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avayan
08-02-2009, 09:44 PM
Recently I have been getting interested in desulfator pulsers. If you do not know what this is, the theory is that apparently 12V rechargeable lead acid batteries develop some sort of sulfate crystal accross the lead plates which act as resistors, limiting the charging current and deeming your battery dead. However, as it turns out, it is an apparently proven fact that by applying a series of high voltage pulses (of short duration, BTW) the sulfation process can be reversed! I was reading that you should have batteries last considerably longer than they usually do. Apparently decades???

Since most of our robots use some sort of battery, I think this is an important topic to discuss. And of course, I have a series of questions perhaps our battery experts can help me with:

1. Do we have some easy to implement desulfater circuit we can share? I found one circuit on the latest Elektor magazine, but as you can imegine, the components are meant to be bought from UK and although I found most alternates on Digikey, there is one inductor I can not find a replacement for.

2. A couple here close to where I live have acquired 100 12V 20AH batteries. They are selling them at $50 a piece. As it turns out, the great majority of them measured voltages considerably below 10V. Heck! Most of them were below 5V. I am thinking these batteries are as good as dead. Is that the case? Can they be brought to life, or am I wishful thinking? They are brand new and never used, so if five years could be gotten out of them, they could be a nice deal.

Thanks for your input!

nuggy
08-20-2009, 05:44 AM
hey ill throw 2 cents in...
from what i understand the chem reaction you describe is true, however the process you describe for reversal applies for i believe ni-cd or maybe ni-mh(not sure) as to rejuvinate a somewhat memory-affected cell by infusing said specimen with a dose of juice in the order of 6-10 X nominal V (disclaimer- im not suggesting you do this.... without serious precaution at your own risk !!!)

the way i understood for lead acid was with a solution and then you replaced elecrolyte entirely after desulphating process was completed, somewhat returning cells to near to new plate condition.

i have kicked a couple of ni cadsback to life, mind you i was some distance from the beast, but indeed it accepted charge whence before it had not.
the lead acid desulphating process on the other hand, ive yet to see acceptable result.

regards

Shozbot
10-11-2009, 08:44 PM
http://leadacidbatterydesulfation.yuku.com/

google desulPHator

ooops
10-12-2009, 07:02 AM
2. A couple here close to where I live have acquired 100 12V 20AH batteries. They are selling them at $50 a piece. As it turns out, the great majority of them measured voltages considerably below 10V. Heck! Most of them were below 5V. I am thinking these batteries are as good as dead. Is that the case? Can they be brought to life, or am I wishful thinking? They are brand new and never used, so if five years could be gotten out of them, they could be a nice deal.

A quick google search returned a number of new 12v 20ah batteries for $49 - $79 dollars. Even if you could resurrect them from the dead, it doesn't seem equitable.