I can mix this if need be. Distilled water and solid KOH is cheap.
Chem goggles, thick nitrile gloves, scale, probably a respirator.
Potentially a lot is needed, so I'm not gonna try to hazmat ship
anything premade like that. But I don't rush into doing anything.
I know that CO2 from the air reacts with the potassium hydroxide and
forms carbonate. If this happens, does this poison the plates for good,
or simply weaken the electrolyte? Their valve caps have been left on,
but they are old.
The 36v batts are long open-topped trays. They all had butcher paper
layered on top and packing tape wrapped around the girth to hold it
down. In a few of the packs, the paper is stained. I don't know if
they were laid on their side at some time or what. Could the electrolyte
have wicked into it? The carbonate crystals that form on top, can they
become hydroscopic and absorb water from the air enough to, under
certain temp/humidity conditions, liquify themselves like copper (II)
sulfate crystals do?
Only one or two batts had the paper actually "wet". The others are
probably just damaged by the chemicals in the crystals. I'm wondering
the best way to handle that, because I don't know if the levels are down
due to drying or draining, of course adding distilled is appropriate for
one and not the other. Would a PH meter be good for testing what's
there? Will that be able to test for carbonate-related electrolyte
weakening?
If the plates were exposed to air, are the cells recoverable by adding
new electrolyte (or water, if dried up)?
Danny
On 4/1/2013 10:01 AM, Roland Wiench wrote:
Hello Danny,
I use to work on aircraft nicads in a battery shop. The nicad electrolyte
does not change which is a solution of 30% potassium hydroxide and 70%
distill water. It is best to get this electrolyte premix.
Once a month we would remove the batteries from the aircraft and discharge
the battery to about 0.2 volts first by applying a load bank and than
installing shorting bars across the battery terminals to lower the voltage
to about 0.1 volt. Match all the other cells to the same voltage. This is
how we balance the cells back then.
Replace the electrolyte with distill water and place the battery on a
vibrating table which is use to remove the crystallization on the expose
surfaces above the electrolyte line.
Another method we use to remove the crystallization and clean the cells, is
after we remove the electrolyte and add distill water, install the caps on
the battery and immerse it into a tank of distill water upside down and than
remove the battery caps. The tank is also a vibrating sonic cleaning tank.
Install new electrolyte of 30% potassium hydroxide and 70% distill water and
charge each cell separately with a constant voltage charger design for
nicads. We use a special 19 lead battery charger that can charge a bank of
18 cells to 28-30 volts which balance charges the batteries.
Roland
----- Original Message -----
From: "Danny Miller" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Monday, April 01, 2013 1:56 AM
Subject: Re: [EVDL] Have LOTS of Saft aircraft nicads
Yeah, I noticed that it rose. Not too far above the level, though. I
noticed that was a minor mistake- actually says on the pack case to
check electrolyte level 2 hrs after full charge.
I kinda wanna get maybe like an electric scooter whose SLAs have bitten
the dust (as they are so prone to doing) and Nicad it?
Danny
On 3/30/2013 11:33 PM, John Lussmyer wrote:
Do NOT ADD WATER before charging them!
We ran into this a LOT with the BB600 NiCd batteries. (BB600 Yahoo
group)
Charge first. Even if they look "empty".
THEN if they aren't full, you can add any needed distilled water.
On Sat Mar 30 20:23:47 PDT 2013 [email protected] said:
Now the box loose cells are "dry". I don't know why, they don't appear
to have external damage. The valves are in place and intact. Can they
be restored by adding new electrolyte? What mix would I make there to
try? What happens if they "dried out" and the electrolyte turned to
powder, and thus would end up overconcentrated?
These things ARE old- are there any tricks to dealing with them? They
appear to have been stored ok, caps in place and all.
--
Tigers prowl and Dragons soar in my dreams...
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