Electric motor for prop

[Dalslandia]

Looks likes my earler estimate make sense.

if adding and everage those 3 trip example, 17 hour total, 46 locks. 538 Ah

http://www.waterwayroutes.co.uk/wr/faq-electric-propulsion.html

Here (Sweden) a "wide beam" lock takes about 8 minuts from going in to going out.

I guess the nb locks is faster, say 6 min? someone?

46 locks a 6 minutes / 60 minutes is 4,6 hour

20 miles

so 17 - 4,6 = 12,4 h on the canal

538 Ah / 12,4 = 43,4 Ah

20 / 12,4 = 1,61 mph average with stop and go, but without locking time.

43,4 Ah * 48V = 2080 Watt ( I said/calculated earler 2,1 kW for a NB)

[Dalslandia]

Double post

Edited January 7, 2014 by Dalslandia

[Dave Simms]

Cheers all some amazing info for me to mull over,

[Dave Payne]

Can you not just have dual/quad alternators running off the electric motor putting power back into your battery bank?

 

Not sure what power the average alternator kicks out and what power the required motor would need?

[Alastair]

Dave, what would power the electric motors?

[Willber G]

Can you not just have dual/quad alternators running off the electric motor putting power back into your battery bank?

 

Not sure what power the average alternator kicks out and what power the required motor would need?

 

To quote Homer Simpson (commenting on Lisa's perpetual-motion machine): "In this house, we obey the laws of thermodynamics!"

Edited January 8, 2014 by Willber G

[Dalslandia]

Sure Dave,

 

can do that, but have to fed the motor with some extra energy.

the motor efficiency is 85-95% as best,

Alternator/generator never better then that either, so need to put in minimum 10% plus 10 % in the battery from where the extra power come from and then 10% extra power to charge the batteries that is being charged.

If it had worked we had that allready.

 

Saw something called rotating "BOSTER" from Scotland, a 230V motor diving a 3 phase alternator, for those that only have 230V but need 3 phase, 400V, it dosent bost power but voltage. the efficiency was 80%, so Bosting was not the correct name for it. but perfect for those on land or sea tha need 3 phase temporarly.

 

I understand the "Mains" is a bit different Here then it is in UK, here every house have 3 phase, but just have to go to Norway and it is different, A freind working in Norway as electician, was going to install a 3 phase socket in a house, but there was only 230V, he found out that 3 houses shared one 3 phase conection, one had line 1, the other line 2...

[Robbo]

Dave, what would power the electric motors?

 

The batteries of course

[Dalslandia]

" I do understand how the electric work, but how can they get the Kerosine to flow in those thin tubes?" :-)

[Dave Payne]

ok so how many alternators would it take to charge the batteries that are running the engine, or is it just not possible?

[Dalslandia]

ok so how many alternators would it take to charge the batteries that are running the engine, or is it just not possible?

 

You are just pulling our sea legs, arn't you? :-)

[Dave Payne]

Nope, not at all.

 

I know next to nothing about such matters, however this same idea popped up in my head a few weeks ago.

 

It must be possible if you have enough batterys to run the motor to also have enough alternators to recharge the batteries whilst moving!?

[Dalslandia]

You lose power every time, as with the Rotating power "Boster" the efficiency is 80% and that without making any mechanical useful work.

It just make 20% heat that is cooled away.

 

So we need to add energy.

like a diesel engine diving an alternator/generator, driving a electric motor, and or charging batteries.

Or Sun panels driving the motor or charging the batteries

or power from the mains shore line.

 

The batteries isn't 100% efficient, 10% is lost every time we discharge or charge.

the alternator/generator isn't 100% efficient

not the electric motor either.

 

if we can make it self going, something need to be more then 100%, if making usefull work=power all items need to be more then 100% efficient.

[Dave Payne]

i see, so a small genny would take it above the 100% needed.

 

What i have been trying to work out in my little head is how much this kind of system would cost, and if it would be worth it!

[Dalslandia]

Nothings is 100% efficient.

we need to add energy, in form of diesel or sun energy, or electical energy.

 

As I wrote in one of the first posts,

a diesel engine, can be 35% efficient. -3% losses in the gearbox, -3% in the prop shaft, the propeller is max 60%.

so the energy put in is 100% but usefull work is 0,35 - 0,03 - 0,03 * 0,6 = 17,4 % when optimal, the rest is heat and noise.

[Dalslandia]

Some example of diesel, parallell hybrid and serial hybrid drives. on a NB, Please correct me if I am wrong.

 

If we want to go 18 miles at 3 mph thats a 6 h tour

 

at this speed the engine takes 1 L/h so 6 liter, = 0,333 liter/miles

A half liter is used for propelling and the other half for runing the engine, cooling pumps and alternators.

 

An electric drive will use 2 kW per hour from the batteries. so 12 kWh for 6 h.

this have to be replaced/recharged, it will take 10% extra power, so 2,2kW -h

 

in a parallell hybrid alá Marin hybrid, with 10kW motor transformed to a 5 kW generator, plus 2- 24V alternators of total 3kW

we have up to 8kW, Marin Hybrid say 7-8 kW, so take 7,5kW then to get a even Nr.

It is best to use the diesel at the end of the day when batteries is low, instead of full, logic?

so say we go electric for 4,5 hour, and 1,5 hour diesel proppullution and charging in the same time.

4,5 h = 9 kW or 9,9, say 10 with losses. 10 kWh charged with 7,5kW = 1: 1/3 hour, but charging is slower at the end and we need some domestic power also. so 1,5 h (but probably 2h)

10 kW is ~13,5 HP using 3 liter of diesel for charging, plus 1,5 liter for propelling and engine. so total 4,5 liter, =0,25 liter/miles

 

The serie Hybrid, will need a bigger electric motor, and probably a bigger battery bank so we don't cook the batteries at full throttle something like 40 HP/ 30kW motor.

But it will probably use the same 2 kW at 3 mph

It will have a gen set, to replace the electric energy.

No meaning to have a small genset that run full time, but if the electicity goes direct from generator to motor, we cut the losses in the batteries, but what´s the point having it running all the time? we can have smaller batteri for just the times we need full power.

but 2, 4 or 6 times the normal need? 4-12 kW gen set., but a big generator is uneconomical to drive when charging the last 10% into the batteries, but can be used to drive the washing machine and electric kitchen.

anyway, in 6 hour we need ~13,5kWh (18HPh) to get into the batteries, that take about 4 liter of diesel, plus a half liter for the engine per hour we run it, so somewhere 1-3 liters depending on how big the generator is and how fast we can charge the batteries, I don't think it is good to recharge with C1 on led-acid batteries.

so the Serial Hyb, will use 5-7 liter of diesel. = 0,278 - 0,39 liter per mile.

Comments?

 

[Dave Payne]

Can someone asnwer a very simple question for me please, on aversge how many kwh does an alternator kick out?

 

Thanks

[Robbo]

Can someone asnwer a very simple question for me please, on aversge how many kwh does an alternator kick out?

 

Thanks

 

amps * voltage = watts

[Biggles]

The on the genset 4810 max potential. And about 4400 on the 2 engine alternators.

[Dave Payne]

Ok, how many amps does the average alternator kick out?

[Robbo]

Ok, how many amps does the average alternator kick out?

 

Around 75% of the stated amps on the alternator as many are not meant to be ran flat out due to overheating. There isn't really an average alternator size as it tends to go with engine size, but most seem to be under 90amp.

[Dave Payne]

So if you got 2 x 150 watt alternators, stick them on the motor that requires 2.2kwh. you have about 2.7kwh going into your batteries, 0.5kwh over what you need to run the motor?

 

Or am i way out?

[Robbo]

So if you got 2 x 150 watt alternators, stick them on the motor that requires 2.2kwh. you have about 2.7kwh going into your batteries, 0.5kwh over what you need to run the motor?

 

Or am i way out?

 

If it requires 2.2kw then how does that go to the battery

[Dave Payne]

So my next question....

 

How many batteries would you need to supply the motor with 2.2kwh for 8 hours?

[Chalky]

So if you got 2 x 150 watt alternators, stick them on the motor that requires 2.2kwh. you have about 2.7kwh going into your batteries, 0.5kwh over what you need to run the motor?

 

Or am i way out?

 

The output of the alternator depends on lots of things, the main one being how fast you spin it and how hot it is. The 70A alternators on our boat produce about 30A on tick over, 40A when cruising and theoretically 65A when the engine is on the rev limiter. This is from manufacturers data sheets and empirical data.

 

The approach used in automotive applications is different. The generator is often a three phase permanent magnet machine built into the engine flywheel. This can be used as a generator or as a starter motor. The output from this machine is fed into a power converter that converts the raw AC into the desired regulated DC voltage. It's considerably more complicated than a bridge rectifier and a voltage regulator! Typical power ratings can vary from 30kW to several hundred kW with the output DC link voltage varying from 100V to 600V. Some of the power converters contain voltage boosters to up the DC link voltage temporarily to increase vehicle performance.

Edited January 9, 2014 by Chalky