Risk of using a VSR with a failing / very discharged battery

[halcyon]

The reason I asked about this, is not because of chatter (which I think is not a problem with the hysteresis curves of modern VSRs) but because I do not like my VSR being already closed due to solar when I start the engine - but because I am worried about start voltage spikes damaging my electronics. Obviously JumbleDuck's solution will not work for this as I need to have the VSR off until after the engine is running. I had wondered about a 'normally closed' relay wired to the starter circuit. Or maybe I am looking for a solution to a non-existent problem?

Fit a normally closed relay in the VSR earth line, connect the coil to the solenoid feed from starter key switch to starter. This drops out VSR before the startermotor turns, connecting to power side can still give a spike.

The hysteresis curves came in in the early 80's, not that modern.

Brian

 

[MattS]

The reason I asked about this, is not because of chatter (which I think is not a problem with the hysteresis curves of modern VSRs) but because I do not like my VSR being already closed due to solar when I start the engine - but because I am worried about start voltage spikes damaging my electronics. Obviously JumbleDuck's solution will not work for this as I need to have the VSR off until after the engine is running. I had wondered about a 'normally closed' relay wired to the starter circuit. Or maybe I am looking for a solution to a non-existent problem?

I think I saw that some VSRs have an ignition protection feature too - not sure if that does what you're after?

 

[VicS]

I think I saw that some VSRs have an ignition protection feature too - not sure if that does what you're after?

Maybe confused with "ignition protected", meaning safe to use in engine or fuel tank spaces
eg
Digital Voltage Sensing Relay (DVSR) 12/24V

 

[MattS]

I think Ignition Protected in this case is about protecting connected equipment from spikes related to starting the engine

Durite Voltage Sensitive Split Charge Relay - 12V 140A

 

[halcyon]

I think Ignition Protected in this case is about protecting connected equipment from spikes related to starting the engine

Durite Voltage Sensitive Split Charge Relay - 12V 140A

Just that the engine and service loads are on different batteries, unlike say 1,2,Both were electronics and engine start are on the same battery, so you get low voltage and spikes on engine start

Not new, think you will find similar statement on our 1982 lit

Brian

 

[ithet]

I think Ignition Protected in this case is about protecting connected equipment from spikes related to starting the engine

Durite Voltage Sensitive Split Charge Relay - 12V 140A

'Ignition protected' means that the the relay does not spark so is safe around a petrol engine. I do not think that is what the advert means by "Protects sensitive electronic equipment from harmful engine start-up spikes" which I think refers to the normal use of VSR which keeps the electronics circuits separated during engine start - except they do not if like me you have solar connected. As far as I know the only VSR that provides an 'Isolate on start' function is the Blue Seas SI.

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

 

[halcyon]

'Ignition protected' means that the the relay does not spark so is safe around a petrol engine. I do not think that is what the advert means by "Protects sensitive electronic equipment from harmful engine start-up spikes" which I think refers to the normal use of VSR which keeps the electronics circuits separated during engine start - except they do not if like me you have solar connected. As far as I know the only VSR that provides an 'Isolate on start' function is the Blue Seas SI.

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

We introduced it in the mid 1980.

Brian