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Recommend me some batteries for solar to replace existing lead acid deep cycle


Lindsay
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Hi all,

I currently have some lead acid deep cycle batteries, 8 x 102Ah, with sets of 2 in series, 4 parallel strings, for a total of 408Ah @ 24V.

I paid around R 16 000 the batteries and am now looking at replacing them as they seem to get quite low overnight and don't even charge fully.

I have a Mecer (Axpert) 3kVA 24V inverter, charging the batteries of 1.5kw solar, and at most drain the batteries 40-50Ah @ 24V overnight running fridge/freezer, security camera system, lights and usb chargers etc. 

I see some Lithium Ion / Phosphate batteries that promise thousands of cycles when they are drained up to 80% of their charge (DoD). I'm only wanting to spend up to R 20k, since my system is quite small. I know I will not get the same capacity as lead acid, but since these other battery types can be drained lower for more cycles, they seem like a much better deal.

I see they also sometimes include the BMS built in, which sounds great.

So what can I get in this price range to replace my existing batteries? Preferably shops that are in Cape Town please.

Thanks!

Edited by Lindsay
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Hi Lindsay

If you are shopping for lithium, it seems to be a good rule of thumb to ensure you get enough battery capacity for your inverter to use in an hour. In your case, the 3.5kWh Pylontechs would meet that requirement.

However, they might not like to do it, like the Pylontechs would only give you 100A for a short time, in order to protect itself.

I don't know much about the Voltronic inverters, but just be that if you get a lithium, your inverter can properly manage it. Some people do have teething issues trying to run the lithiums on Voltronics without ICC, but personally I have no experience with that.

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5 hours ago, jykenmynie said:

However, they might not like to do it, like the Pylontechs would only give you 100A for a short time, in order to protect itself.

I don't think I've ever used much more than 50A from my current setup and that was only for a brief moment. I never run the inverter to it's full capacity, usually peak at less than 1000W.

3 hours ago, Rclegg said:

The Pylontech 3.5Kwh is what I would recommend. 80% DoD - 6000 cycles. They are around 20k. Design life is 10 years.

 

3 hours ago, wolfandy said:

Just be aware that the Pylontech US3000 (3.5kWh) is a 48V battery and your inverter runs on 24V. You would require the Pylontech UP2500 (2.84kWh), which is the only 24V model they offer

Pity they don't offer the sizes for 24v that they have for 48v, 3.5kWh would have been better, although I gather I could put two 24V units in parallel if I really wanted to?

5 hours ago, jykenmynie said:

Some people do have teething issues trying to run the lithiums on Voltronics without ICC, but personally I have no experience with that.

Not sure what you mean, do I need special software to control the charging cycles on Lithium? I thought the voltages being setup correctly on the Axpert and the BMS on the battery would be enough?

1 hour ago, Gerlach said:

Thanks, are these second hand / refurbished batteries and can one trust them to still have capacity and plenty of discharge cycles?

Any other concerns with running Lithium off a 3kVA Mever/Axpert, anyone had any problems, or suggestions?

 

Thanks everyone for all the comments so far!

 

I see that there are places selling Blue Nova Lithium Ion Phosphate batteries that are just drop in replacements for lead acid batteries. Does anyone have any experience with these?

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2 hours ago, Lindsay said:

Blue Nova Lithium Ion Phosphate batteries

These are very good. They do come at a premium though. You should be able to make the required setting changes to that Axpert for the charging values used for Lithiums. There are many on these forums doing that already.

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2 hours ago, Lindsay said:

Not sure what you mean, do I need special software to control the charging cycles on Lithium? I thought the voltages being setup correctly on the Axpert and the BMS on the battery would be enough?

You don’t need it, but a lithium battery is difficult to manage on voltage, as voltage alone isn’t enough to determine a SoC for the battery. Pylontech would also throttle its charging current when the battery is quite empty or quite full.

Most people with a Voltronic inverter seems to go the ICC route to have software sitting in the middle between the inverter and battery to “interpret” the requests from the BMS and relay that to the inverter. Again, this isn’t something I know anything about as I have a hybrid inverter that can communicate with the Pylons without an intermediary.

I have heard that in Australia the full warranty on Pylontech batteries don’t apply if it wasn’t used with a proper hybrid inverter (not one marketed as such) not sure about SA.

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18 minutes ago, jykenmynie said:

Most people with a Voltronic inverter seems to go the ICC route to have software sitting in the middle between the inverter and battery to “interpret” the requests from the BMS and relay that to the inverter. Again, this isn’t something I know anything about as I have a hybrid inverter that can communicate with the Pylons without an intermediary.

It is not 'relay' the Pylon BMS data to the Axpert but rather control the Axpert based on the Pylon BMS data. It switches the Axpert between Utility and SBU/SUB based on the Pylon BMS data (instead of the inverter doing itself based on it's own voltage readings). However, it does not have any influence on the charging side of things - this is still completely managed by the Axpert based on the set voltages. Have a look at https://iccsoftware.co.za/ for more details

2 hours ago, Lindsay said:

although I gather I could put two 24V units in parallel if I really wanted to

Yup, it seems that the 24V model can be paralleled same as the 48V ones

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12 hours ago, Lindsay said:

I don't think I've ever used much more than 50A from my current setup and that was only for a brief moment. I never run the inverter to it's full capacity, usually peak at less than 1000W.

 

Pity they don't offer the sizes for 24v that they have for 48v, 3.5kWh would have been better, although I gather I could put two 24V units in parallel if I really wanted to?

Not sure what you mean, do I need special software to control the charging cycles on Lithium? I thought the voltages being setup correctly on the Axpert and the BMS on the battery would be enough?

Thanks, are these second hand / refurbished batteries and can one trust them to still have capacity and plenty of discharge cycles?

Any other concerns with running Lithium off a 3kVA Mever/Axpert, anyone had any problems, or suggestions?

 

Thanks everyone for all the comments so far!

 

I see that there are places selling Blue Nova Lithium Ion Phosphate batteries that are just drop in replacements for lead acid batteries. Does anyone have any experience with these?

He stocks 2nd life and new ones. I got the second life ones and 212dats later and still no problem and they work really good. My bms gives me all the info per sell and SOC and power going in and out. I ones hammered the first bank to 135amps toe see what will go first and it kept going. Got 2 sets now so the power is spread over the 2 units now. Planning to get n 3de set end of the year. 

Revov sels second life and new units to. Eaton Nissan batteries to. 

Edited by Gerlach
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15 hours ago, Louisvdw said:
17 hours ago, Lindsay said:

Blue Nova Lithium Ion Phosphate batteries

These are very good. They do come at a premium though. You should be able to make the required setting changes to that Axpert for the charging values used for Lithiums. There are many on these forums doing that already.

Cool, they seem to have built in BMS, but does that mean I can just put two of them in series (12v + 12v)? Or do they need some knowledge how they are connected to each other? And how do these compare to the Pylontech?

15 hours ago, jykenmynie said:

You don’t need it, but a lithium battery is difficult to manage on voltage, as voltage alone isn’t enough to determine a SoC for the battery. Pylontech would also throttle its charging current when the battery is quite empty or quite full.

 

Ok, my Mecer / Axpert only has USB out, so I guess there's no way to connect it directly to the Pylontech.

14 hours ago, wolfandy said:

It is not 'relay' the Pylon BMS data to the Axpert but rather control the Axpert based on the Pylon BMS data. It switches the Axpert between Utility and SBU/SUB based on the Pylon BMS data (instead of the inverter doing itself based on it's own voltage readings). However, it does not have any influence on the charging side of things - this is still completely managed by the Axpert based on the set voltages. Have a look at https://iccsoftware.co.za/ for more details

Ok, if it's just switching the inverter to utility when the batteries are low (and back again once charged), I'm not sure I'd need to do that automatically, I'll check out the link though, thanks.

Does the float bug that these Axpert type inverters suffer from have any adverse effect on Lithium batteries (lifespan/damage) and also, how temperature dependant are Lithium batteries, I know lead-acid gas if the ambient temperature is high and the boost voltage is too high?

5 hours ago, Gerlach said:

Revov sels second life and new units to. Eaton Nissan batteries to.

Thanks, it does seem that you can get the second hand ones at about half the price.

3 hours ago, DeepBass9 said:

As a matter of interest, are the prices of lead acid coming down now that Li are more popular, or were they already as cheap as they were going to get?

If anything I've notice lead-acid has gone up in price. The 100Ah ones I have are a few hundred more expensive than 3 years ago.

2 hours ago, gooseberry said:

For interest's sake, can you put two Pylontech US2500 batteries in series if you upgrade your inverter later?

I'm obviously not the expert on here, it's probably not nearly as bad as mixing old and new lead-acid batteries, but still probably not recommended? Someone else would have to comment on this ;)

 

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1 hour ago, Lindsay said:

does that mean I can just put two of them in series

These 12V versions don't have communications. 
I am not sure if they will handle series connection. You might need to contact the supplier.
I do know that if you want to avoid issues with lithium batteries it is normally better to use them for what they were designed for. I would not add them in series. Rather use the 24V versions instead.

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8 hours ago, Lindsay said:

Ok, if it's just switching the inverter to utility when the batteries are low (and back again once charged), I'm not sure I'd need to do that automatically, I'll check out the link though, thanks.

The biggest benefit is that the switching happens on accurate Pylon BMS data and not the Axpert's voltage guesstimate.

An example: This morning my Axpert briefly switched to Utility when a 1500W load was switched on, even though my SOC was still above 30% and I have ICC set up to switch at 24%. The Axpert's 'Back to Grid' voltage is set to 47V (as a safety net in case something goes wrong with ICC - which it never has though). According to the ICC log the switch was not triggered by ICC, which means that it must have been triggered by the Axpert itself. I can see that the Pylon voltage took a brief dip when the load was switched on, but according to ICC (= Pylon BMS data) only down to around 49.2V - so in reality nowhere near to the 47V Axpert setpoint. The only way that I can explain the switch to Utility this morning is that the Axpert's own battery voltage measurement must have dropped below 47V to trigger the switch. In my view the Axpert's inaccurate voltage measurement does not allow you to take full advantage of the capacity of the Pylon (without at the same time running the risk of depleting it below 20% and impacting lifespan).

To me, the (in sight of the total investment of my system) relatively low cost of ICC/Pi to accurately control my system was probably the best investment I ever made in my system

8 hours ago, Lindsay said:

Does the float bug that these Axpert type inverters suffer from have any adverse effect on Lithium batteries (lifespan/damage)

I am using the custom firmware from @Coulomb and Weber for my Axperts, which addresses the premature float bug - but I do not know if that firmware also exists for your model. Maybe @Coulomb can advise or you can check in the AEVA forum yourself

8 hours ago, Lindsay said:

how temperature dependant are Lithium batteries

High temperatures negatively affect the lifespan of lithiums and if I remember correctly, you are not allowed to charge them if colder than 5 degrees celsius (mine have never even dropped below 20 degrees, so that is not something that I need to really worry about)

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11 hours ago, wolfandy said:

In my view the Axpert's inaccurate voltage measurement does not allow you to take full advantage of the capacity of the Pylon (without at the same time running the risk of depleting it below 20% and impacting lifespan).

I think @Anish also mentioned before that he is struggling to close to get full capacity out of his Lithiums as his inverter cannot use the BMS data as therefore switches prematurely using only overall battery voltage. I think he has 9.6kWh can use about 6kWh (don't quote me).

You'd like to avoid the position where you paid for a 3.5kWh Lithium and can only really use say 2.2kWh, instead of the 2.8kWh you'd get on 80% DoD. However, if you overspecced on the battery capacity, I guess you'd get a long life out of it if you manage it like that, but you should just be aware of that.

Obviously the battery's BMS is still only guessing, but it has MUCH more information available to it. All the internal cells' voltages etc.

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21 hours ago, Louisvdw said:

Rather use the 24V versions instead.

I would definately rather get the 24v versions then.

14 hours ago, wolfandy said:

To me, the (in sight of the total investment of my system) relatively low cost of ICC/Pi to accurately control my system was probably the best investment I ever made in my system

Ok, understood. I already monitor my Axpert and some shunts using a Raspberry Pi and my own code. I'm sure I could get spec somewhere for the comms on the Pylontech and monitor this as well with my own code.

14 hours ago, wolfandy said:

High temperatures negatively affect the lifespan of lithiums and if I remember correctly, you are not allowed to charge them if colder than 5 degrees celsius (mine have never even dropped below 20 degrees, so that is not something that I need to really worry about)

I think where I store the batteries is always under 30 degrees and not less than 10 degrees, so I think it should be ok, but I'll check back on this forum if I need to change voltages depending on the environment they are being stored in.

3 hours ago, jykenmynie said:

You'd like to avoid the position where you paid for a 3.5kWh Lithium and can only really use say 2.2kWh, instead of the 2.8kWh you'd get on 80% DoD. However, if you overspecced on the battery capacity, I guess you'd get a long life out of it if you manage it like that, but you should just be aware of that.

Obviously the battery's BMS is still only guessing, but it has MUCH more information available to it. All the internal cells' voltages etc.

Well I hope that undercharging them doesn't affect their lifespan too negatively. If I have this problem I'll probably need to get two of the 2.8kWh packs.

I'm hoping I could get some good data out of the Pylontech BMS, like Ah in and out over a day. Anyone know what is available?

Thanks

 

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On 2020/08/25 at 8:25 PM, Lindsay said:

Does the float bug that these Axpert type inverters suffer from have any adverse effect on Lithium batteries (lifespan/damage)

Fortunately no, unless it causes your battery to eventually run down to below about 20% SOC, when it otherwise would not have. It does however affect the life of lead acid batteries, since they last longest when kept fully charged. Lead acid batteries are not uncommon still.

17 hours ago, wolfandy said:

but I do not know if that firmware also exists for your model.

There is no patched firmware for any 24 V model, and likely never will. The line has to be drawn somewhere, unfortunately.

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21 hours ago, Coulomb said:

Fortunately no, unless it causes your battery to eventually run down to below about 20% SOC, when it otherwise would not have. It does however affect the life of lead acid batteries, since they last longest when kept fully charged. Lead acid batteries are not uncommon still.

I should probably just have gone for Lithium from the beginning, once lead-acid ones start to go bad they really seem to go downhill fast. I only got about 3 years from my lead-acid batteries even though they should have only discharged on average 10-15% overnight.

21 hours ago, Coulomb said:

There is no patched firmware for any 24 V model, and likely never will. The line has to be drawn somewhere, unfortunately.

I guess this won't matter now anyway then since I'm def not going lead-acid anymore.

19 hours ago, wolfandy said:

This is the info that ICC displays

This is very cool data. Is there any spec available for the communications protocol?

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Hi there.

 

I have also research this a lot. I just bought a 48v Battery pack from Lithium Batteries SA. It has brand new cells and it comes with a 5 year guarantee. 

Please check out their website, they have  24v and 48v configurations. 

 

They shipped it for me to cape town for less than R500 or you can send your own Courier 

 

image.thumb.png.3367db04f586b222b74fc783dfed435f.png

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1 hour ago, jykenmynie said:

Have you considered getting a 48V inverter also? Since you do not have a terribly expensive one currently, it might be worthwhile? Not sure about the downsides of 48V compared to 24V.

I already have some things in my house which run directly off the 24V dc (originally I didn't even have an inverter!) and my needs for AC power aren't much more than 1000W (induction cooker and slow cooker), so my 3kVA Mecer is fine for now. I'd only consider 48v if I was going to move completely to solar, at the moment I'm 60% on solar.

24 minutes ago, Krokkedil said:

I have also research this a lot. I just bought a 48v Battery pack from Lithium Batteries SA. It has brand new cells and it comes with a 5 year guarantee. 

Please check out their website, they have  24v and 48v configurations. 

It's a reasonable price, do you know if you can run two of these in parallel? Ideally I'd like to have 4kWh or more, although I'm not sure I could afford 2 of them. Could they custom build to a clients requirements if you want something just a bit bigger?

 

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