Off grid battery / lighting / lathe etc

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RobSmith
Posts: 37
Joined: Sun Jul 25, 2010 9:32 pm

Off grid battery / lighting / lathe etc

Postby RobSmith » Wed Nov 02, 2011 10:34 pm

We are making our plans to move to Wales, maybe sometime next year.
We will be part of this group... http://www.lammas.org.uk but we will be slightly more 'techno' than the others.
My plan is to have a willow burning stirling cycle engine generating around 300W of electrical power.
Edit: This will be continuously charging so allowing us to draw about 6kwh / day.
This will charge big batteries. This will most likely be a fork lift pack or two.
We will be wanting to power LED or CFL lights. What are peoples views on going for 12v / 24v dc or inverted and use 240v ac.

I am intending to use one or several APC un interuptible power supplies to provide 'mains' power.
My problem is the different loads are very variable from a few watts for phone charging up to washing machine loads. It appears I should roughly match the size of UPS to the load to get reasonable efficiency. That is ok but then the small UPSs use a 24v battery pack and the larger ones 48v. Could I take individual UPS feeds from different 'tapping' on the same battery pack? .... and how that might work whilst charging at the same time.

I shall change the rough single phase motor on my lathe for a DC motor to run directly from the batteries.
What motor should I use and where might I find one. The motor is 3hp. Speed can be anything from 1000 to about 3000 rpm. Edit: Start up load is high especially in winter when the lubricating oil is cold.

There is a lot to think about so any ideas would help.

Rob

mattcarr
Posts: 389
Joined: Sat May 12, 2007 2:27 pm
Location: Hampshire

Re: Off grid battery / lighting / lathe etc

Postby mattcarr » Thu Nov 03, 2011 9:00 am

Hi Rob, I would suggest going for 240 volt through out your property. This makes it easier for wiring and in the end more efficient. If you were to try and put in wiring for low voltage that is run from your batteries you would have such large voltage drops at the end of the wires that the voltage would be so low as to hardly light the bulb.

I would recommend that you dont "tap" in to the battery pack with different sized UPS's. Use the whole pack so that it does not become unbalanced.

Try and size your 240 volt inverter to be twice the size of your largest appliance to allow for start up surges.

Grumpy-b
Posts: 985
Joined: Sat Dec 01, 2007 12:06 pm

Re: Off grid battery / lighting / lathe etc

Postby Grumpy-b » Thu Nov 03, 2011 9:16 am

WE are in the process of extending our simple 160w solar system that largely feeds my solar water panel pumps, (It never manages 160w). I have one large 12v 200amp lead acid pack at the moment. This also supplies some LED downlighters directly. The next step is to extend the system, by having a number of 12v packs around the house in a sort of distributed ring main. It will lessen the voltage drop and als give some additional reserve to the main pack. So only the cables to the battery locations needs to be large sized, and individual local power usage is then by relatively small cable size.
Personally i like the idea of low voltage, and my latest led 3w mr16 spots are brilliant in all respects, they are even available now in the uk for not much more than what I paid for them from China. No need for 230v.
We are a semi rural village in suffolk and get loads of power outages, so having alternative light sources has been really nice.
So much kit now works with 12 v dc supplies its riduculous. Even Phones can genetally be charged with car chargers that plug in, so no need to convert to mains then back to low voltage dc. Many things charge from USB sources, and the adaptors for car usage are also cheap.
Keep it simple.

Grumpy-b

mattcarr
Posts: 389
Joined: Sat May 12, 2007 2:27 pm
Location: Hampshire

Re: Off grid battery / lighting / lathe etc

Postby mattcarr » Fri Nov 04, 2011 8:30 am

I used to have a 150 watts of solar on my roof and I was fortunate enough to get the old batteries from my employers old UPS system - so I had a 1100 ah 12 volt pack. I had a localised 12 volt supply in the battery room for all 12 volt things and I had a 1.2kw sine wave invertor for 220 volt supply.

RobSmith
Posts: 37
Joined: Sun Jul 25, 2010 9:32 pm

Re: Off grid battery / lighting / lathe etc

Postby RobSmith » Sat Nov 05, 2011 12:28 am

Hi All,
I have decided to go for 48v battery and may go for 240v ac for all lighting. It seems the easiest way to get all the usual home things in the home and then just leave the batteries, inverter and other stuff the wife would not understand out in another room she never goes in.

Rob

RobSmith
Posts: 37
Joined: Sun Jul 25, 2010 9:32 pm

Re: Off grid battery / lighting / lathe etc

Postby RobSmith » Tue Nov 08, 2011 8:02 pm

Hi All,
I have bought a Nikko 2.7kW 48v dc motor, with a brake, off ebay. I have not picked it up yet but it will at the weekend.
It has four terminals. three at one end of the motor body and one at the other. I will need to quiz you about these connections. Is there a Nikko Motor guru here?
I want to run my lathe using this motor taking power from a forklift battery pack.
Should I have a motor controller between the two? or just a big contactor? The lathe is a big heavy start especially when the oil is cold.

I was also offered a new 48v forklift battery pack. A forklift company near here ordered it for a customer who said for weeks and weeks he was going to come and collect it and then a few months later admitted he could not afford it. It is a brand new battery but it may never have been charged so maybe sitting there for months discharged. Whould it have deteriorated significantly in this time if it was discharged? The chap at the forklift company said it was about £2k and just wondering what I should offer him for it....if it is any good now?
Some advice from you guys might help.
Rob

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ChrisB
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Location: Hampshire on the Southcoast
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Re: Off grid battery / lighting / lathe etc

Postby ChrisB » Tue Nov 08, 2011 10:04 pm

RobSmith wrote:Hi All,
I have bought a Nikko 2.7kW 48v dc motor, with a brake, off ebay. I have not picked it up yet but it will at the weekend.
It has four terminals. three at one end of the motor body and one at the other. I will need to quiz you about these connections. Is there a Nikko Motor guru here?


I'm no guru but suspect you'll find two terminals will be for the field and two for the armature i.e Brushes

ChrisB
I reject reality and substitute my own !!!!!!

RobSmith
Posts: 37
Joined: Sun Jul 25, 2010 9:32 pm

Re: Off grid battery / lighting / lathe etc

Postby RobSmith » Sat Nov 12, 2011 6:01 pm

Picked up the motor for the lathe today:
Image
Image

It has four terminals. Three terminals at the brush end of the motor and one at the other end of the motor.
The three at the brush end are Marked up LA, LB and LE. The one et the other end of the motor is LF.
There are four brushes onto the armature at 90 degrees to each other (90 degrees by eye) LA is connected to two opposite brushes and LB are connected to the other pair of opposite brushes. LE heads off towards the field windings and is also connected to LF so I am presuming LE and LF are the field windings.
I tried to measure the resistances. The field winding resistance is immeasurably small with my cheapy meter. The armature connections measure about 4.5 ohms and varies a a little bit with rotation.
I connected 12v to the field windings with a car headlamp bulb in series to limit the current and put 12v across LA/LB. It whired (at a sensible speed) into life nicely in both directions.
Edit: The arcing marks on the terminals were there already where someone has had a previous play about.

I am wanting to use this on my lathe so could do with advice regarding controlling the motor.
If the motor wants to rev itself to pieces then with the lathe in high gears it would probably have enough load to stop this happening. With the lathe in low ratios the motor could just whizz itself to pieces if I did not wire or control it correctly.
Some form of softer starting would be great too.

Hope you guys can give me some pointers for this.

Kind Regards

Rob

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EV_dub
Posts: 93
Joined: Sun Jan 24, 2010 8:31 pm
Location: Dorset/Devon

Re: Off grid battery / lighting / lathe etc

Postby EV_dub » Sat Nov 12, 2011 6:37 pm

You could just run a resistor in series with the motor for low gears and then using a relay to bypass this resistor for heavier loads or higher gears. This would also give you a more sft start. The resistor must be able to cope with the high current though!
1993 Veedub Golf, 156v, 1200A, 150ah's

RobSmith
Posts: 37
Joined: Sun Jul 25, 2010 9:32 pm

Re: Off grid battery / lighting / lathe etc

Postby RobSmith » Sat Nov 12, 2011 7:07 pm

Is there a better way of controlling the motor as a resistor is just a small electric fire and would be using electricity I could do without it using.
I shall just refresh my memory to remind myself what layout the armature and field windings are in.... I know one configuration allows it to rev to destruction.

Edit: Series wired with no load seems to be the route to destruction.
Edit 2: Looking at Wikipedia it seems it might be intended as series connected as it has a very low resistance field. I suppose it could be designed to work with a controller and seperately exited. I will ask in a more appropriate section.

Rob


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