RULE 3700 36 volt pump power options?

[sdowney717]

I made an error not pursuing a faulty EBAY transaction within the 45 day period. So I am perhaps stuck with a 36 volt DC pump and my system is 12 VOLT DC. It was advertised as 12 VOLT.

So, is there any reasonable way to run a 36 volt DC pump using a 12 volt DC battery system?
I was wondering IF, you could take an inverter from 12v DC to AC and run the 120 volts thru a bridge rectifier dropping the voltage and making a DC voltage
supply to the pump. Pump theoretically could draw 20 amps if rotor was locked

 

[kmacht]

Sure, it can be done. You can trade amps for more volts but the components to do it at 20 amps are going to cost you a small fortune. I am assuming it is a bilge pump? Have you tried running it at 12vdc? Many dc motors are rated at a max voltage and will run just fine at a lower voltage, just a litte bit slower.

Keith

 

[Ford12508]

The inverter is not 100% efficient, so depending on how much the pump costed, it might just be time to chalk up a loss and buy a new one.

 

[nehog]

How much current does the pump draw? What are the specifications on the pump (electrical).

An inverter, to a 120 to 36 volt power supply is an option. No simple rectifier setup will work (the voltage will be way wrong). There are 12 volt to 36 volt converters too, but current is a factor as is price.

 

[sdowney717]

yes, boat pump. Seller said it was 12V, BUT it is a 36 volt model.
It is rated 5 amps at 36 volts or 7 amps at 32 volts
If you try running the pump at 12 volts, it spins, but it has no power to push the water.

The 12 volt version can use up to 20 amps if rotor is locked, I think.

I had been thinking of adding an inverter anyway to take 12v DC to 120V AC.
This pump is a backup to 2 Rule 2000 pumps.
So it would only need to run in an emergency flood situation.

So, I would consider a rectifier bridge off the inverter.
I have a forward electric anchor windlass that someone sort of adapted to run on 120V AC by adding a 4 prong rectifier bridge inside, or perhaps it was made for that. I opened it up and recall a 48V DC motor in there. I think it was like an electric battery operated lawnmower motor after looking up the motor numbers. Runs great off the AC 120V line. I do have n AC generator, So it was wired up with that, but you need to run the gen to pick up the anchor. (another reason for inverter) I think I measured the DC output at ~48VDc on it.
Anyway I would not mind running the 36V pump at 48V DC
Battery to inverter to rectifier to automatic bilge switch to pump
Any ideas on components, inverter size, etc?

 

[sdowney717]

well, I contacted the seller today and was told If I ship it back, ****** will refund me the money. So how would you send it, delivery confirmation etc?
It is worth about $53 back to me.

 

[nehog]

...
I had been thinking of adding an inverter anyway to take 12v DC to 120V AC.
...
So, I would consider a rectifier bridge off the inverter.
...

You would need more than just a rectifier bridge to get suitable voltage. A 120 volt AC line would give you 1.7 times the voltage at the output of the rectifier, or almost 200 volts. I doubt a 32 volt motor would last very long at that voltage, probably about as long as it takes to say 'BANG'.

As to shipping it back (best choice!) I would use Priority Mail, with delivery confirmation. Delivery confirmation is free if you do the shipping label/postage online (USPS.com). Be sure to pack it properly, do not use foam peanuts, tape the box properly (don't use duct tape or masking tape!) and you should be OK.

 

[kbs2244]

Send it back.
It will cost more to make a jury riggerd system.

 

[ishiboo]

Send it back.
It will cost more to make a jury riggerd system.

Agree 100%.

In addition, two 2000 GPH pumps is a pretty big setup. Very few boats will have a 3600. I would stick with the two 2000 GPH pumps. There are usually two types of issues - a minor leak most pumps can keep up with, or a major disaster only an engine-mounted dewatering pump can deal with.

Remember; a 40' boat with a 1" hole sinks much slower than a 16' boat with a 1" hole, so you don't necessarily need a ton of pumps the bigger the boat gets, at least with recreational boating

 

[rockwithjason]

you could use 3 12 v batteries in series.

 

[ishiboo]

you could use 3 12 v batteries in series.

Its a boat... getting a new pump would make a lot more sense than dedicating 3 batteries to the bilge pump, both cost, weight and basic common sense

 

[sdowney717]

yes, I sent it back used UPS store as it was cheaper than USPS by about $3, plus no waiting. The USPS is so busy I hate going there.

Now I want to get another pump to take it's place. The boat is a 37foot Egg Harbor sedan cruiser. I do believe in extra good bilge pumping systems. You can be out on the water and in a heavy sea, you can theoretically take a lot of water on board. If you dont get it out quickly, then you might founder. I also have 2 pumps under the aft deck, the boat is divided into compartments, rear compartment is watertight to the first, so if you take on water in the back, the boat theoretically has a better chance of staying afloat.

One thing I would like to add is a collision bulkhead up forward.

 

[sdowney717]

Remember; a 40' boat with a 1" hole sinks much slower than a 16' boat with a 1" hole,

true, but it still sinks