VSR Problem.

[Alpha22]

I have a twin engine set up with 2 engine start batteries, one for each engine and a domestic battery.

The domestic is charged by the starboard engine with a VSR. The port engine and its battery are totally independent.

The problem is the VSR does not drop out immediately the engine is stopped, it requires a domestic load to drop the voltage far enough to cause it to drop out. So when we stop at a lock and then restart the engine in a short space of time the VSR is still connecting the domestic to the engine start.

This would not be a problem, but when re-starting then engine the voltage drops far enough to cause the VHF and domestic radio/CD to drop out. The VHF comes back on, but the radio/CD has to be turned back on. I'm not sure it is doing the electronics much good.

I have found another VSR from Blue Sea that has an Ignition Isolate function.... but they appear to be US only and quite expensive to import one specially.

Does anyone know an inexpensive way around this annoying problem???

The VHF is new Standard Horizon and is connected with fairly thick cable with a direct route to the domestic battery. (with a fuse). The radio/CD is an expensive (1990's) Pioneer.

https://www.bluesea.com/products/7610/SI-ACR_Automatic_Charging_Relay_-_12_24V_DC_120A
https://www.bluesea.com/resources/63

 

[sailorman]

Are your battery's ok
i have only 1 engine with a vsr & no issues as you describe.
when you start the engine the voltage will drop & the vsr should separate the banks @ around 12.8v

 

[aquapower]

I used to get the Blue Sea VSR and battery switches from Aquafax,
have got the Victron Cyrix i x2 on my boat.

 

[annageek]

Does your existing VSR have a seperate 'sense' line? Do you know what the cut-out on the VSR is at present? If it is only slightly lower than the domestic battery voltage following engine turn-off, then you could put a schottky diode in series with the sense line so it sees a slightly lower voltage. You'd just have to check that the slightly lower voltage wasn't then below the cut-in voltage of the VSR when the alternator was up and running and your engine start battery had reached top of charge and stopped dragging the voltage down. Worth a try for the sake of peanuts, perhaps.

Failing that, if you have an equivalent of an 'ignition' line anywhere near the VSR, you could use this as the sense voltage, such that when you had no ignition the VSR would cut-out (worth checking the input current on the VSR's sense line though, and ensuring it'll be OK with the 'ignition' line). Then, when the engine is switched off, the VSR will drop out immediately.

 

[Alpha22]

Great ideas annageek, I like the idea of the diode.... I have some knowledge in that direction so it should be possible to get it working. Thats the kind of solution I like!!