Idiots guide to electrics...

An alchemy of sparks, copper wire and earth

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California Dreamin
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Re: Idiots guide to electrics...

Post by California Dreamin »

Smosh wrote:
ianders, why P & I rather then W & A? because surely that would have made more sense?

It is a mistake to think that this 'OHMS law' was invented by an Englishman and the letters represent 'English' words. The reality is, this was named after a German physicist, Georg Ohm, so it's origins are derived from another language and that is perhaps the reason for the confused letter associations.

My own students struggle with the same.

Martin
Last edited by California Dreamin on 21 May 2014, 14:51, edited 2 times in total.
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ghost123uk
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Re: Idiots guide to electrics...

Post by ghost123uk »

You know when you write a long reply, that has lots of techy stuff carefully explained, then hit the wrong button and it's gone :evil: Well I did that a couple of hours ago re "About batteries" :evil:

But CJH seems to have answered it fine, and somewhat less verbose than mine was :)

Just to add that letting a car or leisure battery drop below about 11.5 volts is bad for it and should not be allowed to happen. So fit a "Low Voltage Disconnect" thingy like this = HERE ;) (if anyone ever needs any advice re wiring those ones up, shout out, they are dead simple, but the instructions are not well written).
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Re: Idiots guide to electrics...

Post by Smosh »

ghost123uk wrote:You know when you write a long reply, that has lots of techy stuff carefully explained, then hit the wrong button and it's gone :evil: Well I did that a couple of hours ago re "About batteries" :evil: .

I hate that, fortunately, Im normally on the receiving end of advice so dont get to write long technical posts :lol:

CJH, thanks that makes sense.

I like the sink Analogy it works for me to get a basic understanding, so does the milk, aprat from I never remember a time of getting milk in either glass or at school! :)

So relays work like starter relays work but for different functions? Should have guessed that one!!! :oops:

Thanks for all the help, I may need to write myself a wiring diagram for the charging/ leisure battery to work out what has already been installed. That way can work out what's done wrong!
1984 Voltswagen 25 Pop-Top (No idea what type!?) 1.9 W/C Petrol based in Guernsey, C.I.

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itchyfeet
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Re: Idiots guide to electrics...

Post by itchyfeet »

Smosh wrote: I never remember a time of getting milk in either glass or at school! :)

That you make you in your 30s or younger then, ahh yes 26
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Fudgy666
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Re: Idiots guide to electrics...

Post by Fudgy666 »

ghost123uk wrote:
Just to add that letting a car or leisure battery drop below about 11.5 volts is bad for it and should not be allowed to happen. So fit a "Low Voltage Disconnect" thingy like this = HERE ;) (if anyone ever needs any advice re wiring those ones up, shout out, they are dead simple, but the instructions are not well written).

Nice suggestion, I'm just about to refit my 12v leisure system and hadn't even thought about battery damage caused by excessive discharging, I didn't even know you could buy a product to protect the leisure battery.

Duly added to the evergrowing shopping list. :ok
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Hacksawbob
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Re: Idiots guide to electrics...

Post by Hacksawbob »

Hi if you want an easy leisure battery charging setup this is about as easy as it gets connect the positives from each battery (with suitably rated wire for the run!) to this and connect the black wire to the negative on the starting battery and your good to go! http://www.thetoolboxshop.com/0-727-33- ... -8096.html" onclick="window.open(this.href);return false;
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itchyfeet
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Re: Idiots guide to electrics...

Post by itchyfeet »

Hacksawbob wrote:Hi if you want an easy leisure battery charging setup this is about as easy as it gets connect the positives from each battery (with suitably rated wire for the run!) to this and connect the black wire to the negative on the starting battery and your good to go! http://www.thetoolboxshop.com/0-727-33- ... -8096.html" onclick="window.open(this.href);return false;

:shock: how much , paid £12 for mine, dont know if it will last but its doing the job

http://www.ebay.co.uk/itm/Self-Switchin ... 43ad251474" onclick="window.open(this.href);return false;
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Hacksawbob
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Re: Idiots guide to electrics...

Post by Hacksawbob »

For ease of installation the extra spends may be attractive to to the more electrically challenged!
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