MFD's knocking out when engine is started

[tonkatoy87uk]

Evening.

Every time the engine is started, all of the units go off and then come back on again like the radio would in your car. How can I wire them so that this doesn't happen? is it supposed too?

 

[tonkatoy87uk]

Evening.

Every time the engine is started, all of the units go off and then come back on again like the radio would in your car. How can I wire them so that this doesn't happen? is it supposed too?


Also whats the best Transducer that can be used with the Raymarine A98 MFD unit?

 

[johnalison]

The radio in my car doesn't. I assume that it has a small back-up battery built in to prevent the voltage drop. Now that it's winter, it would be a good time to change you arrangements so that you have separate house and starter batteries. Not only will this stop your problem but you will not have to worry about the engine not starting.

 

[PaulRainbow]

John is correct, you will be better off with separate starter and domestic circuits, with their own isolators and some form of split charge system.

 

[tonkatoy87uk]

we have 3 batterys, all wired up to an isolator. 1 ,2,both . We have always used both.


2 batterys for start.

Inside there is another isolator switch linked up to battery 3 that runs to an anode, I think looks like a junction box (I got anode as some one has hand written that next to it but the rest is in french)
I connected up the a98 to this and things went a bit wild. There wasn't enough power getting to the transducer for the mfd to read, also the volt gauge that is wired up to the top of battery 3 also started making up numbers.

When I disconnected the a98 from the anode/junction box and rewired as the rest of the mfd's are things went back to normal

1- no 1 battery for start?
2 - no 1& 2 battery for start?
Both banks?- all battery's connected? which could be where the problem is?

 

[Momac]

I have the same issue and thinking of getting a voltage stabiliser such as Victron 12v to 12v converter. However I hesitate as not sure it will do the trick.

 

[davidmh]

When you start an engine the battrey voltage drops significantly even it if is brand new. Many of the Instruments will cut out if the voltage falls too far even momentarily. As other have said much better to have a dedicated starter battery wired separately from the house batteries, then the instruments see no voltage drop. No need for voltage stabilizers.

David MH

 

[Dipper]

Every time the engine is started, all of the units go off and then come back on again like the radio would in your car. How can I wire them so that this doesn't happen? is it supposed too?

I had that problem one year. It was solved by replacing the battery.

 

[PaulRainbow]

we have 3 batterys, all wired up to an isolator. 1 ,2,both . We have always used both.


2 batterys for start.

Inside there is another isolator switch linked up to battery 3 that runs to an anode, I think looks like a junction box (I got anode as some one has hand written that next to it but the rest is in french)
I connected up the a98 to this and things went a bit wild. There wasn't enough power getting to the transducer for the mfd to read, also the volt gauge that is wired up to the top of battery 3 also started making up numbers.

When I disconnected the a98 from the anode/junction box and rewired as the rest of the mfd's are things went back to normal

1- no 1 battery for start?
2 - no 1& 2 battery for start?
Both banks?- all battery's connected? which could be where the problem is?

That is a truly crap setup, sorry to be blunt. It's a RNLI callout waiting to happen. Doubt if the device you talk of is an anode, more likely a diode.

Lots of threads on here about 1-2-both switches, separate circuits etc. You really need to get this mess sorted out, two battery banks with separate switches. One battery for the engine, with its own switch, the other two batteries for the domestic circuits, again with its own switch and a VSR to keep them all charged up. The 1-2-both neatly placed at the very bottom of the nearest skip :encouragement:

 

[PaulRainbow]

I have the same issue and thinking of getting a voltage stabiliser such as Victron 12v to 12v converter. However I hesitate as not sure it will do the trick.

That'll be papering over the cracks Martyn. Better to spend the cash on a proper cure. I take it you have a 1-2-vomit switch ?

 

[tonkatoy87uk]

most of the above was a question, not a statement.

think I need to get my head around the battery system and the wiring. that Mickey Mouse has wired up previously

 

[Momac]

That'll be papering over the cracks Martyn. Better to spend the cash on a proper cure. I take it you have a 1-2-vomit switch ?

No
The port engine has a starter battery . The port engine alternator charges that battery.
The starboard engine has a pair of batteries charged by the starboard engine.
There is a link switch that joins the above noted batteries together but that is for emergency use.

 

[macd]

battery 3 that runs to an anode, I think looks like a junction box (I got anode as some one has hand written that next to it but the rest is in french)

"Anode" used in this way in French may simply mean positive terminal. (In fact, it also does in English, although in boating parlance it's more commonly used as shorthand for sacrificial anode.) The rest that's in French may conceivably succumb to Google translate if you can contrive access to a computer.

 

[benchmark]

I experienced this problem with my former boat, on close inspection I found that the 12v positive terminal used to supply to the MFD from the same distribution junction that went to the ignition under the instrument panel and what happened when I started the engine was that the voltage on that rail experienced a temporary drop. I solved this brownout by drawing a new + lead directly from the MBBS switch. I am almost convinced that this will solve yours too.

 

[PaulRainbow]

No
The port engine has a starter battery . The port engine alternator charges that battery.
The starboard engine has a pair of batteries charged by the starboard engine.
There is a link switch that joins the above noted batteries together but that is for emergency use.

Better than the vomit switch then

So i guess that the electronics "trip out" when you start the Stb engine, as the electronics are connected to this bank. I'd be thinking along the lines of the single battery starting both engines and the pair of batteries being the domestic bank. That cures the electronics dropping out.

You then need to look at the alternator charging system, there are a number of solutions here, depending on what you have already and a budget. In its simplest form, the port engine charging the engine battery and the Stb engine charging the domestic bank, with a VSR would work. Other, more expensive options would be available.

 

[Frank Holden]

'Dropping out' has never been a problem for me but I do worry a bit about sensitive equipment and 'spikes'.

I have a couple of these .... the first one provides regulated power for my Macbook Pro, my LG screen and the Acer Veriton that I use as a ship's computer, all of which want 19V.

http://www.mini-box.com/DCDC-USB?sc=8&category=981

The second one powered my old computer and screen.. both of which wanted regulated 12.8V. It now charges my handheld VHF.

http://www.mini-box.com/M2-ATX-160w-Intelligent-Automotive-DC-DC-Power-Supply?sc=8&category=981

Good kit...

 

[oldgit]

Common problem with older vehicles and starter batteries nearing their dump by date.
In my trade cars achieve starship mileages very early in their lives which results in problems with aftermarket electronic kit shutting down when car is started.
If a system is in good condition volts on battery will drop from around 14V to 12V on engaging the starter and come back up afterwards.
As the battery ages and the starter motor wears, things get more difficult and on start up volts can drop to 8V or worse , as far as the kit in your car or boat is concerned that amount of drop indicates that you have turned off the equipment and so it shuts down, restoration of volts and it turns back on.
Some equipment will have an internal back up battery or capacitor to compensate.
Many of our customers have great difficultly accepting that a battery has a life of only few years , there is nothing wrong with their kit, they merely need to buy a new battery.
...and get proper capacity replacement , the smallest and cheapest that will fit in the hole, is no good.

 

[PaulRainbow]

Common problem with older vehicles and starter batteries nearing their dump by date.
In my trade cars achieve starship mileages very early in their lives which results in problems with aftermarket electronic kit shutting down when car is started.
If a system is in good condition volts on battery will drop from around 14V to 12V on engaging the starter and come back up afterwards

Those figures are a little high, a rested 12v battery will sit at about 12.8v if it's in good condition. You'll likely get up to a couple of volts drop at the electronics end on a boat though, so your principal is correct.

 

[macd]

As Paul wrote, a 12V battery won't show 14V unless it's just been on charge, so a drop from high 12s to 11-ish volts is more likely when the starter's engaged.

Our car's GPS navigator (which has a small internal battery) announces that it's power has been disconnected and it will shut down in 15 seconds whenever the car is started. (It doesn't fallow through on that because the car always fires up long before, touch wood.) Same basic phenomenon as the OP's. I'll not be wiring it to a second battery, but I certainly would if it were in a boat -- not least because in some easily imaginable circumstances, starting the engine is the very time when you least want to lose instruments.

 

[Lightwave395]

Evening.

Every time the engine is started, all of the units go off and then come back on again like the radio would in your car. How can I wire them so that this doesn't happen? is it supposed too?


Also whats the best Transducer that can be used with the Raymarine A98 MFD unit?

I had exactly this, instruments and autopilot dropping out until the start of last year. Initially had 2 X 110Ah batteries with 1-2-both switch which with hindsight seems pointless on a sailboat because on a long passage if the battery in use discharges enough to require switching to the second then you're surely on borrowed time until there's not enough power left in the second to start the engine. I fitted a third engine start only battery and linked the two 110Ah's together with on/off switches for both, a Mobilec monitor and a Sterling Pro split charge/ isolator controller (other brands available...).
Sailed for three months down as far as La Rochelle last summer with no more starting or instrument drop-out problems, well worth the money and peace of mind