12v batteries or 24v batteries, this is a question.

[oldjohnt]

21 hours ago, Johnxhc said:

Hi,John,

The Victron Inverter/Charge has 2,400w but peak power is 6,000w, when I select wire (I assume it is 4 gauge?) should I consider the 6,000w peak power?

John up above I looked at a worst case scenario and being conservative considered even if you drew 250 amps (which is 12 volts and 3000 watts) I suggested 4/0 Copper wire. HOWEVER at 2400 watts at 12 volts you would only draw (subject to efficiency) 200 amps.

REGARDLESS I doubt you would ever in reality draw  200 amps for any appreciable time. If an Inverter powered AC unit drew 15 amps at 120 VAC,  that's maybe (subject to efficiency) 15 x 11 = 165 12 volt battery amps still less then 200 !!!! Ask yourself what all at the same time for very long might you use that Inverter for ?????????  

But based on the 12 foot distance from batteries to Inverter you quoted (but maybe your latest design is less) I WOULD STILL SUGEST 4/0 COPPER EVEN IF ITS OVERKILL AND OVER ENGINEERED TO REDUCE VOLTAGE DROP, HEAT, AND SO THERES LESS I SQUARED R WASTED ENERGY LOSS.

So NOOOOOOOOOOOO I don't see you need to consider that 6000 Watt peak power but even if its bigger then you need Id still use 4/0 Copper. 

Voltage Drop Calculator:  https://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=0.1608&voltage=12&phase=dc&noofconductor=1&distance=10&distanceunit=feet&amperes=200&x=116&y=19

Voltage Drop Calculator results:   200 Amps,,,,,,,4/0 Copper Wire,,,,,,,,12 Volts,,,,,,,,,ONLY 0.20 Volts drop at 12 feet

See, 4/0 is MORE then needed (but still subject to length) and is MORE THAN adequate for your 200 amps .

Still, its YOUR RV,,,,,,,,YOUR choice and sure smaller wire can work, especially if the distance is reduced from the 12 feet you spoke of. While I've heard complaints when wire size was too close for comfort and excess voltage drop occurred, no one complains if its too big within reason. 

PS Power in Watts = Volts X Amps. Last post from you it said you were considering keeping your batteries and Inverter at 12 Volts so I used 12 Volts in the above current and wire size calculations. If you change to 24 volt batteries Power still = Volts X Amps but the battery to Inverter current cuts in half meaning you can use smaller wire .

You may be over thinking this and so may I lol

John T

Edited September 8, 2020 by oldjohnt

[Johnxhc]

On 9/7/2020 at 4:35 PM, jcussen said:

Yes, would not worry too much about surge, that will probably be less than a second. I size for the normal full output of the inverter, but bare in mind you will seldom be running at full output of inverter. I have a lot of gear in my coach, and seldom draw more than 2000 watts off my 3000 watt inverter.

I use this chart for sizing wire.

https://www.bluesea.com/support/articles/Circuit_Protection/1437/Part_1%3A_Choosing_the_Correct_Wire_Size_for_a_DC_Circuit

Thank you.

Just received my batteries ::)

https://photos.google.com/share/AF1QipNx1xRmo46mnFyBdiqlvmfCVJVD4crG_yFMl079x0rlzYCgzYiep7AH0zWpse-Etw/photo/AF1QipObkKxN12l7oOPNgZAtv_3LBdVXcAqHMooN1nFe?key=UE96VU1CTldHbDJiQ1Z3X01DeXpadHZXY3BNN0V3

[jcussen]

33 minutes ago, Johnxhc said:

Thank you.

Just received my batteries ::)

https://photos.google.com/share/AF1QipNx1xRmo46mnFyBdiqlvmfCVJVD4crG_yFMl079x0rlzYCgzYiep7AH0zWpse-Etw/photo/AF1QipObkKxN12l7oOPNgZAtv_3LBdVXcAqHMooN1nFe?key=UE96VU1CTldHbDJiQ1Z3X01DeXpadHZXY3BNN0V3

They are beautiful, just like mine. The adventure begins.

 

[oldjohnt]

40 minutes ago, Johnxhc said:

Thank you.

Just received my batteries ::)

WOW those are beautiful, congratulations. Connect them so they ALL get equal load and charge balance, keep their SOC up as much as possible so as to avoid using up life cycles, avoid overheating, and they should last you 10 yeas no problem, Makin me jealous lol

  http://www.smartgauge.co.uk/batt_con.html

John T

[jcussen]

13 minutes ago, oldjohnt said:

WOW those are beautiful, congratulations. Connect them so they ALL get equal load and charge balance, keep their SOC up as much as possible so as to avoid using up life cycles, avoid overheating, and they should last you 10 yeas no problem, Makin me jealous lol

  http://www.smartgauge.co.uk/batt_con.html

John T

Actually John, most LiFePO4 battery manufacturers do not recommend keeping SOC at 100% if at all possible.  Lithium never really has to be brought to 100% like lead acid. Battleborn told me  60 to 80% was optimal.. I do this by turning on and off one solar array. Tesla recommends keeping SOC below 85% for best battery longevity, if not going on a trip where max, mileage is needed.

I liked my smartgauge when I had lead acid, but found that the smartgauge algorithm will not work with lithium, so had to go to a shunt type battery monitor.

Agree with equal  load and charge balance, I used the same size wire and length when wiring my batteries to  common busbars.

 

[oldjohnt]

18 hours ago, jcussen said:

Actually John, most LiFePO4 battery manufacturers do not recommend keeping SOC at 100% if at all possible.  Lithium never really has to be brought to 100% like lead acid. Battleborn told me  60 to 80% was optimal.. I do this by turning on and off one solar array. Tesla recommends keeping SOC below 85% for best battery longevity, if not going on a trip where max, mileage is needed.

I liked my smartgauge when I had lead acid, but found that the smartgauge algorithm will not work with lithium, so had to go to a shunt type battery monitor.

Agree with equal  load and charge balance, I used the same size wire and length when wiring my batteries to  common busbars.

BIG THANKS JC good information,,,,,HEY I WOULD TAKE BATTLEBORNS ADVICE OVER ANYONE ELSES FOR DARN SURE  LOL I DEFER TO THEM, THANKS FOR THE SPECS !!!!!!!!!!!

 Regardless, my thinking and advice is still if you keep them at whatever the recommended SOC (be it 60 or 80 or 100%) WHAT I STILL ADVISE IS TO KEEP THEM ADEQUATELY (per manufacturers specs of course NOT mine where incorrect) CHARGED so you don't use up the finite x amount of "Life Cycles". Regardless of the optimum  SOC (60% or 80% or whatever) each time you discharge and have to recharge YOU USED UP ONE OF THEIR LIFE CYCLES. If your solar or smart charger keeps them supplied and floated at SOC all the time YOU REALLY DONT EVER USE UP MANY LIFE CYCLES.......Your charger is re -supplying what the batteries are pumping out, they're not having to do much lol  should last forever !!!!!!

 I'm NOT aware the battery chemistry (Lithium or Lead Acid etc) affects the best connection methods such that EACH receives the same degree of charging and contributes equally to the load. Some of the Smart Gauge very impressive data involves (albeit tiny) resistance and small voltage drop differences. It appears to me (regardless if lead acid or lithium) if EACH battery has the exact same cable distance and resistance to the charger and loads, each has to be better equalized then in ladder only connected where current (and resistance and voltage drop) has to flow through more and/or different cable lengths to reach different batteries. Its hard to see how the batteries closest to the buss work the same as those further away.      BUT HEY THATS A QUESTION FOR SMART GAUGE that's above my pay grade lol

But it looks like we agree, that's how you said you are connected, I bet its working GREAT 

" Agree with equal  load and charge balance, I used the same size wire and length when wiring my batteries to  common busbars."

UNFORTUNATELY FOR ME grrrrrrrrr Mine are ladder connected and I've never seen a bank wired as Smart Gauge suggests, but if I were starting over and investing $1000  in each battery, rest assured my goal would be they EACH contribute equal to the load and EACH receive the same charge and its still my opinion if each and everyone (regardless of chemistry) had the exact same cable and resistance and voltage drop (load to battery) that just has to be better      BUT HEY I DEFER TO SMART GAUGE ON THIS ONE we will have to ask them if their connection method is different for lead acid versus lithium DARN IF I KNOW OR UNDERSTAND HOW THAT COULD BE LOL

PS Im talking Smart Gauge method of multiple battery connection methods NOT ANY CURRENT MONITORS 

PS I agree 100% a shunt type meter is the ONLY way to go regardless of batteries 

PS even though its possible and even if Battleborn says its okay, if I invested that heavy in them to the extent reasonably possible (given enough solar and batteries) I wouldn't prefer to draw them down much over 80% on any regular basis if I didn't absolutely have to, but hey that's just me. 

Here's what I'm talking about   http://www.smartgauge.co.uk/batt_con.html the imbalance and differences based on connection methods  IS VERY VERY DIFFERENT I was quite surprised

Still its Johns RV Johns money Johns choice how he connects them regardless what we might think 

Its a pleasure sparky chatting with you and geeking and nerding out at the risk of boring others, we need to do lunch lol

Thanks again for posting those Battleborn Specs, that may help others and educated me....I don't own any of their batteries nor have their instructions, SILLY ME I would have thought if they were discharged Id allow my solar charge controller to keep pumping charging current into them until they achieved the full 100%, oh well I'm never too old to learn lol  

Take care JC, Best wishes n God Bless

John T

      

Edited September 10, 2020 by oldjohnt