I didn't top balance my packs before installing

[Joeboy]

Had a quick look this morning. If you know about PTech 88% and above readings, then you know.

If you don't, Pylontechs have a habit of sticking at 88% SOC for a long time then make a leap up towards 89% then very swiftly hit 100%. In my case they will stay at 100% and charging as power is flowing from the Ptechs to the LF280's.

Last night due to the low temps and low starting soc the stack hit 88% and stayed there for 45mins before 05.30 trigger and it then started to discharge.

Looking back to a better starting soc graph and thus hitting 88% earlier in the charge window I can see that the stack would sit at 88% soc for 2hrs 50 minutes given the chance. How long it would sit at 100% given the chance i don't yet know but i do know know that i'd quite like that extra 7kWh of power to be in the stack. Roll on delivery of the 1500W charger...

[Tinbum]

Mine do it at 89% give half a chance.

[Stinsy]

Had a quick look this morning. If you know about PTech 88% and above readings, then you know.

If you don't, Pylontechs have a habit of sticking at 88% SOC for a long time then make a leap up towards 89% the very swiftly hit 100%. In my case they will stay at 100% and charging as power is flowing from the Ptechs to the LF280's.

Last night due to the low temps and low starting soc the stack hit 88% and stayed there for 45mins before 05.30 trigger and it then started to discharge.

Looking back to a better starting soc graph and thus hitting 88% earlier in the charge window I can see that the stack would sit at 88% soc for 2hrs 50 minutes given the chance. How long it would sit at 100% given the chance i don't yet know but i do know know that i'd quite like that extra 6kWh of power to be in the stack. Roll on delivery of the 1500W charger...

I see this "sticking" at 88% too. And heard it described by others too.

I've always seen it as a symptom of the inherently inaccurate reporting of charge percentage. My guess is that the batteries hold a constant voltage while being charged. So while the actual amount of charge being held by the batteries increases this cannot be reported because the voltage stays flat.

[Saladin]

I've always seen it as a symptom of the inherently inaccurate reporting of charge percentage. My guess is that the batteries hold a constant voltage while being charged. So while the actual amount of charge being held by the batteries increases this cannot be reported because the voltage stays flat.

Agree. Specifically it's when a device is using voltage to infer SOC as opposed to the more accurate and expensive correct way of measuring it using a coulomb counting device or Ah counter.

You can always fit one externally.

I heart SImarine. Here's a cheap and cheerful alternative.

You can get away with voltage derived SOC with Li-ion. You definately can't with Lead Acid.

[Stinsy]

I've always seen it as a symptom of the inherently inaccurate reporting of charge percentage. My guess is that the batteries hold a constant voltage while being charged. So while the actual amount of charge being held by the batteries increases this cannot be reported because the voltage stays flat.

Agree. Specifically it's when a device is using voltage to infer SOC as opposed to the more accurate and expensive correct way of measuring it using a coulomb counting device or Ah counter.

You can always fit one externally.

I heart SImarine. Here's a cheap and cheerful alternative.

You can get away with voltage derived SOC with Li-ion. You definately can't with Lead Acid.

Seeing as the percentage displayed is more for our entertainment because we're used to seeing our phones and laptops displaying it in that manner, then it doesn't really matter!

[Tinbum]

I've always seen it as a symptom of the inherently inaccurate reporting of charge percentage. My guess is that the batteries hold a constant voltage while being charged. So while the actual amount of charge being held by the batteries increases this cannot be reported because the voltage stays flat.

Agree. Specifically it's when a device is using voltage to infer SOC as opposed to the more accurate and expensive correct way of measuring it using a coulomb counting device or Ah counter.

You can always fit one externally.

I heart SImarine. Here's a cheap and cheerful alternative.

You can get away with voltage derived SOC with Li-ion. You definately can't with Lead Acid.

I think the pylontech do coulomb count.

[Saladin]

If that's the case it's a function of increased charge time due to diminishing charge current after the transition to CV absorption.

Phones and laptops have an compensatory algorithm. But that stops working as soon as the aging atrophy makes the batteries behave erratically.
e-bikes just use voltage to infer percent so I change the display to read voltage so I can use my noggin' instead and compensate for load/no-load.

It's pretty obvious to spot which it is, based on it's behaviour....eg. the percentage reserve raises when the load is dropped = voltage inference.

It mattered in lead acid days because charge completion at 90% SOC versus 120% SOC was the difference of 8 years extra service life.

[Andy]

This shows the 88% pause that the batteries did right from the start. I couldn't find a constant current example, but you could almost continue the prior charging straight line from 88% up to 100%. It was very strange behaviour. I read somewhere that it is balancing in that time.

[Andy]

Never turn off the PSU with the battery connected to the output you can damage it without the opposing voltage..you can use a diode to protect it but that'll mess with the meter accuracy. That said you need an highly accurate meter for this, it's unlikely a PSU display meter will have high enough resolution.

Hrrrrm, this is what I was doing with the Eltek. I used a smart switch to turn them off. It is still alive, but I am assuming from what you are saying I should leave it on but command zero current?

[Saladin]

I damaged the display output on a PSU charging a battery and letting reverse current into the PSU after turning it off.
The higher the voltage of the battery the more likely you are to do harm.

You often get away with cells because the potential difference isn't that great.

Elteks are probably diode protected outputs because they're designed to be paralleled.

It's best practice to disconnect the PSU before you turn it off so current always goes to the battery instead of into the PSU.

Horses and courses depends on the PSU topology and potential difference whether there's an issue or not.
I'd be super cautious with anything over 12volt.

Shyt rolls down hill: current goes from higher voltage to low.
A good example of this is the way grid tied solar intrinsically goes to your domestic load before the grid.