Batteries in series. Need feedback!

[Repro]

I was in contact with a well known dealer for a VE Quattro 5000 48V. See the transcript below. I was floored. I did redact some of the content to avoid any problems. Please give me some feedback. I am a little shaken by the recommendation given to me.

(06:20:58)	*** Repro joined the chat ***
(06:20:58)	Repro: Interested in VE Quattro 5000 48V. Do you help in programming? Would need to set it up for self consumption mode. Only use grid power to charge batteries when solar can't keep up, and battery voltage hits 48V. I have four 12V 200Ah LiFePO4 batteries, a VE 150/70 controller, Cerbo GX, 500A SmartShunt and battery SmartSense module. My heaviest load is 2900W if everything would turn on at once. Normal load is less than 1000W. Can you help me?
(06:22:30)	Customer Service: We apologize for keeping you waiting. Our sales/tech reps are busy at the moment, please be patient for another minute or so, or if you prefer to leave your email we will contact you as soon as possible.
(06:23:15)	Repro:
(06:24:19)	*** Customer Service joined the chat ***
(06:24:59)	Customer Service: It's easy to configure. We can walk you through it or connect to it remotely if you have a Cerbo.
(06:25:08)	Customer Service: Have you purchased all of your equipment?
(06:25:53)	Repro: All I need is the Quattro and the MVK3 adapter. The rest has been in use for about 6 months.
(06:27:00)	Repro: I also have a 40A dedicated AC line running from my breaker box to the space where the inverter will be installed.
(06:28:38)	Customer Service: We can talk you through the AC Input Control Settings.
(06:28:53)	Repro: I was in touch with VE. They recommended you.
(06:28:57)	Repro: Sounds great
(06:29:37)	Repro: OK, I will have to order the Quattro. Would you recommend the 48V version with my battery bank?
(06:30:06)	Customer Service: What kind of batteries do you have?
(06:30:44)	Repro: four 12V 200Ah LiFePO4 batteries from Ampere Time. They have a 200A BMS.
(06:32:01)	Customer Service: I would never recommend series lithium batteries with an internal BMS. You can consult with the supplier or manufacturer of these batteries but rarely is this a good idea.
(06:33:16)	Repro: They can be connected either 4S or 4P or 2S2P.
(06:33:37)	Repro: That is from the manufacturer
(06:33:52)	Repro: I can do 12V, 24V or 48V
(06:34:26)	Repro: I am skeptical about connecting 12V to a 5000VA inverter.
(06:34:40)	Customer Service: Yeah, I would be too...
(06:34:52)	Customer Service: taht's a lot of power for a 12V system.
(06:35:08)	Repro: Do they sell a 24V Quattro?
(06:35:30)	Customer Service: Yes Sir.
(06:35:44)	Customer Service: Victron Energy Quattro 5000 Watt 24 Volt Inverter & 120 Amp Battery Charger Part Number: QUA245023110 Note: To do advanced Inverter configuration and setup you must have a VE.Bus To USB MK3-USB Interface. www.solar-electric.com
(06:35:45)	Repro: Would you think that would be OK?
(06:36:04)	Customer Service: I didn't say it wouldn't be OK to do the 48V.
(06:36:14)	Customer Service: You asked for my recommendation.
(06:36:34)	Repro: So you would recommend using 48V batteries.
(06:37:27)	Customer Service: I don't recommend series 12V lithium batteries. No reputable manufacturer or application engineer would recommend one series 12V lithium batteries for applications with cyclical operation.
(06:38:16)	Customer Service: Yes, exactly. One would want to use a 48V battery (with internal BMS) for applications that require a 48V inverter.
(06:40:37)	Repro: OK, I thank you for your recommendation. I have a dilemma here, I have $6000 in new batteries and need an inverter with 4000-5000 watt capacity. I feel insecure about the safety of using these batteries in that capacity now.
(06:41:00)	Repro: I am going to have to rethink my options and get back to you. Thanks!
(06:42:49)	Customer Service: Happy to help non the less... and will always be honest when someone asks for "my" recommendation. Sorry I put you in a dilemma.
(06:43:00)	Repro: Thank you!
(06:43:07)	Customer Service: Welcome.
(06:43:13)	Repro: Have a great Holiday weekend.
(06:43:24)	Customer Service: You too.

​

 

[snoobler]

I'm not the least bit surprised at the exchange. You have a high-end manufacturer with one philosophy, and a mid-range-ish battery manufacturer saying something else. Who do you trust? Both, but you get educated.

VE's concern is that the individual 12V voltage can wander, and the BMSs between the batteries don't talk, so there's nothing stopping batteries from being different voltages. There are a few examples on this site where series separate LFP batteries do not play well on an ongoing basis.

This is NOT a concern on lead-acid because lead-acid has something of a natural tendency to "balance" during the charging process, and they are significantly more tolerant of over-charge than LFP.

Battleborn recommends that you notify them if you plan to series their batteries when you order, so they can perfectly match them, and they recommend that they be broken down and charged to full as 12V once a year.

It is CRITICAL that you charge the Ampere Time batteries to full as 12V batteries in parallel to ensure they are all top balanced with each other prior to deployment. If you can't do parallel, you can do them individually, but it's best to minimize the time between first and last.

You will need to periodically monitor your batteries to ensure they are staying near the same voltage.

Lastly, install one of these on each battery:

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One is connected to each battery, and then the units are connected in a string. They communicate with each other and actively balance their voltages, i.e., they MOVE CHARGE from the higher voltage batteries to the lower voltage batteries seeking to keep all voltages within something like 0.05V.

I personally have one of those balancers on each of my 4S2P Trojan T-1275 batteries powering my 48V Quattro 5K.

Hopefully, you have enough information to make an informed choice.

 

[Repro]

Thanks Snoobler! Big Time. I had a 24V Growatt that ended up having to be returned due to wild voltage fluctuations. Since then I have been running a Giandel 12V 2200W inverter with no issues, other than I need more capacity. So my batteries are already in parallel and fully charged. I like the balancers. So even with the batteries in 4S @ 48V, just connect the cell connections to each battery and connect the balance leads to each balancer module in a string? Are the connectors included to connect them to each other?

I am very impressed with the Quattro 5K, and I think it will fit my needs well. I did learn a lot through this. I have only been actively building and configuring my own solar equipment for about 1.5 years. I have learned so much, and learn more everyday thanks to people like you and this forum. Thanks again, and have a great Memorial Day Weekend (Everyone)!