Can you charge LiFePO4 batteries with different capacities and SOC in parallel?

Рет қаралды 38,180

7 ай бұрын

4 batteries in parallel, different capacities, different state of charges. What could possibly go wrong??? Well, maybe nothing if it is LiFePO4. We explore how these batteries react when we connect and charged them in parallel.
This test was, once again, requested from some of my viewers and in today's workshop, we will find out what is going to happen.
I prepared four 51V batteries with different SOC and connected them in parallel. I started charging this setup from solar as well as from my other large battery bank to increase the current. A bit too much at one stage but nothing serious happened!
We can see and explore why LiFePO4 is so easy to parallel and use. With the help of a sponge, I explain exactly what happens with these batteries and why LiFePO4 is safer and more forgiving than other chemistries.
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Пікірлер: 289

@kalon9999 5 ай бұрын

You know you've graduated from primary school to high school when you've watched Will Prowse and feel comfortable with all his content and start watching Off-Grid Garage and appreciate the depth of explanation of seriously complex concepts!

@jws3925 7 ай бұрын

You continue to explore the various characteristics of LifePo4 cells in a very scientific manner. There are lots of KZfaq channels doing things with this chemistry but I am not aware of anyone doing all the things you have taught us about this specific chemistry. I thank you, sir. I have learned so much from you.

@OffGridGarageAustralia 7 ай бұрын

Thanks a lot, my friend. I'm very happy to share all this with a great community.

@jimhanty8149 7 ай бұрын

You are by far the most thorough and logically detailed person online concerning solar stuff….I have learned a lot….thank you………..jim

@OffGridGarageAustralia 7 ай бұрын

Awesome, thank you!

@Zarinizarin 6 ай бұрын

Thank you Andy for the comprehensive reviews and analysis of the topics. I'm a professional electrician, recently I've also been dealing with solar systems and your videos are of great help to me. Thanks and greetings from Bulgaria!

@Adrian-foto 7 ай бұрын

I always love those dramatic moments of flipping up the cirtuit breaker whatever I do as well :D Greetings from Slovakia

@OffGridGarageAustralia 7 ай бұрын

Even I check everything several times and take all the measurements, it's an exciting moment. Especially in such large systems.

@kevinrtres 7 ай бұрын

Marvelous! Thank you very much for the lab experiments - so much appreciated! This is one reason why I went with LifeP04 from the start - and will actively discourage anyone from using plain Lithium batteries, especially since those are far more prone to dangerous activity.

@OffGridGarageAustralia 7 ай бұрын

Thank you. Yeah, LiFePO4 is pretty save and forgiving. Usually no high currents in these setups.

@gumpster6 7 ай бұрын

Another great informative video from the best solar/battery guy on YT. Thanks Andy!

@OffGridGarageAustralia 7 ай бұрын

Thanks so much😊

@AveRage_Joe 7 ай бұрын

Great explanation Andy! This should clear up any confusion people have when buying or using different batteries! Great Job!!

@alexanderwamuth6073 7 ай бұрын

The comparison with the sponges is ingenious. Thanks for this video. Kind regards from Germany.

@OffGridGarageAustralia 7 ай бұрын

Thankyou. I thought it would be easier to understand...

@samsuffit6229 7 ай бұрын

@@OffGridGarageAustralia Yes it is !!!

@krg038 7 ай бұрын

Great video Andy. I have 10 batteries now. I found using a buss bar vs parallel cables from one battery to another easier to ballance batteries. All JKBMS. Different AH batteries. Normal operation I stay around 80%. Maintenance now every week i take one battery one cell swap out for uohm testing and cell curve testing for my spread sheet. Even grade B cells operating fine. Thanks for your testing.

@OffGridGarageAustralia 7 ай бұрын

Thanks for sharing. Yeah, with 10 batteries in parallel, I would use a bus bar as well. You test one cell every week? I thought I was nerdy... 😁

@haneefacellonics7239 7 ай бұрын

I am from India.. ,,,I am regularly watching your video.. Very interesting..❤

@OffGridGarageAustralia 7 ай бұрын

Thanks a lot and welcome!

@haneefacellonics7239 7 ай бұрын

❤

@loganv0410 7 ай бұрын

Another Great hands-on test backed by fine science and engineering Keep it up!

@OffGridGarageAustralia 7 ай бұрын

Thank you.

@FutureSystem738 7 ай бұрын

Thanks Andy, as usual a great description! Cheers

@OffGridGarageAustralia 7 ай бұрын

Thanks, Dave.

@vmoutsop 7 ай бұрын

Love the doing analogy and that commercial is one of my favorites of all time

@OffGridGarageAustralia 7 ай бұрын

Mr, Dumass! I didn't know it until I searched for it😂

@vmoutsop 7 ай бұрын

@@OffGridGarageAustralia 😂

@meganote 7 ай бұрын

Great demonstration!

@OffGridGarageAustralia 7 ай бұрын

Thank you. A very frequently asked question.

@acinfla9615 7 ай бұрын

Great video Andy 👍 Thank you 😊

@nineteeneighty-four2142 7 ай бұрын

YESSS!! I love the sponge tests

@OffGridGarageAustralia 7 ай бұрын

Sponges are sexy!😂

@davidcassidy2944 7 ай бұрын

Its very reassuring to see a test done like this. Means you know that the batteries will cope. Just as long as it doesn't have a full time running active balancer. I'm thinking for mine of Seplos, with a Neey active balancer for the win.

@OffGridGarageAustralia 7 ай бұрын

You cannot go wrong with the NEEY!

@580guru 7 ай бұрын

Excellent video Andy! Have held off connecting my original well used LiFePo battery with the new one I built from new cells. Time to hook them up!

@OffGridGarageAustralia 7 ай бұрын

Yes, get them connected!

@drdos6718 7 ай бұрын

I recently built a 2nd bank of 16 x 280Ah cells and put them in parallel to the existing 3 year old bank of 16 x 280Ah cells. I have found that the older bank discharges at a faster rate than the new bank. Old will drop ~32%, the new one will drop ~18% overnight. The older bank also charges at a faster rate. They both reach the Absorb voltage at roughly the same time though, and charge tapers off to

@OffGridGarageAustralia 7 ай бұрын

@@drdos6718 thanks for sharing, that is quite a large difference between your two banks. It can only be internal resistance being very different...

@jdell6250 6 ай бұрын

Thanks for the lesson. 👍

@larrybell4599 7 ай бұрын

Thank you for sharing this experiment. I understand much more about lithium iron oxide batteries.

@OffGridGarageAustralia 7 ай бұрын

Great, thank you for the feedback.

@garys-half-baked-offgrid-dream 7 ай бұрын

Hang on a mo!!! Andy was that you I see burning a fossil fuel or was I still tripping??? You got your money's worth out of that sponge dear boy! Luv ya Gaz 🏴󠁧󠁢󠁳󠁣󠁴󠁿

@lkeil84 5 ай бұрын

Thanks so much for this active demonstration. I have thought in my head for some time now that this is exactly what would happen. I currently have 6ea Valence U27-12xp batteries in parallel and have had zero problems on the boat. Most will state to only put 4 in series or parralel at any time, but my 6 have worked just fine. I have purchased another 7 of these batteries to add to the bank and it has been suggested I have different charge controllers. Nonsense I thought, and hooked the all to the same buss bar with verying length of wire. Of course I made sure all the wires had the same resistance (small short ones and long large ones) as when starting a very large diesel engine, I need in excess of 1000 amps and need that balance under this high load. Now with the 13 batteries each capable of 300 amps output for 30 seconds, that should give me almost 4000 amps for engine starting, easy even with different resistance cables as long as they are close. Thanks again for confirming what I always thought was the case.

@michaputzt4933 7 ай бұрын

That's exactly what I like about your canal - you show what happens when... I can confirm it exactly like that... I'm currently building my PV system and have 2x280Ah batteries. I had one at SOC 100% and the other at SOC 40%, the voltages were the same except for 0.01V, so I could connect them in parallel. Unfortunately I'm currently missing the panels on the roof...😊

@OffGridGarageAustralia 7 ай бұрын

Thank you. Yeah, it's quite fascinating watching these batteries charge and discharge when they all have different capacities and also cable lengths.

@Techboxreview 7 ай бұрын

Very interesting. I was waiting for the KABOOM 😂👍

@griswa 2 ай бұрын

i live in Kyiv, UA, KABOOM is our reality now for 2+ yrs so if all my battery pack blows up - nobody gives a shit (( Love this oldman, cheers.

@typxxilps 7 ай бұрын

off grid garage - home of frankenstein battery and its relatives great video

@vinceelliott4362 7 ай бұрын

Nice work.

@dirk_p 7 ай бұрын

What a amazing Power storage, great

@OffGridGarageAustralia 7 ай бұрын

So good for testing. I can combine all sort of batteries and test it all out.

@Fattrucker 6 ай бұрын

Thank you so much for this . Over the years I've asked a number of experts this exact question. All of whom have looked at me as if I'm insane for wanting to mix capacities (of the same chemistry) . "I wouldn't if i were you" is the usual response , with no justification or reasoning why this would be so bad . No evidence, nada , nothing . You are the only person who has actually had the cojones to try , film and publish real world results . As an adendum to this test/demonstration i would be curious if there would be any detrimental effects to each battery over an extended period ? Thanks again Andy. Fattrucker

@OffGridGarageAustralia 6 ай бұрын

Thank s for your feedback. There is no downside of paralleling different capacities with LiFePO4. The voltages are all the same and batteries will balance against each other when fully charged/discharged.

@rcguymike 6 ай бұрын

Such an interesting analogy!

@OffGridGarageAustralia 6 ай бұрын

It's not 100% but roughly how it works.

@wayne8113 7 ай бұрын

Thanks Andy

@OffGridGarageAustralia 7 ай бұрын

Wayne, thank you!

@coolandrew951 7 ай бұрын

love your work

@OffGridGarageAustralia 7 ай бұрын

Thank you!

@bluddybignurk 7 ай бұрын

Maaate. I like your vids and your style.😁

@davidpatrick1813 7 ай бұрын

Groovy .. nice flick

@patrickmaartense7772 7 ай бұрын

I experienced this exactely like that with my 6x16KWH 300AH packs my packs have the Active balancers with voltage trigger set at 54.2 -53.5 works so nice...

@2flight 7 ай бұрын

very good. thank you!!!

@schunkelndedschunke6914 7 ай бұрын

Cant wait to see the video of the Gobel Power with the Neeeee balancer. Have one with the 5A active balancer and a 2nd in order, waiting for shipping.

@OffGridGarageAustralia 7 ай бұрын

I have received the NEEY already, just need to find the time to start the project...

@OneStepToEscape 7 ай бұрын

Very good as always, Andy! Nice to see the same game with discharging. It's interesting to figure out if the lowest capacity battery will be blocked by bms or all the batteries come to the bottom line at the same time 😮, it's a miracle 🎉)). It's really interesting from the current distribution point of view. cheers 🍻

@dougle03 7 ай бұрын

They will all get to charged or discharged state at the same time when in parallel...

@OffGridGarageAustralia 7 ай бұрын

Thank you. Yeah, that's is what I observed as well, regardless the capacity, all batteries will come to the same high SOC or low SOC pretty much at the same time.

@TheWhitik 7 ай бұрын

I’m missing something about that challenge with the active balancer. It stopped charging because one cell hit the 3.65 cutoff. Shouldn’t the active balancer drain off some of that energy and distribute it to the other cells? Lowering the voltage of that cell and allowing it to start charging again.

@krg038 7 ай бұрын

Depending on the charge cutoff the bms will stop charge at the max cell voltage. The highest cell will balance the lowest cell. When the highest cell voltage drops below the setpoint, the charge will turn on.

@evil17 7 ай бұрын

Great explanation, experimentation & analogy with Sponge Bob Andy, it was good to see this done with ur nice big battery setup, but no surprises here after watching ur old videos way back using the Palo cells & bigger batteries when u were in ur early testing phases & a bit of my own experimentation on this. Like to see this again with ur Seplos setup, maybe try 30, 60, 90% SOC or a 10, 50, 90% SOC test & see how they vary. Love ur scientific approach & logic. Cheers

@OffGridGarageAustralia 7 ай бұрын

Thanks 👍 Yeah, I'll repeat the test at some stage. The current will increase slightly when we leave the flat part of the curve and go 10% or 90%. Still, it is not a drama as I have done this with my battery shelf several times. LFP for the win.

@RichardSteigmann 7 ай бұрын

Very nice explanation with Spongebob 😅

@ML-hf6ii Ай бұрын

0:04 oh lord, I'm hungry now!

@OffGridGarageAustralia Ай бұрын

Same here...

@finfin82 7 ай бұрын

The best video showing that communication between the batteries and at least inverter doesn't matter anyway! Thank you very much! ❤

@dougle03 7 ай бұрын

Inverters like to 'talk' to batteries, but it's not technically needed, although some inverters won't 'invert' if they can't 'see' the battery BMS data... No good reason for it...

@OffGridGarageAustralia 7 ай бұрын

I will parallel all batteries I have at some stage without any communication. As we have seen from the battery shelf long-term experiment, coms is not needed. The BMS take care of their individual battery just fine...

@finfin82 7 ай бұрын

@@OffGridGarageAustralia im preaching this since I got it thanks to you experiments... No one is believing me without your proof videos... I guess now they see. Everybody is hardly trying to get the bms talking to their inverter and doesn't know why 😅

@GapRecordingsNamibia 7 ай бұрын

@@finfin82 Technically no, comms is not needed, in a very crude manner you can just set a "cutoff" voltage in the inverter..... But, my question then to you is. How do you know what the SOC of your battery is? Otherwise, what would set your very expensive home inverter system apart from a car battery and and a 12V inverter?.....

@finfin82 7 ай бұрын

@@GapRecordingsNamibia well, do i need to know the SoC? it wouldnt change if i do? im reading the battery-stats with a small nmc and build my own grafana graphs, but actually when the bat is full enough it is used if not, its not... so what? all smart stuff like if the bat is full in morning and the day will give me sunshine i handle in nodered with readed stuff and having the option to suck the rest out of the battery... no inverter communication would help there either?!

@user-dc1kd6ye5c 7 ай бұрын

Excellent video Andy. Suggestion: Could you show the real time results with the same system, this time testing the impact on batteries with less capacity while connected to batteries with more capacity. What is the best approach to limiting the discharge on the smaller capacity batteries with this type of arrangement?

@OffGridGarageAustralia 7 ай бұрын

I have a video where I paralleled a 5Ah 12V battery with a 300Ah 12V battery and showed everything in real time. That may already help? kzfaq.info/get/bejne/nLeqatmLqr-wlo0.html

@MrBellda 7 ай бұрын

Nice....

@zisaurierzisaurier9286 7 ай бұрын

Great

@picobyte 7 ай бұрын

It doesn't matter. Hello! From the Netherlands 😁

@OffGridGarageAustralia 7 ай бұрын

Hello! 👋

@deepu083 7 ай бұрын

Super my buddy

@OffGridGarageAustralia 7 ай бұрын

🥈silver for you

@Dutch_off_grid_homesteading 5 ай бұрын

Heya, because the flet charge curf of LiFiPo4 is differant then lion ( 18650 ) we have to charge differantly and LiFiPo4 holds lot's of high Ah you need an active balancer with some nice amp's balancing current but the active balancer only start balancing in the high end of the CC. that's what I have learned from all the test's that you have done. thanks for that and all the hours of enterteanment.

@domoledlight 6 ай бұрын

Thank a lot for this video i have learn so much. I have a question about lithium battery. I have dev a pcb for a gps tracking that auto cut off when power goes down and switch to battery witch are 2 lithium cell in parralell can i add a passive balancer to each cell

@stephenleclair5133 7 ай бұрын

Hola, I would like to see this same test but with parralle brass bar each side of battery pack instead of cable from top to bottom. I love this show !

@GapRecordingsNamibia 7 ай бұрын

There is no way to do this with packs that do not have the same pole/ terminal spacing....... That is why he used cables.... if all the batteries are the same make and model this is doable, otherwise not.

@OffGridGarageAustralia 7 ай бұрын

What do you expect from brass connections instead of the cables I used?

@ThePetervangils 7 ай бұрын

Hi Andy, nice video (again). Suggestion for an experiment: how does parasitic resistence affect the load on 2 (identical) parallel batteries. E.g. 2 batteries in parrallel where 1 pack gets longer cables and/or additional connectors. My expectation is that the pack with the lowest parasitic resistence, will see the biggest load (= delta in SoC). But how much? Is it significant? Would it wear out one pack significantly faster than the other pack?

@OffGridGarageAustralia 7 ай бұрын

Yes, that's a good experiment as well. I have many batteries connected with different cable lengths and it is very interesting to watch what is happening during charging and discharging. I'll put your suggestion on my list. Thanks.

@aidendeem903 7 ай бұрын

Thanks Andy. Will an active balancer that is always on unbalance the battery if the battery is sitting for weeks at full state of charge?

@OffGridGarageAustralia 7 ай бұрын

Not at full SOC, no. This is the time to balance so that's not causing any issues. the problem is when the cells go back in the flat part of the curves and you would balance there, so below 3.35V. This causes the problems if the balancer is on. But, you should not leave the battery fully charged for several weeks. That's really unhealthy.

@9111logic 7 ай бұрын

Nice one Andy, thank you for sharing this experience🙏 I'm planning to mix at least two types of batteries and I'm glad to see, from your test, exactly what I would expect to see. My mix is going to be a little extreme as I have one 5.12Kvh and one just under 16kWh. PS) Yes, the Zketech 40A is a must and I'm glad to have it as part of my test equipment.

@OffGridGarageAustralia 7 ай бұрын

Thanks. That should be no problem connecting the 5.1kWh with the 16kWh battery. Exactly what I had here in the test.

@germo35 7 ай бұрын

Please! Nobel prize to Andy for sharing knowledge around the world!

@OffGridGarageAustralia 7 ай бұрын

Hahaha, thank you. I'm happy with a S.P.A.T. here and there 🍺

@teeca2 6 ай бұрын

What bms do you recommend with lifepo? Have a griwatt 12kw off grid split phase inverter and a 16s 2 parrell 3.2-48v lifepo pack, having lots of trouble keeping the cells balanced

@giollaliddy5817 7 ай бұрын

I have the seplos 2a active balancer on the way. do you have any plans to do video on it? also are all the 16s connectors interchangable between active balancers? so for example could the wire harness (from gobelpower) fit the neey balancer? so you dwouldnt thave to take apart the battery to change balancer

@MrSpliffsta 7 ай бұрын

Is it perhaps possible to connect 2 several bms? Pace and seplos?

@kswis 7 ай бұрын

On your way to a will in Las Vegas sized collection of battery backup!

@vyore 5 ай бұрын

Can you do this with different BMS example a Pace and a Seplos?

@paulcurtis5496 7 ай бұрын

Like# 397 - no notification again!

@jackoneil3933 7 ай бұрын

Good info Andy, Thanks! It might be interesting to charge the Tesla using those packs at high discharge rate and see how well the discharge balance holds, as I've seen discharge imbalances when paralleling 300wah & 600wah LFE ebike packs, sometimes with one or another pack randomly cutting off on low voltage protection about 10% before the rest, and I suspect it may have something to do with charge imbalance that was not apparent. Otherwise, The pretty much replicates what I've been observing parallel charging different capaticy LFE packs (300wah and 600wah). I've also been testing a single 300wah 48V Li-Ion pack Paralleled with 2 parallel 48V 300wah 32700 LFE (Lithium Iron Phospate) packs charging to 54.6,V and they balance charge very evenly. However, the lithium Ion pack does reach the same cut-off voltage before the LFE packs.

@dougle03 7 ай бұрын

Presume the Tesla feed would need to go to AC first, thus inverter capacity would be the limiter... Fast charge Tesla is 480vdc so would need some battery reconfiguration...

@jackoneil3933 7 ай бұрын

@@dougle03 Andy has a 220v home charger for his Tesla and uses one of his Solar inverters to charge it, essentially using it as a load bank.

@OffGridGarageAustralia 7 ай бұрын

Yes, Tesla AC charging. I can do 16A AC charging (3.7kW max) with my setup. The batteries should not shut down as they all come down to low voltage at the same time. Pretty much the same as we saw charging them, just the other way around. Once one BMS shuts down, it goes quick and the others usually follow soon after. In a good battery design, the Inverter should shut down before we get to such a low voltage so, the BMS are really your last resort.

@Lulastyle 7 ай бұрын

Hi Andy, I would like to ask you for advice, I have a 200ah Victron battery on my camper, I would like to add a second battery but the Victron battery is very expensive, according to your tests can I add a different battery by placing it in parallel? Thank you

@OffGridGarageAustralia 7 ай бұрын

Yes, you can parallel any battery with the same voltage and cell chemistry as long as all BMS have their own individual BMS.

@scooter6334 7 ай бұрын

Will this work if you don’t have batteries with BMS’s that can be set at a certain cutoff charge?

@user-dq2mp8fe1k 7 ай бұрын

Based on your testing, which BMS do you recommend as the most stable/durable for a hybrid system. (S16-2P, 100A) I have been testing Daly (with Daly active load balancer and parallel board. The Calls are 138Ah BYD blade cells. Set up is S16-2p. 2 battery packs in parallel. the BMSs work well for a few months but then start losing connecting with one or more cells, showing those particular cell"s" at lower voltage than they real are, Which in turn end up damaging the cell"s".

@OffGridGarageAustralia 7 ай бұрын

The new JK-BMS is just at the doorstep, so probably wait for the test results. That would get my recommendation.

@launacorp 7 ай бұрын

Haven't we already done a test like this?

@OffGridGarageAustralia 7 ай бұрын

No, not on this channel. And even if so, there are always new viewers ...

@douglasmarquis3446 7 ай бұрын

Great test, would it make any difference if you connect the charging cables diagonal. Positive on bottom battery and negitive on the top battery ? That is the way that Victron recommends connecting parallel batteries.

@furyjk98 7 ай бұрын

That would become a series connection, and the voltage will increase. 51.2+51.2 = 102.4V

@ThePetervangils 7 ай бұрын

@@furyjk98, I think Douglas means that the top pack sees more parasitic resistence of the cables than the bottom packs. By connecting e.g. the positive to the top pack and the negative to the bottom pack (= diagonal), the parasitic resistence is more evenly spread across the packs.

@douglasmarquis3446 7 ай бұрын

Thanks you are correct and you understands what I was trying to explain,@@ThePetervangils

@OffGridGarageAustralia 7 ай бұрын

I have my battery shelf just connected from the top and did not run the negative cable all the way down just to connect it to the busbar there. I have also done the same with the Seplos Polo batteries and the aluminium busbar I installed at the back. I feed this form the top. Theoretically, the top battery sees a bit of a higher voltage while charging and a lower voltage while discharging than the other batteries. From my experience this difference is so small though that it would not matter much. In larger installations (maybe 6+ batteries in parallel) and much higher charge and discharge currents I would connected them across as well.

@gregbell4951 7 ай бұрын

Great Test, I connected 6 Large Capacitors in parallel with 4x 18650 batteries to make 12v jumper battery. I hope it works!

@universeisundernoobligatio3283 7 ай бұрын

Use 6 3000F super caps in series no batteries required.

@kevinrtres 7 ай бұрын

@@universeisundernoobligatio3283...at great expense of course....

@dougle03 7 ай бұрын

Energy needs to come from somewhere...@@universeisundernoobligatio3283

@OffGridGarageAustralia 7 ай бұрын

I have LTO batteries here someone send me. He had them as a 12V starter battery connected.

@gregbell4951 7 ай бұрын

If LTO batteries were as cheap as Lipo4 batteries, I'd build big bank of them.

@giollaliddy5817 7 ай бұрын

you have them daisy chained in parallel. In theory is it ecaxtly the same if they are in parallel via centralised busbar? same results?

@Alicecocoz Ай бұрын

Hi Sir, for the Gobel battery which had an OVP, is the capacity truly 100% or did it jump from a certain percentage (say 85%) to 100% when it hit the OVP? Thus the 292 AH reading isn't accurate anymore?

@amazingtechnology1961 7 ай бұрын

21:18 I haven’t heard any comments regarding this high current to the third battery. Why is that?

@martinstastny9981 7 ай бұрын

Is it possible also paralel blue cells baterie lifepo?

@bjoernkellermann3288 7 ай бұрын

Hi, you are connecting and disconnecting a lot of batteries. Maybe using forklift battery connectors might ease your work. They are available as 80, 169, 320 and 640 amps as a standard. Thanks for your great video! BR Björn

@OffGridGarageAustralia 7 ай бұрын

Thank you, Bjoern. I will need to look at something better in the future, definitely. I have some upgrade to to for this area anyway. It is really just a temporary setup.

@launacorp 7 ай бұрын

GsD hab ich grade nen Teller Gulash vor mir stehen beim starten des Videos🤣 I just have a plate of Gulash in front of me when starting the video 🤣

@OffGridGarageAustralia 7 ай бұрын

Nice, thanks for sharing 😁

@galen__ 7 ай бұрын

👍

@MRB0101 7 ай бұрын

Very interesting. The question that comes to mind now is how the discharge SOC will be managed ? When discharging, the smaller batteries will discharge faster, as they have less charge stored. So how do you manage the batteries not going below 15% SOC, as the smaller ones will reach this before the larger batteries ? Can the BMS be configured to manage the cut-off SOC for each battery independently ?

@dougle03 7 ай бұрын

All parallel batteries will discharge over the same time period, i'e their SOC will be aligned.

@OffGridGarageAustralia 7 ай бұрын

The batteries with the smaller capacity will discharge slower as they have a higher resistance than the ones with higher capacity. Watch this video here with a 5Ah and 300Ah battery in parallel: kzfaq.info/get/bejne/nLeqatmLqr-wlo0.html

@MRB0101 7 ай бұрын

Not the case, please don't reply if you are not qualified to answer the question.@@dougle03

@Pimpasxx 6 ай бұрын

Bottom batery voltage is 0.6v different. Internal resistance of the battery is abour 5miliohms. 0.6v/0.005=120A . You got very high resistance in connections. I'd remeber i connected 2 my batteries in parallel with the 2 thick bars between. Difference vas 0.2v or so... The current was about 30A

@haneefacellonics7239 7 ай бұрын

❤

@bascomnextion5639 7 ай бұрын

Andy have you a hazard warning sign on your garage with all those batteries ?

@OffGridGarageAustralia 7 ай бұрын

Yes, of course.

@billing100 7 ай бұрын

have you got any sodium batteries for testing? (CAL)

@OffGridGarageAustralia 7 ай бұрын

Yes

@TidalShemtov 7 ай бұрын

Does discharging work similarly in reverse, i.e., taking from the higher capacity battery until the Ah of all batteries reach the same Ah then discharges from all batteries equally?

@OffGridGarageAustralia 7 ай бұрын

Yes, it works exactly the same just in reverse.

@TidalShemtov 7 ай бұрын

@@OffGridGarageAustralia Thanks, Andy.

@scrapyardwars 7 ай бұрын

I am thinking those new to solar may be wondering what they can safely do with mixed batteries. Many battery assemblers I use assemblers as often battery's in cases are repacked and rebranded from manufacturer originals and it's not made clear. An example here in the UK is the jakki rebranded by a UK company as Fogstar. These batteries come with a warning only use with other fogstar batteries or words to that effect. So as an owner of 6 parallel connected batteries of the same make and thinking about adding another parallel set of another manufacturer ehat should I be worried about? Anything other than maximum inverter charge and discharge.

@OffGridGarageAustralia 7 ай бұрын

As long as the voltage and cell count is the same, you can safely connect other brands of batteries to your existing ones. You just cannot mix 15s and 16s batteries for example.

@todamnbad 7 ай бұрын

What would you say about using rack mount batteries wired with drop in style lifepo4 batteries? I have some 48 volt rack and several 12 volt drop ins and would like to use the drop ins in my system, only problem I see is that the 12 volt drop ins have a PCM (protection circuit module) instead of a BMS

@OffGridGarageAustralia 7 ай бұрын

Yeah, probably don't do that. You also need to find out if the 12V batteries can be connected in series with such a PCM and can withstand the higher voltage in case one turns of.

@todamnbad 7 ай бұрын

@@OffGridGarageAustralia my thoughts to but figured another expert opinion couldn't hurt.

@royamberg9177 7 ай бұрын

sponges oh my did they swell up

@OffGridGarageAustralia 7 ай бұрын

They don't, mate, they don't 😂

@fox156 7 ай бұрын

Does this video mean thatt its not necessary for me to balance my lifepo4 cells with a power supply before connecting them to my overkill brand bms?

@OffGridGarageAustralia 7 ай бұрын

You should still top balance your single cells to ensure they run optimally as a pack.

@millzee60 7 ай бұрын

I think many of your viewers, including myself, have learned a lot from your videos. Yet many uninformed/uninterested people don't know the difference between the lithium iron phosphate cells and nickel manganese cobalt cells. They regard them as the same as they are both lithium and are wary of them because of the bad press li-ion has received. You have a shed load (literally) of LifePO4 batteries and was wondering if you ever have concerns over safety? Other than doing something silly with them.

@OffGridGarageAustralia 7 ай бұрын

Yeah, both lithium but both very different. No safety concerns, it's all very safe with the place locked when I'm not home. And it's like 60m away from the house, so...

@GapRecordingsNamibia 7 ай бұрын

I can't wait to see the internet engineers comments....

@OffGridGarageAustralia 7 ай бұрын

I'm here for the comments! 😂

@freibuis Ай бұрын

question.. because both of the terminals are connected to the bottom shelf.. wouldnt that mean that there is a greater load on it. it would be getting worn faster? wouldlnt it be better to connect the postive to the bottom battery and the negative to the top battery? spread the load? or am I seeing this wrong?

@GeekFreak007 Ай бұрын

Imma follow this question, because I also have this exact same connection where my battery capacities are different. I want to make sure I connected it right too. Will it be better to have the positive line connected at the larger capacity battery or just the same?

@Samerlifepo4 6 ай бұрын

❤❤❤❤❤

@DanielRichards644 9 күн бұрын

So the TL;DR is if you want to add a second or more batteries to your existing system it doesn't matter the current state of charge, they will eventually balance out

@Tezza66 7 ай бұрын

As I have said many times before. No issues or spikes what so ever.

@georgmuse 7 ай бұрын

Does this means I can connect my two batteries 200Ah and 100Ah in parallel and use them as one 300Ah battery permanently? I wanted to try, but wouldn't like to damage something..

@zoe..d 7 ай бұрын

Exactly correct. Enjoy your growing power bank :)

@OffGridGarageAustralia 7 ай бұрын

Makes sure every battery has its own BMS and circuit breaker. They also need to have the same voltage, cell count and chemistry. Example, 51.2V, 16s, LiFePO4

@swolath 7 ай бұрын

I have a 14s 100p 18650 setup, I would like to add 16s 1p 280AH. Put the 18650 in a steel box outside the shed and hope for the best. What would be your predictions? I would guess that the 280AH cells would discharge first and then the 18650 second as a backup? Lets see that experiment. LOL Ps Love all your videos.

@OffGridGarageAustralia 7 ай бұрын

Be very careful. I don't like different chemistries being matched with these batteries. Looking at the different curves between Li-ion and LFP, my prediction would be that the Li-ion battery will follow the charge/discharge curve of the LFP battery. You will never fully charge the Li-ion battery and never fully discharge it either (unless you go really high and low with the voltage and wait for the LFP BMS to shut down).

@leesaville1284 7 ай бұрын

With all that free power from the sun you could use a induction cooktop to cook your eggs

@OffGridGarageAustralia 7 ай бұрын

I'm in the process of replacing the BBQ with an electric one.

@rhp20001 7 ай бұрын

Seems the 1st battery has reduced it's capacity, though it shows SOC as 100%, FCC and RM shows 91.7 AH. Looks like BMS prob to me.

@OffGridGarageAustralia 7 ай бұрын

That's just a calculation of the BMS. It has nothing to do with the real SOH. I have done a lot of testing with these batteries and BMS including disconnecting the BMS sot he calculation is off until they are calibrated again. They should not show this number anywhere as people may freak out 😉

@cooltrkin 7 ай бұрын

Would it do the same? If the biggest ah batteries are at the lower state of charge from the beginning?

@RandomNoob 7 ай бұрын

It makes no difference what the SOC is they will alwasys charge normally to 100% the only difference is the highest capacity will take the majority of the power.

@GapRecordingsNamibia 7 ай бұрын

Exactly what ☝this person said.. The pack with the lowest SOC at that time will sink the most current..... The pack with the biggest AH rating will take the longest to charge and will take the most energy to "fill up", where as the smaller the AH rating the faster it will charge. But, in the end they should all equal out at "100%" SOC.

@DanBurgaud 7 ай бұрын

Personally, SOC% is not important; what is important is the small voltage delta. 3:00 min 20% SOC, max 80% SOC... hmmm. well since these all have PACE BMS with charge current limit circuit, it is definitely OK to parallel them even when one of them is 100% SOC, while the others are at 0% - because there is a charge current limit circuit. However those other BMSes in the battery 2.0 without charge current limit circuit, its gonna be xxxxx. PS: Charge Current Limit and Over Current Protection circuits are not same. The latter stops charging when over current, the former limits the charge current when a threshold is reached.

@dougle03 7 ай бұрын

The BMS will cut off charging if the current exceeds allowed, there is no moderation of the current by each BMS...

@OffGridGarageAustralia 7 ай бұрын

Yes, the Pace and Seplos BMS have current limiter, so it keeps them save. As we saw, there was only a mere 30A between the 80% and 20% battery. However, I have done this a few times with my battery shelf as well and if the current gets too high, the BMS will simply disconnect the battery, wait a moment and tries again. It may do this a few times until the voltage has equalized and the current is below the protection settings.

@chrisroyle4813 7 ай бұрын

Could the BMSs be connected in any meaningful way in this configuration to an inverter ?

@dougle03 7 ай бұрын

Better of using a single shunt to feed the inverter with information (Battery voltage, SOC). So long as the total battery capacity is properly set there would be no reason for the inverter to 'see' all of the batteries....

@OffGridGarageAustralia 7 ай бұрын

What would be a meaningful way in your terms? There are some (small) benefits in having the BMS talkig to the inverter, but as the other viewer suggested, get a shunt in front of all your batteries and forget about the communication to the inverter. Unless you have a super large system, it's not really a huge benefit.

@chrisroyle4813 7 ай бұрын

Thanks Andy - I suppose I'm trying to get my head around whether/how to mix two SunSynk 5.3kWh LifePO4s with a Seplos Mason 280L DIY kit in the future - I think you've covered how to use Victron kit in the past as a simpler more compact solution than your shelf bank, so I'll re-watch those videos when the time comes. I would then probably add SolarAssistant for monitoring battery packs as well as for controlling the SunSynk inverter.

@ernestkooistra1559 7 ай бұрын

✌

@zingzing6550 6 ай бұрын

Hmmm... This should mean that I would be able to parallell connect my 48 V 5 kWh lifepo4 with my 48 V 10 kWh lifepo4. Getting a total of 15 kWh of energy. Correct?