What's Your Battery Round Trip Efficiency?

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Al asked Dec 17, '21

What's Your Battery Round Trip Efficiency?

I've always wondered how we fared compared to others, either Pb or Li etc with our second hand Hoppekke 2v Flooded lead acid cells, this will not be very scientific and quite a few factors will skew the results, but it would still be interesting to compare for fun.

We have:

Hoppekke 930Ah (C5) x 24 = 1,860Ah (C5) @ 24v / Quattro 8k (batteries probably 4-5years old)

VRM / Connect Battery History:

For the lazy maths calculation: https://percentagecalculator.net/

So for my 5 year old-ish FLA's roughly 85%

That's mine, what's yours!? Imaginary prizes for the most efficient and the least efficient :)

battery

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Al commented · Dec 18, 2021 at 05:06 PM

I was interested in starting this after @JohnC posted his RTE https://community.victronenergy.com/questions/112125/what-goes-into-the-battery-and-what-did-i-take-out.html

I think we have similar banks and there aren't many real world comparisons that I've seen. My old ex 420Ah forklift bank was averaging 76% before I gave it away as scrap to a friend but that's still working perfectly for his much smaller needs. That really doesn't compare to the dream of closer to 98% for Alexandra's though!

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Alexandra answered · Dec 17, 2021 at 07:10 PM

@Al

An interesting comparison for sure. The FLAs are on point.

We are running 12v Blue Novas BN108ah lifepo4 and have cycled/experimented with them between 24v and 12v systems over about 2 years now same bmv though.

using the lazy calculator ....

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Al commented · Dec 18, 2021 at 04:57 PM

You're Currently winning @Alexandra! :) It would be great to see more people with similar systems, it's already looking like it will be quite varied.

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klim8skeptic answered · Dec 18, 2021 at 09:00 AM

4 Winston 300ah cells, 34 months use off grid.

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multivictor answered · Dec 18, 2021 at 03:25 PM

MultiPlus-II 48/5000/70-50 + 1 LiFePo4 BYD LVL 15.36 kWh + Solarsystem SMA 5000 TL /5.6 kWp .
Monfofase 40A + N grid connection.

System started on 01 october 2021.

Disapointing results so far:

Oktober: RTE 69.78% - November: RTE 73,13 %.
01-10-2021 => 17/12/2021: 241.5 kWh charged - 171.2 kWh discharged. RTE 70.89 %

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Al commented · Dec 18, 2021 at 04:52 PM

Hi @MultiVictor have you been manually writing down monthly your results to check your RTE? - It does seem low for LiFePo4?

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multivictor Al commented · Dec 18, 2021 at 07:01 PM

Ik know it's low. :-( System is only three months old.

I didn't take notes manually. I used the real time data shown in the VRM dashboard.

To battery 259 kWh - from battery 180 kWh => 69.5%.

Did I calculate something wrong?
Can't I use the VRM data?

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Al multivictor commented · Dec 18, 2021 at 07:12 PM

Ahh, @MultiVictor do you have a smartshunt / BMV? Look at battery history in VictronConnect or in advanced on VRM to get the totals. I think you'll then be happier ;)

The dashboard of VRM doesn't add everything up, it doesn't currently show how many kWh from a generator have charged the batteries for example, but the accurate totals are shown in battery history.

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multivictor Al commented · Dec 18, 2021 at 07:35 PM

Thx for the tip! I don't have a generator. The battery system is only charged from the solar system. It's a grid connected system.

I have already noticed that the VRM dashboard is probably not working properly.
Ik have also an issue with differences in measurement between the solar/consumption tab and the system overview tab.

I'l try to get acces to VictronConnect or find the correct data in the advanced section on the VRM dashboard.

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multivictor Al commented · Dec 18, 2021 at 07:47 PM

I looked in the VRM advanced section but can't find a widget that shows battery in and outs?

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Al multivictor commented · Dec 18, 2021 at 07:55 PM

Advanced>battery Monitor>battery History - Then scroll down to Charged and discharged Energy

But only if you have a BMV or Smartshunt in the system?

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peter1 multivictor commented · Dec 19, 2021 at 08:16 AM

You also have to take into account the SOC at the beginning and the SOC at the end of the period you are calculating.

Also Ivo you are calculating RTE on the AC side, others here are calculating the RTE on the DC side. That is a big difference.

Normaly you should get around 75% RTE on the AC side with your system.

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multivictor peter1 commented · Dec 20, 2021 at 09:56 AM

Thx Peter. Indeed it is an AC connected system.

(Solar to SMA inverter and battery to Solar and 1x 230V grid via Multiplus II). The real RTE (for my installation) is what goed in on the solar side (no load via grid) and comes out to the AC loads).

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multivictor commented · Dec 21, 2021 at 05:51 PM

Now I used the "History" data shown in the remote console of the ESS system:

- PV output: 431,2 kWh
- Battery input: 238,3 kWh
- Battery output: 230,1 kWh
RTE result: 96,5 %
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On VRM dasboard:
- PV output: 434 kWh
- To Grid: 37 kWh
- Direct AC use: 143 kWh
- Battery input: 261 kWh
- Battery output: 181 kWh

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marekp answered · Dec 18, 2021 at 04:12 PM

@Al

400Ah LiFeYPo4 Winston 48V

95.82%

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ianddindustries answered · Dec 19, 2021 at 05:22 AM

Hi. We have a system in a coffee van that consists of a 300 amp victron lithium and a 3k multiplus. It is 3 years old and runs at about 95%. Uses about 50% of the battery 5 days a week

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Al commented · Dec 19, 2021 at 11:46 AM

95% :)

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Modifications Space

Node Red Space

Answer 1 · 2021-12-19T14:49:05Z

taavij answered · Dec 19, 2021 at 02:49 PM

4 Pylontech US2000b offgrid use and 2,5 years old. BMV 702 is doing measuring work, but I have doubts its accuracy.

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Answer 2 · 2022-07-09T18:02:23Z

soky answered · Jul 09, 2022 at 06:02 PM

Hoppecke 200 Sun Power VRM 6V in 48V system, during 4 years -> 84.6 %

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Answer 3 · 2022-07-09T22:04:51Z

Marco Nijholt answered · Jul 09, 2022 at 10:04 PM

6x Victron Lfpo4 200Ah 25v Smart batteries (30kwh)

96.31% based on this, its currently 100% SoC, i believe i got it with 50% SoC (30kwh bank). Then we'd get to 97%

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