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Mecer LiFePO4 Lithium Ion Batteries: Any experience


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5 hours ago, lyndiesel said:

My question is  - with the built in BMS system in the batteries - am I correct in understanding that there will be no physical BMS connecting data cable to the inverter - other than the charging / load cables?

Hello @lyndiesel You're right, there'll be no comms between the battery and the inverter. The more experienced members of this forum might be able to share some workarounds that you might want to explore since electronics is your forte :)

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On 2021/04/22 at 3:05 PM, Rooney Hat said:

Absolutely something to consider,

But would have to pay around 40k to get to 8.something kwh 80% DOD in Lithium,

or just spend 20k to double AGM capacity from 4 to 8 200ah. getting me a total of 19.6 (9.8kwh with 50% DOD) with the idea that I wouldn't use that amount every night thus extending the battery life of all. Provided they don't fail me.

I wouldn't spend any more on AGM :)

Once these fail - look at a lithium option.

One thing not mentioned before (seems there's only negatives at this point with AGM) is mixing different aged AGMs is not recommended. So if 1 of your pack of 4 breaks 6 months from now  - it's replacing it with a single new one is not recommended - this is as far as I remember from all the "experts" a few years ago. Maybe 6 months is not accurate, but rather after a good number of cycles - don't know what exactly, but the internet should be able to advise. Lithium has no such issue - you can add an additional pack any time -as the electronics take care of any cell differences etc.

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8 minutes ago, Igubu said:

I wouldn't spend any more on AGM :)

Once these fail - look at a lithium option.

One thing not mentioned before (seems there's only negatives at this point with AGM) is mixing different aged AGMs is not recommended. So if 1 of your pack of 4 breaks 6 months from now  - it's replacing it with a single new one is not recommended - this is as far as I remember from all the "experts" a few years ago. Maybe 6 months is not accurate, but rather after a good number of cycles - don't know what exactly, but the internet should be able to advise. Lithium has no such issue - you can add an additional pack any time -as the electronics take care of any cell differences etc.

Just had this very discussion with my brother earlier today. I'm happy to see that I'm learning a lot from these streets 😃

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7 hours ago, lyndiesel said:

Hi guys, I have a strong background in electronics, but pretty new to Lithium battery technology - especially BMS systems and CAN system link ups. I am about to set up a Sunsynk inverter system in a week or so - and an installer has suggested these Vision/Mecer Lithiums as a 10kW battery option - 4 x 12V 200Amp items in series.

My question is  - with the built in BMS system in the batteries - am I correct in understanding that there will be no physical BMS connecting data cable to the inverter - other than the charging / load cables?

The inverter has a pretty decent BMS built in - but worried about how well the inverter can estimate the SOC of this battery bank? will it do so on the voltage/current flow alone?

Thanks

Lyndon

Hi Lyndon,

As always check with the manufacturer on their advise, but only if they are experts with Lithium (LifePO4 in your case) as a technology. It is very different to LAcid batteries, units like yours should not require any balancing. I'd be careful to just connect them in parallel to self balance - in some cases you risk damage to the "unintelligent" BMS'es inside.

If you were ordering individual cells for a DIY build, then an initial balance could help a little, but it's more for capacity check etc - here a link to a well respected guy who explains a little bit about it. - Note this relates to DIY specifically.

What you can do - use a multi meter, DC of course to handle 14+V and measure the individual batteries to see if they are close to each other. If they are - just get them connected on your inverter, and run it a few cycles like that. Then disconnect them and measure individually again  - they should be very close to each other, as the BMS inside controls charge/discharge.

If one of your pack is way out (not sure if you have 2 or 4) I'd charge that up with a Lifepo4 charger first. You mention you don't have one - so perhaps a good idea to get one (think Victron sells a good one for not to much -you don't need high Amps - 5 - 10Amps or so are more than enough) - and charge them individually and then connect them up.

Make sure you have a high enough rated  DC disconnect/ Fuse box for total Amps between them and the inverter. ( both negative and positive) - If you are paralleling 4x of these, a buzz bar might be needed to avoid them fighting with each other, but check with the supplier. As explained previously - these batteries don't usually have smart BMS systems inside, so they don't know about master/slaves in a pack, and doesn't talk intelligently to each other.

 

 

Edited by Igubu
Buzz Bar
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2 hours ago, nembudziya said:

Hello @lyndiesel You're right, there'll be no comms between the battery and the inverter. The more experienced members of this forum might be able to share some workarounds that you might want to explore since electronics is your forte :)

Correct - no CAN/RS485. On your inverter these will be setup as "AGM" - and some settings around charge rates, discharge rate, V settings for full etc - and also some things to disabled as well which were needed for LAcid - but not for lithium. Again the supplier should be able to give you all the settings, or at least the solar installer.

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On 2021/04/29 at 12:35 PM, lyndiesel said:

My question is  - with the built in BMS system in the batteries - am I correct in understanding that there will be no physical BMS connecting data cable to the inverter - other than the charging / load cables?

The inverter has a pretty decent BMS built in - but worried about how well the inverter can estimate the SOC of this battery bank? will it do so on the voltage/current flow alone?

I would seriously consider spending more money for a battery with effective comms to the inverter. These Mecer units have no easy way to access the cell voltages etc so you are quite limited in the extra control you can add. Unless you're going full DIY with your own BMS, I think you're getting your money's worth on proper comms.

As you hinted at, the "BMS" on the inverter just looks at total voltage of the batteries in series. No individual cells or even individual banks. No way of knowing actual SOC, which is critical for best optimization of battery life/utility. I originally ran my battery like this but quickly developed a DIY solution for comms because I saw how inefficient it was. Fine if it's just backup, but painful for everyday cycling.

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On 2021/04/27 at 11:23 PM, nembudziya said:

For some context, I'm a newbie (you probably know this if you've been following this thread) without any fancy equipment at my disposal. So I have no special LiFePO4 charger lying around to assist with top balancing. So I was thinking that parallel connecting them might help with balancing them out before the inverter can charge them after installation. Any thoughts would be much appreciated.

I would hook each 12V battery up seperately to a normal car battery charger (assuming you have access to one) and charge each to max voltage (13.8V?) - just need to watch it doesn't over charge as some cheap batteries chargers are prone to doing! This way you know all of them are close to fully charged before putting them all in series. This is called top balancing.

Parallel connecting only works when you are actively charging them. It is an option here as well if you have a big enough car battery charger. Ideally you want to charge at greater than 5% C-rating. So here you have 200Ah batteries, so charging at 10A (200 x 0.05). But if you have 4 in parallel, you now need 4x10A=40A charging. Not easy to get a car battery charger doing that... (read expensive...)

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14 minutes ago, JaseZA said:

I would seriously consider spending more money for a battery with effective comms to the inverter. These Mecer units have no easy way to access the cell voltages etc so you are quite limited in the extra control you can add. Unless you're going full DIY with your own BMS, I think you're getting your money's worth on proper comms.

As you hinted at, the "BMS" on the inverter just looks at total voltage of the batteries in series. No individual cells or even individual banks. No way of knowing actual SOC, which is critical for best optimization of battery life/utility. I originally ran my battery like this but quickly developed a DIY solution for comms because I saw how inefficient it was. Fine if it's just backup, but painful for everyday cycling.

Tried to explain the advantages of proper CAN, etc a few times, but yet people continue to buy cheap lithium based purely on advertised capacity :) in this instance they were bought already, so just giving some pointers.

I’d be very hesitant to stick an old car charger onto them- easy to damage (and the warranty will be void Im sure)- so dont think there is any need to top balance them- just follow the advice given previously around making sure each individual 12V pack are more or less the same V. They are brand new - and should be balanced already, different pack voltages are fine, the individual BMS will sort that out if they are relatively close to each other.

 

Edited by Igubu
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Posted (edited)
On 2021/04/30 at 1:05 PM, Igubu said:

They are brand new - and should be balanced already, different pack voltages are fine, the individual BMS will sort that out if they are relatively close to each other.

The installer came today and seems this was just about right. He recommended using the AGM setting on the inverter and I wasn't sure if that was right but he's the "expert" so I was kinda stuck. Any thoughts?

IMG-20210502-WA0013.jpeg

Vision SP 12-200 LiFeP04 User Manual.pdf

Edited by nembudziya
Added battery manual
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Hi guys

 

New to this, so please excuse me. Looking at getting the an 200ah Mecer battery and pair it with inverter/charger I have at home already. The only info that I have on it is that it is a 1000w 12V Sky King Pure sine wave inverter, not sure what rate it charges at. Will the BMS look after the battery and prevent over charge? 

 

Any risk leaving it plug in permanently on charge in case of loadshedding?

 

I would also like to add a solar panel and charge controller (MTTP) to the system to go off-grid with my TV, sound and modem. Would a 400w - 500w panel be sufficient?

 

Any help will be appreciated.

 

Thanks

Jacques 

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  • 3 weeks later...
On 2021/05/02 at 8:45 PM, nembudziya said:

 

IMG-20210502-WA0013.jpeg

Hello everyone just thought to post an update on the 3kVa/24V backup system that I've been working on.

Last week the power utility informed us that they would be working on our power line and we would be switched off the grid from 7am on Monday (24 May 2021) to Tuesday (25 May 2021) at 4pm.

They switched us off at about 11:40am on Monday and power was only restored for a few minutes this afternoon (Thursday 27 May 2021).

During that time, with regulated usage of our fridge and freezer, we were able to run our lights, power laptops and charge phones from 11:40am on Monday up to approximately 3pm on Wednesday. 

By regulated usage of our fridge and freezer I mean we ran them for about 4 hours on battery power on Monday and 5 hours on Tuesday (3 in the morning, 2 in the late afternoon).

As for the inverter settings, the cutoff voltage is 24V and following the advise of someone on this forum we used the following battery settings:

Battery type: USER

Settings 26: 27.6V

Setting 27: 26.8V

Hopefully I'll be able to add PV power soon and that should save us the frustrations of dealing with poor service from the utility.

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  • 2 weeks later...

Hi

 

Thanks for the advice and knowledge shared on here, I'm pretty much sold on the Vision 200ah battery paired with my existing RCT Axpert 1kv/12v, problem is finding stock - anyone perhaps know of a shop in GP that's got stock?

Mecer seems to be plentiful, but I feel it could be limiting if I ever decide to go 24v, or add a 2nd in parallel. That being said, stage 4 load shedding may force my hand into settling for the Mecer.

 

Thanks

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So the opportunity finally came to test a theory - does the Mecer have pouch cells or hardcase cells and what exactly is inside?? I managed to get a set of 4 almost new ones for a good price off the forum - two went to my brother for his small home backup system and the other two were for me to look at and hopefully integrate into my DIY battery.

Getting the pack open isn't too hard but not particularly fun. Lots of prying with plastic trim removal tools and slowly pulling on the glued on lid eventually got it off. This is what it looks like inside:

image.thumb.png.22810f2d1d9420e82be495e443ca28f4.png

Honestly, I was a bit disappointed as it was immediately obvious it was some form of pouch cell and not the hard cased prismatic cells I'd hoped for. But as I looked closer I was rather impressed with the build quality. Everything was well secured and held together. Good insulation used and decently beefy cables. I liked that the cells were away from all sides giving extra protection. Opening the top of the insulated inner box revealed the BMS:

image.png.6da38059603f44c06e71eaaa0d0e4422.png

image.png.c4835a68cab7564f2734e26d5323ad60.png

Looking from the side I could now see how the battery was put together - 8 x 100ah pouch cells stacked on top of each other in pairs - each pair flipped to connect in series with the next pair. Nice strong connections between cells and proper balance leads to each pair. Even a temperature sensor!

image.thumb.png.36cedbe068b646d14b7187ade47d67e9.png

I checked the balance between the cells and with this battery close to fully charged I had exactly 3.401V on each cell! Very impressive! BMS looks beefy as well with decent soldering and connections. I guess heat might be the only concern in a sealed battery like this but there's a decent bit of metal to dissipate it.

I'm now quite undecided on what I want to do with my setup. I'm much less keen on mixing my hard case 100ah cells with these pouch cells. So I could just put it back together and sell it on and stick with what I have. The other option is to try and find two more and create one big 48V 10kwh battery with new BMS and then retire my old bank... decisions decisions 😅

I haven't closed it up yet, if anyone has any requests or questions about it.

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2 hours ago, JaseZA said:

So the opportunity finally came to test a theory - does the Mecer have pouch cells or hardcase cells and what exactly is inside??

I was waiting for this experiment 🧪 🥼

Props to you @JaseZA for answering the question for the rest of us :)

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For those interested- here a picture of a newer generation of this: (not my pic so apologies quality)

image.thumb.png.18c9b5589bb3f398ea725461f5980c63.png

Little bit of info some might find surprising: the Pylons also have pouch cells :) afain…

I wouldnt mix pouch and prismatics..

perhaps reach out to Hubble and ask them about their s-100 version - what’s inside.. 

 

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33 minutes ago, Igubu said:

For those interested- here a picture of a newer generation of this

Ah, now that's what I was hoping to find! Which battery is this? Any way of telling if a battery will be like this inside? My Mecers were about 8 months old, so it would have to have been a recent change!

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The picture was from a very different vendor (not mecer or vision) - like was mentioned there are around 20 variants in the market- impossible to know whats inside unless rhey are manufactured - and these guys designed and had them built like this- much better :) 

I’ll try and find out from the guys at Hubble…

Convinced the mecers will only Be pouches.. :(

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40 minutes ago, Igubu said:

For those interested- here a picture of a newer generation of this: (not my pic so apologies quality)

image.thumb.png.18c9b5589bb3f398ea725461f5980c63.png

Little bit of info some might find surprising: the Pylons also have pouch cells :) afain…

I wouldnt mix pouch and prismatics..

perhaps reach out to Hubble and ask them about their s-100 version - what’s inside.. 

 

That is interesting, thanks. Do you know if they can be run in parallel?

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4 minutes ago, Igubu said:

The picture was from a very different vendor

Ah right, thanks for confirming - I agree, from a cost point of view pouches make sense so cheaper Mecers will stick with that. Not that there is anything wrong with pouch cells, just less flexible when trying to use them in a DIY battery!

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10 minutes ago, johanp said:

Do you know if they can be run in parallel?

EDIT: Sorry, just realised you were asking about the hard case cell battery 😅 My comment below was about the Mecer:

I'm honestly not sure why not - there was a good post earlier in the thread about some of the reasons they could possibly request they're not run in parallel. But other than possible balance issues between parallel batteries I can't see specifically why. Well, put it this way: I'm not sure what Vision would do differently to allow parallel on their batteries...

Edited by JaseZA
Not reading properly...
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1 minute ago, JaseZA said:

I'm honestly not sure why not - there was a good post earlier in the thread about some of the reasons they could possibly request they're not run in parallel. But other than possible balance issues between parallel batteries I can't see specifically why. Well, put it this way: I'm not sure what Vision would do differently to allow parallel on their batteries...

Thanks, that makes sense. I've been holding out for Vision(stock expected August apparently), but with stage 4 I may end up taking a chance on Mecer.

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6 minutes ago, JaseZA said:

I'm honestly not sure why not - there was a good post earlier in the thread about some of the reasons they could possibly request they're not run in parallel. But other than possible balance issues between parallel batteries I can't see specifically why. Well, put it this way: I'm not sure what Vision would do differently to allow parallel on their batteries...

I don't know but I suspect it might be something to do with the BMS board that they use. I was warned by a certain supplier to steer clear of a certain brand (I wish I could remember the name of the brand) because the BMS would only support parallel connections. Using the same logic (flawed as it might be) I could see a possibility for BMSes that would only support series connections 🤷‍♂️

Whatever the correct answer is, I suspect the BMS would be the key determinant. The Vision manual claims that the BMS allows both series and parallel connections up to a maximum of 6S6P (that's a lot of power)

image.png.0f6c47799495d5f95a10907dbc8f0071.png

Edited by nembudziya
Added more details on the Vision and corrected a bit of grammar ;)
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12 minutes ago, JaseZA said:

EDIT: Sorry, just realised you were asking about the hard case cell battery 😅 My comment below was about the Mecer:

I'm honestly not sure why not - there was a good post earlier in the thread about some of the reasons they could possibly request they're not run in parallel. But other than possible balance issues between parallel batteries I can't see specifically why. Well, put it this way: I'm not sure what Vision would do differently to allow parallel on their batteries...

The newer versions of the Hubble S-100 can be place in both serial as well as parallel configurations.

"This means that a bank of 16 batteries can be configured at 48V, with a maximum discharge and charge rate of 400A and 200A respectively"

https://powerforum-store.co.za/collections/featured-products/products/hubble-lithium-s-100-12-8v-1-2kwh

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From the hubble spec sheet:

prismatic :)

I cannot say this enough: dont buy a battery based on capacity on paper, with lithium especially- there are many more components that decide if its something that will last or a cheapie… capacity/ volts not everything- you can build 8-cell or 16-cell batteries, both seem “similar” but the latter a lot more actual capacity..

 

image.thumb.png.8f252097566ce7151186846daad3c3b5.png

Honestly it is worth (for those who

have not purchased yet) buying something like this rather than the slightly cheaper variants- they are also local in Jhb and Ctn - so support is at hand- I have seen some

hubble talk on the forum as well- unsure if they are resellers - I only know of a CT based installer/reseller, perhaps you can buy rrp from the direct (no idea)?

 

Edited by Igubu
*They
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