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Thank you for the great forum, Safe Driving over the weekend. Sincerely Jason
Gabriël

axpert woes?

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Hi Gabriel I know how you feel all the frustration with Axpert going back to grid . Tried different settings with no solution . Switch this of to use that until to the frustration was to much . I know that you also had frustation with your previous batteries . I had my problems with my installer .

The solution to my problem was . 1. Replaced 200 Ah battery bank with 300 Ah bank . In your case you are lucky just ad on .

2. Added 3 more 250 watt panels . My total 3750 watt panels . After this for the first time I really have a working system . The extra 750 watt panel have caused no problems .

I know it is more money again but next time we will get it right the first time . Your batteries and panels will be a good investment . Plonkster will have to wait until my Axpert die then I will buy the Blue stuff . Hope the Axpert dies first 

I later installed a 5 Kw Axpert 4500 watt panels with the 300 Ah battery pack . Now running off grid .

 

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23 minutes ago, Chris Hobson said:

you should be able to safely lower setting 13

even lower than 50v?

whilst we are talking; my pylons hardly ever get below 90%soc, is that ok or would they benefit from a good discharge? and if so how low and how frequent?

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40 minutes ago, gabriel said:

even lower than 50v?

I would keep at least 2 V between settings 12 and 13 (Back to Utility and Back to Battery respectively, I hope). Otherwise at night after a few rainy days, you get bypassing with grid charging for too short a time, and the inverter switches too often between battery and bypass modes.

I think that for 15S, 48 V and 50 V are good settings.

Edited by Coulomb

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Well, may be you should expand 2 V to 6 V. Your system is controlled by voltage, not by SOC, and the internal ressistance of the bank makes the system to oscilate todo much.

The discharge Voltage range is 45-54 V, then you can try 46 V and 52 V.

We can't forget that the cut off Voltage of this chem is 2.5 V/cell for the manufacturers i know, as Winston, Calb or Catl. Pylontec increases to 3 V, because they give 6.000 cycles guaranteed.

Edited by Javi Martínez

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It's full at 53.2V. That's what the manufacturer defines as 100%, but you can technically go over that (to 53.8V, at 54V the BMS disconnects) and then you are technically more than 100% full.

I don't know exactly where 20% is, but I'd expect it around 46V, maybe a little more. What you can do is use google to find a voltage vs soc chart of any LiFePO4 sell and just multiply by 15. In my experience, 3.1V per cell is around 25% SOC.

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29 minutes ago, plonkster said:

I don't know exactly where 20% is, but I'd expect it around 46V, maybe a little more

Pylon BMS defines 53,2V as 100%, 50,0V as 10% and 49,905 as 2%.

Further down I cannot assist as the battery switches itself off then ;-)

The rest in 10% increments I have noted down somewhere, but will first have to look for it.

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The voltages for a particular SOC are temperature and load/charge current dependent, and there is a hysteresis. I think there may be a diffusion effect there too.

So quoting the SOC for 2% to 5 significant places is IMHO pointless; it won't be repeatable.

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The SOP for Pylons and Axpert is a cutoff at 47.5V. I have just switched on new monitoring software and will be able to give a more definitive answer oafter a couple of days. I remember that 48V was close to 20% as reported by the BMS.

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57 minutes ago, weber said:

As Coulomb mentioned, we have been working on a set of firmware patches to address this kettle cut-off or premature source switching problem. He also mentioned that we had a major setback when we bricked an inverter in the process. But as of today, I am testing the first working non-bricking development version (YF1_73.00e). Hoorah! But there are some aspects of it that I'd like to run past you gentlemen.

First, we can't decide what to call this feature, KettleKomp™ or AussieBrew™. ;)

Second, we're not sure how well it is going to work on all the many and varied Axpert systems out there. We currently calculate:

voltage_threshold_compensation = battery_current * guestimated_internal_resistance

where

guestimated_internal_resistance = k * (absorb_voltage_setting[26] - float_voltage_setting[27]) / max_total_charge_current_setting[2].

where k is a constant. I tried k = 1 and it was too low, at least for my system. I'm now trying k = 2.

When there are parallel or phased machines, battery_current and max_total_charge_current_setting[2] are summed over all machines.

We're trying to avoid having to provide a user interface to allow setting the internal resistance, as this would be very difficult. This formula is based on the idea that at least some part of the difference between absorb and float voltage settings is due to the internal resistance of the battery causing voltage rise at the maximum charging current.

Axpert owners could help us by telling us how many volts (including tenths of a volt) your battery sags by, when you turn on your kettle; what battery current your kettle draws; and what your values are for settings [26], [27] and [2] (the latter summed over all machines).

Hi I have moved this to a thread of it own as I think it will generate a fair amount of posts and deserved a space of its own. (I included it here otherwise it seems odd but please repond on the other thread (@gabriel - you beat me to the bell so your comment stays :D).

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11 hours ago, gabriel said:

that's a good one, i'd rather help with a name than the math :ph34r:

Hi Gabriel. So which of those two names do you prefer? :)

You don't need to do any math. You can help us to help you by just telling us your battery voltage and current, immediately before and after turning on your kettle. And tell us your settings [26], [27] and [2] (absorb voltage, float voltage and max total charge current).

Please start the ball rolling in the new thread, here:

https://powerforum.co.za/topic/2544-axpert-kettle-voltage-sag-data-request/

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On 2018/11/08 at 2:27 PM, Riaanh said:

Pylon BMS defines 53,2V as 100%, 50,0V as 10% and 49,905 as 2%.

Further down I cannot assist as the battery switches itself off then 😉

The rest in 10% increments I have noted down somewhere, but will first have to look for it.

What settings do you recommend for a Infinisolar 4KW inverter? 

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