96 or 144v instead of 48v

[Sunking]

Your advice is sound. Thank you for your input!

So bottom line here is stick with 48v.

At 6000 watts, 48 volts will work but you are near the top of 48 volt power range. That is the key is maximum Power, and the current required to push it at a specified voltage. At 48 volts with 6000 watt load you are talking about 125 amps of current and a minimum size FLA battery of 900 AH. So you are already locked into 2400 pound $8000 battery that will only give you 4 hours run time. That battery will need replace din a few short years.

I will be striving to build out 8 hours of UP time from the batteries. I would like an Exeltech MX System to get N+1 on the inverter.

Sammy do you understand what you are asking for? 6000 watts x 8 hours = 48 Kwh. At 50% DOD, a line you do not want to cross with Pb you are talking about a 96 Kwh battery. Do the math on that. A Pb battery weight 60 lbs per Kwh and cost $200 to $250 per Kwh. 3 years replace. Double what I quoted above. You are talking about a 5000 pound $20K battery every few years.

I've been looking at commercial LFP but very expensive. Is it practical to consider CALB's and put these in place ourselves? Exeltech can do the inverting, power comes from the CALB's - just need to figure the charging. From a long time lurking here i wont talk about "balancing", but bottom seems easy enough. does that sound OK?

For a Commercial System using LFP, you want Top Balance because it is made for consumers and morons. It takes an expert to use a BB LFP. Pretty much takes the same equipment either way.

As for CALB my friend you are gambling. Yes I know there are claims they will do 2000 cycles to 80% DOD. Those claims have been there since Thundersky began manufacturing. They went bankrupt because no battery they made ever seen 500 cycles. Here we are 9 years later, and on the 4th revision. None have ever seen more than 500 cycles yet. You would be betting the Farm the latest revision will do what they claim. Do you really want to trust a bunch of Red Chi-Coms who have a terrible track record and known to be liars? Be careful with Chi-Coms. None have a proven track record. CALB, Sinopoly/Winston all are regurgitated Thundersky batteries.

Here in the USA CALBS are used by DIY EV builders. None have ever been able to file a Warranty Claim. Be careful. With LFP you can use a smaller AH battery. Run them between 10 and 90% DOD. Never fully charge them, they will last twice as long if you stay between 10/90. To replace a Pb with LFP for every 100 AH of Pb takes about 70 AH of LFP to replace it. Yes smaller and lighter, but more expensive.

Keep this thought in mind. You can get a top of the line Pb battery for around $220 Kwh. Assuming professional care an dTLC you will have a 7-year battery with full warranty from proven technology from reputable companies like Rolls, Crown, and Exide to name a few. A Chi-Com LFP will run you $450 to $500 Kwh and one can only guess how long they might last. Its a gamble. So be careful, your reputation is on the line. If done in the USA, and the batteries fail prematurely, the replacement cost comes out of your pocket. You would be held accountable. Chi-Coms don't give a damn if it bankrupts you, they are untouchable.

Good Luck to you.

[DanKegel]

Seems like one or more UPS's plus your own genset plus the building genset plus the grid should give you four layers of redundancy.
Would that be cheaper than the big battery you were thinking about?

[Sunking]

i like the - 3 hours UPTIME and genset thereafter routine. I think that works.

Mucho better IMO. Even 3 hours @ 6000 watts is a beast of a battery 48 volts @ 750 AH. About 1900 pounds in Pb or 900 pounds in a 48 volt @ 600 AH LFP

So which battery should i look at ? Pb or LFP?

Only way I could sleep at night is with Pb. I know with Pb will cost me half of LFP, save even more by not having to purchase all the auxiliary equipment required for LFP, and proven track record that will in all likelihood will last twice as long. Lots of PB batteries have lasted 7 to 10 years and have done it for the past 100 years. No Chi-Com LFP is known to last more than 3 or 4 years yet. Lots of promises and claims, but no history of doing it. Very poor track record so far.

I could not sleep knowing that. Can you? Only way I would do it is if the customer signed a Release.

[sammy_sparrow]

Seems like one or more UPS's plus your own genset plus the building genset plus the grid should give you four layers of redundancy.
Would that be cheaper than the big battery you were thinking about?

It would - but hard to manage. Not sure how i would manage such a setup - it would be lots of manual plugging and unplugging. Not sure it works.

[sammy_sparrow]

At 6000 watts, 48 volts will work but you are near the top of 48 volt power range. That is the key is maximum Power, and the current required to push it at a specified voltage. At 48 volts with 6000 watt load you are talking about 125 amps of current and a minimum size FLA battery of 900 AH. So you are already locked into 2400 pound $8000 battery that will only give you 4 hours run time. That battery will need replace din a few short years.

SK, are we talking about the same thing? I am talking about keeping the inverter at 48v input - ie, from a 48v battery bank to the inverter. a 900AH Pb battery at 48v feeding the inverter would let me power the 6000 watts with ease. Heck, right now i have a 48v input inverter with 200AH of AGM on it at home and pull 4500 watts off it without issues.

Are you talking about 6000 watts *AT* 48v?

[sammy_sparrow]

Mucho better IMO. Even 3 hours @ 6000 watts is a beast of a battery 48 volts @ 750 AH. About 1900 pounds in Pb or 900 pounds in a 48 volt @ 600 AH LFP

PB batteries have lasted 7 to 10 years and have done it for the past 100 years. No Chi-Com LFP is known to last more than 3 or 4 years yet. Lots of promises and claims, but no history of doing it. Very poor track record so far.

I could not sleep knowing that. Can you? Only way I would do it is if the customer signed a Release.

yeah, food for thought....very very serious thought indeed.