[toddshotrods]

I smile anytime I see someone posting about using different metals or conductive materials together on the internet, because I know the galvanic FUD is coming!

I also love, love, love, getting new engineering interns in my shop so I can teach them how we effortlessly do so many of the things in hot rodding that the books (or inexperienced teachers) say cannot be done. Some are freshman engineering students - I know their professors are going to love me!

[Ivansgarage]

Well guys, thats one good thing about DIY, you can do what ever the hell you want. galvanic FUD, and bacteria doesn't scare me.

[toddshotrods]

I just like being sarcastic. When someone says something like that about certain metals in certain conditions, people with a lot of experience know that it's someone who doesn't have much, or has been indoctrinated into an unreasonable fear by someone who doesn't.

In all fairness to engineers (I really love them, almost went to school to be one), engineers are the reason I know I don't have to be afraid of galvanic reaction in most of these cases. The cars I dissect and put back together (a little differently), and that they originally designed, are full of these combinations of metals. Aluminum engine blocks full of steel sleeves, bolts, bearings, etc, are the example that come to mind first, when the subject comes up.

If one does the homework, they'll likely find (as Miz suggested) that by the time galvanic reaction/corrosion becomes an issue the part or vehicle will have exceeded its intended service life. The ones they're wrong on, have replacements at the local parts stores ready for human consumption; still no major issue, as it's usually just a slow, discernible, wear issue, not catastrophic failure.

[onegreenev]

I would think that the aluminum would pull heat away faster than the water pool. I would opt for an aluminum cooling plate where there are tubes running through the aluminum to pull away the heat from the aluminum and the aluminum pulls heat away from the controller. Being that you now have a huge open hole filled with coolant I suspect that the flow is not so good as to pull heat away fast enough. Kinda like just using a huge block of aluminum to pull heat away from the controller with not fins or fan. Thinking that the huge block of aluminum would suffice. Boy was I wrong. That sucker heated that block up quick and then the heat had no where to go. The controller went into limp mode again. Once I put on a heat sink with fins and a fan I was able to pull the heat away fast enough to never allow the controller to over heat even in 110 degree weather doing stop and go in town with high currents. The coolant tubes within a heat sink will allow the moving water to suck out the heat fast when pushed through a good radiator. A pond will absorb heat but I bet not fast enough. When the water from your tubes hit that pond it all slows down builds pressure then gets pushed once again through a small opening. Odd that there is no track for the coolant to flow.

Try it and see since you have it already but it does not seem to be a sound way to build a coolant heat sink.

[lockduke]

Todd in response to your post about galvanic reactions in this case why not use mineral oil. We have been using it to cool our computers for quite some time and don't get any kind of bio growth in our system and once it reaches temp it tends to stabilize temperature after it runs for a while. As well it is not poisonous to the environment. And also it tends to lower operating temps better than any other type of coolant we have tried. Also a few years back I was running mineral oil in my VF1000 F Honda while club racing here in Indiana plus I did not have to remove it in the winter. I just had to wait for a little while for it to warm up before I turned on the pump.And if my memory doesn't fail me it is inert with almost all materials like aluminum, copper, brass and with steel it tends to be a rust inhibiter. As well it has no problem with teflon, rubber or silicone tubing as far as I know. Just a little bit of homegrown technology from an old hot rodder.

[mizlplix]

During the US depression of the 1930's, my grandfather used Turpentine in his car radiator because he could not get anti-freeze coolant.

Mineral oil...Yah, I can see that would work well.



Bear in mind, I have only got 66 miles on my car. Most of the time, My controller was sitting between 45C-49C. I really had to do a lot of stop light to stop light driving and 400+ amp accelerations (with sitting at a light again) to get it above to 50C. All of this was in 105F to 113F ambient.

My inlet and outlet are the same size and the controller will not push enough heat to boil water, so I doubt if there is any pressure involved.

The Blacksmith dunks his metal in the slack tub,he does not spray water over it, he is in a hurry. If this were a steam boiler, then multiple tubes are king.

Granted that a metered flow along sufficient length of tubing is a perfect match for efficiency. I just feel that one does not need to be that accurate, It is just water. And it is not absorbing as much heat as it is capable.(at least in our instance)

And not to put too fine of a point on my theory, but the water jacket in every liquid cooled engine ever made is just a water tank and they cool just fine. Yes they have air pockets and dead spots, but they work and deal with many, many magnitudes of heat more than a controller can produce.

Miz

[toddshotrods]

Originally Posted by lockduke

Todd in response to your post about galvanic reactions...

Me?! I'm just a jerk being sarcastic when I see comments about galvanic reaction/corrosion. I have never even considered the issue of biological growth in a cooling system, until it was posted here. I would just add something to it, like a couple shots of moonshine (being sarcastic again).

Originally Posted by mizlplix

...And not to put too fine of a point on my theory, but the water jacket in every liquid cooled engine ever made is just a water tank and they cool just fine. Yes they have air pockets and dead spots, but they work and deal with many, many magnitudes of heat more than a controller can produce.

Miz

I don't think I can agree with you there Miz. The water jackets inside, at least modern, engines are more passages than tanks, IMO. The ratio of inlet/outlet volume to internal capacity is what I would look at, if I were concerned about this. If it would take the outlet too long to clear the room, and the inlet is constantly funneling in more, at the same rate, there's more of a chance for some fully heated coolant to wear out its welcome.

That being said, your bathtub plate is obviously doing the job, so I would file this whole concern in the same folder with galvanic so and so: got it, considered it, deemed it not critically relevant - more important things to focus on.

[EVfun]

I have a thermosyphon system on my Buggy controller. The only metal in the system is the controller's internal plate, all other parts are plastic. I run a common propylene glycol based computer coolant. I haven't noticed anything growing and there is no "other metal" to cause galvanic corrosion. It mostly adds thermal mass to the system. The upper hose is noticeably warmer than the lower hose after a drive.

[mizlplix]

(OK moving on)

The last component in my EV "cooling system" is my transmission.

I intend to isolate it and remove it from the cooling system.

REASON;

In the last 50 miles, my pan temperature has never gone over 160 degrees even when I stopped the coolant pump for 25 miles.

Air cooled versions of it were produced for the lighter weight GM cars.

I have removed the biggest heat producer, the torque converter.

Using my new unofficial rule (units must be operating in the upper half of their temperature range to need water cooling) my transmission is not in jeopardy.

On the powerglide, the cooler circuit can not be simply plugged (as it can be on some Ford transmissions). The return oil is directed at several components as a lube circuit. It must be looped.

ATF operates best from 0F-230F. After 230F it starts to slowly degrade and requires replacement. For instance, it will require replacement if operated at 265F for one hour. Synthetics are way above that. 300F-350F is the flash point of ATF, but by then you have cooked everything.

My 160F (105F-113F ambient) is well within the operating range. Using synthetic would be a good plus. Lastly, my system only uses 1 3/4 Qts total.

This eliminates a pump (electrical drain), several feet of hoses and a heat exchanger, all potential future failure points.

Miz

[Ryan800]

Ok, sorry for getting the thread off track, I just figured there might be someone out there reading this that would appreciate the heads up.

I don't think it's fair to call the issue FUD though, aluminum and iron is used commonly, but copper and steel/Al is much worse and I've never seen an OEM use this combination. Oil/transimission coolers use these combinations since oil isn't conductive.

But anyway, I guess it's been done and it works fine for a long time so carry on...