how do you overvolt a pump?

[louie101086]

i see people talkin about it but i dont know how to do it

 

[Newf]

Just 'cause folks talk about it don't make it a good idea...

 

[Mugz]

Why? It won't increase pressure at all, basically all it will do is reduce the life of the pump.

If it's a 12V pump, you'll need a higher-voltage PSU (such only exist around industrial computers - good luck getting bits for those easily). If a 110V/220V pump, good luck! Let me know how you did it if you don't blow something up, I'm something of a research electronics engineer and really would like to know.

 

[Raviolissimo]

one Christmas Eve ... i was re-arranging some furniture and knocked over a lit candle.

i didn't notice the candle.

i went and started my truck and was sitting there thinking, "something doesn't feel right".

i went back inside and found an area of carpet about 2 feet by 4 foot in a seriously Flambe' condition.

if i hadn't gone back inside, i would have burned down a 12 unit condo complex - on Christmas Eve !

on overvolted pump can start a fire just like a knocked over candle. not saying you shouldn't do it. just that you should be careful.

i've seen 2 electrical fires at work, one in a UPS for an aircraft carrier (actually, that was more like an explosion), another in a really expensive radio (solder dendrites growing between power and ground. VP walks in to see demonstration. co-worker throws switch to demonstrate "spec compliance". very expensive behind schedule radio goes Poof ! & takes half of very expensive test system with it. VP not happy.)

2 explosions in 20 years (at work), plus the candle thing.

talking shop is more fun when the whole building doesn't burn down.

 

[Mugz]

I'm just trying to figure out where he's planning to get the extra voltage from.

 

[tool_462]

I think the pumps I have heard of people overvolting, were not connected through the PSU. They have their own plug and are relayed through the PSU.

 

[Mugz]

Like the one in my CM Aquagate. It's a 240V pump.

It has a 240V power lead coming from a 240V socket.

The pump in my tank is also 240V, running off a 240V socket.

I'm still trying to figure out where he's planning to get the extra voltage from.

Forgive the sarcasm... I'm out of practice.

 

[Newf]

Unlike overclocking, changing voltage to a pump will not easily come in the small steps necessary to provide a (possibly) satisfactory outcome. You would need a step-up transformer of some kind with multiple small steps, or a higher voltage source with a variable resistor/rheostat to make this work. In any event, what's the point?

 

[blunc]

well, if he was using a 12v pump and he was planning on using the PC PSU, he could us -5V and +12V rather than hooking up GND and +12V. that would give him 17V to the pump but I don't know the current capabilities of the -5V circuit or how it would affect the mobo.

 

[tool_462]

I also don't know how well a pump would handl ~40% more voltage. Some might be just fine, but some might be toast after a short time.

My MCP655 has a rheostat built in and using a multimeter at the lowest setting it draws about 6.3v and at the highest about 12.2v. <-- Doesn't matter, I just decided to share I guess.

 

[Mugz]

It would FUBAR the PSU in very short order. [/electronic engineer talking]

If the PC switches on at all, that is. [/PC techie talking]

@Newf
Just for the hell of it, I've sourced a 240VAC transformer, with multiple outputs (6V to 24V, in 2V increments) from Mantech, ordered the damn thing (along with a horde of components, for power regulation/filtering/switching circuits - if the transformer survives, it's probably going to get hacked into my UPSU concept) and I'm going to compare 3 12V waterpumps under load - one at 12V, one at 14V, and one at 16V.

The point, I'm guessing, is to boost the cooling characteristics of the cooling system. So I'm looking at this and going about this the way an engineer would - it's my training, I can't help it.

The thing won't take the CPU to below room temperature no matter what. That's a given. So let's assume the room temp at 25ºC - a very average figure, my room temp is closer to 15ºC - for simplicity.

At 25ºC, let's assume the CPU temp at idle to be 35ºC. At load it goes up to 50ºC. Okay, increasing the flow rate means more water through the head and through the radiator. The only effect that pushing up the pressure/flow rate is going to give is that the load temp is going to go down by about 5ºC, ditto the idle temp. To fully capitalise on this one would have to upgrade the radiator fans as well.

Increasing the flow rate on the fan(s) on the radiator will probably have a greater effect anyway.

Quite frankly, it'll be cheaper, more effective, and less effort in the long run to only upgrade the fans on the radiator instead of hacking a PSU to overvolt the pump.

As for overvolting a 240V pump... easy. Autotransformer. That's it. I can get one made to take 240V up to, say, 250V... but single-phase AC motors are self-limiting i.t.o. speed, so overvolting it only means it can maintain it's rotational speed under heavier loads, and burn out faster. I'm not going to experiment there. [/far too much experience with 3-phase AC motors to want to muck about with it in my spare time]

 

[nukemaster]

Just dont do it.

Most DC motors will handle the extra power just fine, but the system is designed for so much water flow. If your need more get a higher GPM pump.

For the record. who here has not decided to make a 6 volt toy car(it was wired, so nothing but the motors and swtiches) run on 9?(with a big ass battery pack of 9volts for the extra current) what did you all do as kids(for real, i was over volting shit before i even went to school )

 

[tool_462]

I think when I first did that stuff, I didn't even know why it made it faster :lol: I just knew when I stuck a 9 volt onto the contacts of my RC cars they motors sounded like they were going to explode, which was a good thing

 

[Newf]

It would FUBAR the PSU in very short order. [/electronic engineer talking]

If the PC switches on at all, that is. [/PC techie talking]

@Newf
Just for the hell of it, I've sourced a 240VAC transformer, with multiple outputs (6V to 24V, in 2V increments) from Mantech, ordered the damn thing (along with a horde of components, for power regulation/filtering/switching circuits - if the transformer survives, it's probably going to get hacked into my UPSU concept) and I'm going to compare 3 12V waterpumps under load - one at 12V, one at 14V, and one at 16V.

The point, I'm guessing, is to boost the cooling characteristics of the cooling system. So I'm looking at this and going about this the way an engineer would - it's my training, I can't help it.

The thing won't take the CPU to below room temperature no matter what. That's a given. So let's assume the room temp at 25ºC - a very average figure, my room temp is closer to 15ºC - for simplicity.

At 25ºC, let's assume the CPU temp at idle to be 35ºC. At load it goes up to 50ºC. Okay, increasing the flow rate means more water through the head and through the radiator. The only effect that pushing up the pressure/flow rate is going to give is that the load temp is going to go down by about 5ºC, ditto the idle temp. To fully capitalise on this one would have to upgrade the radiator fans as well.

Increasing the flow rate on the fan(s) on the radiator will probably have a greater effect anyway.

Quite frankly, it'll be cheaper, more effective, and less effort in the long run to only upgrade the fans on the radiator instead of hacking a PSU to overvolt the pump.

As for overvolting a 240V pump... easy. Autotransformer. That's it. I can get one made to take 240V up to, say, 250V... but single-phase AC motors are self-limiting i.t.o. speed, so overvolting it only means it can maintain it's rotational speed under heavier loads, and burn out faster. I'm not going to experiment there. [/far too much experience with 3-phase AC motors to want to muck about with it in my spare time]

The way I see it, more fan airflow and/or a bigger radiator will bring cooling system temps down. By this I mean the long-term stable coolant temp leaving the radiator/reservoir. Increasing the pump voltage/flow will lower the short-term temperature differential between the heatsink and the coolant.
If the cooling system is assumed to be reasonably balanced between cpu heat transfer and radiator heat transfer, then the greatest cost/benefit for most people will be to make the radiator transfer heat faster.
Cooler water flowing to the cpu at a "regular" speed is better than warmer water flowing through at a higher speed. The goal should be to maximize cooling under heavy loads, rather than to maximize instantaneous cooling response. Does that make any sense?

 

[tool_462]

What you are saying is this:

Optimal cooling is the result of the water being in contact with the CPU for the correct length of time to absorb it's full capacity of specific heat. Not less or not more.

Then you want it in the radiator for the correct length of time to remove as much heat as possible.

Am I correct?

 

[Mugz]

My guess is that is what he's getting at.

@Newf
Goal of maximising cooling under load as opposed to goal of maximising cooling response. Makes sense.

Maximising the cooling under load translates as increasing the cooling system's capacity to handle constant high temperatures.
Maximising cooling response translates as increasing the cooling system's capacity to maintain a constant temperature should the CPU suddenly get hotter.

So on the one hand, we have a system which can maintain a constant temp, whether load or idle, and on the other hand, we have a system which prevents sudden short temperature 'highs', but probably won't handle a constant heavier load.

Hmmm... fit a bigger radiator.

Re: long-term effects of overvolting a pump.
The power supply is ready, it has three outputs: 12V VRM filtered, 15V VRM filtered and 18V VRM filtered. The heat source is a thermocouple, with a junction temperature of 55ºC to 75ºC variable, set to 55ºC, one per loop. Radiator is a car heater matrix, one per loop. Fluid is RO water with a degalvanisation agent.

12V loop gives 51ºC at block. 15V gives me 50ºC at the block, while the 18V (for the four hours it went before dying) dropped the block temp to 47ºC. As it died, it took its filtering circuit with it.

Be warned - overvolting a pump WILL damage your PSU.

 

[jt001]

Optimal cooling is the result of the water being in contact with the CPU for the correct length of time to absorb it's full capacity of specific heat. Not less or not more.

I was gonna say this but he beat me to it

Plus, the extra heat will kill the pump faster for sure, and when the pump dies it'll probably take a cpu with it. A pump really isn't anything to mod, if it isn't powerful enough get a more powerful one.

The -5 and -12v on the PSU probably won't handle a pump (both looking from at the specs and the fact I've gotten curious and tried it)

 

[duthoy]

repeat after me:

real bad idea

REAL.....BAD.......IDEA

now serious,
you could blow the engine of the pump, whithout any gain!

 

[Mugz]

I'll post the results from my experiments in overvolting pumps tomorrow. I got a phonecall from my flatmate about an hour ago, telling me (quote) 'the middle pump, like, it's making horrible rattling noises, like, it's not going to blow up is it?'

I get the distinct impression that a mere +25% increase in voltage (12V to 15V) will kill a pump in 2 days or less, considering that that setup was only switched on for the first time at 20H00 last night.

The pump with a +50% ramp in voltage died (to 18V) died after about four hours, around midnight.

 

[blunc]

so it would be best to take a pump motor rated for 12v and optimize the cooling system for 6v operation, then you could increase the voltage for special occasions.

the discussion regarding optimum flow rates thru the CPU heat transfer unit and the radiator are basically correct, if the coolant doesn't stay in contact with the radiator long enough to transfer the heat you would actually cause the CPU to overheat.

the same thing happens in a car when you take the thermostat out of the cooling system, the coolant doesn't stay in the radiator long enough to cool down.

 

[tool_462]

Yeah that is a good way to look at it. My load temp at 6v is 33C after hours of dual prime and folding. Load at 12v is 31C and it jumps back and forth between 31/32. So in my case the increased flowrate doesn't affect performance much.

 

[CompTIA_Rep]

I know someone who overvolted a pump in their case (not gonna suggest how he did it) and the pump melted taking out his motherboard, cpu, .....


No fires though.





Hay great IDEA... .... Save up some extra cash and get a larger pump.

 

[Newf]

so it would be best to take a pump motor rated for 12v and optimize the cooling system for 6v operation, then you could increase the voltage for special occasions.

the discussion regarding optimum flow rates thru the CPU heat transfer unit and the radiator are basically correct, if the coolant doesn't stay in contact with the radiator long enough to transfer the heat you would actually cause the CPU to overheat.

the same thing happens in a car when you take the thermostat out of the cooling system, the coolant doesn't stay in the radiator long enough to cool down.

Coolant is always in contact with the radiator. More flow rate through the cpu/engine means that the equilibrium temperature reached will be based on the radiator's ability to remove heat from the coolant. A car thermostat blocks most of the coolant flow upon a cold start, forcing engine heat to remain in the engine until it reaches a preset temperature. At somewhere between 180-195 degrees F, the thermostat opens and then through varying the system flow rate maintains engine temperature. Take the thermostat out and an engine will take a very long time to heat up, reaching its maximum temp at a lower value than optimum.
For a cpu, you have no thermostat. You do not want one. Cooler is better. Flow rates through the cpu cooling block are likely to be better than needed compared to the radiators ability to throw off heat.
In any event, the cooling system in your computer has a 100% cpu load equilibrium temperature of X. X is also the maximum operating temperature. Idle temps are meaningless. How fast you system reaches it's maximum temp is not relevant. Increasing flow rates/water block effeciency will impact this non-relevant factor. It will only impact system equilibrium when it is woefully inadequate as part of a properly designed balanced system, (very unlikely). That leaves the radiator/fan as the single most important component to modify.
An exception: Your goal is to OC a D805 to 4GHz, run a 2 minute benchmark, publish it and then throw the system away...

 

[Mugz]

The 15V pump casing melted. The pump itself seized. The concept has been killed. It doesn't work.

In any case, the pump was transferring large amounts of heat to the coolant while overvolted.

The concept is flawed. Next!

 

[Rugger]

Here is a link to a thread where Cathar talks about "How much pump is enough?" In one of the replies there is a link to equipment that will allow you to overvolt your pump. There are only a few pumps that really benefit from overvolting - the most significant is the MCP600 - now known as the Aquaxtreme 50Z. It is only a slight overvolt, 12V to 13.8V. One of the major things that you have to worry about with overvolting is adding a lot of heat to your watercooling system, but this particular overvolt isn't too significant because the 50Z sheds very little heat, something on the order of 3W. Great thread that I highly recommend you reading.