Nu solar power

[Bryan1]

Hiya's

       This could prove to be a techincal question but here goes. I just installed my old solar panels off the house now they are set up on my shed in a 24 volt array but off talking with a few great friends off this board I'm still stuck. I'm trying to use a 2422 BP 24 volt solar regulator to try to charge a 24 volt bank of military nicad batteries they are a bank of 10 batteries rated at the nicad range which I think is 2.6 volts per cell. But if anyone has previous experience with deep discharge Nicad batteries and with the right solar regulator circuit I will be greatly appreciated.

 http://www.electro-tech-online.com/viewtopic.php?t=12657

 here is a link to electro-tech that shows my battery's I did fix the one pictured but I've been told Nicad's are and lead acid batteries are a  totaly different story.

Cheers Bryan

[johnlm]

Not that is solves your problem, but Nicads are nominal rated 1.25V per cell.

You might need to describe in more detail what problem you are having.

regards

John

[jimjjnn]

I believe these are NiFe (Nickel Iron) batteries. I think they have a slightly different voltage than Nickel-Cadmium batts.

[scottsAI]

Something I found: http://www.oceannavigator.com/site/csrv/content.asp?id=639

Wet nicad cells use a dilute solution of potassium hydroxide (KOH) in water, with small amounts of lithium hydroxide (LiOH). This facilitates an alkaline reaction, rather than the acid reaction of a lead-acid cell. But, unlike the lead-acid cell, the nicad electrolyte acts only as an electron-transfer medium, and does not change chemically as the cell is charged or discharged. Therefore, a hydrometer cannot be used to monitor the state of charge (SOC). A metering system is needed for tracking SOC (which is of course more convenient). An accurate voltmeter is the minimum requirement, but ideally there should also be metering of current flow and an amp-hour calculation.

The voltage of a fully charged nicad cell is 1.65 volts, direct current (VDC), falling to between 1.00 and 1.15 VDC when fully discharged. Ten cells are therefore linked in series to make up a 12-VDC system. Nicad cells of various capacities are available that have the same voltage characteristics but differ in their amp-hour capacities and physical size. Cells linked in series should be identical (however, different strings of cells can be paralleled as long as the cells within each string are the same).

The cell you have pictured is TWO cells in series. That is why your seeing 2.47v.

Notice the two caps.

I have no idea where you can get replacement electrolyte.

Have fun.

[jimjjnn]

Scott,

He may be able to find the electrolye online. Proper mixture ratio, he will have to find somewhere tho.

[Bryan1]

Hiya's,

       Ok just a bit of an update upon checking out the nicad array this morning the BP solar regulator is working fine and at 7.45 am the batteries are showing a voltage of 27.8 where as yesterday they we 26 volts. The only downside is I have to use 2 seperate arrays using the nicad's on 1 and the lead acids on the other. Anyways thanks for the input guys and I'll let ya know how these batteries pan out running my beer fridge which is a 300 litre domestic fridge.

Cheers Bryan

[richhagen]

I believe that NiCd batteries have a slightly higher over voltage when charging than Lead Acid batteries.  The Trace Charge controllers had a resistor that you would snip for the NiCd batteries to up the charge voltage a smidgin (a volt or so for a 12V bank).  Without that your controller may think the pack is prematurely charged, or in a multistage charger, switch to trickle charge prematurely, slowing the charge rate.  I'm not sure about this, but it seems like a possibility.  Rich Hagen

[Bryan1]

Hiya guys,

          Well I rang plasmatronics that's the mob that make programmable solar regulators but only sell wholesale to resellers. After talking with a guru there I've been asked to e-mail details on the nicad's and they will program 1 of their regulators to suit and sell it to me direct. As the techy said my situation is pretty unquie so they don't mind helping me out directly and cutting out the middleman so that will save me a packet.

Cheers Bryan

[Peter V]

As for replacement electrolyte.

Chances are you don't need any.  Flooded NiCad cells absorb the electrolyte during discharge and release it during charge.  When fully discharged the electrolye will usually be far down below the plates and may even appear tobe missing.

Give the cells a full charge and then look to see the electrolyte level.  If it still low after a couple charge/discharge cycles, you can top it off with pure distilled water.  NiCads gas during charge just like Lead Acids and need to be periodically topped off with fresh water.

It's important that you use pure water (distilled or reverse osmosis) because impurities can destroy the electrolyte.