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Trojans dying, time for Lithiums. A few questions:


DeepBass9
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After 3.5 years my Trojans are on their way out. I have 8 x 150Ah 12V T1275s, which cost me about R20k for the lot, they've lasted about 40 months, so R500 per month is not bad. I am off grid and usually they were kept at about 60-70% SOC, but sometimes they worked like Trojans :P

Now they are starting to sukkel to hold charge overnight, and are bubbling and leaking and generally making a mess, so it is time for them to go.

So the question is, which Lithium batteries to get? Is there any real difference apart from price with the various brands? (Pylontech, BYD, Freedom Won, etc)

Also, as I understand it you can add more batteries as required, so If I bought some now in summer, and then added some more closer to winter that would not be a problem, correct?

I have Microcare MPPTs and all the charge settings are adjustable, can these be configured to charge the lithium batteries with no problem?

Tx. 

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@DeepBass9

I have no personal experience.

However, there is ongoing accelerated battery tests at : http://batterytestcentre.com.au/reports/

It would appear some are better than others.

There are lots of parameters taken into account and you should apply your own requirements when interpreting the results.

Although the Pylontech's appear good the BYD B-Box seem to fair better according to my interpretation.

Anyway, that site is probably the best most reliable reference you are going to get.

Then there is the BMS system, I recall @plonkster mentioning that Victron equipment could only handle 1 BMS. 

I don't know really know if that mean 1 BMS type, or 1 BMS per battery or per battery bank, but it does seem to mean that there may be some sort of charger comparibility/limitation applied to the size of the bank. This may apply to other inverter makes as well.

@plonkster, maybe you can expound on this?

 

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33 minutes ago, phil.g00 said:

Then there is the BMS system, I recall @plonkster mentioning that Victron equipment could only handle 1 BMS.

Both Pylontech and BYD batteries link together with a canbus cable and appears to the outside world as a single BMS. BYD physically constructs this as multiple BMSes linking together into a sinle BMU. A single consolidated stream of canbus info is broadcasted and that is what is used.

So no problem, both these batteries work just fine.

But the reason I mentioned that, is that the MyPower24 (aka SolarMD) battery works differently, which is what makes it so hard to support.

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@plonkster, Thanks that is good to know.

I suppose we have to factor price in to the equation as well.

A very quick google:

https://renewables.herholdts.co.za/product/byd-b-plus-2-56kwh-battery-100-dod-48v/

BYD @ R18097.57 vat excl. for 2.56kWh (claims of 6000 cycles @ 100% DOD?)

https://solaradvice.co.za/shop/solar-power/solar-batteries/pylon-tech/

pylontech 2000B @ R13913.04 vat excl. 2.4kWh ( claims of 6000 cycles @80% DOD)

( I don't know if the 2.4kWh is the 80% capacity, or if only 80% of 2.4kWh is available).

The pylontechs seem a very good price from when I googled a while back.

 

 

 

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My current thinking is to get 3 Pylontechs or BYDs now, and then another 1 or 2 closer to winter to spread the cost a bit.

A small detail would be what sort of connections do you use to the inverter? Normal battery lugs or something else?

Edited by DeepBass9
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44 minutes ago, phil.g00 said:

I suppose we have to factor price in to the equation as well.

To my mind... BYD is 16s, Pylontech is 15s. If all other things are equal (price per kwh, cycle life), I'd take the BYD. Slightly better voltage efficiency since it lives around 55V rather than 53V, and of course you get that 1/16th extra capacity :-)

BMS wise... both batteries have features that frustrate me, although Pylontech is probably a bit more sane. What frustrate me about Pylontech is the very narrow voltage range (absorb at 53.2V, by 54V it shuts down abruptly with no margin or grace period (as you would have with an LG for example). BYD on the other hand publishes a 56.5V charge voltage (on CANbus) voltage but won't let you come near it, when you hit 55V it signals a stop-charge condition. Neither battery does smooth voltage control, which is something you only really get with FreedomWon (aka Orion BMS) and the Victron high energy line.

Voltage control: This is when the BMS adjusts the overall charge voltage down to compensate for a high/low cell instead of attempting to regulate it by doing a hard stop every time it reaches some voltage... :-)

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7 minutes ago, plonkster said:

To my mind... BYD is 16s, Pylontech is 15s. If all other things are equal (price per kwh, cycle life), I'd take the BYD. Slightly better voltage efficiency since it lives around 55V rather than 53V, and of course you get that 1/16th extra capacity :-)

BMS wise... both batteries have features that frustrate me, although Pylontech is probably a bit more sane. What frustrate me about Pylontech is the very narrow voltage range (absorb at 53.2V, by 54V it shuts down abruptly with no margin or grace period (as you would have with an LG for example). BYD on the other hand publishes a 56.5V charge voltage (on CANbus) voltage but won't let you come near it, when you hit 55V it signals a stop-charge condition. Neither battery does smooth voltage control, which is something you only really get with FreedomWon (aka Orion BMS) and the Victron high energy line.

Voltage control: This is when the BMS adjusts the overall charge voltage down to compensate for a high/low cell instead of attempting to regulate it by doing a hard stop every time it reaches some voltage... :-)

But that is now quite different to normal battery charging, will I be able to set up my microcare to do that? 

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18 minutes ago, DeepBass9 said:

will I be able to set up my microcare to do that?

You don't have to use the fancy canbus voltage control. You can also just set everything to 55V (for BYD) and be done with it. Works perfectly well and you still have a BMS that will disconnect things if there is a major problem. So you can just program your Microcare charger to absorb at 55,.2V and float at 55V. Also see here.

The only thing I do know about Microcare... if the BMS opens a contactor while it is running at full power, they sometimes blow up.

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2 hours ago, phil.g00 said:

@plonkster, Thanks that is good to know.

I suppose we have to factor price in to the equation as well.

A very quick google:

https://renewables.herholdts.co.za/product/byd-b-plus-2-56kwh-battery-100-dod-48v/

BYD @ R18097.57 vat excl. for 2.56kWh (claims of 6000 cycles @ 100% DOD?)

https://solaradvice.co.za/shop/solar-power/solar-batteries/pylon-tech/

pylontech 2000B @ R13913.04 vat excl. 2.4kWh ( claims of 6000 cycles @80% DOD)

( I don't know if the 2.4kWh is the 80% capacity, or if only 80% of 2.4kWh is available).

The pylontechs seem a very good price from when I googled a while back.

 

 

 

You can use 80%, or 2Kwh of the 2400Wh on the Pylontech, hence it being called "2000B" ;)

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1 hour ago, PJJ said:

While we are on the subject, does anyone know if you can parallel the BYD 10kWh bank Heroldts is selling?

The 10kwh bank they are selling is most likely a rack of individual modules... so the 10kwh is already 4 modules in parallel. Yes, you can add more. I worked on a system recently with 20 modules in parallel.

Edited by plonkster
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21 hours ago, PJJ said:

While we are on the subject, does anyone know if you can parallel the BYD 10kWh bank Heroldts is selling?

https://renewables.herholdts.co.za/product/byd-10kwh-lithium-ion-48v-battery-bank-complete/

Because if so, going off grid just got a lot cheaper?

Are these not the BYD batteries that are suspect?

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47 minutes ago, DeepBass9 said:

Another question, how easy is it to communicate with the BMS on Pylons, what do you need, or is it simpler to use a BMV?

What is simple for me might not be simple for you. Like wathing a mechanic stick his hand into a relay box, rummaging around, unplugging one and suddenly the cooling fan turns on and he says... there's your problem! And I'm like... sure... I could probably eventually figure that out... but it'd take me a day! :-)

(True story by the way).

How easy is it? Well, in theory, the battery practically shouts to the world what it is doing. It broadcasts that information on its canbus connection. The trouble, the bit that makes it hard, is that connecting to the canbus requires special hardware (which, because it is not mass-manufactured like USB hubs tend to cost a little), and then you usually need some kind of code that knows how to dissect the binary-packed data. I'd say it is about in that "it would take me a day!" category. It's not difficult to do if you persist a bit at it. I mean, at least it isn't difficult in the same way as NMEA2000 is difficult (where the people who made the standard purposefully kept it secret to make it hard for others).

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A further complication. One of the suppliers says that I need an ICCM module to control the pylons. Is that true?

"Bad-luck , the Inverter don't have RS485 comms , the Microcare also dont support proper comms with Lithium batteries. so neither devices will be able to communicate without the ICCM or BMU.  No comms and the battery will shutdown to protect itself against destruction. That is the way all new Lithium batteries work. Else you can have fires and insurance wont pay out. You will be able to set the voltage in the microcare MPPT for lithium, but that is not adequate you will need comms to the battery to give it the correct instructions for operations.So you will need the ICCM."

 

Inverter Control Center Module

Storage Systems - Communication Module

• Real-time monitoring of all the different power sources in use in a solar system (solar panels, batteries, grid power, etc). 

• Calculating the total cost savings brought about by the solar system. 

• Can gather over 50 different values from every connected inverter. 

• All data is captured, stored and can be exported for a specific time period. 

• Multiple dashboards available anywhere in the world presenting everything happening in the system in real-time. 

• Specific monitoring of the batteries in use. 

• Can monitor up to 9 inverters in parallel.

• Support for a host of different Voltronic inverters.

• Can monitor grid tie as well as hybrid inverters. 

• Support Pylontech batteries with true SOC and voltage monitoring.

• Hourly trend analysis of the load, the solar panels, the batteries as well as the utility consumption and/or production.

Cost R 3750 -- 00 Excl Vat

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4 minutes ago, DeepBass9 said:

A further complication. One of the suppliers says that I need an ICCM module to control the pylons. Is that true?

"Bad-luck , the Inverter don't have RS485 comms , the Microcare also dont support proper comms with Lithium batteries. so neither devices will be able to communicate without the ICCM or BMU.  No comms and the battery will shutdown to protect itself against destruction. That is the way all new Lithium batteries work. Else you can have fires and insurance wont pay out. You will be able to set the voltage in the microcare MPPT for lithium, but that is not adequate you will need comms to the battery to give it the correct instructions for operations.So you will need the ICCM."

 

Inverter Control Center Module

Storage Systems - Communication Module

• Real-time monitoring of all the different power sources in use in a solar system (solar panels, batteries, grid power, etc). 

• Calculating the total cost savings brought about by the solar system. 

• Can gather over 50 different values from every connected inverter. 

• All data is captured, stored and can be exported for a specific time period. 

• Multiple dashboards available anywhere in the world presenting everything happening in the system in real-time. 

• Specific monitoring of the batteries in use. 

• Can monitor up to 9 inverters in parallel.

• Support for a host of different Voltronic inverters.

• Can monitor grid tie as well as hybrid inverters. 

• Support Pylontech batteries with true SOC and voltage monitoring.

• Hourly trend analysis of the load, the solar panels, the batteries as well as the utility consumption and/or production.

Cost R 3750 -- 00 Excl Vat

Ok, so that is ICC with a Raspberry Pi, but I don't see that it says ICC is compatible with MicroCare?

 

BlueNova will work with MicroCare as they do things a little different. It's a bit more expensive and they are situation in Cape Town if you need help with anything.

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Gaaah. No, an LFP battery doesn't just burst into flames. It's a completely different chemistry to Lithium Ion or Lithium Polymer (those can actually burn). Besides, Pylontech has approved offgrid use of their batteries, even with an Axpert inverter (which has no voltage control either). I don't even know what ICC does (other than log and use the SOC to switch the inverter), but it certainly isn't doing anything fancy with the voltage and current info (Edit: And in an offgrid situation it can't even do anything with SOC info either).

The BMS in the battery is the last line defence. It will disconnect if you screw it up to protect the battery. Simply set the inverters and charge controllers to 53.2V absorb and 53V float (there is a whole discussion elsewhere about how to derive these voltages). Ideally one would want to set float lower, but often there is a hardcoded amount of Volts in the inverter that the voltage has to drop before it goes back to Bulk charging (4V is a common value for lead acid), and if you make float too low the chargers might never get out of float.

Edited by plonkster
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