48V to Lynx Distributor 1000 to ???

[SailingTy1970]

once I connect the 48V 304Ah LiFePO4 Battery bank to the Lynx Distributor, where would I put the 48V / 12V DC to DC converter so that the 12V fuse panel can operate appropriately? I am still in the design phase. see attached diagram of what I would like to actually accomplish without using 5 of BattleBorn D8 12V 270Ah Batteries. I would like to build my 48V bank using 16 of 3.2V 304Ah LiFePO4 batteries in series. This would reduce space, weight, cost and have more Ah total. I just cant figure out how to get it down to 12V where I need it such as the fuse panel. the rest of the diagram makes sense to me.

or should I just buile 5ea of 12V 304Ah LiFePO4 banks? my thoughts are:
1. The referenced picture they are using 5 12V 270Ah D8 Battleborn LiFePO4 Batteries ($2399 x5 = $11,995). I believe the way the are attaching them individually to the Lynx Distributor they are obtaining 270Ah x 5 = 1350Ah or am I wrong?
2. If I build the 48V 304Ah system (3.2V 304Ah @ $123.99ea x 16 = $1959.98) cheaper but it would still only be 304Ah correct?
3. If I build my own 12V 304Ah system (3.2V 304Ah @ $123.99 x20 = $2479.97 plus 250A BMS @ $217.32 = $1086.80 {total cost $3566.77}) still significantly cheaper and providing overall 1520Ah??

Ultimately here are my questions that I for some reason can not untangle my brain on

1. is the overall Ah when individually attached to the Lynx distributor increase as if in series? five 304Ah batteries = 1520Ah or remains 304Ah
2. is the 48V 304Ah going to be more that their five 12V 270Ah attached individually like in photo attached? or is their five 270Ah batteries = 1350Ah
3. If the 48V 304Ah bank going to be ok, where do you install the DC to DC 48 / 12 converter? after the Lynx Distributor and before the Fuse panel or what?

For Reference, I am designing this to be on a sailboat.

Advise, suggestions?

 

[Rocketman]

I think I understand your questions.

In that drawing of the Victron Lynx “stuff” there are three different items in the “Main Bus Bar”

A. On the left side is a Lynx Power In. This is what all the batteries connect to. Each cable that attaches to a battery needs to be the same size, length,etc.

B. In the middle they have a Lynx Shunt. This has a main system fuse and a shunt (to measure current (amps) in and out of the batteries.

C. On the right side they have a Lynx Distributor- this is where all loads and chargers attach. Your 48v to 12v converter would attach to this side.

That is how Victron designed a fabulous bus bar system.

I was just helping my Brother-in-Law with planing a system for his 5th wheel RV. Because cost was important to him - we designed the main bus bar system just a little different.

We added fuses to the Power In (battery side).
Then used two 1/4” x 1” (a few inches long) copper bars. And attached a on/off switch on the positive bar and a Victron BMV712 (shunt) on the negative bar.
Then these were bolted to another PowerIn (with fuses added).

In your setup - if you are just having one 48v battery you could forget about the left side PowerIn and attach the 48v battery’s positive wire to a Class T fuse then to on/off switch then to a PowerIn (with fuses). The negative wire goes to a shunt (Smartshunt or BMV712 or Lynx shunt), then to the PowerIn. Everything leaving the “Main bus bar” needs to be fused- if you have more than the four items you can connect two PowerIn’s together or you can also add some MBRF fuses and get two more fuse spots on the right end of the PowerIn.
(Did this make sense?)

To answer a couple of your other questions…

Ah (Anp-hours) are only for a specific voltage. To compare you have to adjust to the different voltage.

So five 12v 270ah batteries has about 16.2kw (12v*270ah* 5 batteries = 16,270 watts= 16.2kw)

One 48v 304ah battery has abot 14.5kw (48v*304ah= 14,593watt = 14.5kw)

They are roughly about the same (ok those 5 Battleborn batteries have a little bit more power but a LOT more cost).

The real question is do you want 48v, 24v or 12v for you boat?
What size of inverter do you want?
How much solar? (Never enough on a boat).

If you go 12v you can just wire those same 16 cells into four 12v 304ah batteries-each with its own bms.

At 24v you would have two 24v 304ah batteries- each with its own bms.

There 16 cells will provide the same power (watts) regardless of the cell arraignment.

Did I miss any of your questions?