Traction vs. Stationary FLAs

stephendv

What are the differences between FLA traction batteries (e.g. for forklifts) and stationary FLA batteries for use in backup, telecom and solar applications? The former are usually called "PzS" batteries and the latter "OPzS" (in Europe anyway). I know many on the forum are quite happy with their used traction batteries - would you still consider them a good buy if they were new and more expensive?

The traction bats also seem to have a choice between thinner plates but more of them, or fewer thicker plates for the same given capacity. (The total amount of material in the electrodes stays about the same). The Battery FAQ says thicker is better, but does it take the number of plates into account?

I don't know enough about how batteries work to compare, but here's an example from the same manufacturer for 2V 810Ah (C10) cells of type OPzS and PzS:

Stationary:
- 7 OPzS 811Ah with 7 plates, 42kg without electrolyte, 60kg with.

Traction:
- 9 PzS 810Ah with 9 plates, 37kg without electrolyte, 46kg with
- 5 PzS 750Ah with 5 plates 31kg without electrolyte, 41kg with
- 10 PzS 800Ah with 10 plates 35kg and 44kg

The stationary batts are heavier even though they're rated to the same capacity (I double checked, they are all rated at C10). Then there's also a difference in the amount of electrolyte in the cell: almost double in the stationary batts!

I think market forces will always keep the traction batts at a lower price than the more specialized stationary ones, so the question is - if you had to spend good money on new FLA batts, would you still consider traction ones?

BB.

Re: Traction vs. Stationary FLAs

You really need to look at the specification sheets for each battery...

Some will take lots of deep cycling (like traction batteries) but need a fair amount of service (adding water, etc.) and they may have a more limited life time (years in service). Also, Fork Lift and Traction batteries seem to "waste" more energy in charging (heating and equalization) and seem to probably have more self discharge losses--especially after the batteries get well aged (and some batteries are intended for "standby" operation--little cycling except in "emergencies").

The other extreme (Telecom Batteries) can use less water, have incredibly large cycle numbers and 40 years of life in service... However, they may only be designed for cycling from 100% to 85% (no deep cycling) to get those incredible lifetime numbers.

Lots of "hand waving" here--but that is what I have seen when looking through specifications and reading about user experiences in the past.

The different types of batteries have the place--And it is important that your usage not fall outside their operational envelope.

Throw AGMs (sealed) batteries into the mix--and there is a lot to choose from. Since batteries are expensive to ship--checking with your local battery distributors for their recommendations and what they stock would be a good idea (if you can get the same batteries 7-10 years later--you don't have to reconfigure you battery bank hardware).

-Bill

icarus

Re: Traction vs. Stationary FLAs

Traction batteries are subject to significant vibration and (I would guess as I don't know!) that the plates might be thicker as a result. They are also subject to much more regular cycling.

Stationary telecom batteries may go their entire service live never having been cycled significantly.

Tony

Cariboocoot

Re: Traction vs. Stationary FLAs

Cost and availability should be considered too. Every type of battery has its advantages and disadvantages. Deep cycles don't produce 'quick surge' current like automotive batteries. But auto batteries will fail rapidly in the AE application's repeated deep discharge/recharge. Telecom batteries being rated for only 25% DOD, which may do on a solar power system. But ...
Most of the time you'll find the electro-motive force batteries are easy to obtain, relatively inexpensive, and will do the job well - including standing up to 'abuse' such as occasional 50% DOD or slightly incorrect charging voltages.

stephendv

Re: Traction vs. Stationary FLAs

Just to clarify that both types of battery I'm talking about here are deep cycle, vented, flood lead acid's. (Sometimes terms like 'telecom batteries' could refer to FLAs, GELs and AGMs).
I had an interesting chat with a manufacturer this morning - he says that in principle the electrical and chemical properties of the batteries are identical, the main difference is that the traction batteries are limited in size and so can't hold as much electrolyte - therefore they'll need more topping up. Also, as Icarus was saying, the tractions are mechanically more robust to handle vibration and movement.

BUT because they produce many more traction batteries, the price will always be lower than the stationaries - and the difference in price could mean that I could afford a bigger capacity traction battery, with the caveat that I'll have to water it more.
Life expectancy characteristics is the same for both types (from the same manufacturer and assuming they're both well looked after).

Dave Angelini

Re: Traction vs. Stationary FLAs

In Marine the batteries from Surrette are built for healing (tilting off axis) and do have a little less electrolyte capacity do to the extra material to protect the battery from vibration as well as keep the electrolyte over the plate while healing.

In your design take a look at the 2V cells these folks are coming out with. Trojan also has them. I don't know if 1000ah @2V on the 20 hour rate is the right capacity for you but take a peak!

stephendv

Re: Traction vs. Stationary FLAs

Thanks for the input guys. Just an update that I've received a quote for the traction and stationary batts from the same company:
- Tractions are 30% less than the same capacity stationaries
- Tractions are 50% less than the same capacity Rolls Surrette 5000

On another note, some of the traction manufacturers also sell electrolyte circulation kits with their bats (which seems to be just a pump that pumps air into the electrolyte to mix it up). One manufacturer claims 20% more efficient charging using this system and longer life (because the plates wear away evenly rather than wearing down on only one part because of stratified electrolyte). I guess it's also advantages as you don't have to do equalisation charges as often.

Anyone use systems like these? Or DIY versions of them?

Dave Angelini

Re: Traction vs. Stationary FLAs

It is my opinion that all aftermarket equipment that is sold for batteries is just a waste of money. Bubblers, desufators and anything else that is not sold by the battery manufacturer is probably a waste of money.

If you have never lived offgrid before I would tell you to buy the best. Others will tell you to buy a "training" set of batteries but if the system is well thought out it will just be duplication of effort.

You will get what you pay for and this is especially true with batteries. Living offgrid has plenty of challenge so batteries should not make being successful more of a challenge.

stephendv

Re: Traction vs. Stationary FLAs

Hi Dave, yes I was originally going to go directly for the Surrette's because of their reputation, but money is tight and I really want to stretch my euro as far as it'll go. So while I'll grant that the Surrettes are probably 'better' than the tractions, it's a question of how much better? With the quotes I have, they'd have to last exactly twice as long to be worth it - which I find hard to believe given how well other off-gridders are doing on used sets of traction bats.

I may be speaking out of my a$$ here, but I don't think there can be that much difference between batteries using the exact same technology. These traction bats are tubular plate flooded lead acids designed for deep cycling up to 80% with antimony added to the plates. Different manufacturers could bring out products that differ in maybe a few percentage points - but a 50% difference is hard to swallow.
While I don't want to complicate my off-grid adventure, I _do_ want value for money, especially when I could invest it in other balance of system components, like a bigger PV array.

In the case of this particular traction manufacturer, the air bubbling kit is actually sold by them as part of the battery system, details in their leaflet (under Airlift): http://www.sunlight.gr/Uploads/PZS.pdf

Dave Angelini

Re: Traction vs. Stationary FLAs

The model I am talking about is the S1380 and it is a 4000 series L16. It is near 1050 AH @ 20hour rate. This is easy to move, well 117 pounds is never easy but this is where I draw the line for my customers.

Oh yea, I think there is a huge difference and expect 10 to 15 years life out of what I buy. You know what? I get it and I have before!

PS apples and oranges. Make sure you are comparing the same charge rates. We use C20 for solar!

BB.

Re: Traction vs. Stationary FLAs

From what I have seen, the "gadgets" that do improve battery life/performance/efficiency:

1. Remote Battery Temperature Sensor equipped Charge Controllers (both solar and grid powered).
2. Battery Monitor--Allows owner to monitor battery capacity 24x7 without needing a hydrometer or resting batteries for a few hours and using a DMM to measure voltage.
3. AGM Batteries: Much more efficient than flooded cell batteries (very little/no equalization necessary.
4. Following Manufacturer's instructions: Minimum/maximum charging current, equalization per instructions (even AGM's should probably have a light equalization once or twice a year to ensure all cells are fully/equally charged).
5. Not letting batteries sit for days+ at lower than 75% state of charge (prevent sulfates from hardening--one AGM mfg. claims that their batteries do not experience sulfate hardening--don't know if this is a feature of their battery or all AGM's--but would not like to test this on my battery bank--if I had one).
6. Checking water levels and keeping properly filled with distilled water.
7. Aftermarket Battery Caps: Can help keep battery cleaner/use less water.
8. AGM batteries: Much more efficient and cleaner to run.
9. Enough Battery Charging Energy (solar panels, generator backup, alternative sources, etc.) to ensure that battery bank is not "deficit" charged (is recharged promptly back to have 75%-90% of capacity within hours/1 day).

Would be interesting to hear anyone's experiences with a air/electrolyte mixing system... I could be convinced either way (although, such a system probably needs to be designed into the battery rather than just an aftermarket add-on).

-Bill

stephendv

Re: Traction vs. Stationary FLAs

Dave Sparks wrote: »

Oh yea, I think there is a huge difference and expect 10 to 15 years life out of what I buy. You know what? I get it and I have before!

I would expect a similar life out of the tractions. Comparing the cells is difficult, but there are a few points that we can compare:
Surrette 4000 L16: design criteria of 1300 cycles (no mention at what DoD). 35kg dry weight. 735Ah @ C5 (I'm using C5 here because I don't have the C20 or C100 value for the tractions). About 331 Euros.

Surrette 5000 4KS (4V): design criteria 3300 cycles (unknown DoD). 49kg dry weight. 773Ah @ C5. About 557 Euros.

PzS traction bats: design criteria 1500 cycles (according to German standard DIN 43539 - but again, I don't know at what DoD). 36kg dry weight. 840Ah @ C5. About 133 Euros.

Now if we look at the prices (on this side of the pond anyway), the 4000 are more than double the price of the tractions - but they're similarly specced in terms of weight and cycles.
The series 5000 costs 400% more than the tractions for the same capacity (note that they're only 36% heavier). So they'd have to last 4 times as long as the tractions to be worth the money... which is the bit I find hard to believe.

mikeo

Re: Traction vs. Stationary FLAs

PzS traction bats: design criteria 1500 cycles (according to German standard DIN 43539 - but again, I don't know at what DoD). 36kg dry weight. 840Ah @ C5. About 133 Euros.

The DEKA traction batteries that I have and most I have seen or rated at 80% DOD for their use at a 6 hour rate. Mine are rated at 660 Amp/hrs at 6 hr rate and 940 amp/hrs at 20 hour rate. They do use more water and have a higher self discharge rate.

niel

Re: Traction vs. Stationary FLAs

bb,
you better add, do not deficit charge. this means the batteries have to achieve full charges or sulfation will start. it is not enough to just keep them at 75% or higher soc if they don't get to 100% you are inviting trouble.

BB.

Re: Traction vs. Stationary FLAs

niel wrote: »

bb,
you better add, do not deficit charge. this means the batteries have to achieve full charges or sulfation will start. it is not enough to just keep them at 75% or higher soc if they don't get to 100% you are inviting trouble.

#9:Enough Battery Charging Energy (solar panels, generator backup, alternative sources, etc.) to ensure that battery bank is not "deficit" charged (is recharged promptly back to have 75%-90% of capacity within hours/1 day).

Dave Sparks was saying in another thread:

Dave Sparks wrote: »

I learned this strategy from Dave Surrette (Rolls) in the late 70's. Pretty much the bible on how I design my systems for off-grid.

Assume that the system will never reach more than a 90% state of charge.

Try not to go below 50% SOC, ever! Complete absorption over 90% of the year.

Use the energy stored from 70% to 90% SOC for your daily cycles.
Save the energy from 50% SOC to 70% SOC for aging to get long battery life.

I know Surettes has changed their recommendations over the years but I also know they are in the business of selling batteries! If you do the above you will get 10 to 15 years on their batteries with decent maintenance.

The OP is making it complicated by mixing battery types and not really stating a lot of information that would allow decent specific advice.

Oh yea, I am really happy that Surrette and Trojan are making L16's with 1000 AH capacities @20HR. Been bugging them for many moons to do batteries less than 125LB's!

Does somebody want to work on the list/wording and add in a post to the thread?:

Working Thread for Solar Beginner Post/FAQ

-Bill

niel

Re: Traction vs. Stationary FLAs

oops, so sorry i overlooked it.

stephendv

Re: Traction vs. Stationary FLAs

Found an interesting paper on the expected service life of traction batteries: http://www.zvei.org/index.php?id=163&no_cache=1&tx_ZVEIpubFachverbaende_pi1%5Bdownload%5D=247&type=98

The bits that stand out:
- the huge negative effect that high temperatures have on battery life.
- they estimate that a traction bat discharged to 80% and used for 240 days/year at 30 degrees C is expected to last 5 years. (IMO that's spectacular, if you consider that for off-grid solar use we should only get down to around 15-30% DoD).
- the same bat used at 45 degrees C is expected to last 2.5 years.

With regards to the air pumping systems, the more manufacturers I look up, the more offer this as an option: Hoppecke, Werbat, FIAMM all offer it. They claim:

■ The battery can be fully charged in 5 hour’s time, without any increase of the cell’s temperature.
■ The stratification of the electrolyte is prevented during the charging process of the battery. A homogeneous density and
temperature is achieved throughout the cells, due to the circulation of the electrolyte.
■ It is possible to "partially" charge the battery in order to prolong the autonomy of the electrical vehicles.
■ The overcharge coefficient is 70% lower.
■ The water consumption is reduced by 70%. This extends the battery’s maintenance period.
■ During the charging process energy consumption is reduced by 20%.
■ A longer cell life cycle is achieved due to the uniform decay of the plates.

BB.

Re: Traction vs. Stationary FLAs

Yes, elevated battery temperature during C/5 charging (and heavy discharging too) would degrade its useful life...

Another handy engineering rule of thumb (true for most "things", batteries, electronics, etc.) is that for every 10C increase in temperature, the life is cut by a factor of 1/2 (and the opposite is true too--for every 10C decrease in temp, life would be 2x longer).

If the battery where kept at 40C continuously--its life would also be reduced from 5 years to 2.5 years (according to formula).

And, if the battery where kept at 20C (or lower vs 40C) the expected life would be 10+ years (2*2*2.5 years=4x longer life).

-Bill

Photowhit

Re: Traction vs. Stationary FLAs

OK, I konw this has little out of place here, but I was checkingout the thread as I'm waiting to find a good deal on a Traction/forklift battery.

I still can't imagine a more "efficient" battery for the money than the Cheap true deep cycle Golf Cart Battery. My 24 volt single string is regularly discharged to 50% of capacity for 6-8 weeks in the summer when I run an window AC for 6-10 hours. And while they have had it easier this summer as my fridge has been on the fritz they will be 4 years old in Oct.

Any battery system I have will be abused to some point, they live outside, in the shade of the solar panels, Recieve charging at @C7 (1250watts on a C60 CC), for 6-8 weeks they are often reduced to 50% of charge. If I find they are having problems next summer, likely I'll just pick up another set, at 4x $71 at Sams.
Even though I could think about the state of charge less and likely just run my AC off of thermostat during summer months Trojan L-16's are 3x the cost.

The other factor is; will I be here 4,5,6 years from now? I own the property, but have other interests, still like to take one more long cycling trip before I quit long distance touring, the only time I've killed batteries was due to inattention.

That said, My guess is going to a large traction battery for me, would/will be less of a hardship, as monitoring and equalizing is a way of life. Going off grid from on, I can see were suggesting AGM would be very reasonable.

FWIW - I did put 2 - 24 volt solar battery desulators on this system shortly after I installed it, can't recall exactly how it claims to work, the small maybe 2 watt panel loads a capacitor which gives a pulse charge to the battery? I had just read an article in Homeppower or perhaps else where suggesting that they do work to some degree. I'll look for it when I have time.

icarus

Re: Traction vs. Stationary FLAs

Photo,

I actually agree with you at some level. I was running a set of 6 L 16s. I got them free and they were ~6 years old. I built a new building, and was going to move these in, but two of them failed. After looking at my loads, and my charging, I figured that 4 t-105s, while smaller,if they lasted 5 years in similar service rather than the expected 8 of the l-16s they were way cheaper on a per watt hour basis.

I think the real answer is to have the "right size" bank for the expected loads and charging capacity. I started with 2 t-105s, ten years ago and these are still going strong, but they have always been lightly loaded. I think what killed the l 16s was they were too big, and never really got charged. It seemed like a good idea to have a huge bank, until I learned (here) the value of proper sizing.

T-105's since they are available everywhere are real cheap ah for ah. I would guess,on average about 1/2 of what a l 16 goes for with net/net similar ah capacity.

NWAS has 325 ah l 16 for ~ $300. 225 ah T 105s can be found for ~$100?

Tony