Results of testing old batteries which have been desulphated

[mael]

[Amr]

Thank you guys for your reply

SeaMonkey, do you relay mean I can reform a 30V rated capacitor to 74 by charging it with a 50k resistance in series? if this is so, then you have saved me a lot of troubles, I'm trying to use available items from the market and over 40 V capacitors with large capacity is very difficult to find. AC capacitors are up to 440 V but with only 16 mf.

Any way, I think I should not deliver 74V to a 12 V battery, so may be I'd better make the PS gives me only 24 V. Again, and if I understood the label on the welding machine (the switched mood supply) it should deliver 24 Vmax when on load, and 74 when not on load i.e. oped circuit voltage. For some reason (maybe as the load is considered very small by the power supply) so it keeps outputting 74 V, if this is the case, then shouldnt I use a lamp as a load but in parallel not in series? shouldnt this trick the PS to think there is a load and then steps down to 24 V? If what I'm saying is correct then should I use a 220v/100w lamp ? Maybe I should make some tests and see.

If I put a resistance in series, this will limit the V as you said, but then, when the output steps down to 24 V, the resistance will still limit the V and it may drop to less than desired.

Meal, If I can some how get say 80 V rated capacitors, which I'm not certain I can get, then the circuit will need to be more complex, I hope I can spare the output semiconductors so I hope I would control the volt coming from the switched mood supply to avoid complicating the circuit. As you advised, I keep a PC fan permanently on the transistors.

I bought that welding machine that uses switched mood instead of transformer as all the local experts warned me of buying any thing that has a transformer as their wires are of low quality copper that heats up and the insulation would melt and then an internal short will happen so it will not last, if the wounds are not from copper they will be from aluminum which is even worst (I'm talking about the local market of course - importing a transformer from digy key or something will cost triple original price due to shipping)

The machine's data: 999 sanjiu welding - model zx7-160

[SeaMonkey]

I failed to mention that once an electrolytic
capacitor has been 're-formed' at the
higher voltage, the high resistance which
was used to limit current flow during the
reforming process can be removed from
the circuit. Its purpose is only temporary.

After re-forming, the capacitors will operate
safely at the higher voltage without any
danger.

Of course, as Mael suggests, using capacitors
with a high voltage rating is the preferred
method. Capacitors with a higher voltage
rating may be used without any problems
in low voltage applications.

It is only when one desires to use a low
voltage electrolytic capacitor at a higher
voltage than its rating that the 're-forming'
procedure has merit.

During the re-forming process the dielectric
oxide barrier layer which forms on the
positive plate is made thicker and stronger.
Increasing the thickness of the dielectric
layer will cause a decrease in capacitance.

[mael]

AMR.

Can't you contact an air-conditioning company? I just imagined you might have some contacts there as you are an architect, and air-conditioners are decided as the plans are drawn in te office.

I always use ther caps from old (discarded) air-conditioners. - When an air-con breaks down the service-people usually just change the whole circuit board, and there are at least three 1000 mFd caps rated for a couple of hundred volts in a domestic-sized air-con. You'll find them in the compressor attached to the drive semi-conductor(s) which power the compressor.

* If you can get some old parts from air-conditioning repair-men then you can also get the output semiconductors.

* I'm intrigued about your transformer situation. The trasnsformers I've seen are usually virtually indestructible unless you make a big effort to destroy them. - But then I almost always have a computer-fan blowing on the transformers I use as well. - I like things cool ... if a transformer is too hot to hold then I am not comfortable. I know transformers can work at over 100 C, but I am very cautious.

* And, in many transformers there is a thermal fuse under the paper/plastic they use to cover the coils. If you have an open circuit on a transformer then you may finda small thermal fuse on the primary. You can replace the fuse, or if you want to take a chance, you can just twist the fuse so its legs are shorted and try to remember not to let it get so hot next time.

[mael]

I don't do much battery work these days - which is a shame. I know it works, but it isn't failsafe, so until the cost of batteries sky-rockets, people will prefer t just buy a new one.

I was called out to help a lady today because her battery gave up the ghost. I just swapped her battery for one of mine that I'd 'done' a while ago and I'm pulsing her battery now on a nice slow puse.

She asked me how much for the battery? And I told her I'd take her daughter. Unsurprisingly she agreed. Mother in-laws get free battery work.

[Amr]

again, thank you guys.

I tested the 4 12,000/30V capacitors and they all are dead (open circuit no resistance) so I will get new ones, I learned about a man that has 63V / 56,000 mf capacitors, I will give him a visit.

In the mean time, I made a test on the PS, if I put a 220V/100W lamp in parallel, the ps would drop the V to about 46.7 V which seems fine for me and I think this will keep me within the voltage range that you were preferring, the lamp does not glow very much so it is neither pulling a lot of power nor will it cause much heat dissipation, may be using it along with the new caps (if I find them) will make a good configuration.

We do not have inverter air conditions here and the ones we have only has caps with 10 - 16 mf with good large V, but the ones I was told about are from old telephone central switches. I will seek them soon. if I found them I will get all what the man has for future duplication of the machine

the last resort for me would be using lots of 1000 mf /220V capacitors that are available in the market as a bank of power, lots of connections means more chance for something to go wrong.

[mael]

[SeaMonkey]

[mael]

[mael]

[mael]

[Amr]

[Amr]

[Amr]

[Amr]