I am swapping 2- 6 volt, 230ah, deep cycle lead acid for 2- 12 volt lifepo4 100ah in parallel. It is becoming a bit more complicated than a direct swap. Is there a simple way to monitor the lifepo4 batteries? I am fusing each solar-powered panel to 30a mppt charge controller, charge controller to busbar positive, each battery positive to busbar positive. Is a fuse also necessary to rv charge controller/ fuse panel? Thanks.
Battery monitor
- Thread starter Talque
- Start date
hwy17
Anti-Solar Enthusiast
Not if the wire from the bus bar to RV fuse panel is adequate to handle the sum of both battery fuse currents. If it isn't, then it needs it's own OCP and one end of it.
hwy17
Anti-Solar Enthusiast
I guess technically you would want to be adequate for the sum of the battery fuses and the CC fuses combined, because it could draw from all of those.
To monitor Lithium batteries in an RV - get a Victron Smartshunt or BMV712.
All negative wires need to go through the shunt to the battery.
It is a great device.
The difference is the Smartshunt only does Bluetooth (and it’s a bit of a week signal) - your phone will need to be within 5 to 6 feet of it.
The BMV712 in addition to Bluetooth it has a very basic display. It also has a relay that can be triggered, and the Bluetooth antenna is in the display away from the batteries and large battery currents, also if you are going all Victron and have a Cerbo (GX device), the data wires for that are in the display.
I like the BMV712 better (have had both) because of the Bluetooth range and the better (for my rig) connection to my GX device (aCCGX-older unit). I just mounted the display way back in an area I can’t see but is out of the way and convenient for the cables.
As you are installing new batteries is a great time to add the shunt into the system.
Good Luck
All negative wires need to go through the shunt to the battery.
It is a great device.
The difference is the Smartshunt only does Bluetooth (and it’s a bit of a week signal) - your phone will need to be within 5 to 6 feet of it.
The BMV712 in addition to Bluetooth it has a very basic display. It also has a relay that can be triggered, and the Bluetooth antenna is in the display away from the batteries and large battery currents, also if you are going all Victron and have a Cerbo (GX device), the data wires for that are in the display.
I like the BMV712 better (have had both) because of the Bluetooth range and the better (for my rig) connection to my GX device (aCCGX-older unit). I just mounted the display way back in an area I can’t see but is out of the way and convenient for the cables.
As you are installing new batteries is a great time to add the shunt into the system.
Good Luck
Yes you can have as many batteries as you want (I have seen a friend with five 100ah batteries), the only thing is all “negative power” must flow through the shunt - no other connections on the battery negative wires except other batteries and all those batteries go to the battery side of the shunt.
Then from the loads/charger side of the shunt is where everything connects- it is usually best to get a buss bar so there is a wire between the shunt and the bus bar and then lots of stuff on the bus bar. (Get a tin plated copper bus bar if possible- yep they cost more than the brass ones - but they are better).
Keeping the wires the same length is very good - a lot depends on how you decide to wire the batteries.
(All these numbers are made up). With 2 batteries what I usually see is a 14” cable from battery1 neg to battery2 neg, then a cable from battery 2 neg to shunt.
Then a 14” cable from battery1 pos to battery2 pos, then a cable from battery1 pos to the bus bar.
You will notice that battery2 neg goes to shunt (and then the bus bar) and battery1 pos goes out to bus bar. The two “interconnection” cables are both full size and the same length and quality.
Once you leave the battery on the way to the buss bar or shunt &bus bar those don’t need to be the same length.
Was I clear?
Good Luck
Then from the loads/charger side of the shunt is where everything connects- it is usually best to get a buss bar so there is a wire between the shunt and the bus bar and then lots of stuff on the bus bar. (Get a tin plated copper bus bar if possible- yep they cost more than the brass ones - but they are better).
Keeping the wires the same length is very good - a lot depends on how you decide to wire the batteries.
(All these numbers are made up). With 2 batteries what I usually see is a 14” cable from battery1 neg to battery2 neg, then a cable from battery 2 neg to shunt.
Then a 14” cable from battery1 pos to battery2 pos, then a cable from battery1 pos to the bus bar.
You will notice that battery2 neg goes to shunt (and then the bus bar) and battery1 pos goes out to bus bar. The two “interconnection” cables are both full size and the same length and quality.
Once you leave the battery on the way to the buss bar or shunt &bus bar those don’t need to be the same length.
Was I clear?
Good Luck
Thanks- what I had originally planned were cables from each battery positive (fused at each battery) to a busbar, where all other connections would be made (trailer fuse panel, solar charge controller, possibly inverter) now that I am including battery monitor on negative side, would I make the cable, including the shunt, the same length to busbar as positive cables to busbar?
Here are several examples…
#1 The 2 positive cables to bus bar need to be the same. 18” each
The 2 negative cables from battery terminals to shunt need to be the same. 18” each
#2 Those positive cables vs the negative cables do not need to be the same - I.e. positive cables can be 12” and negatives can be 24”.
#3 Also, an interesting thought,
Battery1 - pos 12” neg 24”
Battery2 - pos 24” neg 12”
Is also just fine… because both batteries have 36” of cable - they are the same.
That is the real rule each battery has the same total length of cable. I think you were referring to #2 in your question.
Good Luck
#1 The 2 positive cables to bus bar need to be the same. 18” each
The 2 negative cables from battery terminals to shunt need to be the same. 18” each
#2 Those positive cables vs the negative cables do not need to be the same - I.e. positive cables can be 12” and negatives can be 24”.
#3 Also, an interesting thought,
Battery1 - pos 12” neg 24”
Battery2 - pos 24” neg 12”
Is also just fine… because both batteries have 36” of cable - they are the same.
That is the real rule each battery has the same total length of cable. I think you were referring to #2 in your question.
Good Luck
Thank you, Rocketman- that was my concern- I thought the shunt would interfere with cable to busbar, affecting the total length. So what you are saying, is on the negative cable, the shunt has no affect, as long as each battery cable to the shunt plus the positive cable add up to the same length.
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