blingo batts

[timpootle]

The aircraft batteries get pulled out and serviced every 3 months! I think our batteries would benefit from that sort of care, but only if they were good to begin with. As Chris says, shorting out a cell won't straighten a bent plate once it has happened.

[ChrisB]

The aircraft batteries get pulled out and serviced every 3 months! I think our batteries would benefit from that sort of care, but only if they were good to begin with. As Chris says, shorting out a cell won't straighten a bent plate once it has happened.

But then aircraft units are generally, or appear to be generally, made up of individual cells, where as ours are blocks of batteries, which is another problem when it comes to doing the full discharge shorting idea, you can not short individual cells, the closest you get is to be able to discharge and then short a 6volt mono block, attempting to do this could push some of the cells in the mono block into reverse polority, which the paper says and I know is never a good thing for nicads.

I cant see anything really in the paper that we could take and use on our Saft mono blocks

There is one thing that I was aware of but others might not be, it also mentions it in the paper,

h) Vent caps should be checked for security and also to ensure that gas exit holes are
free from dirt or potassium carbonate crystals. Clogging of vents causes excessive
pressures to build up, resulting in cell rupture or distortion of parts. Cell valves,
when fitted, should also be checked for security and freedom from dirt or crystal
formation. Dirty vent caps or valves should be removed and cleaned (see
Paragraph 4.4.3).
NOTE:Potassium carbonate is a white crystal formed by the reaction of potassium
hydroxide with carbon dioxide in the air; it is non-corrosive, non-toxic and nonirritating.

and

4.4.3 When it is necessary to clean vent caps and valves, they should be removed from the
cells, using the correct extractor tool, and should be washed in warm water to
dissolve any potassium carbonate crystals which may have accumulated within the
outlet orifices. They should then be rinsed in de-mineralised or distilled water, dried
and re-fitted. Valves should also be tested for correct functioning in accordance with
manufacturer's instructions before re-fitting.

Now I've wondered if part of the failing of our safts are these crystals forming in the fill ramps of the batteries and thus stopping the battery from receiving the correct amount of water during the watering cycle.

While to start with it may not cause a much of a problem, if over time a reasonable amount of over spill is not allowed through our watering system i.e the time you leave the water to continue to flow from the overflow before disconnecting the fill connector, then you could end up not filling some of the batteries enough with water due to the fill ramps being blocked or partially blocked with these crystals.

I tend to leave the overspill running now for at least a minute or longer to hopefully dissolve any crystals that could be blocking or starting to block the fill ramps.

Another good reason in my view not to allow the water fill pipes to run dry, as by keeping these full of water means theres less chance of the air getting to the fill ramps and the CO2 causing these crystals to form.

Well thats my view, not sure if its right view but its how I run my batteries now.

ChrisB

[timpootle]

Thanks for taking the time to read through that document, Chris. Your comments are very interesting, and you have a good understanding of these STM blocks.

Regarding the dead short procedure, if it was a good thing to do, perhaps we should be driving a self-tapper into the inter-cell link. Or maybe not.

[harry morris]

Well gentlemen, something I spotted the other day whilst trying to absorb the various problems with our beloved NiCads and this was the AGEING of the electrolyte, the article which was on the internet seemed to suggest that the electrolyte would deteriorate with age and should be replaced say every five years or so, couldn't quite get my head around this one either but the article also suggested that the specific gravity of the electrolyte would also be affected. HARRY MORRIS

[ChrisB]

Thanks for taking the time to read through that document, Chris. Your comments are very interesting, and you have a good understanding of these STM blocks.

Regarding the dead short procedure, if it was a good thing to do, perhaps we should be driving a self-tapper into the inter-cell link. Or maybe not.

I think the "maybe not" is best

The crystal build up thing I've discussed with Flying John many years ago I think, after John found a similar paper.

Well gentlemen, something I spotted the other day whilst trying to absorb the various problems with our beloved NiCads and this was the AGEING of the electrolyte, the article which was on the internet seemed to suggest that the electrolyte would deteriorate with age and should be replaced say every five years or so, couldn't quite get my head around this one either but the article also suggested that the specific gravity of the electrolyte would also be affected. HARRY MORRIS

I'm not sure about ageing ??

It does get weaker over time due to the watering, while its said theres no loss of electrolyte during the watering, there is suggestions and I've also proved that a small amount of electrolyte is lost when the cells overflow during the watering process.

As we cant get to the internals of the cells, being able to measure the SG or even replace the electrolyte is pretty much impossible, so that sort of negates going down that route,

In my view the best care we can give our batteries is regular careful watering, and avoid driving them outside their ratings i.e keep within the green area of the "eco" meter.

ChrisB