydream believer]

I have a new Volvo Penta D1-30. I have seen numerous posts about the MD1 unit failing & how they can be byepassed using a momentary switch connected with 2 wires to 2 of the 3 terminals on the bottom of the MD1 box. (ie. not using the glow terminal)
So to be one step ahead of the game I have purchased a 60 amp waterproof momentary starter switch. I will mount this somewhere convenient -approx 4 ft from the MD1 unit. Then if I get an issue I have a pre wired get out.

My question is- How big do the wires have to be for a momentary start procedure, bearing in mind the length will effectively be 8ft.
Is 8 ft too much & does the switch need to be right in the engine bay to keep the wires as short as possible.ie 2 * 18 inches.
Thanks

 

[PaulRainbow]

To start the engine you can just wire the switch between the heavy battery cable on the starter solenoid and the solenoid trigger wire. 2.5mm is more than enough. Fit a fuse in the wire from the battery cable to the switch, as close to the switch as possible.

 

[Daydream believer]

To start the engine you can just wire the switch between the heavy battery cable on the starter solenoid and the solenoid trigger wire. 2.5mm is more than enough. Fit a fuse in the wire from the battery cable to the switch, as close to the switch as possible.

I cannot access the starter motor due to the position of the alternator. I do not want to remove it & risk disconnecting the wiring to gain access.
When the Volspec engineer came to commission the engine I had to get him to connect the starter motor. (As an aside-The engineer was the technical editor of motor boat & yachting for some years)
The recognised method - as advised by him & by the you tube vids- is to connect to the very accessible terminals on the MD1 unit which enables the MD1 to bye pass it

May I ask--Why would I need any fuses as the switch is momentary & not permanently carrying a current? Bear in mind this is only there as an emergency aid.

 

[Refueler]

I'm with Paul on this - but as DB asks - why a fuse for a line that is not used except in emergency.

TBH - its pretty well how most older engines are started anyway ... by triggering the solenoid .... mine has a momentary push button using the trigger terminals of the solenoid.

DB - think you missed that Paul mentioned the solenoid - not the starter ... unless you have an all in one job ?

 

[PaulRainbow]

If the MDI is easier, no problem going with that.

Ref the fuse, if one line to the switch is positive it needs to be fused, lest it shorts out an becomes an electric fire element.

If that wire is connected to the MDI, you've shorted out the MDI, how much is a new one ??

 

[Tranona]

While there were problems with MDI failures in the 2013-2015 period and bypassing it for starting became popular, the problems were solved in 2016/7 and all potentially defective units changed through a recall (including my 2015 engine, which did not fail). AFAIK there have been no problems since. When I did a google search last year because I was considering fitting a new D1 30 I could find no recent reports of failure unlike 7 years ago when forums were full of it.. I did not fit a bypass switch and never had any problems.

Not the greatest bit of design mounting the box of electronics in a location subject to heat and vibration but my understanding is that the internals were redesigned to be more robust to withstand the vibration which caused internal connections to fail.

 

[William_H]

What sized wire. Well assuming you are activating the solenoid on the starter motor then you are talking perhaps up to 10 amps. However you not want to go smallest wires possible as they become less robust and prone to corrosion and damge. So use a fairly robust wire perhaps more for 20 amps 12g or heavier. ol'will

 

[Daydream believer]

While there were problems with MDI failures in the 2013-2015 period and bypassing it for starting became popular, the problems were solved in 2016/7 and all potentially defective units changed through a recall (including my 2015 engine, which did not fail). AFAIK there have been no problems since. When I did a google search last year because I was considering fitting a new D1 30 I could find no recent reports of failure unlike 7 years ago when forums were full of it.. I did not fit a bypass switch and never had any problems.

Not the greatest bit of design mounting the box of electronics in a location subject to heat and vibration but my understanding is that the internals were redesigned to be more robust to withstand the vibration which caused internal connections to fail.

I take your points. However, they are still having reports of regular failures coming up on the My Hanse forum. It seems a simple thing to add just to be safe, That is why I posted the question.

 

[Daydream believer]

If the MDI is easier, no problem going with that.

Ref the fuse, if one line to the switch is positive it needs to be fused, lest it shorts out an becomes an electric fire element.

If that wire is connected to the MDI, you've shorted out the MDI, how much is a new one ??

I would not need to do it unless the MD1 failed in the first place. I just want the system in place. I get sea sick very quickly; so fixing it at sea is a no no. One just knows that sod's law dictates, that if it is going to go wrong, it will do so at the most dangerous moment. Having an emergency byepass up & running can save the day . Having it may mean that I never need it.

My last Volvo needed several replacement glow relays in its lifetime. After the first one went I carried spares. I could tell straight away what was happening & take the cover off & swop in under 2 minutes. Without the spare & the knowledge I would have been in trouble.

It is just a case of being prepared.

 

[Alex_Blackwood]

I have a new Volvo Penta D1-30. I have seen numerous posts about the MD1 unit failing & how they can be byepassed using a momentary switch connected with 2 wires to 2 of the 3 terminals on the bottom of the MD1 box. (ie. not using the glow terminal)
So to be one step ahead of the game I have purchased a 60 amp waterproof momentary starter switch. I will mount this somewhere convenient -approx 4 ft from the MD1 unit. Then if I get an issue I have a pre wired get out.

My question is- How big do the wires have to be for a momentary start procedure, bearing in mind the length will effectively be 8ft.
Is 8 ft too much & does the switch need to be right in the engine bay to keep the wires as short as possible.ie 2 * 18 inches.
Thanks

What size are the wires already on these connections? Maybe a clue Sorry I have not seen this box in real life and a bit difficult to be more precise from the literature.

 

[Daydream believer]

What size are the wires already on these connections? Maybe a clue Sorry I have not seen this box in real life and a bit difficult to be more precise from the literature.

I will check, but quite thick from what I recollect (6mm???). But I am not sure that makes a difference, as it is only a linking wire to cause the solenoid to trip & that is why I have asked the question.
All the wires(12 No) from the control panel are fairly thin & a pair of them must do the same job in some way; albeit via the circuitry in the MD1 unit. But they may only be tripping a relay inside the unit.

 

[Tranona]

I take your points. However, they are still having reports of regular failures coming up on the My Hanse forum. It seems a simple thing to add just to be safe, That is why I posted the question.

Yes, I know and also on the Bavaria forum. BUT none of them refer to engines post 2017. I have just googled again to see if there is any change and all I can find is reference to pre 2017 engines, some of which had the really dodgy batch that were replaced and others for random failures of very old units. The basic MDI unit has been in use since 2004/5 when the D1/2 engines came. Trouble free until 2013/4-7 and post 2017 when the latest version came in. This

youtube.com/watch?v=jW47QE8YWog

may help your wiring if you do decide to add the by pass.

 

[PaulRainbow]

I would not need to do it unless the MD1 failed in the first place. I just want the system in place. I get sea sick very quickly; so fixing it at sea is a no no. One just knows that sod's law dictates, that if it is going to go wrong, it will do so at the most dangerous moment. Having an emergency byepass up & running can save the day . Having it may mean that I never need it.

My last Volvo needed several replacement glow relays in its lifetime. After the first one went I carried spares. I could tell straight away what was happening & take the cover off & swop in under 2 minutes. Without the spare & the knowledge I would have been in trouble.

It is just a case of being prepared.

If you are installing something in readiness to be used, any wire coming from the MDI to a switch, that is live, must be fused, You are bridging the battery positive to the starter solenoid, so the battery wire will be live, whether you use the switch or not, this must be fused close to the MDI. If it shorts, the wire will melt in very short ordewr, possibly causing a fire. No big deal to add an inline blade fuse.

 

[VicS]

What size are the wires already on these connections? Maybe a clue Sorry I have not seen this box in real life and a bit difficult to be more precise from the literature.

Surprisingly only 1.5mm² according to the wiring diagram (attached, I hope) but on earlier engines eg MD 2010 series and 2001 series the wiring between the starter solenoid and the starter relay is 2.5mm².

 

[PaulRainbow]

Surprisingly only 1.5mm² according to the wiring diagram (attached, I hope) but on earlier engines eg MD 2010 series and 2001 series the wiring between the starter solenoid and the starter relay is 2.5mm².

I said 2.5mm in post #2

14 posts later, still being debated !

 

[Alex_Blackwood]

I said 2.5mm in post #2

14 posts later, still being debated !

Quite correct Paul, did wonder about the 60 amp switch though!

 

[Daydream believer]

Quite correct Paul, did wonder about the 60 amp switch though!

Is there a problem having a switch with reserve amperage capability, as opposed to too little?

 

[Alex_Blackwood]

Is there a problem having a switch with reserve amperage capability, as opposed to too little?

Absolutely not. However just wondered if there was significance?

 

[VicS]

Is there a problem having a switch with reserve amperage capability, as opposed to too little?

Absolutely not. However just wondered if there was significance?

The solenoid does draw an appreciable especially initially. They do (sometimes,/ usually, not sure which) have a pulling winding and a hold on winding, the pull in winding taking quite a high current. I was surprised how large when I measured it but I forget the actual figure.
A heavy duty switch or push button is therefore essential. A 60amps rating would not be inappropriate.
You'd not want the contacts in a switch of inadequate rating to weld themselves together

 

[andyc352]

I too became concerned about these units failing. Several years ago I fitted a remote push button start switch on a bracket close to the control unit on the side of my D2-55. Tested it after installing but never had to use it in anger. I used 2.5mm wire.