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Re: Wind Gen/alt connections

PostPosted: Mon Feb 11, 2019 4:39 pm
by jaahn
Hi JUles :)
I believe Harry is referring to the solar cells(panels) not the battery cells. :?:
Harry you seem to be sorting it out a bit at a time. ;)
Jaahn

Re: Wind Gen/alt connections

PostPosted: Mon Feb 11, 2019 6:51 pm
by jules
Ah, thanks jaahn :?

Re: Wind Gen/alt connections

PostPosted: Sun Mar 17, 2019 10:48 am
by harrydiculous
I have now transferred the batteries from the shed to a new, purpose built facility adjacent ;) .

ImageNew shed by jibbonpoint, on Flickr

Imageinshed con by jibbonpoint, on Flickr

1) I mentioned earlier that it was tripping out when operating Washing Machine. You will notice from the second shot that there are now three cables running from the inverter to the batteries. Two of similar size were supplied with the Inverter. I measured them at 15.9mm^2 each. The specs on the Inverter state that their 3000 watt unit needs cables of 66mm^2. This one is 3.5 kw. Well under their own spec. Made worse by, I understand, two cables together requires a 20% discount on power. Anyway, I added the third cable which
is 50mm^2 and I've had no problem since.

I have ordered 83mm^2 cable to replace the three seen here.

2) The common garden variety spade connection. There seems to be a restriction where the electrons are squeezed just prior to the attachment to the Battery/Inverter. I Haven't been able to see anything that lessens my concern on the net so I was thinking about machining up a set designed to avoid this.

(My background is mechanical. there's some things in electrical engineering that's counter intuitive, like electrons flowing in two directions through the same wire.)

3) I was thinking about fabrication a Bus Bar. A straight through piece of copper rod about 10mm square from the battery terminal, through the wall, then a right angle return to which connections could be made. Is possible? :geek:

4) And finally, a switch to isolate the + or - inverter from the Battery. The caravan type unit seems a bit inadequate. Probably a further constriction. Looking around, I can't seem to find anything.

I still haven't been able to solve the RF problem, but our Lady that shares my house & life has found that the station she likes also transmits on FM band. Pressure off (for now.... ;) )

Thanks again.

(I noticed that the relevant certificate hasn't been renewed for this site. I hope its all OK. I did see the recent thread where this was mentioned.)

Re: Wind Gen/alt connections

PostPosted: Mon Mar 18, 2019 6:21 am
by jaahn
Hi Harry, :)
Looks like you are moving foward. This forum is languishing for lack of a sponsor ! who knows what will happen to it ?
You must be careful with the insulation and safety of the 240 AC voltage. It will kill you just as well as the mains ! :shock: It is hard to see what is there in the photos.
Yes you can make copper bus bars for your low voltage DC. I have worked on older DC installations with bus bars carrying the current through the system. Usually copper flat bar perhaps 25mm x 3mm or thicker depending on the amps. They were supported with bakelite boards holding the switches and meters. A bit higher voltage than you are using. But with multi cabinets the main bus bars ran along through the length of them with each individual control cabinets having feeder bars bolted to the main ones. All very organised and easy to follow. THey are used in all cabinet installations for AC too.
Look at these for ideas. https://www.shutterstock.com/search/busbar?studio=1
Your DC should be fused to prevent shorts causing fires etc. Or breakers.
Jaahn

Re: Wind Gen/alt connections

PostPosted: Mon Mar 18, 2019 6:30 am
by jaahn
Harry :)
I could not edit my post, the function was not available ? :shock:
You must be very careful with bare bus bars. The power must be off to work near them with any sort of metal tools. So having a covering or shield of insulating sheet of some sort is a good idea to prevent accidental contact or things falling on them etc. Having circuit breakers with a manual trip is easy and effective.
Jaahn

Re: Wind Gen/alt connections

PostPosted: Mon Mar 18, 2019 11:04 pm
by davidg
harrydiculous wrote:I have now transferred the batteries from the shed to a new, purpose built facility adjacent ;) .

You need to protect the battery cables from the shed sheet metal the same goes for any STD electrical cable going through sheet metal, with a bushing, conduit or similar.

Using
If it's 150A 24Vdc 3.5kW unit 35mm2 for upto 2m is perfectly fine (2% Voltage Drop) higher VD smaller cable
If it's 300A 12Vdc 3.5kW unit 120mm2 for upto 2m is perfectly fine (2% Voltage Drop) higher VD smaller cable
Higher VD means more heat generated in the cable because it's such a low voltage being used the % becomes very important.

Options use welding wire which is available in metric sizes or use XPLE from electrical wholesalers but it is somewhat stiff (I use this, it has a pretty high temp rating 110C), use proper crimp lugs and ideally crimp them on.

harrydiculous wrote:I understand, two cables together requires a 20% discount on power.

Poppy cock, mm2 area is the same regardless, although it's certainly preferable that all cables in parallel are the same mm2 size so that the VD is the same in each one and for battery cable to inverter cable they are the same length.

harrydiculous wrote:The common garden variety spade connection. There seems to be a restriction where the electrons are squeezed just prior to the attachment to the Battery/Inverter.

A spade type connector typically offers a high resistance point for large currents which is highly likely to become hot the higher the current the hotter it gets. The longer it has sustain high current the hotter it will become and faster it will fail.

harrydiculous wrote:there's some things in electrical engineering that's counter intuitive, like electrons flowing in two directions through the same wire

I'll stick to DC for the moment. Not really the direction the elections flow represent which direction the power is flowing, for instance in relation to the battery/batteries current will either flow into or out of the batteries it will not do both at the sametime.

harrydiculous wrote:And finally, a switch to isolate the + or - inverter from the Battery.

Both cables should be able to be isolated and fused. Look for a Fuse Switch or a Fuse isolator that uses at least 2 x ceramic HRC fuses in it or a high current DC Circuit Breaker ignore ELV units, for instance use either say a 400VDC CB or Fuse Switch rating 160A or for 12V then 250A, it's highly unlikely looking at the small size of the batteries you could sustain any serious currents for any lengthy period of time.

Heres a 160A on Aliexpress that will suit for 24VDC
https://www.aliexpress.com/item/HR17B-3 ... 4297f16429


harrydiculous wrote:(I noticed that the relevant certificate hasn't been renewed for this site. I hope its all OK. I did see the recent thread where this was mentioned.)

Looks like it's unlikely to happen unfortunately.

Re: Wind Gen/alt connections

PostPosted: Thu Mar 21, 2019 9:24 am
by harrydiculous
Had trouble logging in. If the forum drops away, thanks for all the help.

I won't be doing anything on the 240 volt side without the assistance of a licensed electrician. I'm just running leads at the moment but I would like to hardwire shortly.

The system is 12 volt. If I get rid of this inverter, I'd go 24 volt. The solar banks are now 3 banks of six panels. The banks are in series of two & joined in parallel in accordance with Gordon's advice.

Given away the Bus Bar idea.

I've decided to draw up & machine more effective connectors. I'll post on here when they are done.

Curses; I've bought 83mm^2 cable. The distance will be 1m from the - & about 600 mm from the +ve. A bit premature. Maybe I can double it. I've got 3000mm).

To be frank, this inverter doesn't cause much confidence, innacurate voltage readings, (say 252+ when it's 240 v out. It seems to give higher input readings as well, leading to the alarm sounding & cutting off supply. I've altered the setting on the VR to compensate.)

Should the cabling between the batteries be the same?

Batteries are 4 x 100 amp/hr Lead Acid.

(I do fancy your Hybrid 3000 watt Inverter, Dadidg.)