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Voltage per plate
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cmac0351 Offline
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Post: #1
Voltage per plate
What is considered too high a voltage per plate on a dry cell?

I read one of Gary's posts who said that 6 was the magic number for the Tero cell, where most people consider it to be 7. I have had problems with my dry cell not being able to produce amps with 7 plates on a 12 volt power supply (1.7 volts per plate).

Last night, I shorted two end plates together, so 2 volts per plate and my amps jumped from 1.8 to about 6. I then shorted 3 end plates, so 2.4 volts per plate and the amps went up to almost 10 and production was very high (haven't tested the amount yet, though).

At what point is the voltage too high? I was thinking maybe building a 6 plate dry cell -nnnn+, so I would get 2.33 volts per plate when it is on my car. Is that too high for a dry cell; will it heat up too much?

I suppose if I built it with the 6 plates and it turned out to be too high, I could use ZFF's PWM to dial the plate voltage down to closer to 2.
(This post was last modified: 10-16-2008 04:49 AM by cmac0351.)
10-16-2008 04:45 AM
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colchiro Offline
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Post: #2
RE: Voltage per plate
Your first problem is your supply is 12 volts, where in your vehicle, would be closer to 13+ volts with good wiring.

Also 7 plates is 6 cells since the space between the plates is the cell so plates minus 1 is your cell count.

Two volts is doable, but you'd have to have a very strong electrolyte so I like 2.5 volts better. I'd try to keep it under 3 volts per plate since your efficiency will drop quickly (and heat increase) after that.

7 plates (6 cells) @ 13 v is 2.1 vdc
6 plates (5 cells) is 2.6 vdc
5 plates (4 cells) is 3.25... a little high.

You might take a voltmeter and measure from your supply to your cell to see if you get a voltage drop of more than a volt (indicating your wire size is too small). Another indication would be your wires getting warm.

Also remember by decreasing the number of plates you'd have to decrease your electrolyte concentration to have the same amperage.

Rick

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10-16-2008 03:07 PM
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pimpa Offline
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Post: #3
RE: Voltage per plate
"I suppose if I built it with the 6 plates and it turned out to be too high, I could use ZFF's PWM to dial the plate voltage down to closer to 2. "

make it with 7 plates , short 1`gap with a relay. when the temperature rises the extra plate can be installed which decreases the current and temperature, increases efficiency. no pwm required!
10-16-2008 04:21 PM
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cmac0351 Offline
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Post: #4
RE: Voltage per plate
I know that my pc power supply is not the best way to test because of the voltage, that is why in another thread I was hoping for a circuit to build that could step that up to 14. I am sure that is possible but I still am looking for one.

It is nice to know that 7 plates = 6 cells and I should be measuring voltage across the gap. That makes the math a bit easier.

My plan is still to build with 6 plates, so 5 cells and use the ZFF PWM to dial down the voltage if that is too hot. 5 cells and 13.5 volts from the car ≈ 2.7 volts. So if if gets too hot, I will use the PWM to get less like lutherp40:

http://www.youtube.com/watch?v=0fD-Dj4XcBI

colchiro Wrote:Your first problem is your supply is 12 volts, where in your vehicle, would be closer to 13+ volts with good wiring.

Also 7 plates is 6 cells since the space between the plates is the cell so plates minus 1 is your cell count.

Two volts is doable, but you'd have to have a very strong electrolyte so I like 2.5 volts better. I'd try to keep it under 3 volts per plate since your efficiency will drop quickly (and heat increase) after that.

7 plates (6 cells) @ 13 v is 2.1 vdc
6 plates (5 cells) is 2.6 vdc
5 plates (4 cells) is 3.25... a little high.

You might take a voltmeter and measure from your supply to your cell to see if you get a voltage drop of more than a volt (indicating your wire size is too small). Another indication would be your wires getting warm.

Also remember by decreasing the number of plates you'd have to decrease your electrolyte concentration to have the same amperage.
10-17-2008 10:36 AM
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sroll42507 Offline
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Post: #5
RE: Voltage per plate
cmac0351 Wrote:I know that my pc power supply is not the best way to test because of the voltage, that is why in another thread I was hoping for a circuit to build that could step that up to 14. I am sure that is possible but I still am looking for one.

It is nice to know that 7 plates = 6 cells and I should be measuring voltage across the gap. That makes the math a bit easier.

My plan is still to build with 6 plates, so 5 cells and use the ZFF PWM to dial down the voltage if that is too hot. 5 cells and 13.5 volts from the car ≈ 2.7 volts. So if if gets too hot, I will use the PWM to get less like lutherp40:

http://www.youtube.com/watch?v=0fD-Dj4XcBI

colchiro Wrote:Your first problem is your supply is 12 volts, where in your vehicle, would be closer to 13+ volts with good wiring.

Also 7 plates is 6 cells since the space between the plates is the cell so plates minus 1 is your cell count.

Two volts is doable, but you'd have to have a very strong electrolyte so I like 2.5 volts better. I'd try to keep it under 3 volts per plate since your efficiency will drop quickly (and heat increase) after that.

7 plates (6 cells) @ 13 v is 2.1 vdc
6 plates (5 cells) is 2.6 vdc
5 plates (4 cells) is 3.25... a little high.

You might take a voltmeter and measure from your supply to your cell to see if you get a voltage drop of more than a volt (indicating your wire size is too small). Another indication would be your wires getting warm.

Also remember by decreasing the number of plates you'd have to decrease your electrolyte concentration to have the same amperage.

Guys, try to remember that the current is what you really want to see and that is what you control with a PWM NOT the voltage. voltage only gives you the potential for work, current or amps actually do the work, in a parallel circuit your current will be the same, in series the voltage is same, get yourself an Amp meter, and calculate your surface areas then, try to calculate for the current you want to supply to your plates/Grid.

Steve
11-09-2008 08:58 PM
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