Larger LiFePo4 vs Mulitple

[bobsh2000]

This may be silly, but do multiple batteries in parallel have the same discharge rate as 1 larger battery? I am thinking about a 200Ah or 230Ah vs 2-100Ah batteries. The large one can run a 2500W inverter, can the 2 smaller ones? The only inverters I have used are small ones. Now my wife wants to run a microwave off 12V in a travel trailer.

 

[42OhmsPA]

Welcome to the forum.
Not a silly question.
A few things to consider.
It really comes down to the BMS and C rate of the cells, ideally you stay under 0.5C to keep them happy; 50A on 100Ah cells.

You could run 230Ah cells with a 200A BMS @ 0.5C for 115A charge/discharge.
You could run 3 packs of 100Ah cells in parallel with 100A BMS's @0.5C for 150A charge / discharge.

Hope that makes sense.

 

[sunshine_eggo]

theoretically, yes. In reality, even if you use best practices like line #6 in my signature, it's never perfect. Assume a 10-20% margin on additive current, i.e., if you have 2X 100A in parallel each capable of 100A, assume 160-180A is a sure thing

 

[bobsh2000]

42OhmsPA: thanks. Yes that does make sense.

sunshine_eggo: So, I am better off going with a larger battery than multiple batteries.

Equalization won't be a problem with a larger battery, either. I just got a 220W solar panel for my trailer and the same thing is true: it is better to have fewer, larger panels and not have to worry about loosing current or voltage through connections.

 

[time2roll]

If the larger battery will discharge at 200 amps it will be fine. If the pair of smaller batteries are rated to discharge at 100 amps each will also be fine. If you go with the pair make sure the connections are balanced between the batteries so they will discharge as evenly as possible. Wiring is simplified with the single battery. My microwave pulls about 75 amps from each battery with no start surge.

Excellent question.

 

[Budsy]

Welcome to the forum.
Not a silly question.
A few things to consider.
It really comes down to the BMS and C rate of the cells, ideally you stay under 0.5C to keep them happy; 50A on 100Ah cells.

You could run 230Ah cells with a 200A BMS @ 0.5C for 115A charge/discharge.
You could run 3 packs of 100Ah cells in parallel with 100A BMS's @0.5C for 150A charge / discharge.

Hope that makes sense.

Hi I’m brand new and have purchased 2x 24 volt 200 ah life04 batteries and a 24 v 3000 watt hybrid inverter. As I understand it I would need at least 175a fuses on both Batteries postitive wire. Would it be ok to use 200 amp fuses(as I have two of them)?

 

[Dooug]

Hi I’m brand new and have purchased 2x 24 volt 200 ah life04 batteries and a 24 v 3000 watt hybrid inverter. As I understand it I would need at least 175a fuses on both Batteries postitive wire. Would it be ok to use 200 amp fuses(as I have two of them)?

Only if the wiring can handle 200 amps can you use a 200 amp fuse.

 

[Budsy]

Only if the wiring can handle 200 amps can you use a 200 amp fuse.

I was going to use 2/0. Would that work?

 

[Budsy]

I was going to use 2/0. Would that work?

I just found a chart and it looks like it’s 3/0 minimum so I’ll just but new fuses. Thanks

 

[upnorthandpersonal]

You also need to think about redundancy: if one pack in a parallel configuration goes offline, you still have power. One large battery goes offline, you're in the dark.

 

[42OhmsPA]

I was going to use 2/0. Would that work?

I would be comfortable using it and am using 2/0 for my battery to inverter connection.
There are many charts, I refer to this one frequently.

Part 1: Choosing the Correct Wire Size for a DC Circuit - Blue Sea Systems

Engineering high quality marine electrical components for safety, reliability and performance

www.bluesea.com

It won't hurt anything to go larger.

 

[OffGridForGood]

One large battery goes offline, you're in the dark.

...unless you are located at 63 degrees North, and it's June...

 

[dktool]

This may be silly, but do multiple batteries in parallel have the same discharge rate as 1 larger battery? I am thinking about a 200Ah or 230Ah vs 2-100Ah batteries. The large one can run a 2500W inverter, can the 2 smaller ones? The only inverters I have used are small ones. Now my wife wants to run a microwave off 12V in a travel trailer.

In my rv for the same reason as you I did a single 200ah with 200A bms and a 2200 watt inverter.
This particular inverter will even start my Coleman mach 3 A.C., I experimented with 2 others including the renowned Renology that wouldn't come close to starting it. This one hardly blinks.
And has the best remote control, actually has useful information not just a color graph of battery voltage.

 

[OffGridForGood]

A single battery with 200A capacity BMS or two parallel packs with 100A capacity BMS each will do the same job. It may be important to you for the batteries to be separate to make them easier to move around, or to fit the space you have for them. As @upnorthandpersonal said, multi packs allows you to remove one for service while still having (reduced) power output. Up to you.