Amps On a Narrowboat

[WotEver]

1 minute ago, Loddon said:

Er no it wont trip immediately or even within a few minutes A 16amp mcb will easily pass 20amps for a surprisingly long time. On Parglena when washing machine, tumble dryer, batrery charger, aircon etc were all on it was not unusual to see 25amps being drawn off a 16amp supply!

It entirely depends on the mcb. Plenty of reports on here about 16A feeds tripping out at 15A. 

[GUMPY]

Just now, WotEver said:

It entirely depends on the mcb. Plenty of reports on here about 16A feeds tripping out at 15A. 

In which case the mcb is faulty. They are designed to pass 16amps indefinitely just as a fuse does........

[WotEver]

13 minutes ago, Loddon said:

In which case the mcb is faulty. They are designed to pass 16amps indefinitely just as a fuse does........

Absolutely.

As I said, it entirely depends on the mcb. 

Edited August 26, 2017 by WotEver

[Chewbacka]

I just had a look at the Schneider MCB trip curves and it shows that a 16A mcb passing a 25A current will trip between 90 and 400 seconds, which is a fair bit slower than I expected.  Surprisingly a 16A mcb at 16A could trip as soon as 1000 seconds, though it can also be much longer, up to never.

[Mark May]

On 26/08/2017 at 06:02, Tony Brooks said:

 

Are you going to run any of this stuff via an inverter at any time? If so divide the watts by 10, not 250 to get the current drawn from the batteries.

 

 

 

Hi Tony, where do you get "10" from? I might be missing something here but, considering that to convert Watts to Amps (Amps is what the appliance draws from your battery), the equation is (Amps = Watts divided by Volts). Inversely, to convert Amps to Watts, the equation is; Amps multiplied by Volts (Amps x Volts). So the equation to determine the depth of discharge (draw) on a 12 Volt battery/s system would be: Watts divided by Volts(12). Plus whatever amps your inverter draws in operation

Example: 800w microwave oven in a boat or caravan (800w / 12 volts = 66 amps)

[dor]

15 hours ago, OldGoat said:

 

I'm on thin ground here - but methinks the alde type heater is really designed for caravans and occasional use so perhaps not best suited to a domestic environment and do they work well with a calorifier for  hot water - showers  / bath etc.

 

A fair comment if you are referring to the old Comfort 2928 type Alde heaters. But do you have experience of the Alde 3010/3020?  It heats up our 60 litre calorifier very quickly (I've got a temperature sensor on the side so I can see how quickly it is heating up).

I'm not saying it is cheaper to run than a Webasto or similar, but it does have some advantages.  It's near silent for a start, doesn't clog up if it is cycled on and off quickly, isn't sensitive to slightly low voltage and doesn't need regular servicing.

[BruceinSanity]

4 hours ago, Mark May said:

Plus whatever amps your inverter draws in operation

That's the crunch point. Losses in the inverter mean that dividing by 10 gives a better estimate of likely current draw from the bank. It's pessimistic but that's the way to go when nursing lead acids.

[Alan de Enfield]

10 hours ago, Elliott0184 said:

What are the marinas like with just taking a canister for it to be filled up with diesel

A small 'drop' of diesel produces quite  noticeable 'rainbow' of pollution o the water - few people can fill from a can without spilling a 'drop' (unless you have a pumping out system and can catch the last drop from the end of the pipe.

If you slip and spill 20 litres of diesel in the marina it becomes a 'major incident'.

 

Few marinas will allow you to refuel from cans on your berth - you are required to move to the fuelling berth where pollution equipment is available in case of accident.

A boater was evicted from our marina for refusing to fuel up on the fuel-berth (but being petrol it was even more dangerous than just a spill)

 

If moving the boat to re-fuel is going to be 'annoying', may be you would do well to consider a flat / house with a water view, rather than a boat.

 

On the question of 'tank size' some boats have (maybe) 100 litre tanks, some have larger - mine has a 2800 litre tank but I only fill up once a year at a cost of around £2500

[Tony Brooks]

5 hours ago, Mark May said:

Hi Tony, where do you get "10" from? I might be missing something here but, considering that to convert Watts to Amps (Amps is what the appliance draws from your battery), the equation is (Amps = Watts divided by Volts). Inversely, to convert Amps to Watts, the equation is; Amps multiplied by Volts (Amps x Volts). So the equation to determine the depth of discharge (draw) on a 12 Volt battery/s system would be: Watts divided by Volts(12). Plus whatever amps your inverter draws in operation

Example: 800w microwave oven in a boat or caravan (800w / 12 volts = 66 amps)

An 800 watt microwave is unlikely to be anything of the sort. *00 watts look very much like cooking power to me, not electrical consumption. Without seeing the consumption data assume its around 1600 watts.

As Bruce said, the 10 assume an inverter efficiency of 80% and its very easy to use in mental calculations. You can bet the inverter efficiencies published were measured under the most favourable conditions and load so 80% will sometimes be pessimistic but with a large inverter supplying a small load like a phone charger it is likely to be optimistic. Again, as Bruce said, for long battery life when away from shore power its est to overestimate your consumption and also  vastly  overestimate what you think the charging time will be.

[Alan de Enfield]

5 hours ago, Mark May said:

Example: 800w microwave oven in a boat or caravan (800w / 12 volts = 66 amps)

 

32 minutes ago, Tony Brooks said:

An 800 watt microwave is unlikely to be anything of the sort. *00 watts look very much like cooking power to me, not electrical consumption. Without seeing the consumption data assume its around 1600 watts.

As Bruce said, the 10 assume an inverter efficiency of 80% and its very easy to use in mental calculations. You can bet the inverter efficiencies published were measured under the most favourable conditions and load so 80% will sometimes be pessimistic but with a large inverter supplying a small load like a phone charger it is likely to be optimistic. Again, as Bruce said, for long battery life when away from shore power its est to overestimate your consumption and also  vastly  overestimate what you think the charging time will be.

Just to reinforce what Tony has explained

The  COOKING POWER of the microwave is 800w.

You 'don't get owt for nowt' so the actual input power of the microwave will be much higher. The manufacturers rarely quote this figure but as a guide assume the input power is 2 times the output power, so your input is around 1600 w (max)

Working on the basis of inverter losses (you dont get owt for nowt, and nothing is 100% efficient) the microwave will be drawing 160amps (max) from your batteries.

 

Real Life Test Results : my 700w microwave. Powered by the inverter - it draws around 120 amps (but the readings may be slightly affected if the fridge is running or not)

[Robbo]

1 hour ago, Alan de Enfield said:

A small 'drop' of diesel produces quite  noticeable 'rainbow' of pollution o the water - few people can fill from a can without spilling a 'drop' (unless you have a pumping out system and can catch the last drop from the end of the pipe.

If you slip and spill 20 litres of diesel in the marina it becomes a 'major incident'.

I use a jiggler hose when filling from jerrycans and jam the hose in the tank filler with a bit of wood.  A lot better than other methods I’ve tried in the past!

 

[WotEver]

10 hours ago, Chewbacka said:

I just had a look at the Schneider MCB trip curves and it shows that a 16A mcb passing a 25A current will trip between 90 and 400 seconds, which is a fair bit slower than I expected.  Surprisingly a 16A mcb at 16A could trip as soon as 1000 seconds, though it can also be much longer, up to never.

Yup. Depending on type (C, D etc) they will 'instantaneously' trip on 3 x rating, 5 x rating etc but trip more slowly on a lesser overload as you note. They vary, which was my point above. 

6 hours ago, Mark May said:

Hi Tony, where do you get "10" from?

It allows for inverter inefficiencies and is therefore the commonly used 'rule of thumb' when doing these calculations. 

[Robbo]

A lot of marinas also wouldn’t be able to supply 16amp as it may be shared with other boaters, etc.  I wouldn’t build a boat around reliying on a constant supply (like for electric heating).

[WotEver]

1 minute ago, Robbo said:

A lot of marinas also wouldn’t be able to supply 16amp as it may be shared with other boaters, etc.  I wouldn’t build a boat around reliying on a constant supply (like for electric heating).

If you're planning on drawing 16A for extended periods you'll need deep pockets too. 

If you take 12p/kWh as a working price that's costing around 44p per hour. If you draw that current for just a third of the time then it's around £1300 per year. Very rough estimates but hopefully they serve to demonstrate the point. And 12p is a very reasonable unit price. 

[Robbo]

6 minutes ago, WotEver said:

If you're planning on drawing 16A for extended periods you'll need deep pockets too. 

If you take 12p/kWh as a working price that's costing around 44p per hour. If you draw that current for just a third of the time then it's around £1300 per year. Very rough estimates but hopefully they serve to demonstrate the point. And 12p is a very reasonable unit price. 

As someone pointed out, same as bottles gas.  My neighbour had one of those paraffin heaters and used the special parrafin.  I pointed out that his electric was cheaper to run!

[rusty69]

We had Ants on a Narrowboat.

I got some nippon, cleared them up in no time, and they weren't even Japanese ants as far as I can tell. 

[Mikexx]

15 hours ago, ditchcrawler said:

There is at http://diesel.fibrefactory.co.uk/ but the data is on as good as we the users supply. I always make a point of sending an update when passing places that advertise their price.

 

Thanks, there is a great range of prices, but with updates from weeks to years ago. If the table was better known it might get updated more often.

[Bromleyxphil]

Is an instantaneous gas water heater not a more efficient way to heat the water when not using the engine that much?

[Robbo]

7 minutes ago, Bromleyxphil said:

Is an instantaneous gas water heater not a more efficient way to heat the water when not using the engine that much?

If your on shore power a good way would be to use a immersion on the calorfier.   Gas water heater is good as well but you’ll be changing gas cylinders often which is quite a ball ache!

[rusty69]

10 minutes ago, Bromleyxphil said:

Is an instantaneous gas water heater not a more efficient way to heat the water when not using the engine that much?

Don't know about efficiency, but I favour gas water heating (instantaneous) over electric(immersion)  as its cheaper in our case

[Mikexx]

1 minute ago, rusty69 said:

Don't know about efficiency, but I favour gas water heating (instantaneous) over electric(immersion)  as its cheaper in our case

As I indicated earlier, bottled gas works out more expensive than (non-generated) electricity.

Why is it cheaper in your case? How much do you pay for your gas/electricity? There is also boiler efficiency to take into account.

[rusty69]

19 minutes ago, Mikexx said:

Why is it cheaper in your case? How much do you pay for your gas/electricity? There is also boiler efficiency to take into account.

I'd rather not say, but the gas works out cheaper, i buy 19kg bottles 

[Mikexx]

3 minutes ago, rusty69 said:

I'd rather not say, but the gas works out cheaper, i buy 19kg bottles 

Calor gas prices seem to be around the £38 - £40 mark for the 19kg cylinder which works out at 14p/kWhr, more expensive than the 13kg.

It is also a whopping 43kg which means handling is awkward for many.

There are quite strict rules on the price of reselling electricity so it sounds a little strange you're paying more than this.

[Richard10002]

9 minutes ago, rusty69 said:

I'd rather not say, but the gas works out cheaper, i buy 19kg bottles 

Where do you store those? Big Locker?

[Mikexx]

2 minutes ago, Richard10002 said:

Where do you store those? Big Locker?

At one time I could store these, but with the new rules regarding venting I had the base raised so can now only take 13kg variety.

I doubt many boats can nowd accommodate the extra height of the 19kg bottles whilst ensuring the base is well above the water line.