Community Forums

wantabe351 · 09-19-2021, 04:50 AM

I've decided to go with Lithium batteries for my RV, and shopping for batteries I'm thinking of starting with a 200ahr battery now and wondered is there a advantage to using 2 -100ahr battery to 1-200ahr battery...

Marine359 · 09-19-2021, 05:40 AM

2 x 100 gives redundancy in case one fails. But there is a price penalty for that, as a larger battery always costs less per amp hour than two smaller ones. More importantly is to choose a LiFePo4 with a good BMS. You should be able to review those specs on the manufacturer’s website. Cheap batteries may have an inferior BMS. Although, you can find a really good battery/BMS for far less than the top of the line batteries. If it’s made in USA and has a 10 year warranty, you’re better off. I used to carry my old Marine grp24 deep cycle as a back-up to my single LiFePo4, but don’t anymore, as the LiFePo4 has proven itself bulletproof, so I shed the extra weight. Of the marine battery.

Camper25 · 09-19-2021, 07:06 AM

Is there a made in the USA LifePo4 battery.... many of the expensive brands are made in China and assembled in the USA.

Itinerant1 · 09-19-2021, 07:42 AM

All cells are made in China shipped to America then bought by American assemblers.

To the OP question 1 200ah battery would do fine just pay attention to the allowed discharge current.

twanger · 09-19-2021, 06:41 PM

I thought two 100 ah lifepo4 could output more amps than one 200. Is there no truth to that?

Marine359 · 09-20-2021, 06:16 AM

Quote:

Originally Posted by Itinerant1

All cells are made in China shipped to America then bought by American assemblers.

That is correct. But what’s in a word? Many other products considered or labeled “made in USA” are assembled mostly from parts and components made in China. The advantage to buying from a USA manufacturer (or assembler if you choose that word) is that they have phone customer service, and you can have some degree of confidence of warranty service.

Persistent · 09-20-2021, 09:15 AM

Quote:

Originally Posted by twanger

I thought two 100 ah lifepo4 could output more amps than one 200. Is there no truth to that?

There is generally no truth to the above rumor. As we leave the may myths about lead acid batteries behind, I suppose it is time to develop some new ones.

Any kind of battery uses multiple design techniques to produce the battery for some defined purpose. What the designer decides to include depends on his desired outcome.

The best manufactures test their designs and then again test the production build. They publish their results.

An 80 amp hour lithium can be designed to have higher current output than a 400 amp hour lithium battery. It will deliver that high output for a shorter time. It all depends on the design.

Some battery parameters you might find useful in published specifications:

Maximum Current = How fast the battery can deliver power to a high capacity inverter or such and still maintain minimum voltage and long life.
Total Amp Hours = How long it can deliver a standard current and still maintain standard voltage.
Voltage = You probably understand this
Internal Resistance = Virtual power loss inside the battery.
Maximum Charge rate = The highest current the battery is capable of absorbing.
Optimum Charge Rate = Charge rate that provides most number of recharge cycles.

There are many more parameters that are important for many applications. Lithium batteries especially now, come with lots of different capabilities and chemistries. Things are going to change a lot. Rules of thumb being passed around now will change tomorrow.

757driver · 09-20-2021, 09:32 AM

Quote:

Originally Posted by twanger

I thought two 100 ah lifepo4 could output more amps than one 200. Is there no truth to that?

Yes there is. For any given lithium battery manufacturer each of their batteries (a 100 AH model and a 200 AH model) will most likely have the same BMS and the same limit on the max amps it can deliver (ie 100 AH). The 200 AH battery can only put out 100 AH max without tripping the BMS. Two 100 AH batteries which can put out 100 AH each without tripping the BMS can give you a max of 200 AH max which now could run a microwave for a short period of time.

My lithium manufacturer actually cautions against this when choosing the number of batteries and their size.

Itinerant1 · 09-20-2021, 09:55 AM

Lifeblue for the 200ah & 300ah batteries allows discharge of 150a continuous and 200a for 30 minutes.

I'll bet most folks will run out of inverter first.

757driver · 09-20-2021, 10:18 AM

Quote:

Originally Posted by Itinerant1

Lifeblue for the 200ah & 300ah batteries allows discharge of 150a continuous and 200a for 30 minutes.

I'll bet most folks will run out of inverter first.

Hmmm. Their current data charts for the batteries show the 100 AH and the 300 AH with a max continuous discharge of 100 AH. The 200 AH battery shows a 150 AH max continuous discharge.

Itinerant1 · 09-20-2021, 10:29 AM

Just looked at their webpage 100ah is 100a, 200 & 300ah is 150a discharge.

If I was going to do it over I would still stay with my GBS though.

757driver · 09-20-2021, 10:38 AM

Quote:

Originally Posted by Itinerant1

Just looked at their webpage 100ah is 100a, 200 & 300ah is 150a discharge.

If I was going to do it over I would still stay with my GBS though.

Looks like Larry has some work to do. The data sheet link at the bottom of the home page shows different to what you have. Hard to say which is correct.

Itinerant1 · 09-20-2021, 11:22 AM

Even the Lifeblue download data sheets shows what I posted.

I would hope the manufacturer's page would be correct.

757driver · 09-20-2021, 05:30 PM

Quote:

Originally Posted by Itinerant1

Even the Lifeblue download data sheets shows what I posted.

I would hope the manufacturer's page would be correct.

That’s my point the LifeBlue data sheets from the bottom of their home page shows what I posted. I guess one is correct and the other is not. Only Larry knows which one is correct.