Cell Progress Update

[spencyg]

For the sake of putting myself out there for "critique", I'd like to provide an update on my cell progress.

As a preface, the application for this unit will be to boost a '96 Nissan Pathfinder, OBD2 emissions. Next year my wife and I are selling the house, storing the shop and goods, and going on a year long expedition across the US, Canada, and Central America. The Pathfinder will be the medium in which we experience the world. I hope to get between 25-30 MPG once all is said and done...fully loaded, with an expedition trailer.

I've selected a series cell as the base for the project. It is fairly standard fair, with plates separated by gaskets and sandwiched between lexan endcaps. I have taken the heed of Bob as well as others in the selection of a series cell, but diverged on a couple points for ease of use duing the trip.

This will be a pumped cell. Electrolyte will flow in one end, and electrolyte and gas will come out the other. I know there have been various discussions on this board regarding the use of pumping....some favorable, others not. The biggest benefit for my situation will be the ability to monitor water levels remotely in the gas separator tube. There will be a separate pump (low volume, intermittent use rating) which will top off the electrolyte loop when it senses the need. I'm going to use a gear type fuel pump for the electrolyte circuit...it should handle the duty acceptably. At this point I'm not intending to vary the speed of the pump, but if the need arises, I can just use a simple PWM circuit.

For driving the cell itself, I'm going with a single channel signal generator capable of varying frequency (0hz-120khz) and mark space (0-100% duty
). This will drive a MOSFET which will run the toroid coil stepped up to provide 24V to the cell (15 cell ~ 1.6V ea). Worst case scenario, I'll be able to use the signal generator to vary my current through the cell...best case, I'll get some benefit with the transformer/inductor circuit.

The cell is completed and I'll post pics tomorrow on my project page. The MOSFET for my signal generator is on order, so I should be able to have the circuit completed by the middle of next week. I have my eyes on a couple toroid transformers.

As for the application of the booster to the vehicle, I'm still unclear whether I should go down the road of a oxygen sensor modifier circuit, or whether I should cut right to the chase and dig into the programming of the ECM...?? I was intending to run the gas input into the intake manifold directly, as running it into the airbox would pass the gas by the MAF sensor, which I would imagine could lead to a thermal event...

Spence

[glenn_aircooled]

sounds good Spence.
I know I should wait for the pics but:
- what grade of stainless is the plates.?
- how are you going to move the electrolyte through the
cell to best benefit bubble removal?
- have you worked out the " Safety " Bubbler yet.?
Keen to see it Cheers,,Glenn.

[spencyg]

[kevinsatterfield]

Hey Spence , after try'n it out real fast ...its a lil more complicated than i first thought so im just gonna mark that one down as a tired "goofy" idea.....lol I like the idea but its gonna require a lil more thought an fabrication so I'll get bak to ya on that one.

Im sure you've read about wat electrolytes you can use with Lexan have'nt ya?

[slash1]

Spence,

Nice job on the cell… Looks great! Man I need a mill!!

Anyway, just wanted to make sure you knew about the conditioning you need to do to get best efficiency.

Here are some posts where Bob talks about it:




Also, you may not have to modify the O2 sensor feedback signal on a vehicle with a MAF. I’m pretty sure (you will have to check on your particular vehicle) that on an OBD2 vehicle, only the MAF is used for the main fuel control. The O2 sensors are used for a backup in case the MAF fails and the engine must run in speed density mode, as well as emissions diagnostics. An easy way to verify this is to unplug a vacuum hose and notice that the vehicle will begin to run lean and missfire (monitor the O2 sensor signal) due to the extra air getting in without going through the MAF sensor. If you then unplug the MAF, the engine will increase RPM due to the O2 sensors taking over and adding fuel to adjust for the lean condition.

Good luck and keep us posted on your progress.

[glenn_aircooled]

Excellent Work.
I wish I had your machining skills.
-
Lexan........might be bullet proof but chemical resistence???????
I did search on this forum, found Bob Boyce Said "

[ Mon Oct 09, 2006 10:00 am Post subject: Reply with quote Edit/Delete this post Delete this post View IP address of poster]

Mark

Please keep in mind that polycarbonate (lexan) is not chemically compatible with KOH, but it is fine with NaOH. Thanks go to Wayne in FL for discovering what happens when KOH is used with it.

Leakages will follow any flowing electrolyte, so use caution. Not only can it leak, it can also cause electrical disharges within the cell causing an explosion hazard.

Bob "
--------------------------------------------

The holes Idea , whilst good in theory may not be good for electrical leakage.
I hope it works and it may prove to be outstanding but first attempts
usually seem to be a learning experience.
- I was hoping that the holes for the electrolyte flow may have been
in the bottom. with enough flow up - it may have avoided unwanted
electrical leakage. Blue had a good idea - hope he doesnt mind me
sharing.....
I added a little bit to it - With the use of a perspex shaft which runs
along the bottom of the cells [ say across the centre line of all the
cells - thats one shaft. ] the shaft seals holes that feed into the bottom of the
cells. You grind notches in this shaft so that when turned - the shaft
will allow flow through the notched area into the cell.
You arrange the notches so that not two are open at the same time.
So the flow is in surges , one cell after another. No electrical leakage.
- - - And then theres the top Outlet tube. Gas flowing out will not carry
electrical current with it but excess electrolyte flowing out will short it over
to subsequent cells. Gets very awkward.
-
The shaft idea is very complicated to set up, has to be turned to function
correctly. Doesnt fit well with the Keep It Simple S_ _ _ _ _ philosphy.
Well at least it would look very technical.!

[spencyg]

[spencyg]

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[spencyg]

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[spencyg]

[kevinsatterfield]

[spencyg]

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