PIP-4048MS and PIP-5048MS inverters

[Adverse Effects]

I have several of these, cheap and very good quality clone. Plus it has serial out, no crc requests required
http://s.aliexpress.com/vuUV7fyQ

fixed the link

12 V 24 V 48 V 60A MPPT controlador de carga solar MPPT150I60A com verdadeiro MPPT fuction

[lopezjm2001]

That's great news, John. I look forward to hearing how the modified version goes.

I think it is safe to say my PIP4048MS went into float mode. Thanks.

[solamahn]

Latest Job
48 x 300w MPPSolar PNG panels
16 x 10A DC breakers
2 x 20A RCBO, 2 x 10A mcb
Generator connection
2 x 4048MSD inverters in parallel
32 x 400Ah CALB Lifepo4
28 x 18w 1200mm LED tubes
4 x 50w LED spotlights on daylight sw
14 double GPO's
12 switches
Earth stake

[weber]

Sounds great. What about battery fusing and isolation?

[solamahn]

None

[offgridQLD]

Yikes....Hopefully for the unlucky person it's a quick death then with no interruptions.

[coulomb]

The PIPs do have a 200 A fuse in them. I've now heard of one of them blowing [ Edit: but that might have been an external fuse ] (on the South African PowerForum inverters forum), so there is that protection.

[andys]

There seems to be a minor bug/issue with the charge logic:

Given these conditions:

1. recharging is nearly complete or already completed and on float, and
2. high AC load (3-4kW), and
3. high PV input (3-4kW)

If the load suddenly gets removed, the charge voltage seems to spike really high as it dumps kilowatts of excess PV input into the already-charged battery.

It takes 10 seconds to ramp down the PV input back to low levels and during that time the battery voltage goes high above float.

I don't really have a problem because I'm on LiFePO4 and I only charge to 90-95% so can easily soak up the excess charge.

But I imagine this would be bad if it happened repeatedly, or if you had a Lead Acid pack which had high resistance due to a recently finished charge cycle, the voltage must skyrocket?

[Northland]

LEAD ACID PARADOX

So I was having a debate with someone on another forum.

He was charging his agm bank at night using off peak (no solar), then running his pip during the day. I explained that this was costing him money instead of saving it.

He strongly disagreed, explaining to me that agm was 100% efficient, if he put 100Ah in, he can get 100ah back out.

Knowing this to be false, I showed the math. I tried to find research to disprove the amps in vs amps out theory. But it seems this conversation is a first. I could not find anything one way or the other. Then by accident some time later I came across this scientific study
See the highlighted areas below



If you operate your batteries between 100% and 80% SOC, then you will extract LESS THAN 50% of the energy put in to them.

[offgridQLD]

Yes shallow cycling a big led acid bank gives terrible round trip efficiency.

From memory (need to check as I haven't checked it in a long time)After a lot of fiddling and trial and error I settled on something like 98...99% efficiency setting on my lithium bank.

Kurt

[antiscab]

You'd have to include the inverters own round trip efficiency

yeah, charge off peak to support peak loads is a bad plan

[Johny]

You'd have to include the inverters own round trip efficiency

yeah, charge off peak to support peak loads is a bad plan

Currently true, however most of the electricity suppliers have put forward schemes to attempt to cut peak load by heavily penalising users who exceed their average usage by (insert formula here). The Victorian Minister for Energy has only agreed if it is an "opt in" scheme - which is kind of useless.

Anyway - in this case, charging a modest bank off-peak and supplementing the 5PM->8PM heavy use would be encouraged by suppliers.

The Grattan Institute published a paper on this:
https://grattan.edu.au/report/fair-pricing-for-power/

[offgridQLD]

I was talking about the battery charging metering eficiancy measured from the Solar charge controllers. As in take a measured 2.5kwh out from the bank (DC) then return 2.5kwh DC.

(not DC kwh in from PV vs AC out from a inverter) That gets nasty even with the high efficacy of lithium (particular with big inverters running small loads)

[Northland]

Let's say you want to use 1kw to charge. Just by having the pip connected, you waste 50w. So the actual consumption is 1050w.

Let's assume the charger is 90% efficient. Your 1000w is now 900w.
Your batteries store 50% (being generous) of that 900w. It's now 450w.
When you run the inverter from the batteries, you again pay a 50w penalty. You now have 400w.
The inverter is about 90% efficient. It's now 360w.

1050w in, 360w out. 34% efficiency.

That's assuming no large loads which will give a much worse result. Also ignored is the life used up in the batteries and inverter, which typically costs between 10c and 15c per kwh.

[Northland]

I am also in a discussion with a guy who must be one of the top 5 in the world re battery technology. He consults to SpaceX and Nasa. I asked him about the most efficient way to use lifepo4 with a secondary consideration being life. He suggests going to 17S, read below:

"I haven't tested the specific cells you are referencing .. and cells will vary .. even in the LiFePO4 family there are variations ... that having been said. The testing that I did showed of a different LiFePO4 cell .. showed maximum cycle efficiency at the lower SoC/SoE parts of the curve .. Bottom ~20% was about ~96.5% Energy cycle efficient , and about ~99.5% Coulomb Ah cycle efficient ... By the top ~20% it was down to about ~95% Energy cycle efficient , and about ~98.8% Coulomb Ah cycle efficient. However .. even the same cells under different conditions can also effect the results ... For Example .. Other research I've seen done showed a change of 0.2% more Coulomb Ah Cycle Efficient 99.8% vs 99.6% and simultaneously 3.6% less Energy Wh cycle efficient 95.6% vs 92% ... when the same LiFePO4 cell was cycled at 21A instead of 105A ... the higher rate increased the Coulumb Ah cycle efficinecy , but simultaneously decreased the Energy Wh Cycle efficiency. If you batteries behave like the one's I've tested .. 60.4v top end (CV portion) for 16s1p pack is making a choice to chase the last top tiny bits of available energy , and give up some Years & Cycles of service life to get it ... if that's what you want for your application is up to you. Exactly how much will depend on context ... for example .. how fast you reach that top CV point ... For example .. the cells I tested .. At a 3C (CC) charge rate ... the 3.50V point was only about ~80% SoC ... but the same 3.50V at a slower 2C charge rate was about ~90% SoC ... and the same 3.50V at a even slower C/2 (CC) rate was about ~96% SoC ... At the slower C-Rate (CC) charge rates you listed ... there is very little (less than 5%) to be gained from pushing the CV phase above 3.50v ... unless your intent is to try and skip or reduce the amount of time in the cv phase .. than a higher CC voltage is ok. Keep in mind ... the longer the amount of time .. the cells are held at a higher SoC/SoE ... the shorter the service life (years/cycles) ... but the trade off is that you have more available Wh or available energy to do useful / desired work. If your design needs the higher voltage up near ~60.4v ... than 17s1p would be better (at that CV point) for pack longevity (Years/Cycles) .. going to 18s1p @ 60.4v (CV phase) is too low (I think) of a per cell v ... I wouldn't go under 3.45 (3.40 at lowest) ... it's just a case of diminishing returns .. sure 3.35v (CV) from 18s1P would be 60.3V .. and that is closer to the middle .. and such .. and yes it would likely give more years/ cycles .. but now your whole pack is closer to the middle .. and the usable Wh of energy storage is closer to the middle .. etc .. 1 more cell from 16s1p @ 60.4v (~3.775v per cell) .. to 17s1P @ 60.4v (~3.55v per cell) .. that has I think .. a bigger (more worth) benefit to total service life (years / cycles) .. but at the same time , it gives up very little in terms of usable Wh of energy storage ... as long as you have a CV phase at that top ~60.4v .. and you are only doing the CC phase at the low C-Rates you listed .. and also assuming the pack won't be significantly cold or hot. Colder means less usable W of power , or Wh of energy storage , but more cycles and years ... Hotter means less years and cycles , but more W of power ,and Wh of energy storage .. usually around ~room temp is the middle ground .. and there are costs of keeping the battery colder than __ and warmer than _ ... exactly when and how much it's worth thermal management is again a pro and con choice."

[paulvk]

I read a paper on lead acid and efficiency they found that at 80% charge the highest efficiency was achieved, they also found that with proper full charges at the correct times battery life was not to adversely affected.
I would like to read the same sort of tests of nickle cadmium pocket cells because what I have read so far is that by only using 15% battery life in excess of 25 years is achieved and there are batteries still in use at 50 years also I have read that there are no thermal run away problems, no memory and few deep discharges to 80% does not cause a great reduction in life.

[Northland]

But they have the worst efficiency. Something like 2v charge and 1.4v nominal? Efficiency is #1 in my book

[PGutti]

What tool is used for updateing the firmware? Watchpower does not have this option.

[coulomb]

The tool for doing the update is part of the zip or rar file that has the update.

I should stop calling my patched firmware a patch; it's a complete patched firmware file. The official patches also include the patch tool, and instructions.

[Solar Junky]

Hey guys! Got two pip's going in the USA using a step down transformer & lifepo4 batteries. What float & charge voltage settings are you guys using for the lifepo4 cells?
this is my system https://www.youtube.com/watch?v=K7OaZ3tzMxk



[ Edit Coulomb: added Tube tags ]

[lopezjm2001]

I hope your battery cabinet is fire-proofed. I use 54.7v for bulk charge and 53.7v for float charge.

[Solar Junky]

Awesome Thanks!!!
Not fire-proofed made of wood.

[weber]

Hi Solar Junky. Thanks for showing us your system. For 16 series 180 Ah LiFePO4 with one PIP and a 3.4 kW PV array (the "Black Monolith" mentioned earlier in this thread) we use:
Bulk/absorb voltage = 55.2 V (3.450 Vpc) (Param 26)
Float voltage            = 53.7 V (3.356 Vpc) (Param 27)
Low cutoff voltage   = 50.8 V (3.175 Vpc) (Param 29)

We also have a BMS that monitors individual cell voltages and controls contactors to disconnect the loads if any cell goes undervoltage or overtemperature while discharging, and disconnect the charging sources if any cell goes overvoltage or overtemperature or undertemperature while charging.

[Solar Junky]

Cool! Thanks!
Does that require your firmware for those settings?

[Solar Junky]

What kind of BMS are you using??