MFD's knocking out when engine is started

[PaulRainbow]

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

Good man :encouragement:

 

[Momac]

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.
.

Yes the electronics are on the twin battery domestic bank, which also starts the starboard engine.
Your suggestion is a good one . I am wondering why it was not built like that.

 

[PaulRainbow]

Yes the electronics are on the twin battery domestic bank, which also starts the starboard engine.
Your suggestion is a good one . I am wondering why it was not built like that.

Some are built like that. I'd have the port alternator charging the engine battery and the Stb one charging the domestic bank. You could additionally fit some split charging to the port alternator, so you'll get a lot more charging for the domestic bank, with no Ah being used up for engine starting.

 

[halcyon]

It is probably a battery issue, not new and relating to battery design or manufacture.

Back in 1983 we supplied Sealine a twin alternator / three battery bank VSR and no problems.

1990 Sealine introduce two bank system to save money, port start / starboard start and domestic power, no big problems bar some low recharge levels. Got round by fitting a VSR between port and starboard batteries.

1998 Sealine suddenly got system drop outs on engine starting, radars etc, I made them a diode pack that allowed them to draw power from the highest charged battery. So when volts dropped in starboard battery bank during engine starting, power was drawn drawn from port battery bank to supply radar etc.

Today the simplest and cheapest is just fit a VSR between battery isolator switches, but remember to start port first, even then you can get drop out due volt drop as the starter can pull a lot more power than the alternator can produce. Also remember cable loading and VSR loading during starting.

If you can seperate the power feed to critical equipment, so you have a seperate power feed to circuit breaker / fuse, then the diode option can be the better path as it does not have the volt drop issue during starting.

Brian

 

[Skylark]

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

+1

Very typical response from a terminally ill battery.