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New Drycell won't pull much amps...
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BeaverRat Offline
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Post: #1
New Drycell won't pull much amps...
Hello- this is my first post!
Anyway, down to buisness, my dry cell configured as +NNNNN-NNNNN+ can't seam to pull the amount of amps that I am used to. Here is lots of data about the cell.

SS 304 Plates
+NNNNN-NNNNN+
2.25 volts (measured) per gap
3 teaspoons Sodium Hydroxide/half gallon electrolyte
13.8 volts input
1.5 amps current draw.

Is there any particular reason why my cell won't pull very much amps? I am shooting for 15 amps, but no matter what I do I can't get there! Is 3 teaspoons/half gallon not enough electrolyte? If I short it out to +NNN-NNN+ it will pull 11 amps at this e-lite concentration, but I heard that that is not enough neutrals...

Any ideas? Thanks
02-10-2010 04:20 PM
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jbalat Offline
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Post: #2
RE: New Drycell won't pull much amps...
You will need to condition the plates first. The amps will go up as you condition and clean.
02-14-2010 07:57 PM
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abe Offline
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Post: #3
RE: New Drycell won't pull much amps...
You didn't say the spacings between plates? It's probably 1/8 or 1/16 if so you need more Sodium Hydroxide. I used about 6 per 1/2 gallon,but I use a PWM to control amps. If your spacing is more than that, you might want to make them closer.The further apart they are the harder it is to get the current to go through the electrolyte. That why your not pulling many amps. Hope that helps Good Luck.
(This post was last modified: 02-15-2010 04:09 PM by abe.)
02-15-2010 04:08 PM
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BeaverRat Offline
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Post: #4
RE: New Drycell won't pull much amps...
Right now the spacing is 1/16th inch. Elyte was up to 40 teaspoons in 1/2 gallon.
02-17-2010 04:25 PM
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benny Offline
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RE: New Drycell won't pull much amps...
(02-17-2010 04:25 PM)BeaverRat Wrote:  Right now the spacing is 1/16th inch. Elyte was up to 40 teaspoons in 1/2 gallon.

What are you using to power your generator during testing? Bench power supply, battery, or are you testing in vehicle?

Try configuring your generator as +NNNN-NNNN+, then, without using a PWM, from a low electrolyte concentration, increase your electrolyte concentration gradually, by adding a small amount of KOH, or NaOH, depending on which you are using, and note any change in current level at each increase.

If you manage to get current to the level you are looking for, then you have won a watch. It is advisable to then use a PWM to regulate the current.
(This post was last modified: 02-18-2010 01:22 AM by benny.)
02-18-2010 01:21 AM
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BeaverRat Offline
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Post: #6
RE: New Drycell won't pull much amps...
Ok, to power the cell I am using a 50 amp max DC 13.8 volt PSU. Here are the results of more testing.

-NNNNN+NNNNN-
60 Teaspoons NaOh/half gallon water
6 amps
1/16th inch spacing
2.3 volts per gap

-NNNNN+NNNNN-
8 Teaspoons NaOh
2 amps
1/16th inch spacing
2.3 volts per gap

-NNNN+NNNN-
8 Teaspoons NaOh/half gallon water
27 amps
1/16th inch spacing
2.6 volts per gap

Why is it that the 5N setup won't pull very much amps, but when I switch to 4N it actually works really great? Shouldn't the 5N setup pull more than 2 amps at 8 teaspoons NaOh?

How much NaOh/half gallon water is generally used with a 5N setup?
02-18-2010 10:41 PM
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benny Offline
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Post: #7
RE: New Drycell won't pull much amps...
(02-18-2010 10:41 PM)BeaverRat Wrote:  Ok, to power the cell I am using a 50 amp max DC 13.8 volt PSU. Here are the results of more testing.

-NNNNN+NNNNN-
60 Teaspoons NaOh/half gallon water
6 amps
1/16th inch spacing
2.3 volts per gap

-NNNNN+NNNNN-
8 Teaspoons NaOh
2 amps
1/16th inch spacing
2.3 volts per gap

-NNNN+NNNN-
8 Teaspoons NaOh/half gallon water
27 amps
1/16th inch spacing
2.6 volts per gap

Why is it that the 5N setup won't pull very much amps, but when I switch to 4N it actually works really great? Shouldn't the 5N setup pull more than 2 amps at 8 teaspoons NaOh?

How much NaOh/half gallon water is generally used with a 5N setup?

With fewer plates the voltage across each individual cell is higher.
KOH acts as a non linear resistor. Above a certain voltage, the resistance will decrease dramatically giving high current increase for further low voltage increase.

Use only enough KOH in solution to give you the required maximum current draw with the generator cold, then use a PWM to regulate this. As the generator heats, it will draw higher current at a certain voltage, than it would when the generator is cool. You could end up with thermal runaway if you do not regulate the voltage/current. ie current would increase with heat, heat would increase with current, and so on. Another good reason to have a fuse in line.

Been there, seen it, had it done to me.
(This post was last modified: 02-19-2010 02:54 AM by benny.)
02-19-2010 02:52 AM
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BeaverRat Offline
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Post: #8
RE: New Drycell won't pull much amps...
About how much NaOh/gallon of water should I be running? In teaspoons or tablespoons please...
02-19-2010 11:23 PM
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benny Offline
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Post: #9
RE: New Drycell won't pull much amps...
(02-19-2010 11:23 PM)BeaverRat Wrote:  About how much NaOh/gallon of water should I be running? In teaspoons or tablespoons please...

Read post #5
02-20-2010 03:30 AM
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BeaverRat Offline
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Post: #10
RE: New Drycell won't pull much amps...
Thanks- if i reconfigure it to -NNNN+NNNN-NNNN+NNNN- it will pull 30 amps easy with 8 teaspoons of NaOh. Isn't -NNNNN+ better than -NNNN+ though? Would the 4n make steam?
02-21-2010 12:33 PM
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