# Industrial traction batteries



## peskanov (Dec 13, 2011)

Hello,
a friend of mine works in a factory where some AGVs work nearly 24/7/365. These vehicles use lead-acid batteries built with large individual 2v cells (you can check and replace a defective one easily).
I am impressed with those battery packs, as they stand THOUSANDS of cycles without much problem. And I think these packs don't even use BMS. 
From time to time, one cell is found to be wasted, and they replace it. But full pack replacement is very rare, after many years working nonstop.
Price is pretty close to common golf car deep cycle batteries.

Here is an example I found;

http://www.alibaba.com/product-gs/503053428/sealed_traction_battery_with_2V_165AH.html

Sealed, cycling >1200. Energy density at 1/5 C: 34 wh/kg.

I see many advantages over normal golf car batteries: very good cycling, good price, and the possibility of balancing, checking and replacing each cell separately.

So, my questions to the experts of the forums is:

What are the drawbacks? Nobody uses industrial traction batteries in the EV conversion world...what's the reason?


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## Ziggythewiz (May 16, 2010)

Primary drawbacks would be connection count and availability. You would need 3-4x as many connectors and you're not going to just pick these up at your local supplier.


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## peskanov (Dec 13, 2011)

Well, that's the funny thing. AGV and LGV are pretty common machines in USA & Europe, therefore it should be easy to locate local suppliers...
Unfortunately I made several searches on the web and found little info. Alibaba holds much more info about this kind of traction batteries than most specialized USA/Europe shops. 

Here is a picture of the AGV batteries I mentioned in the first post (there is little info on the web about them):










BTW, many of the tractions cells I found on Alibaba are NiCd (1.2V). It seems Lead-acid is not a standard for this kind of vehicle.

I don't think the number of cells is such a problems. LiFePo packs are built the same way, and these are selling very well.
BMS would be a problem though, it seems there is little BMS options for lead-acid packs.


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## Ziggythewiz (May 16, 2010)

The number of interconnections for lithium doesn't apply. For lithium it's accepted because other benefits outweigh that drawback. When comparing lead to lead you can't use a lithium con.

Lead doesn't need a BMS, nor balancing, so I wouldn't expect there to be many providers.

The cell in the picture, is that 48V 375 ah? If so that would greatly reduce the number of connections needed, but what does that thing weigh/cost? 720 lbs? $1200?


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## peskanov (Dec 13, 2011)

The weight is shown in the picture, 580 kg, about 1300 lbs. I don't think weight is much different to common deep cycle batteries.It's a flooded battery, btw.
One thing I noticed about those traction batteries is that they are rated at C5, while common deep cycle is rated at C12. C5 is more realistic for EVs.

The pack in the previous picture is made with 2V cells, connected this way:










I don't know if packs like these are available in sizes matching EV conversion needs. 
Maybe something like 3 packs of 48v/100ah could be found.

I am not sure about full BMS, but I have seen circuits available for balancing lead-acid packs.
Equalizing charging ages the battery unnecesarily, the use of voltage limiting at cell level when charging should prolong battery life.


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## Ziggythewiz (May 16, 2010)

The numbers I quoted were calulated based on other commonly available lead acid, so if that pack is 1300 lbs it's nearly half the density of other options.


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## peskanov (Dec 13, 2011)

That number does not sound right...can you tell me the brand/model of the battery you have in mind?

My numbers: a golf car battery like the Trojan T106 has the following specs:
-185 Ah for 5 hours discharge rate
-6V
-28 KG

This gives 39 wh/kg. Not so far from the 34 wh/kg I got from the Alibaba 2V cell.


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## Ziggythewiz (May 16, 2010)

Ones I've used are 1500 Wh/60 lbs (DC-29) and 1080 Wh/63 lbs GC8s. I guess GCs are closer to 40 wh/kg. Of course, those are with 20 hr rates. I got 30 for the 48V pack you posted.


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## rwaudio (May 22, 2008)

I do have to agree that the cycle life if industrial lead acid batteries is actually quite good. I've been around them for a decade in electric forklifts and although they do require regular watering they don't need a BMS and there is a relatively consistent "range" over the main life of the battery. It does decrease over time though.

The most drastic negative is the weight. They are typically used in applications where battery weight is a benefit to the vehicle. Many years ago I saw a car audio competition SPL van (who's the loudest) using a 48v forklift battery connected up as a 16v 1000+ Ah battery. The vehicle did very well, but the suspension was modified in the Chevy Astro to carry the extra weight.

For a decent performing conversion you would need 3 of these for a minimum 144v pack and the weight would be insane.


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## athlon (Feb 27, 2012)

FIAMM is a very old italian battery factory , they mainly focus on long lasting heavy duty batteries.
http://www.fiamm.com/fiamm.php?s=579

They also made Nickel Sodium battery (Zebra battery) for trains , E-bus and E-truck 
http://www.fiamm.com/sodium-nickel-battery-mobility.php?s=3010
(molten salt battery) 
http://en.wikipedia.org/wiki/Molten_salt_battery


If you buy some fiamm battery just be sure are original and not fake , prices are medium to high for single battery but they made very good offers for bigger quantities or group buying


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## piotrsko (Dec 9, 2007)

Back to the original question: They are big, heavy, and very expensive. AGV batteries have thick lead plates, different electrolytic chemistries. As a result the capacities are perhaps 20% lower, but you can take them to "dead" and revive them many times. If you have a need to severely abuse them then perhaps, otherwise they aren't a candidate.


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## peskanov (Dec 13, 2011)

Ziggythewiz,
I think traction batteries are always rated at C5, or 5 hour rate. Of course, at C12 capacity is higher.

rwaudio,
yes, the battery pack I showed needs maintenance, but the ones I keep finding in Alibaba are sealed. I am not sure if they are are as good as the flooded ones, though.
I still think that a battery regulator (like this one) could benefit those batteries:

http://www.evdl.org/pages/hartregs.html

gottdi,
the smallest capacity 2V traction cell I found is here:

http://www.alibaba.com/product-gs/272274728/SEIDEN_Traction_forklift_batteries.html

it's 50ah, 4 kg. But it seems an uncommon size, and energy density is extra-low.
I think voltage would be a problem trying to use 2V tractions cells, as common capacities start at ~100AH. It's still workable for 80-96V EVs, like those using AC 48V.
About rating, those batteries carry a realistic rating, unlike many deep cycle batteries rated at C12!

athlon,
Fiamm got some kind of deal with MES-DEA involving the Zebra battery, and now they advertise the techonlogy. I tried to contact them some time ago, but as usual they will not sell you a battery easily. It seems the Zebra technology will never be available to hobbyist.

piotrsko,
20% extra weight does not seem like a show-stopper to me, for batteries that could last 100.000 km. But there could other problems that I am not aware, and that's the reason I opened the thread.
Maybe its Peuker constant is very bad? Maybe they sag strongly under loads higher than C5? That's the kind of things I would like to know.


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