Lead Crystal vs Lead Acid Battery testing

[MJLorton]

I have just changed over to the lead acid battery to see how well it does for the next two weeks on the "Automated Battery Killer!" : http://www.youtube.com/watch?v=B74IvpUlQ0Y

I have started compiling the raw data and it is still very much a work in progress but I thought I would post it here for those that might want to see it.

[SeanB]

From my experience the SLA battery will degrade from around 5 full cycles, and will have almost half the capacity gone by around 20 cycles. Especially the cheap chinese ones like you have ( and which are about the only ones you can buy in SA).

You do get fake ones of these, where there is only a single plate for each pole, the rest being taken up by polystyrene sheet.

[MJLorton]

Latest results and information related to the video: "Lead Crystal vs Lead Acid Battery - Which is best for Solar Power?"


This is a test to see if a lead crystal battery lives up to the claims that it can be cycled to full depth of charge (and beyond) without too much harm. I'll log the results and compare to a standard lead acid battery.

Thanks to ExSolar for the Lead Crystal battery used in this test: www.exsolar.co.za

More info on Lead Crystal Batteries:
http://www.deltecpower.co.za/sites/deltecpower.co.za/files/Deltec%20Lead%20Crystal%20-%20Brochure.pdf

Items used or mentioned in this video:

* Metrix MX3282 Graphical multimeter with data logging, dual channels for power measurement.
* 220 volt mains relay - double pole, double throw.
* 12 volt car / auto light.
* Battery Tender / Power Tender Plus 12V Compact Charger
* How does a deep cycle work?
* How does a car battery work?
* What is a lithium iron phosphate (LiFePO4) battery?  (also called LFP battery)
* http://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery
* Charging of solar power battery bank.
* Trojan golf cart batteries.
* How to solar power you home / house?


I'll continue testing and hope to add a Gel battery to the test as well.

Anyone wanting to see more on  lithium iron phosphate (LiFePO4) battery testing should watch Dacian's video (ElectroDacus):

LiFePo4 A123 Systems, best rechargeable Battery 18650 for EV, Solar, Wind and more -> https://www.youtube.com/watch?v=ZWxPDnQMC04
A123 20Ah prismatic LiFePO4 battery for solar and wind energy storage -> https://www.youtube.com/watch?v=GpQcrvRoigc

Cheers,
Martin.

[jpscales]

Hi Martin
Excellent and useful results. I am installing 48 off 1000Ah lead crystal batteries at my home pv installation in Buawayo and really wanted to see what your initial tests showed

Please consider treating your "failed" 18Ah lead acid battery with EDTA and installing a desulphator across same with a view to seeing if this battery can be recovered or restored into useful life again. As I understand it, the EDTA dissolves the crystalline PbSO4 thereby removing the plate "cancer" and exposing full surface area to udeful life. I have been trying same on failed deep cycle batteries but am working blind not knowing how long, how much etc.

The desulphator should (theoretically) stop the Crystalline PbSO4 forming in the first instance ensuring it remains in its reversible amorphous form

The results are promising so far. Kind regards, Julian

[MJLorton]

Hi Martin
Excellent and useful results. I am installing 48 off 1000Ah lead crystal batteries at my home pv installation in Buawayo and really wanted to see what your initial tests showed

Please consider treating your "failed" 18Ah lead acid battery with EDTA and installing a desulphator across same with a view to seeing if this battery can be recovered or restored into useful life again. As I understand it, the EDTA dissolves the crystalline PbSO4 thereby removing the plate "cancer" and exposing full surface area to udeful life. I have been trying same on failed deep cycle batteries but am working blind not knowing how long, how much etc.

The desulphator should (theoretically) stop the Crystalline PbSO4 forming in the first instance ensuring it remains in its reversible amorphous form

The results are promising so far. Kind regards, Julian

Hello Julian,

Thanks for your post, very interesting to hear what you are doing.

I will certainly look into treating the lead acid battery with EDTA. It's certainly not something I had considered or know much about.

If you have the time please post a picture(s) on your setup as I'd love to see what it looks like.

What are your power requirements and what are you installing?

Cheers,
Martin.

[jpscales]

If you would like to learn more and would like to build your own desulphating device you can with a Google search "Lead Acid Battery Desulfation"

I am installing 40 x 290W panels (two strings of 20) into a 12kW Sunny TP SMA invertor. I propose to have a battery back up of 48V and hence have purchased 48 2V 1000Ah lead crystal batteries (two banks of 48V in parallel) which will drive 3 x 5kW Sunny Backup invertors complete with the interface with the grid enabling me to access the REFIT tariff once it becomes available in Zimbabwe. I have attached a picture of the set-up and will document its installation.

[MJLorton]

Excellent. Thanks again for all the info. I look forward to following the installation.

I'm about to post some of the latest results I have from my lead crystal battery testing and they certainly seem to be doing very well thus far.

Cheers,
Martin.

[MJLorton]

The testing still continues but here is a snap shot of the results so far....36 cycles and still going....

I'm doing a "recovery" charge cycle i.e. a small discharge and full charge for a couple of days to see if this brings them back to the original state....then I'll start the abuse again.

[anieuwstadt]

Hi,

May I suggest that the performance of the batteries be compared using Wh instead of Ah, as comparing Ah does not take into consideration the differences between the nominal and under-load voltages of the batteries. The nominal voltage of LC battery is higher and therefore delivers more Wh that its AGM, SLA, or Gel counterparts when using a non-constant power loads.

Whilst the voltage difference appears to be small, over time and a few 1000 cycles, the "throughput life" of the battery in Wh will be higher.

Warmest regards
  Andre

[MJLorton]

Hi,

May I suggest that the performance of the batteries be compared using Wh instead of Ah, as comparing Ah does not take into consideration the differences between the nominal and under-load voltages of the batteries. The nominal voltage of LC battery is higher and therefore delivers more Wh that its AGM, SLA, or Gel counterparts when using a non-constant power loads.

Whilst the voltage difference appears to be small, over time and a few 1000 cycles, the "throughput life" of the battery in Wh will be higher.

Warmest regards
  Andre

Hi Andre,

I totally agree with you in terms of using Wh instead of Ah. I have said this in previous videos on battery testing. I used Ah on the "summary" page of the collated data just to "keep it simple" but I have logged the Wh as well. You'll see this data in an earlier post.

I think I'll change the summary data to include Wh to paint the full picture.

Thanks for the post.

Cheers,
Martin.

P.S. Where you the Sysop for XYZ BBS?

[anieuwstadt]

Hi,

No I was not, we may have touched base somewhere else.

Warmest regards
  Andre

[anieuwstadt]

Hi,

Congrats on the installation. I spoke with Ex Solar about the size and length of the linking cables and keeping the batteries in balance.

I cannot see from the video, but it is very important that the interlinks present the batteries with equal paths otherwise over time the imbalance will cause premature degradation of the battery bank.

Another important safety item is that the cable must be able to carry the fault current of the battery bank. The lead crystal batteries have a very low internal resistance and the 150Ah battery will have  fault current of about 3kA which makes the combined fault current some where in the region of 6kA. This means that the cables should be in the region of 25mm˛ in size or larger. (check the cable manufacturers specs). Sometimes only voltage drop is used to determine the cable size and fault states are not considered.

I am not sure what charger has been set to, but to take advantage of the lead crystals, I suggest the following:
 - Absorption voltage ideally should be a little higher than normal and should be about 58.4V
 - Float would be 55.2V
 - Turn off "storage mode"
 - Absorption time: 6 hours unless proper temperature compensation has been configured and the battery enclosure/setup ensures that the batteries have all surfaces within a couple of degrees of each other. If the thermal aspects have been addressed, the absorb time can be lengthened without significant increase in battery degradation risk.

If the thermals issue are adequately dealt with, there will be no need to the use the Victron "safe" charge function.

Consider increasing the gap (5-8mm) between the batteries so that the common faces are kept at similar temperatures to the outer faces.

Warmest regards
  Andre

[MJLorton]

Hi Andre,

Thanks very much for the valuable input. I think you have touched a few points that I need to check and address....

I really appreciate the post.

Cheers,
Martin.

[SeanB]

Martin, go buy more of that light duty racking you are using for the batteries, and use it to make some matching shelving in the garage as well. Better than the Makro stack boxes that are there, and can handle more. They are not terribly expensive from any shelving supplier, shop around for some prices, and beware of those that give a 500 page glossy catalogue in the post...................80% premium for the free catalog, but good to show what is there.

[MJLorton]

Martin, go buy more of that light duty racking you are using for the batteries, and use it to make some matching shelving in the garage as well. Better than the Makro stack boxes that are there, and can handle more. They are not terribly expensive from any shelving supplier, shop around for some prices, and beware of those that give a 500 page glossy catalogue in the post...................80% premium for the free catalog, but good to show what is there.

Yes...good idea. I will do at some point.