Victron Battery combiner

[Brian2]

Hello,

I am thinking of adding a battery combiner to my CD 28. I have 2 batteries completely isolated, a start battery and a house battery. The start battery is wired thru the engine, starter and alternator, and house battery is charged from a 3 amp solar panel, and is attached to the house panel. I did this to avoid voltage drop to my electronics when starting the engine after a day of sailing. I used to have a 1/both/2/off switch, and the house panel and engine were always together, so when I would start the engine, there would be voltage drop to anything that was on thru the house panel. With my new on/off/combine switch, I can combine if necessary, but mostly they are isolated, and no voltage drop to elctronics when starting. The solar panels give me more than I need under sail (I use about an amp under sail with CP, wind, depth, radio). The solar panel more than keeps the house battery charged, so I was thinking of adding the Victron Cyrix 12/24-120 intelligent battery combiner so the extra juice could keep my start battery topped off at anchor or mooring.

The question I have is: when I go to start the engine, if they combiner is "combining" under solar, does it disconnect when I start? I really like the setup I have of only using the start battery to start the engine, so I don't want the combine when starting and allow heavy draw on my house battery when starting. I can't seem to find the answer to this in the Victron literature.

Thanks, Brian

[Russell]

If the voltage is there, on a nice sunny day for instance, they will indeed be combined when you go to start the engine. You could put a switch in there to manually cut off the combine before starting. But its an additional step and you would have to remember to flip the switch again after starting, kind of defeating the purpose of the automatic combiner in the first place.

Is the voltage drop causing a problem I assume? Like electronics reseting because of it?

[Brian2]

Russell, thank you for your reply. Sometimes the electronics reset, more often they just fade out, and come back. I haven't tried starting with both batteries since I isolated them and installed the solar panel. My starting battery is 1000 cranking amps, and works well. My house battery is a group 24 battery and serves me well, but the draw starting from it isn't what is was meant to do. I thought there were some combiners that isolated the batteries (even if they are comining under charge) when the start key is turned and they sense a voltage draw, but I guess the Victron isn't one of them.

[hilbert]

Bue Sea's SI-series automatic charging relay has a wiring option to temporarily isolate the house load from the engine circuit during engine cranking.
http://bluesea.com/viewresource/63
Instructions:
http://bluesea.com/files/resources/inst ... 170140.pdf

It requires some extra signal wiring that I haven't yet added to the spade terminals (center bottom) :

[Russell]

Bluesea sure manages to come up with some clever things! Sounds perfect for this situation.

[Brian2]

Thanks J for you reply. How has the Bluesea worked for you? I see you have large wire. I think I will only be combining under much smaller loads. What charge/combine load do you have?

Brian

[hilbert]

Brian,
The relay is activated by voltage and the current is not relevant, as long as one does not exceed its rated capacity.
This is yet another work in progress. I can tell you what I'm doing, but not how well I've done.

On my installation, the cranking battery and engine (starter & alternator) are on the left bus bar and the house battery and solar charger will be on the right. The main DC panel switch can take power from either bus bar or both (thereby combining the two battery banks). The batteries have fuses at the positive terminal and I am running 2 awg wire to the bus bars (4 awg to the panel switch). The engine is isolated from the DC panel and draws directly from the left bus panel, with its own dedicated switch.

[Maine Sail]

Hello,

I am thinking of adding a battery combiner to my CD 28. I have 2 batteries completely isolated, a start battery and a house battery. The start battery is wired thru the engine, starter and alternator, and house battery is charged from a 3 amp solar panel, and is attached to the house panel. I did this to avoid voltage drop to my electronics when starting the engine after a day of sailing. I used to have a 1/both/2/off switch, and the house panel and engine were always together, so when I would start the engine, there would be voltage drop to anything that was on thru the house panel. With my new on/off/combine switch, I can combine if necessary, but mostly they are isolated, and no voltage drop to elctronics when starting. The solar panels give me more than I need under sail (I use about an amp under sail with CP, wind, depth, radio). The solar panel more than keeps the house battery charged, so I was thinking of adding the Victron Cyrix 12/24-120 intelligent battery combiner so the extra juice could keep my start battery topped off at anchor or mooring.

The question I have is: when I go to start the engine, if they combiner is "combining" under solar, does it disconnect when I start? I really like the setup I have of only using the start battery to start the engine, so I don't want the combine when starting and allow heavy draw on my house battery when starting. I can't seem to find the answer to this in the Victron literature.

Thanks, Brian

Just buy the Blue Sea 120SI combiner. The SI stands for "start isolation" and when wired to the ignition button it breaks the relay when you engage the starter. These are a very well built relay, simple and robust. I've literally installed 60-70 of them and never seen one fail. I used to use the Yandina's, which are also excellent, but I did not like the chinsy battery lug posts one them and while better than the Cyrix they are a far cry from the quality of the Blue Sea 120SI.. The 120SI also has an LED option for a dash light so you know when the batteries are combined. You can install an on/off switch in the neg leg if you feel you want to power it on or off. I am not a huge fan of the Cyrix and find it rather cheaply built and executed..

[Brian2]

Thanks very much for your reply Mainesail. Do I need the battery sized wire to connect batteries thru a combiner? I was planning to use #10, my solar paenl only outputs 3A.

[hilbert]

Larger cable is better and proper fusing is a must.

The Automatic Charging Relay will be closing a circuit between the two battery banks (the terminal studs on the SI-series are 3/8"). Keep in mind that the ACR is bidirectional. If the engine is operating and the house battery is low, then there can be a significant current flow from the alternator to the house battery. You should size the wire for the maximum current that you expect to flow between the batteries and then add fuses on each end, to protect the wire! The fuse should be within 7 wire inches of the positive terminal of each battery or you can use battery terminal fuses (http://bluesea.com/products/5191).

Also, while the solar panel will never exceed its maximum rating, the wire from the solar panel (or solar controller) is connected to a powerful battery. On the battery side, there should be a fuse to protect this wire.