I am working on finding parts for a wacky prototype idea, and I could really use some help from you folks. I need to run a DC water pump off a bank of D batteries. I know the pump in the link is not exactly meant to run off such a power source, but I literally need it to run for about 2 seconds, 3 times a day. Do you guys think I would be better off using 4 D batteries with a step-up transformer to get the 12 volts, or would I need to use 8 cells?

https://tinyurl.com/yc39xe8u

I looked for some step-up transformers, but could not find any that will pump out the needed 70 watts. At least not ones that are in the price range i would like to find.
If someone would be willing to chat with me and help find the best solution it would be awesome

Thanks so much,
Jono

 

Hi Jono, I'm wondering whether your idea really needs a 70W pump or, since you are only running it briefly, whether something like https://thepihut.com/products/subme...-bONs9bTzKVCtFicXJ8kRku-YRoNsyohoCHGMQAvD_BwE would do? What head of water do you need?

A "transformer" won't boost the voltage of DC - you'll need a switching DC boost converter to increase voltage which just adds cost. If you are only running a few seconds per day, better to use smaller batteries like AA in series - and there are lots of relatively low cost battery holders for 4 x AA batteries so two of these in series would be a neater solution if you stick with your chosen pump.

 

Lithium primary cells (if you don't need rechargeable) have about 3V output so you would only need 4 of those.

 

Your requirements are somewhat unusual.
A pump to run 2 seconds 3 times a day. That means a 'small' amount of fluid pumped. Can be a wimpier pump for a longer time; can be run on batteries, can run on 120VAC, can run on wall adapter.
70W... Well, maybe, pumping is not rated in Watts... Can be for higher pressure, can be for low pressure, and flow.

There is maaaany choices on the market. Pick the one that performs the way you want or the one for the electric supply you prefer. Even fish tank pumps for low $... Fountain pumps... For unbeatable $0 I canibalized 120VAC dish-washer, clothes-washer pumps that proved very reliable out from defunct discarded appliances.

 

For such a small amount, you could always put a gallon of fluid in a container and put it on a high shelf, then just use a valve.

 

A pump rated at 12V 70W implies a ~6A current when running. The start-up current is likely to be several times that, perhaps 20A?

 

I am working on finding parts for a wacky prototype idea, and I could really use some help from you folks. I need to run a DC water pump off a bank of D batteries. I know the pump in the link is not exactly meant to run off such a power source, but I literally need it to run for about 2 seconds, 3 times a day. Do you guys think I would be better off using 4 D batteries with a step-up transformer to get the 12 volts, or would I need to use 8 cells?

https://tinyurl.com/yc39xe8u

I looked for some step-up transformers, but could not find any that will pump out the needed 70 watts. At least not ones that are in the price range i would like to find.
If someone would be willing to chat with me and help find the best solution it would be awesome

Thanks so much,
Jono

If you can find a DC transformer that is not a fraud, it will be a miracle. That has already been mentioned, I am just repeating it because the closest you will find is a small inverter of some kind. But no inverter is 100% efficient, and so the losses will always be there. So if you have space for them, the 8 size "D" batteries will be the most efficient. The smaller battery size suggested will have a greater internal resistance and so the performance will droop sooner than with the larger cells. And rechargable batteries may be a better choice, if recharging is easily possible.
Unfortunately, at least with the pumps I am familiar with, two seconds run time will not be enough to get the fluid being pumped moving. Certainly the RV water pump that I am familiar with takes quite a few more seconds to get the flow moving.

But since we have no hint as to the application it is not possible to give accurate advice, but rather only reasonable suggestions. We do not even know what sort of pump it is. Diaphram, centrifugal, gear pump, rotary vane pump, or a reciprocating piston type. A positive displacement pump starts flow quickly but usually at close to full load, while a centrifugal pump starts up a small bit more gently.

 

https://tinyurl.com/yc39xe8u
Jono

That link shows "Sold Out".
{not visible}.

 

I did not do real great about pitching this let me add some context and I bet you guys can help better. I am wanting to make a water gun alarm clock... literally it shoots water in your face for 2 seconds, then turns off and gives you maybe 30 seconds to get out of bed and run across the room to turn it off before it sprays you again I want something that can put out enough pressure to shoot like 12 feet so the unit is setup far enough away that after being sprayed in the face, if your not totally awake, now you have to get on your feet and walk across the room to disable the 2nd heart pounding spray. I am going to look at a number of nozzle options, so if you wake up with your head 3 inches from where you fell asleep, you can set it to give a pretty straight shot, but if you roll around and are going to have your head 2 feet away by morning, you can set the spray to accommodate that. An X GF brought up the concern of "what if your bed partner doesnt want to get sprayed", and that is a concern that I would need to address. But for the time being, I would like to get the electronics side worked out. I wanted people to not have to have access to a plug in for this, but if the options are "electrical fire from a reckless battery setup, or having to use an outlet, I'll do the outlet lol"
I should not have pitched this with the precursor of needing to use batteries, so I am sorry for making my post hard to answer, and probably people wondering what the heck this guy is trying to do". If I can make this work with a 120 AC pump, I would be totally cool with that

Thankyou again for all the feedback, and don't steal my idea!
Cheers
Jono

 

OK, now the application is understood. I have experimented with a water cannon, which would deliver ove a quart oof water in less than a second. THAT application used compressed air stored in a tank rated to 1800 PSI, so bursting at 120 PSI was not likely. It also had a 3/4 inch port solenoid valve to allow rapid air flow.
Your squirt gun could be a much smaller version of such a device. A much smaller air tank such as a 2-liter plastic pop bottle, with about a pint of water in it, could be pressurized with air from even a small portable bike air pump. Then a solenoid valve drawing only a few watts could operate and the flow would start almost immediately And it would be much quieter than any pump.
For just a 2 second squirt, it would probably only need pumping up once a week.
The solenoid valve could be recovered from a scrapped dishwasher machine fill valve. But the coil would need to be rewound because most of those valves operate on 120 volts. So a 12 volt coil would need to be created. Not that big a deal.
So there you have another option suggested. Please Let us know how it works out.

 

Go to an automotive wrecking yard and pick up an old windshield wiper motor. Modify the length of the stroker arm and connect that to a piston pump. The wiper motor has three wires, one wire runs the motor back to the park setting, one wire gets the motor running FROM the park setting and the third is negative. All you need is a brief period of time to start the wiper motor. Long enough to get it away from the park setting. Once it's away, power on the main wire will drive the wiper one full revolution. That single revolution can be set to deliver as much or as little water as you like. Something like a syringe would do. But you then have to figure a way to refill the syringe every pump. A set of one way valves would work. One draws water into the syringe on every pull back stroke, then closes off fur the forward stroke. The forward stroke also has a one way valve to prevent the syringe from pulling air back into it.

You then build a timer that will run the pump at the set time and wait a period of time before the next spray. That will continue until you switch it off or reset it for the next alarm time.

Personally I doubt you'll ever build this - there have been many threads on ways to wake-you-up here. I've never heard of one actually being built. Nevertheless, I could be wrong. IF you build this you'll not be the first, nor the last. For decades people have been trying to figure a way to get a heavy sleeper up at a given time. Some even use tilting the bed up and making the dose'r slide out of bed and on to the floor. Fire alarms, clackston's, vibrating devices - many before you have tried to invent a better alarm clock. For me nothing works better than a big glass of water before going to bed. My bladder can become very insistent come morning, and I'm often up before the alarm clock set time. In fact, I'm up now because of my bladder being full. It's 5:30 AM here. The only problem is that my bladder doesn't recognize Saturdays, Sundays or Holidays.

 

Whilst you're there, pick up a windscreen washer pump as well. They can put out a good volume of water, and if you add a non-return valve to keep it primed that should start instantly.

 

The compressed air water squirt system will cost much less and use much less power. In addition it will take up much less space, and pose much less of a hazard for electrical issues.
My question is about how it will be triggered. While a clock radio has an arrangement to switch on the radio power, the plain electronic alarm clocks that I have only use a weak piezo-electric sounder that does not get enough drive power to light an LED.
So what would be triggering this wet-wake-up system? Can the TS share that bit of information with us?

 

The solenoid valve could be recovered from a scrapped dishwasher machine fill valve.

Could you give a link to a dishwasher that fills with water, please?

-no stones have been thrown in this post-

 

Every dishwasher I have seen, used, or installed had a water connection. The actual "fill" is probably less than a gallon. And certainly a dishwasher appliance qualifies as a machine. So what is the point in asking for a link?????
Both of the "Kitchen Aid" dishwashers have a solenoid water valve, How else would the water used for the wash process be controlled? Also, I do not do links .

 

Ditto what @Ian0 said. Except just get the windshield washer pump unless you want the wiper motor for something else!

Or just buy a new windshield washer replacement pump at the autoparts store. The ideal type has hose barbs for inlet and outlet so you can use any convenient container as the reservoir. The pumps are cheap.

 

A solenoid valve will provide a quicker start of the flow, which can be adjusted by setting the pressure. And be almost silent.
And I am thinking that a while back this same TS was asking about how to trigger it from an alarm clock. Sometimes folks never give upon a project. Is waking up really that difficult???
We never did learn how the alarm clock trigger project worked out.

 

Every dishwasher I have seen, used, or installed had a water connection. The actual "fill" is probably less than a gallon. And certainly a dishwasher appliance qualifies as a machine. So what is the point in asking for a link?????
Both of the "Kitchen Aid" dishwashers have a solenoid water valve, How else would the water used for the wash process be controlled? Also, I do not do links .

I agree that they have a water connection but they don't "fill" with water. The spray arms are where the water goes over the contents. At most there is only less than 2" of water in the bottom of the dishwasher. Never saw one that filled the inside. The door isn't water proof enough to allow it to fill.

 

We never did learn how the alarm clock trigger project worked out.

You may, as do I, suspect this is a cerebral project. No tools or parts will ever be applied to this project

Never saw one that filled the inside.

Semantics. I understood the "Fill" part of the statement to be filling the bottom only of the washer. Maybe 2 inches deep at the most. The sprayer pump pushes water out to the wash arms that spin and dispense water all about the machine. In this case "Fill" doesn't mean "Full".