Can I mix and match Victron Lithium Batteries (External BMS) of different capacities? 100/200/330ah

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Neo Nos asked Jan 8, '24

Can I mix and match Victron Lithium Batteries (External BMS) of different capacities? 100/200/330ah

Sorry I am a newbie and new to Victron. I setup my own van rig in 2020 and been learning. Just saved up and bough all the Victron Equipment. I want to but batteries now, I am under the impression that with Lithium and Victron in particular unlike other batteries i can mix and match batteries in parallel without any down site is that correct, as long as they are all relatively new?

Can I setup my system with an 100ah battery then add a 330ah in parallel next month? or should I always consistently buy the same capacity batteries? Also how long/after how many months would it not be a good idea to add a brand new battery without damaging it?

I ended up buying a 200AH battery just to be safe in case you guys tell me to always get a battery of the same size I thought the 200AH was a decent size, but I want to invest in 330AH as I add them but after buying 10K but now I am wondering if I should double check and perhaps I am wrong and it is not a good idea to mix and match victron batteries?

I read some other posts on this topic but not one really gave a straight forward answer, it was mostly along the lines of that the separate BMS and voltage similarity of the VE batteries is the same and can easily be mix and matched if they are in parallel.

Most answers try to explain the physics of it outside the scope of Victron, I am only interested in a practical application of the specific Victron Lithium batteries, however seems like these are relatively newer products and less discussed on the forum.

Thank you for your time, and sorry for my lack of knowledge. I am an engineer and will learn fast now that I have become so heavily invested in Victron after much research.

Also if it matters I have the SmartBMS 12/200 after much research the Alternator function and lower price appealed to me over the Lynx BMS. I did purchased a Lynx Distributor and open to going Lynx in the future.

I have many Orion chargers and MPPT chargers and a MultiPlus || 2x all 12v system.

Lithium Battery BMS lifepo

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frankmsc68 commented · Jan 08 at 10:10 AM

@Neo Nosrati ,hi there,i invite you to go to www.batteryuniversity.com where you find all the answers there...Frank

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Neo Nos frankmsc68 commented · Jan 08 at 07:32 PM

I have a lot to learn at the university I was hoping someone could help me with this yes or no question so I can buy the right equipment.

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Neo Nos frankmsc68 commented · Jan 08 at 07:35 PM

Those also seem to be in general. I am interested on the benefits of the VE batteries and the claims of ability to mix and match and anything worth considering.

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frankmsc68 Neo Nos commented · Jan 09 at 12:46 PM

Sorry NeoNosrati,i'm not using Lithium batteries,can't say from this experience...Mixing different size capacities is'nt easy ,worse if different build from different suppliers are mixed.Usually the weekest gets stressed the most and is therefore the first candidate to fail.But as i said i'm not using Lithium;for several aspects....Frank

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Answer 1 · 2024-01-08T19:45:38Z

Justin Cook answered · Jan 08 at 07:45 PM

The answer is yes with a but; see section 4.5.6 of the Lithium Smart battery manual for details and recommendations.

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Neo Nos commented · Jan 08 at 11:06 PM

Thank you so much . This is helpful but it even makes me feel like peoples opposition is overrated, (I only will have parallel no series at all) interestingly using different capacities in Parallel does not even have the astrix for : ²⁾ The age difference should not exceed 3 years.

Does this mean you can add really old batteries with new batteries? That really confuses me cause I know time changes them after many cycles... But I guess in Parallel it just changes the discharge to not even among batteries which I am guessing is not a super big deal as long as one doesn't completey discharge before hitting voltage of the other battery which won't really happen when they are all Victron.

Also I understand that I will have no need for a battery balancer.

If I understood correctly I can do what I intend to do without any reasons not to.

Thank you so much for pointing out the section.

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Neo Nos commented · Jan 08 at 11:15 PM

Let me ask you this? Should I just keep upgrading by Adding more 200AH batteries for the next few months? Thinking adding a battery every month for the next consecutive 3.

Or do I have no reason to not add 330AH batteries since they are better bang for the price. I calculated 100AH:$7/ah, 200:$5.5/ah and 330:$5/ah.

So that is my main reason for thinking of buying 330 in future.

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Justin Cook ♦♦ Neo Nos commented · Jan 08 at 11:57 PM

"...makes me feel like peoples opposition is overrated"

LOL, yes, welcome to the world of batteries... you'll get a million and one opinions on everything under the sun when it comes to batteries, thus why just referring back to the manual is always the safest bet. In this case, to be fair to those arguing against it, support for varying battery capacities in the same bank, along with several other factors, was updated in the manual by Victron relatively recently in the past year or so, so I don't blame anyone for still considering it verboten.

In general I would personally consider it not the best of practices to mix ages and capacities, but since it's supported in writing, it's your call. Just make sure that the installation itself is correct and proper in terms of wiring and data cables and etc and you shouldn't have issues!.

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klim8skeptic ♦ Justin Cook ♦♦ commented · Jan 09 at 01:57 PM

@Neo Nosrati @Justin Cook paralleling different age / capacity batteries does not any problems as long as the BMS is monitoring cell voltages / temp, and proper charging / balancing takes place.

Batteries will absorb charge current and deliver current to loads proportional to their capacity.

Things will go wrong with an aged battery, or a battery that has been abused. One cell in the battery will have a reduced capacity, and will trip cell OVP /UVP before it has reached it's nominal Ah rating. Result is reduced overall bank Ah capacity.

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jjduke klim8skeptic ♦ commented · Jan 09 at 03:10 PM

You say "reduced overall bank Ah capacity."

Do you know how the LYNX Smart BMS behaves when there is an OVP/UVP in the single cell of the aged battery?

Specifically, Is there a general ATC/ATD "off" signal stopping all charging/discharging from the entire bank? OR, is there a targeted signal sent to the single battery with that cell OVP/UVP to stop charging/discharging for just that one parallel battery?

I would hope the latter answer is how it works. Otherwise, the aged/misbehaving cell takes out the whole battery bank.

(I've had the LYNX BMS and (4) 25.6v 200Ah for over a year and have never had any cell ovp/uvp conditions like this, but i am considering adding a string of (2) 12.8v 330Ah in series to the bank. it's a sailboat and i think i can fit the (2) 12.8/330's in a space where a single 25.6/200 can't fit.)

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klim8skeptic ♦ jjduke commented · Jan 09 at 10:14 PM

@Jjduke Specifically, Is there a general ATC/ATD "off" signal stopping all charging/discharging from the entire bank?

This^. When discharging the first cell to trip UVP will disable discharge from the entire battery bank.

Otherwise, the aged/misbehaving cell takes out the whole battery bank.

This wont happen unless there is a damaged cell that has a reduced Ah capacity, that would be the cell to run out of puff and trigger UVP.

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Answer 2 · 2024-01-09T00:07:33Z

regman54 answered · Jan 09 at 12:07 AM

I don't know what else to add. You've been given sound advice and direction but sometimes that just isn't good enough therefore one has has to experience things on their own through trial and error. Experience takes longer but like an apprenticeship program it's the best way to learn.

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