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Mecer LiFePO4 Lithium Ion Batteries: Any experience


Corné

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I have connected 2 of these in series for a 24 volt system. I checked the voltage on both before installation and they were the same. After running for about 8 weeks the one battery sits at 13.9 volts and the other at 13.2 volts. I have been looking for a battery equalizer/balancer but can't seem to find anything. I am now buying a charger to charge both batteries to max and will then reconnect them. I do however believe they will become unbalanced again. Any advice please?

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Hi,

Basics first :) please ignore if this seems trivial, but you newer know…

as always… a slightly longer explanation- I like to share :)

This might be easy- cables, or not easy- new kit…

Battery cable lengths for interconnects need to be the same length and thickness, and your end cables (+ batt1 and- batt2) to the dc fuse also the same, as well as your fuse to inverter cables. Also at least 35mm, ideally 50mm for 200A. Can you confirm? Also perhaps how they are physically connected, assuming good crimps etc- maybe a photo!

also which inverter and what settings? Might have mentioned earlier, sorry but I’m not following the thread closely..

If all of this checks out- then unfortunately another example of non intelligent bms limitation. I’ll explain:

There is always a difference between say first cell closest to charge terminal (can’t remember if it’s + or - side!) and the last cell furthest away. Just how electrons flow… Thats part of the function of the bms, to monitor individual cells within the battery and balance them per cell. Balance really means controlling charge to each cell individually. A “fancy” bms that supports series properly talks between all the bms’es and that way balances all of them to be the same. (Small diff if 100mV or so) It also talks to the inverter via CAN- and actually controls all the charging- so while cells are settling it might instruct a bit more charge here and there- eventually balancing perfect between all cells.

Using a lithium battery without this means it’s treated as normal lead acid battery, so basically the inverter charges it bulk to get it to “full” say 14.6V. Lithium cells also settle- similar in a way to old lead acids- so they are “overcharged” to say 3.6V per cell and they then settle to 3.4V as an example- differs per type of cells, but it’s controlled very finely per cell. With your setup the inverter just see’s a big 24V battery, and it controls and charges till whatever setting you set- say 24V (just a value to illustrate 100% full) and lets assume you have 4x cells per battery- so if they were perfectly balanced each cell V would eventually be 24/8 = 3V. Unfortunately you might very well have a couple at 3.2V, some even at 2.9V - many reasons for this - but the total is 24V- so inverter stops charging. Repeat this a few times = unbalanced! 

Another part of a bms is to report individual cell health- sometimes a cell is always under- showing a fault, but you wont know that with the basic bms. 

To get rid of this problem you need 2 things: A smart BMS with CAN interface, and an Inverter with CAN. No amount of external “balancing” will help.

Was discussed earlier- there are diy battery builders (I know of somebody in WCape) that will build you a new battery- using your cells, but then adding a new bms with CAN etc - but it’s really expensive, and of course your inverter needs to support CAN to get the most benefit, withou that you’ll get the balancing sorted at least (it will be an eigth cell single 24V battery, not 2x 12V in series anymore) but still the other negatives of at least 30% unusable capacity.

much better to sell them as individual 12V’s, get rid of the inverter if it’s a non CAN,  buy a newly made up 24V battery and inverter that supports CAN..

Hope it helps!

 

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Forgot to comment about buying a charger- if you want to a decent lifepo4 charger will set you back at least 1500-2000! And its only 12V, so lots of disconnecting battery terminals every few weeks- which is downtime- and dangerous! 100A is deadly.

A cheap charger will damage your batteries quickly.

You’d be throwing money at a problem- better to spend it on the correct batteries and inverter.

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  • 11 months later...
On 2021/08/11 at 9:32 PM, Igubu said:

Forgot to comment about buying a charger- if you want to a decent lifepo4 charger will set you back at least 1500-2000! And its only 12V, so lots of disconnecting battery terminals every few weeks- which is downtime- and dangerous! 100A is deadly.

A cheap charger will damage your batteries quickly.

You’d be throwing money at a problem- better to spend it on the correct batteries and inverter.

Thanks for all that contributed to this topic. Makes interesting reading.

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  • 3 months later...

So these batts have been around for 2+ years.  Any long term reviews on them? I have a small 12V 600w trolley inverter with 2 x 100Ah lead acids that I'm thinking of replacing with 1 of these 200Ah Mecers (SOL-B-L-M200)

Good/OK/Bad idea?

Or should I just bite the bullet and spend the extra cash on a Hubble S-200 (which for right now is significant for me so I don't reaaaaaly want to do it).

Edited by Zombie
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Are you happy with the trolley as such? Also are you CT based or elsewhere?

not sure if the s-200 has also moved to lifepo4 like the new am’s - if not i’d look for something that is… I could send you to somebody that manufactures these- but he’s CT based- might save you some cash.

also unsure if the mecer’s have perhaps changed to prismatic lifepo4 cells, maybe try and find out.

I’d wager all manufacturers are moving to it as the old pouch cells all fail after around 3 years…

 

Another option perhaps- look for somebody who has some 2nd hand ones and buy a couple on the cheap (around R1500 each)- stick 2x or even 4x together and at your modest 600W load they might be good for another few years.

Edited by Igubu
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22 minutes ago, Zombie said:

So these batts have been around for 2+ years.  Any long term reviews on them?

I was on a budget when I bought these for my uncle's house. So far, my uncle and aunt are happy with their batteries, but I cannot give any objective review beyond what they told me over the phone. You can take that for what its worth.

If you can help it, I would suggest taking @Igubu's advice as that will save you money in the long-term. I know money can be tight but waiting on the purchase and saving for a little longer may score you good quality batteries that will give you many happy years of reliable service 

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1 hour ago, Igubu said:

Are you happy with the trolley as such? Also are you CT based or elsewhere?

not sure if the s-200 has also moved to lifepo4 like the new am’s - if not i’d look for something that is… I could send you to somebody that manufactures these- but he’s CT based- might save you some cash.

also unsure if the mecer’s have perhaps changed to prismatic lifepo4 cells, maybe try and find out.

I’d wager all manufacturers are moving to it as the old pouch cells all fail after around 3 years…

 

Another option perhaps- look for somebody who has some 2nd hand ones and buy a couple on the cheap (around R1500 each)- stick 2x or even 4x together and at your modest 600W load they might be good for another few years.

Hey man I'm in JHB and yes, still happy with with the trolley

Yea the Mecers are 2nd life LiFePO4 with about 1500 cycles it seems @ R7k and change

https://www.mecerpc.co.za/Mecer-SOL-B-L-M200-p-239794.php

The hubble has indeed moved to LiFePO4 with about 2000 cycles @ R12k 

https://www.hubblelithium.co.za/s-series

 

Thanks for the comments... will try find out the pouch/prismatic makeup

Edited by Zombie
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I see hubble has a s-200 now… also prismatic lifepo4, and online around R12K. Would be much better option than 2x mecers.

I know you said cashflow is an issue, but you are wasting a lot of money long term sitting with old 12V inverters and batteries. Also lose at least 30% of usable capacity because of not using CAN interface between the battery and inverter.

a hybrid or even off grid 48V inverter with a 48V battery will be much better in the long run, and you could even add 3 or so panels (which you can find 2nd hand) and at least get some money back… not sure if thats an option. As an example you could buy  a proper Dyness 5.5kW for around R26K, and a small 3kW kodak around R10k or so (i’d recommend a sunsynk hybrid of course but it’s a lot more)

Add a few panels and you could run most things with a bit of management….

Edited by Igubu
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13 hours ago, Zombie said:

but both the s-200 and mecer are 12v 200ah 2.3/2.5kwh...  so I wouldn't need 2 mecers?

Anti Mecer perhaps? Trying to convince you to buy Hubble.........

I have 2 x Mecer and doing quite well after being in use for about 2 years. And yes I also do not use it on a 48V system and also don't need comms as I get along quite well.

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Not anti any Brand, there are more than 20 different rebranded versions of this same battery on the market in SA…

I’m offering advise based on experience…you are lucky to get 2 years, but have you actually ever load and capacity tested them? New and now?

I’ve said this a few times- people that don’t understand the technology just look at one thing: Price. They think a mecer/any brand of these cheap lithium’s @ Rx thus Rx per kW are way cheaper than another brand based on selling price only…. Surprise surprise it’s untrue.

There is a very small niche market where these could be used, ie LA replacement- think gate motors, alarm backup etc, where very low current is required, and cycling doesn’t happen - so NOT a solar system in SA where we load-shed constantly.
 

There are many Technical reasons- you can speak to installers who’s in the business for many years- or educate yourself a bit- simple few google searches to explain the basics of batteries, chemistries, BMS and comms control systems etc.

The correct battery will give you 6000+ cycles and retain 70-80% after that- thats many years… vs your cheap lithium that will probably not even give you 100% capacity on day 1 (they use 2nd life cells that are already years old) and degrade to 30% in under 3 years… 

So purely advice to not waste money in the short term…

 

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13 hours ago, Zombie said:

but both the s-200 and mecer are 12v 200ah 2.3/2.5kwh...  so I wouldn't need 2 mecers?

Apologies, based on you currently running 2x 100a’s thought you’d replace with 2x. Purely based on AH, yes 1x could do- but remember there is a big difference in how lead acid and lithium’s “percentage full” (SOC- state of charge- lets learn the lingo :) ) are measured. Your trolley inverter only understands Volts- and the decharge curves are completely different. In layman’s terms- you will get less actual capacity with the Lithium compared to the LA with the same settings- especially under load.. 

glad to explain in more detail if you want to- but it becomes a long post then :)

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OK if you want to charge to 100% full. I might be the lone wolf that follows battery university guidance of not keeping my my Hubble or Mecers fully charged but do charge them full now and again for balancing.

Lithiums are very forgiving and need not be charged to 100% and this gives a lot longer life out of them.

It is quite strange to see how the market place works. Hubble had S-100 in stock but it seems nobody want them as they all want the newer S-120.

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BU is old school yes… don’t think they are updated with latest developments in new batteries… Lithium absolutely wants to be charged to 100%- lifepo4 anyways… the older ncm based ones used in EV’s preferred the 20%-80% band, but more so for the “fast charge” portion… they are very different to lifepo4 ‘s used for solar storage…

It proves the point there is a lot of miss-information around, lots of outdated articles etc, and a lot of confusion with acronyms etc. Most people just think “Lithium” of “LFP” is enough to indicate what it is- but it’s not unfortunately.

Biggest impact on your Mercer's is rate of discharge/charging and temperature. The inherent chemistry will give you the cycles it can - but remember they are already used/2nd life and even “cycle count” is calculated differently between manufacturers… :)

Edited by Igubu
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Thanks for valuable information. If I understood this whole discussion it is about old type of pouch cells used in the Mecer and Hubble S-100 12V drop in batteries used by so many people with their 12V/24V inverters. Even some guys having 48V systems. There are 1000's of campers that also use them together with the DIY which are the new lithium type.

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1 hour ago, Igubu said:

BU is old school yes… don’t think they are updated with latest developments in new batteries… Lithium absolutely wants to be charged to 100%- lifepo4 anyways… the older ncm based ones used in EV’s preferred the 20%-80% band, but more so for the “fast charge” portion… they are very different to lifepo4 ‘s used for solar storage…

It proves the point there is a lot of miss-information around, lots of outdated articles etc, and a lot of confusion with acronyms etc. Most people just think “Lithium” of “LFP” is enough to indicate what it is- but it’s not unfortunately.

Biggest impact on your Mercer's is rate of discharge/charging and temperature. The inherent chemistry will give you the cycles it can - but remember they are already used/2nd life and even “cycle count” is calculated differently between manufacturers… :)

Very happy to say my 2nd life Hubble started at about 114Ah vs quoted 100Ah when I bought them. At present they and the Mecer are still providing over 100Ah. Mecer are over 2 years old.

Just sharing my experience with both sets of 2nd life. I will never be able to state upfront that they will only last 3 yrs. I have the same tech laptop batteries that I gave a 2nd life for my camping lights. They are way down on capacity but still fit for the application driving LED lights after 13 years.

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  • 2 months later...

Hi

I am replacing my very old 36V Tescom inverter used in a cottage .

This is a for a cottage and not full-time use , maybe 2 hours per day . A rough test playing a dvd on the TV and some led lights indicated around 0,175kwh usage in 1 hour . This system is only for lights / entertainment . Attached permanently to the  DB board .

Will a 12V 100ah LiFePO4 BlueNova paired with a Victron MultiPlus 12/1600/70 Inverter Charger be a good match .

Please supply name of person in the Western Cape that builds batteries and will it be cheaper compared to buying a factory manufactured one from a dealer .

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If it’s for a cottage- probably more remote- so self built batteries not the best idea- as they tend to be slightly cheaper, but have a lot more returns/issues. The builders sort you out eventually-  but if you don’t want the hassles, pay a little but more for something proven.

 

Victron good reliable kit for sure- think exsolar in Somerset West are one of the main guys. They also sell FreedomWon batteries- more expensive- but built to last- so a lot of over engineering- again might be the right choice for a cottage if it’s remote.

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Hand-me down 600w rebranded Must EP20-0612 PRO (sold locally rebranded as Synapse or RT) connected to a Mecer 12V 200Ah SOL-B-L-M200 purchased from the super-helpful loadshedbuddy.co.za.

When the battery is nearing fully charged, the little inverter goes haywire, with the voltage reading fluctuating randomly between 10V and 40V, with the alarm LED blinking until it would eventually stop with alarm code 45 - AVR Fault.

After setting the following to the minimum values available in UPS menu options - the voltage reading fluctuates for a while when battery reaches 13.6V - but then it eventually stops charging and UPS shows normal.

Bulk current: 5A
Absorption Charge: 13.8 V (minimum)
Float Charge V: 13.5V (minimum)
Shutdown voltage: 10.8V (as per battery sticker)

Setting the absorption charge higher invokes the AVR Fault Alarm condition. My guess is that the BMS and UPS charge controller are fighting each other once the BMS starts to limit charging current.

I'm remotely supporting the installation with a very non-technical user, and it will be a while before I can confirm readings with a multimeter. I'd very much appreciate any theories on the reason for the fluctuating voltage readings and the AVR Fault alarm condition on the UPS. Buying the battery was a massive investment for the user, and buying a different inverter to use with the battery isn't an option ... 

sticker.png

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5 minutes ago, Multiform said:

BMS starts to limit charging current.

BMS does not "limit" charging current. It disconnects the charging FET completely for at least a while when it reaches the limit, but I don't think that is what is happening here. I suspect you are hitting cell over voltage protection - one of the cells voltage is going too high, and the charging FET disconnects. Basically your cells are out of balance so far that the BMS cannot fix it with your charger.

I would drop the bulk current to 1A and every time you see it going haywire, discharge the battery for 10 minutes and repeat.

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  • 2 months later...

Quick update. So I've had zero issues with the Mecer 200AH + RCT Axpert 1kw combo, and only managed to run it down once recently when I accidentally bumped the power plug out of its socket without noticing.

Upgrading to a fully installed Deye system now, but I can HIGHLY recommend this for running TV and other electronics, I even had a fridge/freezer connected to it.

 

The only caveat is that it's VERY noisy, so it needs to be installed in a garage or far away from people.

 

Edited by johanp
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