Starting engine makes chart plotter switch off... Any idea why?

[Captain Crisp]

Hi any idea how I can sort out this rather tedious issue?
It didn't happen last year, but happens every time I switch the engine on now...
Thanks,
Crisp

 

[Blue Sunray]

Hi any idea how I can sort out this rather tedious issue?
It didn't happen last year, but happens every time I switch the engine on now...
Thanks,
Crisp

Most likely the draw from the started is causing the supply to the plotter to drop below the minimum required. Plotters often have the ability to display their supply voltage, if so get this displayed and watch what happens to it when you start the engine.

 

[RichardS]

It's probably either a starter battery that needs charging or replacing or a poor connection somewhere on the power cabling to the plotter.

First thing is to fully charge the starter battery and check the voltage.

Richard

 

[WGWarburton]

Tired battery (or higher starter load from, e.g., thicker engine oil) is causing voltage to dip below the threshold where the 'plotter stays on...?

If so, fix with new battery (or other mechanical fix, as above), or separation of engine battery from electronics supply to maintain voltage to electronics during starting.

 

[Baggywrinkle]

Jump start it with a known good battery (the one from your car?) and see if the problem goes away. If it does, replace the battery.

 

[oldmanofthehills]

I presume that the OP has switchable battery system rather than dedicated engine battery.

Finding out voltage at plotter might indicate a volt drop between battery thus suggesting poor wiring, or it might be that battery by design or age is simply not up to the task of starting engine while keeping electronics above their minimal cut off voltage.

Our old boat had switchable main/backup system and engine start always turned off the plotter. I changed battery and wires with no improvement so put it down to ancient cranky plotter. I found it less annoying than the ebispacher not starting at anchor if cabin light were left on more than a few minutes but its nice not to have on our newer boat

 

[Refueler]

Common problem where battery voltage drop on starting an engine is low enough for plotters etc. to default off.,

Many manuals in the past used to advise NOT having such equipment on when starting engine ....

My Lowrance Plotter always cut out when I started engine from cold ... but usually stayed on when engine was warm ..... cold takes more power from battery to get it turning fast - cold oil etc.

My new Onwa doesn't care and stays on ...

 

[Captain Crisp]

Many thanks!

 

[ColinR]

Hi any idea how I can sort out this rather tedious issue?
It didn't happen last year, but happens every time I switch the engine on now...
Thanks,
Crisp

I had the same issue when I had a 1-2 Both switch. The voltage briefly drops too low for the plotter and it switches off. I fitted a VSR so the batteries don't see each other except when charging and it solved the problem. A much better solution and I had some helpful advice on this forum ab out wiring it correctly.

BEP Dual Battery Single Engine DVSR Cluster | Force 4 Chandlery

 

[oldmanofthehills]

Common problem where battery voltage drop on starting an engine is low enough for plotters etc. to default off.,

Many manuals in the past used to advise NOT having such equipment on when starting engine ....

My Lowrance Plotter always cut out when I started engine from cold ... but usually stayed on when engine was warm ..... cold takes more power from battery to get it turning fast - cold oil etc.

My new Onwa doesn't care and stays on ...

My cranky one was an old Lowrance, and as you note a warm engine restart did not always turn it off.

 

[Bodach na mara]

A common problem. The radios in my last 3 cars did that, even when the cars were new.

 

[oldgit]

A common problem. The radios in my last 3 cars did that, even when the cars were new.

We used to install all sorts of electronics in cars.
Drivers would complain that kit switched off when vehicle started.
First suggetion was always to check water level in cell with negative post on battery this solved 50 % of problems.
After its anew battery chum or very rarely starter motor was on its way out.
We did on one or two occassion make up a little system to hold the volts up while engine was started.

 

[PaulRainbow]

A penalty of using one battery for domestic loads and the engine. Cannot happen if the engine battery is the engine battery and all other loads are on the domestic bank.

 

[Refueler]

A common problem. The radios in my last 3 cars did that, even when the cars were new.

mmmmmmmmmmmm

 

[starfire]

Got a similar problem on an axiom.
Plotter stays on, but the inbuilt gps looses the fix

 

[PaulRainbow]

A common problem. The radios in my last 3 cars did that, even when the cars were new.

If your new car radio goes off while you are cranking the engine, that's by design, not because the starter motor is pulling the battery voltage down so low that the radio cannot function.

 

[William_H]

So to sum up from previous posts. It has started to happen now and not before because the battery when starting the engine is dropping in voltage more than before. Probably battery getting near end of life. So a new battery might fix it. Might also save you hassle in the future with battery failing to start the engine. All this much depends on the age of the battery.
I presume you have a one battery system. A dual battery system with VSR such that a deep cycle battery just for domestic services would be a better more expensive alternative. The plotter would run off the domestic battery so not connected to starter. This option also gives you a standby jump start option if/when engine battery dies or is accidentally flattened.
The cheapest fix for the short term is to fit a diode in the supply of the plotter and a large capacity capacitor (2000 microfarrads) from the input to the plotter to ground.
The capacitor acts like a low capacity battery. The diode allows current to go to the plotter and capacitor but when supply voltage of the battery falls down during cranking the diode stops current flowing back to the battery from the fully charged capacitor but the capacitor can supply power top the pl;otter for the short cranking period.
Diode 1N5822 Schottky 40V 3A DO-27 | Jaycar Electronics
2200uF 16VDC Low ESR Electrolytic Capacitor | Jaycar Electronics
A smaller value capacitor will probably be OK larger certainly better. Holds supply up for longer period (cranking) ol'will

 

[Refueler]

Question to OP :

If you have 1-0-2-Both switch system as in older boats ..... does the Plotter go off regardless of which battery used ? What if both batterys on - does it go off then ?

If its a single battery system ..... then why not add a smaller second battery ? You don't need a large capacity battery - a small Lawn Tractor battery of 25 - 30A/Hr is more than enough for plotters / autopilots etc. if charged via VSR / both or whatever.

Even the SLA style like emergency start packs have can be wired up to run the plotter and be charged ....... making the installation of a second battery easy to find small hole somewhere.

Example ... I have a 7A/hr SLA sits under the rear deck of my soviet mobo ... charger is a 5W solar panel about size of A4 sheet of paper .... that keeps the SLA charged more than enough to give me auto bilge pump .. LED nav lights and LED spotlight .....
Similar could be setup for the plotter .... with a switch to link to main battery in case of SLA discharged ...

Just a thought.

 

[Jmc1764]

I had this start and it was only when I checked the plug in power lead I saw a lot of green crap on the connections, I cleaned these and since then no issue...its worth a try !