Victron Multipus and start batteries

[mitiempo]

Originally Posted by Dave Isom

A VSR will only work on standard alternators not smart alternators.

A VSR (ACR in North America) will work regardless of what type of alternator you have. It will combine the banks when the voltage of the charged battery - typically the house bank - reaches about 13.6 volts depending on the brand. It will isolate when the voltage drops to 12.75 volts or less, meaning that charging has stopped. It is wired from the house bank to the start battery. It doesn't care what type or brand your alternator is. It doesn't even care if you have an alternator. It works only on voltage. It works with shore powered chargers, solar, and wind generators as well. It is one of the simplest most reliable electrical items on a boat. I have installed many dozen from Blue Seas and Victron but there are others.

https://www.bluesea.com/products/761...12_24V_DC_120A

[wiekeith]

Originally Posted by Dave Isom

Right....the alternator first charges the start battery which should then be connected via a VSR ( voltage sensitive relay) to the house batteries.

So I'd assume the VSRs also provide the connectivity for the starter batteries to be charged via the house bank when on shore power?

[sowwaninii]

Here’s the voltages of house and start batteries after being on shore power for several days.

[wiekeith]

Originally Posted by sowwaninii

Attachment 245875Attachment 245875
Attachment 245875
Here’s the voltages of house and start batteries after being on shore power for several days.

I think it's difficult to tell from a 'snapshot' without following the trends and knowing the characteristics of the ARCs. Maybe wait until the housebank gets to 13v, say, then see if the start batteries voltage start increasing. If so, that would indicate that the ARCs have kicked-in and the starter batteries are charging.

[Stu Jackson]

Originally Posted by Dave Isom

Right....the alternator first charges the start battery which should then be connected via a VSR ( voltage sensitive relay) to the house batteries. Once the start battery reaches 13.7 volts or thereabouts the VSR will allow the house batteries to charge. When the engine is off and you are using house batteries the VSR will isolate the house battery at about 12.8 volts and not allow the house to run the start battery down. A VSR will only work on standard alternators not smart alternators.

mitiempo was very diplomatic in his reply.


This post by Dave is so incredibly wrong in so many ways.


A VSR closes when charging sources are present that raise the voltage past the set point, NOT "...Once the start battery..." Like mitiempo said, it works on voltage, not what a battery is doing.



Europeans have an unusually odd habit of obsessing over their start batteries and mistakenly route their primary AO to them instead of their house banks which always need more input than a start bank. This phenomenon has been going on for decades and most of us believe (humorously) that it's because of so many Lucas starters in their cars that never worked! The AO should be to the house bank, the VSR goes to charge the start bank, or you use your 1-2-B or other switches to route charging to the start bank and disconnect the start bank once charging ceases. The reason is that since the house bank needs more current than the start bank, why run all that current through the VSR.


All a VSR does is what a switch does, only automatically. And shuts itself off so you don't have to remember to turn a switch when charging stops.


VSR work with any kind of regulator or alternator, or any charging source. Nonsense about "smart alternators" - there is no such thing. Perhaps he meant regulators. But that's like confusing a jib and a main sail...