32 minutes ago, nembudziya said:

Hey @WJP thanks for your helpful posts. This is quite encouraging.

If you don't mind sharing:

1. How long have you had them installed? 
2. What's your average load in kW that's being powered by these batteries?
3. What's been your target DoD?

It's always great to hear from someone that's put them through their paces.

I'm sure @Igubuand the others would love to hear as well (be prepared to do battery surgery as we request you to go under the hood 😂)

Hello, less than a week. However the performance of these Mecer LiFePo4s is night and day when compared to the Pb batteries (even when they were new). Not the average but the "base load" is around 200-400w continuously. Keep in mind my use case here is different. This inverter is purely for "emergencies", a power backup. It's not designed for off-grid, it's a load shedding solution. So the batteries will only be cycled when it rains, a conveyor belt snaps or some unhappy union strikes To be honest it's very unlikely I'll open them. 

8 minutes ago, WJP said:

Hello, less than a week. However the performance of these Mecer LiFePo4s is night and day when compared to the Pb batteries (even when they were new). Not the average but the "base load" is around 200-400w continuously. Keep in mind my use case here is different. This inverter is purely for "emergencies", a power backup. It's not designed for off-grid, it's a load shedding solution. So the batteries will only be cycled when it rains, a conveyor belt snaps or some unhappy union strikes To be honest it's very unlikely I'll open them. 

Haha thanks for your response. I hope they'll give you a super long service life. I'll use mine as a power backup until I can connect PV input.

 @Tim003 I'm sure your earlier question has been partially answered

This might be a stupid question because my math sucks,

I am thinking about getting 4 of these Mecer 200ah units to replace my existing 4x 200ah AGMs with a 5KW Growatt inverter.

What is the maximum load these batteries can handle? lets say it's overcast and I have 100% battery capacity, could these handle a 4kWh load from the geyser for an hour?

And another question while I am thinking about it, can my AGMs handle that kind of load without causing damage?

42 minutes ago, Rooney Hat said:

This might be a stupid question because my math sucks,

I am thinking about getting 4 of these Mecer 200ah units to replace my existing 4x 200ah AGMs with a 5KW Growatt inverter.

What is the maximum load these batteries can handle? lets say it's overcast and I have 100% battery capacity, could these handle a 4kWh load from the geyser for an hour?

And another question while I am thinking about it, can my AGMs handle that kind of load without causing damage?

I'm sorry I don't know the answer to the battery question, I'm interested in how your 4kw geyser is wired to your 5kw inverter. 

On 2021/04/20 at 2:42 PM, Buyeye said:

I'm sorry I don't know the answer to the battery question, I'm interested in how your 4kw geyser is wired to your 5kw inverter. 

Oh the geyser is just going through the main DB with a timer, I have everything on the DB going through the Inverter, but have downscaled the geyser to a 3kw so that I have just enough Solar to power the geyser without hitting the batteries during a perfect day.

If the inverter overloads (Someone turns on a kettle etc), it cuts over to Eskom. I'm looking into smart connections to avoid that, but because my Interter is Growatt, I'm having a hard time getting live readings that can translate to Home Assistant.

 

On 2021/04/20 at 1:58 PM, Rooney Hat said:

What is the maximum load these batteries can handle? lets say it's overcast and I have 100% battery capacity, could these handle a 4kWh load from the geyser for an hour?

Doing the maths with info from the spec-sheet:

Capacity:

12V x 200Ah = 2400Wh
2400Wh x 80% = 1920Wh
1920Wh x 4 batteries = 7680Wh - or 7.68kw for an hour or 3.84kw for 2 hours

Max Power (Continuous Discharge is 100A from Spec-sheet):

12V x 100A x 4 = 4800W

I don't think I'd personally want to put my batteries through that regularly though - it would definitely shorten the life and would work the inverter hard as well. Better to try and run the geyser as much as possible on solar.

1 hour ago, JaseZA said:

Doing the maths with info from the spec-sheet:

Capacity:

12V x 200Ah = 2400Wh
2400Wh x 80% = 1920Wh
1920Wh x 4 batteries = 7680Wh - or 7.68kw for an hour or 3.84kw for 2 hours

Max Power (Continuous Discharge is 100A from Spec-sheet):

12V x 100A x 4 = 4800W

I don't think I'd personally want to put my batteries through that regularly though - it would definitely shorten the life and would work the inverter hard as well. Better to try and run the geyser as much as possible on solar.

You Legend, thanks!

Yup, totally agree, hate hitting batteries with heavy loads. They just offset what solar can't carry during the day 12pm to 2pm, So unless we have 0 sun, and the batteries have somehow gotten back up at 54v, it will use Eskom on those days.

Just wanted to be sure because I am having issues with my AGM batteries, 4 faulty in the past year. (Voltage off causing the combined voltages to drop)
Just re-crimped all my cables again, confirmed equal cable length and have ordered a HA02 battery balancer. So hopefully it doesn't happen again... getting tired of lugging these 60kg batteries back to the supplier.

16 hours ago, Rooney Hat said:

Oh the geyser is just going through the main DB with a timer, I have everything on the DB going through the Inverter, but have downscaled the geyser to a 3kw so that I have just enough Solar to power the geyser without hitting the batteries during a perfect day.

If the inverter overloads (Someone turns on a kettle etc), it cuts over to Eskom. I'm looking into smart connections to avoid that, but because my Interter is Growatt, I'm having a hard time getting live readings that can translate to Home Assistant.

 

Morning

It does get explained now and then on the forum - but here a quick (sorry it always does require a longish explanation) summary.

All batteries have a spec sheet that indicates the recommended charge/discharge rate - called a "C" rating. With Lead/AGM's there's normally a table that shows you different cycle life depending on what C rating you apply. An important value that's often missed is also temperature. (usually 25 deg C) - when your temp's go up - say to 35 or 40 deg (often in a small room/garage in summer) it has a massive impact on the life of the battery. This also applies to lithium - and as many people are now finding out - the small print on the long warranty on lithium say if you expose the battery to higher temps - no warranty.   With lead batteries, you can however abuse them - so pull a lot of amps - it will work - but shorten the life - ie "damage" them - but you'll never know it's happening - just one morning when putting some load on the inverter will trip and the batteries will be done.

Lithium batteries have the same suggested C rating which also dictates cycle life, warrnty etc, but with a BMS built in, the C rating is enforced (not fool proof  - but that is part of the BMS's job). You get basic BMS modules and Smart BMS with an intelligent method of talking to the inverter - either CAN/RS485. So while you might have gotten away with a lead battery to "spike" to say 4kW for periods of time (and shortening their life considerably) with a lithium battery with BMS it will trip the inverter.  There are of course ways on lead to also limit this - victron had some good battery management control options for older batteries.

This brings me to the point often missed with batteries. Most people "buy or sell" lithium based on 1 thing only - capacity. So a "Mecer 200AH" (there are 20+ variants of this on our market) battery is sold as 10kW at price XYZ - so it seems like a good deal or price per kW - but you don't take into account 2 things. 1. The BMS has no CAN interface - so the inverter needs to guess the state of charge (SOC) and it's not very accurate - especially when you are putting load on the batteries. With a Growatt set to "AGM" mode - it only measures Volts - and under load your battery could drop 1-2V. In practice this means your inverter might measure 47V under load - and 49V under idling.  The explanation is complicated - but in simple terms - a 2V difference on lithium could be 30-50% of total capacity! So your inverter "thinks" batteries are empty - and disconnects. The net result is you lose around 30%+ of "usable" capacity - suddenly you really only have 7kW instead of 10 available - so the price isn't that great anymore. You also sit with constant disconnects during load. A Smart BMS measure each individual cell voltage and reports this very accurately to the inverter - so you get almost 100% use out of the battery.  If you had a hybrid inverter like a sunsynk, it would be less of an issue, as your inverter would blend the three sources together, but Growatt unfortunately cannot.

There are however many different lithium batteries, all built differently, different cells, different quality BMS, configuration etc. And many of them do allow a full 1C rating and still offer long warranties (5000+ cycles/ 10 Years) - you do pay more for them, but in the long run they are a much better option.

Growatt does have a CAN bus  interface (the 5kW units I know) - so as a bare minimum I would not buy a Mecer replacement battery as you want to cycle and use them, but something that has CAN interface to give you much more accurate SOC and usability. If you can, buy something that offers high C rating sustained (1C or so) - this excludes the mainstream Pylontec, Dyness etc. Either something like Hubble, or one of the DIY type ones offered - in JHB area you can look at LithiumbatterySA (just make sure of the C ratings - I don't know them that well) or if you are in Cape Town I can recommend somebody as well that has a few options for high C rated batteries, with full CAN interface, and as it's built locally the pricing is very good.

I know of many guys who replaced there old "lead" bank with a single new fancy lithium - only to have constant disconnects, trips etc - and afterwards realize they now need to add 3x more of the batteries to get the same usable capacity.  It's a shame sellers/installers don't explain this properly.

 

 

42 minutes ago, Rooney Hat said:

You Legend, thanks!

Yup, totally agree, hate hitting batteries with heavy loads. They just offset what solar can't carry during the day 12pm to 2pm, So unless we have 0 sun, and the batteries have somehow gotten back up at 54v, it will use Eskom on those days.

Just wanted to be sure because I am having issues with my AGM batteries, 4 faulty in the past year. (Voltage off causing the combined voltages to drop)
Just re-crimped all my cables again, confirmed equal cable length and have ordered a HA02 battery balancer. So hopefully it doesn't happen again... getting tired of lugging these 60kg batteries back to the supplier.

Are you sure the batteries have not reached the end of their usable life? Remember the V rating doesn't tell you the state of their health unfortunately. It's when you put load on them that would know if there are gone of not. Unsure of the life of them, but my guess is if they have been abused 50+ times over the last couple of months, maybe a year, they are done - and it's a bit late for the balancers/monitoring. Even a short few high C rating discharges (and charging) is enough to destroy them very quickly.

Very similar to a car battery, or a gate motor - if you discharged them a few times to 10V or less, you throw them away.

2 hours ago, JaseZA said:

Doing the maths with info from the spec-sheet:

Capacity:

12V x 200Ah = 2400Wh
2400Wh x 80% = 1920Wh
1920Wh x 4 batteries = 7680Wh - or 7.68kw for an hour or 3.84kw for 2 hours

Max Power (Continuous Discharge is 100A from Spec-sheet):

12V x 100A x 4 = 4800W

I don't think I'd personally want to put my batteries through that regularly though - it would definitely shorten the life and would work the inverter hard as well. Better to try and run the geyser as much as possible on solar.

The maths seem right on paper - but let me explain the issue from experience.

The BMS is not intelligent, so it does not know that there is 1 master and 3 slaves in the chain. If the installation is done properly (I have not seen many that are) with a proper buzzbar, the correct cable lengths adn correct thickness you MIGHT be lucky that they draw equally, but more often they don't and become imbalanced and disconnect way earlier because 1 of the 4 is lower.

Also as I mentioned in the long post above, without CAN bus and individual cell monitoring and reporting, you easily lose  30% or more usable capacity under load. So the inverter will disconnect when your batteries are around 50% (tested many of these Mecer types in the field with Growatts over the last year - now stay far away from them for new installs) I cannot stress this enough - there is a massive difference in SOC accuracy with measuring V and with a proper BMS with CAN or RS485 interface.

Are these Mecer batteries a good idea/great price for capacity? In some usecases sure. First with old inverters that don't have CAN interface - think Axpert 5kW (and all the rebranded flavors of the same - Kodak/Synapse/RCT etc etc) - and often where  a bank of 4x or 8x AGM's were in play before.

Second use case is where they are primarily used for UPS/backup function only - and not for high C rated "whole house" scenarios.  So and existing install, older inverter, some old AGM that's finished - sure replace them with 4x of these but understand the limitations and what they are made for. Not all "Lithium batteries" are the same, and you do get what you pay for - trick is to know what you are paying for.

For any other new installation, with newer inverters etc - I would spend the money up front and get the correct batteries.

 

@Igubu dropping 'em value bombs as always 🏆

23 minutes ago, Igubu said:

Morning

It does get explained now and then on the forum - but here a quick (sorry it always does require a longish explanation) summary.

All batteries have a spec sheet that indicates the recommended charge/discharge rate - called a "C" rating. With Lead/AGM's there's normally a table that shows you different cycle life depending on what C rating you apply. An important value that's often missed is also temperature. (usually 25 deg C) - when your temp's go up - say to 35 or 40 deg (often in a small room/garage in summer) it has a massive impact on the life of the battery. This also applies to lithium - and as many people are now finding out - the small print on the long warranty on lithium say if you expose the battery to higher temps - no warranty.   With lead batteries, you can however abuse them - so pull a lot of amps - it will work - but shorten the life - ie "damage" them - but you'll never know it's happening - just one morning when putting some load on the inverter will trip and the batteries will be done.

Lithium batteries have the same suggested C rating which also dictates cycle life, warrnty etc, but with a BMS built in, the C rating is enforced (not fool proof  - but that is part of the BMS's job). You get basic BMS modules and Smart BMS with an intelligent method of talking to the inverter - either CAN/RS485. So while you might have gotten away with a lead battery to "spike" to say 4kW for periods of time (and shortening their life considerably) with a lithium battery with BMS it will trip the inverter.  There are of course ways on lead to also limit this - victron had some good battery management control options for older batteries.

This brings me to the point often missed with batteries. Most people "buy or sell" lithium based on 1 thing only - capacity. So a "Mecer 200AH" (there are 20+ variants of this on our market) battery is sold as 10kW at price XYZ - so it seems like a good deal or price per kW - but you don't take into account 2 things. 1. The BMS has no CAN interface - so the inverter needs to guess the state of charge (SOC) and it's not very accurate - especially when you are putting load on the batteries. With a Growatt set to "AGM" mode - it only measures Volts - and under load your battery could drop 1-2V. In practice this means your inverter might measure 47V under load - and 49V under idling.  The explanation is complicated - but in simple terms - a 2V difference on lithium could be 30-50% of total capacity! So your inverter "thinks" batteries are empty - and disconnects. The net result is you lose around 30%+ of "usable" capacity - suddenly you really only have 7kW instead of 10 available - so the price isn't that great anymore. You also sit with constant disconnects during load. A Smart BMS measure each individual cell voltage and reports this very accurately to the inverter - so you get almost 100% use out of the battery.  If you had a hybrid inverter like a sunsynk, it would be less of an issue, as your inverter would blend the three sources together, but Growatt unfortunately cannot.

There are however many different lithium batteries, all built differently, different cells, different quality BMS, configuration etc. And many of them do allow a full 1C rating and still offer long warranties (5000+ cycles/ 10 Years) - you do pay more for them, but in the long run they are a much better option.

Growatt does have a CAN bus  interface (the 5kW units I know) - so as a bare minimum I would not buy a Mecer replacement battery as you want to cycle and use them, but something that has CAN interface to give you much more accurate SOC and usability. If you can, buy something that offers high C rating sustained (1C or so) - this excludes the mainstream Pylontec, Dyness etc. Either something like Hubble, or one of the DIY type ones offered - in JHB area you can look at LithiumbatterySA (just make sure of the C ratings - I don't know them that well) or if you are in Cape Town I can recommend somebody as well that has a few options for high C rated batteries, with full CAN interface, and as it's built locally the pricing is very good.

I know of many guys who replaced there old "lead" bank with a single new fancy lithium - only to have constant disconnects, trips etc - and afterwards realize they now need to add 3x more of the batteries to get the same usable capacity.  It's a shame sellers/installers don't explain this properly.

 

 

Thanks,  this is very good to know! Makes a lot more sense. 

I am not a fan of the voltage measurements of the AGM to determine battery %, but the safe zone is that 50% is a little under 49v, so I have it set to a cut off of 47v (As the load drops voltage by 1/2) Then it settles back up at 49%. 

 

3 minutes ago, nembudziya said:

@Igubu dropping 'em value bombs as always 🏆

Intention is not to offend - for me it's a hobby, and have just seen too many "friends & family" ripped off and not being explained to properly what they are getting. So yes it takes some energy, I like to waffle on about things I'm passionate about as you can see - but it's a public forum so "advice" is there to be given, and ignored of course.

 

1 minute ago, Rooney Hat said:

Thanks,  this is very good to know! Makes a lot more sense. 

I am not a fan of the voltage measurements of the AGM to determine battery %, but the safe zone is that 50% is a little under 49v, so I have it set to a cut off of 47v (As the load drops voltage by 1/2) Then it settles back up at 49%. 

 

It's a bit of a dance yes - not sure if you already bought the Lithiums - seems not - but if your AGM's are on the way out - just some "free advice" on what to replace them with - and perhaps what not

4 minutes ago, Igubu said:

Intention is not to offend - for me it's a hobby, and have just seen too many "friends & family" ripped off and not being explained to properly what they are getting. So yes it takes some energy, I like to waffle on about things I'm passionate about as you can see - but it's a public forum so "advice" is there to be given, and ignored of course.

 

I wonder who would take offence with such great information that's meant to help them. People can ignore sound advice at their own peril and I guess they have a right to learn whatever mistakes they might have avoided on their own ¯\_(ツ)_/¯

I personally appreciate the value that your posts bring and the longer they are, the clearer they become to newbies like me. Hopefully, there are more that can resonate with my sentiments 🙂

24 minutes ago, Igubu said:

Are you sure the batteries have not reached the end of their usable life? Remember the V rating doesn't tell you the state of their health unfortunately. It's when you put load on them that would know if there are gone of not. Unsure of the life of them, but my guess is if they have been abused 50+ times over the last couple of months, maybe a year, they are done - and it's a bit late for the balancers/monitoring. Even a short few high C rating discharges (and charging) is enough to destroy them very quickly.

Very similar to a car battery, or a gate motor - if you discharged them a few times to 10V or less, you throw them away.

Calculated at my current usage, they should be nowhere near their end of life. 
1) Batteries are not in a confined space and have good breathing room. So I don't think they go above 25 degrees, might go a bit over in summer.
2) I only discharge to standing 48/49v, should be roughly 50%, rough calculations should get me at least 3 years of life.
3) Charge and Float v are on the within the safe values for the batteries. 

On an average day, they will only discharge to 50% once at night and might have a bit off usage during the day to offset Solar. (And I know I asked about the 4kw load, I don't think my batteries have ever had to do that kind of heavy lifting due to the times I set for the geyser. I think the most they get hit with is 2kw from the kettles at night.) 

The faulty battery is getting replaced though, So all batteries will be in working order. I asked around about my problem and someone recommended a balancer, and after looking into the HA4, sounds like a very useful thing to have and should extend the life 

After I bought the system, After 2/3 months I noticed something was off and It took me a while to figure out the issue was one of the batteries because the inverter was balancing the voltages while charging, only picked up that 1 battery's voltage was 1/2v off when I disconnected the batteries from the inverter after they had been discharged a bit.

Then a month later, discovered the brand new battery and one of the older ones had the same issue. and then last month again another one down. Can't figure out what it is, so I have re-crimped all my cables and ordered the balancer now. When the replacement gets back, I guess I'll see how long it lasts.
 

5 minutes ago, nembudziya said:

I wonder who would take offence with such great information that's meant to help them. People can ignore sound advice at their own peril and I guess they have a right to learn whatever mistakes they might have avoided on their own ¯\_(ツ)_/¯

I personally appreciate the value that your posts bring and the longer they are, the clearer they become to newbies like me. Hopefully, there are more that can resonate with my sentiments 🙂

Totally agree, I started from scratch during lockdown and did everything myself with 0 knowledge, If it wasn't for the guys on this forum, I'd be lost

17 minutes ago, Igubu said:

It's a bit of a dance yes - not sure if you already bought the Lithiums - seems not - but if your AGM's are on the way out - just some "free advice" on what to replace them with - and perhaps what not

Thanks, totally appreciate it! As you said, people just throw more capacity and don't consider what kind of loads are intended for the batteries and how it hurts these new affordable batteries that everyone jumps on.

My original plan was to get the AGM and upgrade to lithium in a few years when they are cheaper. But I get the feeling that's biting me in the ass now. 

8 minutes ago, Rooney Hat said:

Calculated at my current usage, they should be nowhere near their end of life. 
1) Batteries are not in a confined space and have good breathing room. So I don't think they go above 25 degrees, might go a bit over in summer.
2) I only discharge to standing 48/49v, should be roughly 50%, rough calculations should get me at least 3 years of life.
3) Charge and Float v are on the within the safe values for the batteries. 

On an average day, they will only discharge to 50% once at night and might have a bit off usage during the day to offset Solar. (And I know I asked about the 4kw load, I don't think my batteries have ever had to do that kind of heavy lifting due to the times I set for the geyser. I think the most they get hit with is 2kw from the kettles at night.) 

The faulty battery is getting replaced though, So all batteries will be in working order. I asked around about my problem and someone recommended a balancer, and after looking into the HA4, sounds like a very useful thing to have and should extend the life 

After I bought the system, After 2/3 months I noticed something was off and It took me a while to figure out the issue was one of the batteries because the inverter was balancing the voltages while charging, only picked up that 1 battery's voltage was 1/2v off when I disconnected the batteries from the inverter after they had been discharged a bit.

Then a month later, discovered the brand new battery and one of the older ones had the same issue. and then last month again another one down. Can't figure out what it is, so I have re-crimped all my cables and ordered the balancer now. When the replacement gets back, I guess I'll see how long it lasts.
 

Sounds like you have  good action plan! The balancer will surely help.  I was concerned mostly with the 4kW load comments yes - that would probably exceed the AGM"s recommended C rating.  Hopefully the replacement sorts it out

 

17 minutes ago, Rooney Hat said:

Thanks, totally appreciate it! As you said, people just throw more capacity and don't consider what kind of loads are intended for the batteries and how it hurts these new affordable batteries that everyone jumps on.

My original plan was to get the AGM and upgrade to lithium in a few years when they are cheaper. But I get the feeling that's biting me in the ass now. 

At least you are doing some weight training! My first install years back was 4x 200Ah AGMs = 65kg each I think...

In lockdown there was often stock shortages, so that might be why AGM's were used, and for backup purposes they do work. At least if they fail in a year or 2 you can replace them

Maybe a bit more "training" for future reference - especially in the theme of AGM/Lithium:

Charge Efficiencies is the word

AGM  - on a good day, with the best kit, maybe 70%, maybe 75%. In practical terms - 30% loss of power when charging them. So every 1kW of power you use to charge, you only get 700W into the battery. Lithium (slight variations)  - around 95-99%.

So practically - you could "under size" your PV array 30% to charge the same amount of battery capacity for lithium, or for the glass half empty - your AGM bank's a further 30% less efficient in terms of cycling and power usage to charge them up! Or if charging from grid - it takes 1.3kW of eskom power to charge the AGM's with 1kw - price per kW 130%

Does make AGM look even less of a great option these days If you start calculating all that into the price you can see lithium wins on price alone easily at a R/kW .. and did I mentioned the energy density - it's 100% better on W/KG ignoring DOD rates, "usable capacity"etc. Lithium (Lifep04 specifically). A 100AH AGM = roughly 27.5kg - a 100AH Lithium = 12.5kG. Conservatively work on 50% usable for AGM and 80% usable for Lithium - the difference becomes staggering.

Keep us posted if you got the AGM's sorted.

 

Edited April 22, 20215 yr by Igubu

8 minutes ago, Igubu said:

At least you are doing some weight training! My first install years back was 4x 200Ah AGMs = 65kg each I think...

In lockdown there was often stock shortages, so that might be why AGM's were used, and for backup purposes they do work. At least if they fail in a year or 2 you can replace them

Maybe a bit more "training" for future reference - especially in the theme of AGM/Lithium:

Charge Efficiencies is the word

AGM  - on a good day, with the best kit, maybe 70%, maybe 75%. In practical terms - 30% loss of power when charging them. So every 1kW of power you use to charge, you only get 700W into the battery. Lithium (slight variations)  - around 95-99%.

So practically - you could "under size" your PV array 30% to charge the same amount of battery capacity for lithium, or for the glass half empty - your AGM bank's a further 30% less efficient in terms of cycling and power usage to charge them up! Or if charging from grid - it takes 1.3kW of eskom power to charge the AGM's with 1kw - price per kW 130%

Does make AGM look even less of a great option these days If you start calculating all that into the price you can see lithium wins on price alone easily at a R/kW .. and did I mentioned the energy density - it's 100% better on W/KG ignoring DOD rates, "usable capacity"etc. Lithium (Lifep04 specifically). A 100AH AGM = roughly 27.5kg - a 100AH Lithium = 12.5kG. Conservatively work on 50% usable for AGM and 80% usable for Lithium - the difference becomes staggering.

Keep us posted if you got the AGM's sorted.

 

Haha yup, definitely doing the weight training.

If I knew then what I know now, would have given the AGMs a skip. Though for capacity sakes because I already have 4, I could consider doubling down and getting 4x extra 200ah batteries would give me about 9kwh @ 50% DOD... provided they stop becoming duds. This would push me through the night, but introduces the 3kw load the geyser has at 5-6am  Much to consider!  

Just got confirmation that they swapping out for new battery today. So I'll see how it goes!

32 minutes ago, Rooney Hat said:

Haha yup, definitely doing the weight training.

If I knew then what I know now, would have given the AGMs a skip. Though for capacity sakes because I already have 4, I could consider doubling down and getting 4x extra 200ah batteries would give me about 9kwh @ 50% DOD... provided they stop becoming duds. This would push me through the night, but introduces the 3kw load the geyser has at 5-6am  Much to consider!  

Just got confirmation that they swapping out for new battery today. So I'll see how it goes!

Not to talk shop really... but I know that a 1C rated new cell (10Y Warranty) locally built one with CAN - 5kW sells for about R23k. you could go 2nd life same CAN, probably around 20K, but think 2 or 3Y warranty on capacity then. (And its worth saying all warranties are different! - Lithium gaurantees a percentage of usuable capacity after the warranty period - most around 70 or 80% of original capacity- so still Very much usable after the few years)

So would compare that to 8x total agm price for roughly same usable capacity

 

 

 

16 minutes ago, Igubu said:

Not to talk shop really... but I know that a 1C rated new cell (10Y Warranty) locally built one with CAN - 5kW sells for about R23k. you could go 2nd life same CAN, probably around 20K, but think 2 or 3Y warranty on capacity then. (And its worth saying all warranties are different! - Lithium gaurantees a percentage of usuable capacity after the warranty period - most around 70 or 80% of original capacity- so still Very much usable after the few years)

So would compare that to 8x total agm price for roughly same usable capacity

 

 

 

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.

So finally the batteries are here. There were several delays in shipping the consignment but fortunately they arrived in good shape.

The installation will be done on Sunday, then we'll be testing them soon. In the meantime, I've been thinking about balancing them. Do you guys reckon I can just parallel connect them until Sunday?

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.

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