16 hours ago, plonkster said:

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.

Are you using lithium batteries? Can you confirm that this is the case? I don't want to spend a lit of money and then have problems. 

2 hours ago, DeepBass9 said:

Are you using lithium batteries?

Yes. I have 12.8V Victron LFPs :-)

Until very recently (with the release of DVCC, distributed voltage and current control) Victron inverter's also didn't care about the charge voltage or current limits the BMS sent: You configured a static absorb and float value. This is still done for many batteries (LG for example) and works just fine.

In an off-grid situation with DVCC it will use the charge voltage values, and it will limit the solar chargers to the maximum charge current, but it STILL cannot stick to the maximum discharge current, that totally depends on your loads. Again, the decision was made that the BMS is in charge: If the BMS thinks you're discharging too fast, it is better that the BMS turns things off than that the inverter does it (potentially prematurely).

The one difference with the Victron inverters is that there is a "Lithium batteries" tickbox in veconfigure, and when you select that it uses a lower "go back to bulk" offset, in other words, there is explicit support for it in the inverter. That is the only thing I'd check for your Microcare: At how much below float will it go back to bulk?

So now the latest story I hear from this supplier goes like this:

The other issue with the pylontech is that it can only handle 25Amps , if you go over 25Amps for a few minutes the battery will also shut down..

I really don't want to be a jerk,  just want to protect both of us against future losses with Pylontech. For Off-Grid our Nova Battery is the best. Its LiFE with Ytrium ( Arare earth miniral that helps with heat issues in Lithium Chemical compounds) and can handle 250A continues! It also handles cold and hot temperatures much better than the Chinese products. In the winters when the temp drops below zero the pylontech will degrade fast. Have a look at the pylontech temperature range....

Not that I will buy from this guy, but is this story true? Only 1. 3kW from a pylon, so 3.9 kw from 3 of them? What if I want to weld?

I am now doubting whether Lithium is the way to go, considering my inverter is not approved for use with Pylons. It is approved for use with freedom won, but that is R20k extra for the same capacity. I can replace my trojans for R27k which will probably last for another 3-4 years, or spend R70k for something that will last 10 years. The sums are not making sense, given that there would likely be no guarantee if i bought pylons.

I'm wondering if I should just buy another set of trojans, and then reassess the issue in 2022.

Apart from Plonky who says there will be no problem, can anyone else say whether my inverter will work with pylontech if there is no comms and the BMS is just working on voltage? Same as the inverter would?

 

 

Edited December 13, 20187 yr by DeepBass9

Maybe I should put this in the form of a poll. Should I :

1. Buy 7.2kwh pylons for R50k, with no guarantee and hope for the best

2. Buy 8kwh Freedom won for R70k with guarantee.

3. Buy 8kwh Bluenova for R70k, guarantee status unknown

4. Buy 8x 150Ah trojans for R27k and worry about this again in 3 years time.

Currently I think option 4 makes the most sense, but am open to persuasion.

4 minutes ago, DeepBass9 said:

1. Buy 7.2kwh pylons for R50k, with no guarantee and hope for the best

no guarantee???

1 minute ago, gabriel said:

no guarantee???

Unsupported inverter.

1 hour ago, DeepBass9 said:

Currently I think option 4 makes the most sense, but am open to persuasion.

I would look at J200RE's if that is your decision.

@DeepBass9, You know I am inclined to agree with  your doubts, lithium batteries seems a bit like you are putting a square peg in a round hole a bit.

I just think that the revolution is coming but time is not yet ripe. I acknowledge all the potential, but these are damned high prices to have to be fiddly.

Right now, and opinion may and hopefully will change, I think I would nurse a set of Trojans with my BMV and my HA02 balancers and reassess when they were done.

Thank you pioneering types,  but I also think I'd sit the next round out.

6 minutes ago, phil.g00 said:

Thank you pioneering types,  but I also think I'd sit the next round out.

And then there is two ... also think they need to "mature" a wee bit more.

If my T105RE's decide it is time, I would be torn between J200RE's with 1600 cycles and 12v AGM's with 1700 cycles.

 

3 hours ago, DeepBass9 said:

The other issue with the pylontech is that it can only handle 25Amps , if you go over 25Amps for a few minutes the battery will also shut down..

Not true. Of course, if you draw more than 25A for too long a period and either 1) a cell exceeds 40°C, or 2) cell voltage drops too low, or 3) overall voltage drops too low, then it will shut down. It doesn't shut down immediately just because you went over for a little bit.

Look at the spec sheet: It says peak discharge is 5kw (ie around 100A) for 15 seconds. That's around 2C... quite typical for LFP.

3 hours ago, DeepBass9 said:

For Off-Grid our Nova Battery is the best

Is he talking about Blue Nova? Let me tell you something about that battery: It's capacity is based on a C/10 discharge rate (Pylontech is C/2). In other words... it also employs some marketing tricks to look good. Its unlikely that it has a better cycle life than the Pylontech. There is an upside to them being local: if something goes wrong at least you can get support. But it also costs more.

2 hours ago, DeepBass9 said:

Currently I think option 4 makes the most sense, but am open to persuasion.

You're off-grid, and there is the matter of the inverter. This might actually not be a bad option

Mmmh, the more I think about it, the supplier isn't completely wrong. The Pylontechs do have a fairly low maximum continuous discharge rate. It has always been something that counted against them. My initial optimism about them didn't take into account that you will be running a welding machine at times :-)

It is also true that these batteries (LG, Pylonteh, even BYD) generally just fare better when it has a grid it can fall back to.

So perhaps rather surprisingly, I find myself voting for your option 4.

 

3 hours ago, gabriel said:

no guarantee???

context gabriel context!!!  😏

3 hours ago, DeepBass9 said:

Maybe I should put this in the form of a poll. Should I :

1. Buy 7.2kwh pylons for R50k, with no guarantee and hope for the best

2. Buy 8kwh Freedom won for R70k with guarantee.

3. Buy 8kwh Bluenova for R70k, guarantee status unknown

4. Buy 8x 150Ah trojans for R27k and worry about this again in 3 years time.

Currently I think option 4 makes the most sense, but am open to persuasion.

how often do you need to weld from the batteries? And how much current does your welder draw?

 

Should the batteries not rather be used for emergencies only? Perhaps if you do weld a lot, a small genset for that purpose could be worth-while? My 200A inverter welder works perfectly well on a 4Kw PSW inverter with 2x100A batteries. To me, batteries are purely there to run emergency equipment at night when there's load shedding so I can get away with a small cheap battery bank

Edited December 13, 20187 yr by SilverNodashi

40 minutes ago, SilverNodashi said:

My 200A inverter welder works perfectly well on a 4Kw PSW inverter with 2x100A batteries

You're probably not welding at the full 200A though? Most arc welders have a voltage around 50V-80V (makes it easier to strike up an arc) and holds a voltage around 20V while welding, so at the full 200A that would max out the inverter and draw over C on those batteries :-)

But it's a good point though. If 4kw is what you need to weld (and in my experience you rarely need that much, I'm not the world's best welder by a long shot, but I've never had either of my welders (160A and 200A) at full power, then you need 80A, or around 3 x Pylontech racks (which is what you were aiming for anyway).

But the no-warranty thing... that still bothers me.

10 hours ago, plonkster said:

You're probably not welding at the full 200A though? Most arc welders have a voltage around 50V-80V (makes it easier to strike up an arc) and holds a voltage around 20V while welding, so at the full 200A that would max out the inverter and draw over C on those batteries 🙂

But it's a good point though. If 4kw is what you need to weld (and in my experience you rarely need that much, I'm not the world's best welder by a long shot, but I've never had either of my welders (160A and 200A) at full power, then you need 80A, or around 3 x Pylontech racks (which is what you were aiming for anyway).

But the no-warranty thing... that still bothers me.

With my old oilbath I sometimes weld at 120A and it seems to work well as well, although I can only weld about 35 minutes with with then it needs to cool down

The welder was an example, but I do sometimes do a fair amount of welding, that 3kW limitation seems a bit on the low side though.

What I am looking at now is these https://www.trojanbattery.com/pdf/SAGM_06_375_AGM_DS.pdf

Maintenance free 6V AGM batteries, 375Ah (so bigger than the 300Ah I currently have), +- 2000 cycles at 50% DOD, 3000 cycles at 30% DOD (Possible?)  about 9kWh capacity at 50%,  about 6kWh at 30% DOD. 

I will now have a single string of batteries, rather than the 2 parallel strings of 12V, which is also much better.

Its still going to cost R50k, but this seems a better option. I'll look at lithium batteries again in 2025.

Edited December 14, 20187 yr by DeepBass9

23 hours ago, DeepBass9 said:

 

I really don't want to be a jerk,  just want to protect both of us against future losses with Pylontech. For Off-Grid our Nova Battery is the best. Its LiFE with Ytrium ( Arare earth miniral that helps with heat issues in Lithium Chemical compounds) and can handle 250A continues! It also handles cold and hot temperatures much better than the Chinese products. In the winters when the temp drops below zero the pylontech will degrade fast. Have a look at the pylontech temperature range....

 

Pylons can warm their own cells not something I really worry about but since large parts of China the Mercury drops like it is in freefall its clever that they thought of that. My brother is a deputy headmaster for an international school in China and he and the family attended the Harbin Ice Festival where the temperatures were a balmy -22°C.

On 2018/12/13 at 9:14 PM, The Terrible Triplett said:

I would look at J200RE's if that is your decision.

At what cost?

19 hours ago, DeepBass9 said:

The welder was an example, but I do sometimes do a fair amount of welding, that 3kW limitation seems a bit on the low side though.

What I am looking at now is these https://www.trojanbattery.com/pdf/SAGM_06_375_AGM_DS.pdf

Maintenance free 6V AGM batteries, 375Ah (so bigger than the 300Ah I currently have), +- 2000 cycles at 50% DOD, 3000 cycles at 30% DOD (Possible?)  about 9kWh capacity at 50%,  about 6kWh at 30% DOD. 

I will now have a single string of batteries, rather than the 2 parallel strings of 12V, which is also much better.

Its still going to cost R50k, but this seems a better option. I'll look at lithium batteries again in 2025.

Why 6V AGM (375Ah) instead of the 12V Trojan J200RE's (200Ah)?

1 hour ago, Antony said:

Why 6V AGM (375Ah) instead of the 12V Trojan J200RE's (200Ah)?

He has 300Ah now, so he'd have to make two strings of the 200Ah ones to get to an equal-or-better position. And multiple strings are also a bit more troublesome. Using the 375Ah batteries allows a single string AND a bit of an upgrade. And AGM, so no maintenance.

7 hours ago, plonkster said:

He has 300Ah now, so he'd have to make two strings of the 200Ah ones to get to an equal-or-better position. And multiple strings are also a bit more troublesome. Using the 375Ah batteries allows a single string AND a bit of an upgrade. And AGM, so no maintenance.

At almost double the cost? Is AGM really worth it?

1 minute ago, Antony said:

At almost double the cost? Is AGM really worth it?

Don't know... I didn't look at the cost when I answered :-)

12 hours ago, Antony said:

At what cost?

I recon about R5300 incl per batt.

AGM's, also now out in 12v 200ah at 1700 cycles at 50% are about R6400.

Deepbass'es 6V AGM batteries 375Ah makes a lot more sense though.

Just some thoughts:

• Think about going with 2v cells instead of 6v/12v batteries. Most are rated to last MUCH longer and you can also monitor individual cells
• Think about upping your battery bank size just in general (3 years is really short period of time)
• Consider whether you inverter/charger is adequately charging your batteries
• Consider if you are actually saving money? (or are you completely off grid?)

I would definitely not go the Lithium route. 3.5 years with a battery bank means something is off. Either you are draining your batteries too much, the batteries suck or the inverter/charger sucks/misconfigured. By going Lithium, you could still have a problem and end up paying R50k or whatever in 3 years again

I mean if you are spending R20-R30k on batteries every 3.5 years, I would just as well go for a much cheaper brand see how it holds up. I recently bought 4x Ritar 100Ah batteries for a total of R10k. Sure it is R10k but you can buy 3 sets of them for one set of what you had now.

Or to think of it another way, you could experiment with cheaper batteries and maybe it'll be slightly more expensive (but you are thinking of blowing R50k anyway) and possible end up with something that works well or keep doing what you are doing and end up paying R30k every 3.5 years.

3 hours ago, Antony said:

Is AGM really worth it?

whatever you get, just make sure the seller is reputable and that you have a reasonable warranty - i lost one 12v 250agm just out of warranty, lost nearly 6k. in the end solar is still way more expensive than grid... but far more reliable

the bottom line re your question really is another question: are you prepared to nurse flooded batteries? also with agms, they must be nursed and looked after - temperature, ventilation, bmv702, balancer etc.... or pay the extra for lions with bms... what if you are out of circulation, health-wise or death, will your team be able to sort out the energy stuff... questions and questions...