Cable Sizes for Lithium Install

[Lamokadave]

Renogy batteries were delivered yesterday. Once the new BIM arrives the batteries will be going in.
As I take inventory of the cables that came out of my 4-6v install, I'm thinking the cables were undersized for the amperage, but like everything else in life, it might be more complicated than meets the eye.
I've been reviewing wire size vs amperage tables and have concluded that for a 300 amp battery pack I should be using 3/0 conductor to support 200 amps that sits on the house positive and negative terminals.
My previous LA battery bank was using 2 awg welding cable for both the series and parallel connections.
My confusions comes in as I found references for welding cable at higher amperage vs "wire" at the same gauge. What I don't know is it because welding cable has a higher heat rating and therefore carries more amps or some other hidden difference??
My plan to parallel the batteries would be to connect battery 1 to 2 using 115 amp 2 awg, battery 2 to 3 using 200 amp 3/0. Battery 3 connects to the positive mains in the MH. On the negative side I would run the reverse sequence so that the 3/0 cable is on the terminal connecting to house negative.

Can anyone shed light on the differences between typical wire ratings and welding cable. Any feedback on my intended wiring plan is welcome as well

[ducksface]

Welding cable uses finer strand wire, making for more copper per cable length.
Use welding cable. The flexibilty is worth the added cost.

Buy the harbor freight hydraulic or a hammer type swedge/crimper.
Swedge, then dip the entire end in a solder pot. Shrink tubing or liquid tape or Tulip fabric paint(craft aisle at Wal-Mart) to seal eye to cable.
I've done far less and it all turned out ok.

Label everything on both ends before removing
and
take TOO MANY pictures before you even touch anything
and
take TOO MANY pictures throughout the entire pricess
and
Label everything when you're finished.

[sportcoupe]

I'm wondering why you are building a high current 6v battery pack.

Increase voltage to reduce amps and cable size.

[lwmcguir]

The only time I have a high amp liad is when operating the microwave or making coffee

I wouldn't worry about the cable size much

As Duck noted welding cable is handy and works well

I made up 25' jumper cables for all family members years ago with copper teeth in high end clamps

Everyone still has them and today they don’t get the use of yesteryear

[ducksface]

I use big cable because right now my inverter/charger is dumping 14.1 volts at 103 amps into My two discharged batteries(I left the fans and fridge on without plugging in to shore power when we got home from our trip). It'll do up to 350amps when I have the batteries to match. It's pulling a Full 20amps a.c. from shore.

[lwmcguire]

I charge at a bit over 100 amps many times and have checked the cables which are 2.0 and they never get hot. Mine will range from 103-108 depending on incoming voltage and usually on my 50 amp plug but sometimes on the 30

Charging 4 T105 AGM from 50% discharged so it takes a while

[16ACE27]

Originally Posted by sportcoupe

I'm wondering why you are building a high current 6v battery pack.

Increase voltage to reduce amps and cable size.

I don't see anybody in this thread building "a high current 6v battery pack".

The OP had (4) 6 volt batteries in a series-parallel configuration to have a 12 VDC battery bank as is common in many motorhomes. I'm assuming he has purchased 12 volt lithium batteries (LiFePO4) which he should wire in parallel to provide up to 400 amps of current with 4 batteries (100 amps each) which would really only be needed for heavy inverter use.

[sportcoupe]

Originally Posted by 16ACE27

I don't see anybody in this thread building "a high current 6v battery pack".

The OP had (4) 6 volt batteries in a series-parallel configuration to have a 12 VDC battery bank as is common in many motorhomes. I'm assuming he has purchased 12 volt lithium batteries (LiFePO4) which he should wire in parallel to provide up to 400 amps of current with 4 batteries (100 amps each) which would really only be needed for heavy inverter use.

The OP stated 4 - 6v pack capable of 300 amps.

Using four, six volt potteries in a series-parallel configuration is written as 2s2p so as not to be confused with just a 6v pack.

[Lamokadave]

Originally Posted by sportcoupe

The OP stated 4 - 6v pack capable of 300 amps.



Using four, six volt potteries in a series-parallel configuration is written as 2s2p so as not to be confused with just a 6v pack.

The 6v pack was actually 420 amps using 2awg welding wire.
The new lithium will parallel together for 300 amps

[16ACE27]

Originally Posted by sportcoupe

The OP stated 4 - 6v pack capable of 300 amps.

Using four, six volt potteries in a series-parallel configuration is written as 2s2p so as not to be confused with just a 6v pack.

No, he said "4-6v install". In the context of a MH that is a 2S2P configuration. What RV do you know of that has a 6 volt house battery buss? Can you even buy a 6 volt inverter?

[Chance]

Originally Posted by Lamokadave

The 6v pack was actually 420 amps using 2awg welding wire.
The new lithium will parallel together for 300 amps

I went back and researched some of your previous posts, and it sounds to me like you may be using Amps and Amp-hours interchangeably at times, which leads to a lot of confusion. Just my 2 cents.

Your previous flooded batteries appear to have been rated at 420 Amp-hours at 20-hour rate.

Your new lithium batteries are rated at 100 Amp-hours each, for a total of 300 Amp-hours of “stored energy”, which in itself doesn’t address current and thus necessary wire sizes.

Electrical current and wire size depends greatly on what you connect to the system and how it is operated. Thus far I see you boondock a lot, but haven’t discussed what you run beyond a residential fridge and occasionally a macerator pump; and also starting diesel generator.

Anyway, I’m a little confused because if you add battery capacity but change nothing else, it mostly means you can operate the same “stuff” for longer periods of time, but doesn’t necessarily mean you will use more peak power/current.

In my opinion if you share more information on what you’re trying to accomplish/operate (initially and or long term), it should help you get more valuable feedback.

[Lamokadave]

Originally Posted by Chance

I went back and researched some of your previous posts, and it sounds to me like you may be using Amps and Amp-hours interchangeably at times, which leads to a lot of confusion. Just my 2 cents.



Your previous flooded batteries appear to have been rated at 420 Amp-hours at 20-hour rate.



Your new lithium batteries are rated at 100 Amp-hours each, for a total of 300 Amp-hours of “stored energy”, which in itself doesn’t address current and thus necessary wire sizes.



Electrical current and wire size depends greatly on what you connect to the system and how it is operated. Thus far I see you boondock a lot, but haven’t discussed what you run beyond a residential fridge and occasionally a macerator pump; and also starting diesel generator.



Anyway, I’m a little confused because if you add battery capacity but change nothing else, it mostly means you can operate the same “stuff” for longer periods of time, but doesn’t necessarily mean you will use more peak power/current.



In my opinion if you share more information on what you’re trying to accomplish/operate (initially and or long term), it should help you get more valuable feedback.

Good point.
The only behavior we might change is to run a Keurig machine in the AM. That's around 1500w. I do agree that the likeliness of huge current draws is low. My original big unknown was understanding the impact of a gen start.
I've since tested that and witnessed the chassis batteries connect in to start the gen so im less concerned. I've settled on linking the batteries together with 2/0 wires rated at 175a at 75c degrees

[Chance]

Originally Posted by Lamokadave

Good point.
The only behavior we might change is to run a Keurig machine in the AM. That's around 1500w. I do agree that the likeliness of huge current draws is low. My original big unknown was understanding the impact of a gen start.
I've since tested that and witnessed the chassis batteries connect in to start the gen so im less concerned. I've settled on linking the batteries together with 2/0 wires rated at 175a at 75c degrees

A full-size Keurig that pulls 1500 Watts will pull “about the same” current as a 1,000-Watt microwave (that’s cooking power), which may be a bit much for your 1,800 Watt inverter (going by your rig’s specs) if powering residential refrigerator at same time. Unless factory inverter has been upgraded (upsized), you may want to consider a smaller Keurig that uses less power/current. My K-cup coffee maker requires a bit more time per cup but pulls under 1,000 Watts of power. We don’t mind the extra +/- 30 seconds per cup — small price to pay.

[Chateau_Nomad]

Originally Posted by Chance

A full-size Keurig that pulls 1500 Watts will pull “about the same” current as a 1,000-Watt microwave (that’s cooking power), which may be a bit much for your 1,800 Watt inverter (going by your rig’s specs) if powering residential refrigerator at same time. Unless factory inverter has been upgraded (upsized), you may want to consider a smaller Keurig that uses less power/current. My K-cup coffee maker requires a bit more time per cup but pulls under 1,000 Watts of power. We don’t mind the extra +/- 30 seconds per cup — small price to pay.

Or use a French press... which uses zero watts. It take me 7 minutes total - 3 minutes to boil, 4 minutes to steep. But then my daughter-in-law calls me a "coffee snob".

[sportcoupe]

Originally Posted by Chateau_Nomad

Or use a French press... which uses zero watts. It take me 7 minutes total - 3 minutes to boil, 4 minutes to steep. But then my daughter-in-law calls me a "coffee snob".

How do you boil with zero watts?

[Chance]

Originally Posted by Chateau_Nomad

Or use a French press... which uses zero watts. It take me 7 minutes total - 3 minutes to boil, 4 minutes to steep. But then my daughter-in-law calls me a "coffee snob".

That’s an option, but is changing subject in my opinion.

If you prefer K-cups you prefer K-cups. That’s what we use at home, and also while touring and camping because it’s easiest for us to deal with waste disposal and cleaning. Mostly we drink different coffee brands and types so K-cups keeps it simple.

Regardless, my point is that if a person prefers Keurig-type coffeemaker, there are options for less power. It just takes a little longer and you have to add water for each cup (unlike larger coffeemaker with water reservoir). On plus side our compact unit is a lot smaller and lighter, which for us is a big plus.

[Chateau_Nomad]

Originally Posted by sportcoupe

How do you boil with zero watts?

The answer would "shock" you... especially if I corrected myself and said "amperes" instead of watts...

Originally Posted by Chance

That’s an option, but is changing subject in my opinion.

If you prefer K-cups you prefer K-cups. That’s what we use at home...

Forgot the flag! But I agree with your "coffee strategy". I'm just the oddball out - that's why my family (who ALSO use Keurigs) call me a "coffee snob"!

NOW... back to the discussion about CABLE SIZE...