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12/24 volt converter.

fudd

By fudd
in Boat Equipment

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PaulG Experienced

PaulG

Posted
Posted

I still think the easiest way is a small 24v battery bank - a couple of cheap, small car batteries for example - next to the toilet and charged by a small charger circuit.

Charger does not need to be very big as the amp hours used will be quite low.

I agree - as I suggested in post #7.

Simple, reliable and cheap.

PaulG Experienced

PaulG

Posted
Posted

If we are playing 'who said it first' how about post #2 clapping.gif

Well, I'm certainly not going to play "let's start an argument over something we agree about"...

wacko.png

fudd Rising Star

fudd

Posted
  • Author
Posted

I've just taken delivery of the bog. Reading the manual it states 24v needs 25 amps. I can easily get a 20 amp converter. Would it be suitable? I know there could be a certain amount of redundancy built in.

Thanks.

Keith M Proficient

Keith M

Posted
Posted

If the manual states 25 amps is that the peak power or the current required after the start up current

 

Some the manual will state running current and not the starting current

 

Starting current can easily be 3 or 4 times the running current

 

Always select a device which will have around 30% in reserve

 

Keith

OldGoat Veteran II

OldGoat

Posted
Posted

Very much IMO, but unlike AC induction motors, the starting current is less of an issue. However, the run current is likely to the reasonably near the published figure.

Remember that the macerator is expected to be powerful enough to shred all sorts of solid matter (loo paper and some non ingested matter as well) as part of their design.

It may appear to be a bit od a faff, but I'd go for a couple of inexpensive c-tec type chargers wired in series (Aldi have them from time to time) together with a couple of low maintenance Yuasa type batteries - they will provide enough grunt for the grinding bit.

Don't assume 25A is the starting current DC stuff is not rated that way.

In similar vein don't assume that the 12/24V converter can handle a peak load of any length.

Arthur Brown Influencer

Arthur Brown

Posted
Posted

A battery on short fat wires has to be a good choice of power supply. The charger could be anything from a Mains driven one, to solar, to a 12v derived one. A good charge regime should help the batteries to last as long as a starter battery.

NMEA Rising Star

NMEA

Posted
Posted

I wonder at how much current this thing draws. Folk have been saying 40A @ 24V, so I'm guessing that a motor rewound for 12V is going to draw about double that? It'll need seriously fat cables if that's the case.

 

Or is the 40A purely to cover start-up surge?

The recommended fuse is 35a for a 24v DC unit so I suspect the draw will be quite a bit lower than 35a certainly nowhere near 40a which is the recommended fuse for a 12v DC unit.

WotEver Veteran II

WotEver

Posted
Posted

The recommended fuse is 35a for a 24v DC unit so I suspect the draw will be quite a bit lower than 35a certainly nowhere near 40a which is the recommended fuse for a 12v DC unit.

Yeah, I have no idea where that 40A came from. I found some specs above showing max at 24V of 25A

Geo Rising Star

Geo

Posted
Posted (edited)

Yeah, I have no idea where that 40A came from. I found some specs above showing max at 24V of 25A

 

It came I think you will find from the OP post #3. I would have thought you would have seen it.

 

 

It needs a dedicated 40 amp supply, and I'm finding it difficult to find a converter that will supply that.

Edited by Geo
fudd Rising Star

fudd

Posted
  • Author
Posted

Yeah, I have no idea where that 40A came from. I found some specs above showing max at 24V of 25A

That would be from me I'm afraid. Getting my 12 and 24 volts mixed up.

Geo Rising Star

Geo

Posted
Posted

The recommended fuse is 35a for a 24v DC unit so I suspect the draw will be quite a bit lower than 35a certainly nowhere near 40a which is the recommended fuse for a 12v DC unit.

 

I would have thought a 30A supply should cope happily.

Geo Rising Star

Geo

Posted
Posted (edited)

A run of about 3m'

 

You will get away with 10mm2 for that run

Edited by Geo
jddevel Rising Star

jddevel

Posted
Posted

Having made a similar- I like to call it slight human error but others would call it a big stupid mistake -I

have been following this topic with interest trying to avoid being beaten but at the same time not wishing to

throw to much good money after bad!! My question is assuming a dedicated battery bank as local to the loo as

possible what precautions are necessary to be both RCD compliant and more importantly safe for personal

reasons, would standard battery boxes be O.K?

Keith M Proficient

Keith M

Posted
Posted

The batteries to be in a battery box

 

The battery box may require external ventilation talk to the BSS office

 

Fuse for the changing supply

 

DC protection between the batteries and the toilet

 

 

Keith

ditchcrawler Veteran II

ditchcrawler

Posted
Posted

The batteries to be in a battery box

 

The battery box may require external ventilation talk to the BSS office

 

Fuse for the changing supply

 

DC protection between the batteries and the toilet

 

 

Keith

Do you think it would also require an Isolation switch?

Having made a similar- I like to call it slight human error but others would call it a big stupid mistake -I

have been following this topic with interest trying to avoid being beaten but at the same time not wishing to

throw to much good money after bad!! My question is assuming a dedicated battery bank as local to the loo as

possible what precautions are necessary to be both RCD compliant and more importantly safe for personal

reasons, would standard battery boxes be O.K?

Is this a new boat? I thought that was the only time the RCD came into play.

jddevel Rising Star

jddevel

Posted
Posted

New boat. My sailaway. The only way I can both afford my dream and hopefully get what I want with all its

idiosyncrasies. I love a challenge. Stupid me!!!

jddevel Rising Star

jddevel

Posted
Posted

On the other hand it may be that a 12/24volt step up converter may be a easier way to go as a 12 volt tail already in place in the toilets location and according to the information available the maximum amps needed is

7.5amps with the what I`m led to believe is the quote "flushed motor locked rotor current (amps)" as displayed in the specification. I would add it is a vacuum toilet not a macerating one so I assume the motor loading is no where so great.

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