SAFT NiCads

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northernmike

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Edit: added pic.

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Hi folks. My boss has a small stock of SAFT NiCads he's going to sell me, I need to come up with a reasonable price to offer him ... they're 27Ah, refillable NiCads .... that have apparently been sitting for 10+ years. He's not sure if he has 12 or up to 20 of them - he's going to let me know in the next few days.

Though the model code name seems obsolete, they look very comparable with SAFT's current offerings in NiCad form. I believe these are SLP 3 type, comparable to something like an STM 300. It looks like electrolytes are still available - I wonder if this is the case for a small end-user like myself, given what little I've read, mostly here....

It would appear that the Peugeot Scootelec ran similar SAFT cells with some success, albeit with 100Ah capacity & 18V potential.

What do you think? Will these be serviceable? What would be a fair price to offer / cell? I sincerely hope there's good news to be heard! :mrgreen:

FYI I am powering a moped with an original eTek and an Alltrax 4834 ... obviously higher volts would be better, but if I can load these appropriately with taller gears, I'm game.

Please advise if you're able!

Thanks and best regards,

- Mike
 
Electrolyte is from memory Sodium Hydroxide, NaOH (used in draino etc - but I would get pure from a proper chemical supply house and make up to the molar amount).

1.45 Also seems high for that chemistry - isn't the voltage 1.2V? 10 years of life unused - I would be cautious - are they empty/never been used? If so, you may be OK. There will be corrosion probably on the plates, and you may find as a result of this that the internal resistance may be high for the first couple of cycles as this works off the plates - it usually ends up as 'scum' on the bottom. Whether or not this is a problem is a very foggy memory.

I remember having encountered these on very large backup power systems ages and ages ago.
 
these nicads are not sealed batteries? the electrolyte needs to be replenished?

i think you should first see if they will work and how much capacity they have left.

1.41V is totally 100% charged, there is something wrong if they are 1.47V.
 
Offer to haul them away free. Proper disposal of those may even cost him, depending on the locality.
 
These sound like the nicads that are used in aircraft batteries. They actually are charged to 1.5 volts. I will say that discharging at 1C will make them quite hot.
 
The EVDL is your friend...
http://www.evdl.org/archive/index.html

Tons of tappity-taps over the years about SAFT nicads... STM-180's etc... If these are floodies, stuff like:

"The solution of KOH also has LiOH approx 7% and has a final SG of about 1.25 to 1.30. That is all it is. NB the electrolyte is only a carrier for ions,
it does not change SG during charge or discharge. The NiCds might improve in capacity after a few charge discharge cycles after replacement fluid.You can
turn the leftover electrolyte into soap if you boil it to make a strong solution & then add fat etc but may not be too good for you due to Ni & Cd
salts."

and:
"Last time I did it, it was through a company called http://www.beutilityfree.com/ Not sure if they still sell it or not.
Any chemical supplier should have it too, but you probably have to have a business license to get it from them.
It's actually partially KOH, with a little bit of LiOH and maybe BrOH???? Not just KOH. And you mix it up in a giant caustic proof
tub (we used a HDPE 32 gallon trash can -- mix it in slowly because the flakes give off a bit of heat as they dissolve -- and of course
have on all your safety gear. Either accurately measure out the weight of each of the flakes to add, or add to the proper specific
gravity. Then keep it away from air so it doesn't carbonate."

Threads like "care & Feeding of NiCads":
http://www.nabble.com/forum/ViewPost.jtp?post=20258907&framed=y

Use the Advanced Search function to look for msgs containing both SAFT and nicad (although usually when folks say SAFT it's the nicads they're referring to and not their NiMH)

Cheers
lLok
 
Lock said:
You can
turn the leftover electrolyte into soap if you boil it to make a strong solution & then add fat etc but may not be too good for you due to Ni & Cd
salts."
Click to expand...

OMG don't do that! Cadmium is really, really nasty stuff -- toxic, carcinogenic badness.
http://en.wikipedia.org/wiki/Cadmium#Toxicity

Which is why it is expensive to dispose of... you should really test those batteries before coming to any kind of price. If they don't work for your purposes, you'll have to pay to dispose of them. I wouldn't want to leave them lying around in my garage.
 
They recommend charging at 0.2C and don't seem to list discharge capabilities on the info I have. HOWEVER - their newer counterparts are designed for vehicular applications - I'm going to have to call them and see what I can find out.

There's tons of vehicles on EValbum.com using SAFT cells. Lots of research to come!

Thanks everyone so far. Lots of good info. Any more help?
 
Looks like their contemporaries, the STH series, is capable of 5C. That'll work for me! I just hope the boss has 20 for me and not 12. I wasn't planning on a low voltage system...
 
OH my. SAFT is making NiMH modules for e-Bike use... complete with BMS, in aluminum IP54 cases, they're beautiful.... up to 36V/15Ah :mrgreen:
 
Took delivery + unpacked. New In Box condition!

1.25V / cell across the board.

All electrolyte levels in acceptable range, +/- 10% of each other.

Specific gravity yet to be measured...
 
Normally flooded Saft Ni-Cads should be stored discharged with shorted terminals when in long time storage.
They should then be revived with a special initial charge routine.
I think that if you look in the evdl or at diyelectriccar you can find more info on them.
The STM5-100(flooded 5cell 6v 100ah block) from Saft will deliver atleast 3C with no problem.

Best Regards
/Per
 
Thanks PM. I have the instructions to do a "commissioning" procedure, as well as electrolyte preparation and replacement, etc -

I agree these were probably stored in less than an ideal manner, and hope to revive them as gently as possible...

I'm looking now for a source of chemically pure water for initial top-up..
 
OK! It took 1.5 liters of water to fill the 20 cells to max capacity! :shock:

Charged @ 1.47 VPC for about 7 hrs (all I had time for) with an AC Delco lead acid charger @ 6A setting.

At the end of the charge (6am today) they were making some nice sounds and gassing gently.

Terminals are beautiful - 17mm nuts with spring washers.

First discharge tomorrow.
 
Mike:
Did you fill them first and then charge them, or did you first fill them a little and then charge them and filled again.

I know that the STM-5 blocks used in most french Electric cars should be fully charged and then filled within 15 -20 minutes.
This is done because the electrolyte is at is max level when fully charged and from there you should add to the max.

But perhaps these cells has a larger headroom to acomondate the extra e-lyte when fully charged.

Best Regards
/Per Eklund
 
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