Inverter, batteries and a Solar panel or 2

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richjdavies

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StellenboschStudent said:
15 Amps will definitely kill you.
Click to expand...

But you won't get 15Amps through your body from a battery.
http://en.wikipedia.org/wiki/Ohm's_law

V= IR --> so I = V/R

A battery is known as a Thevian Equivalent -- it effectively can give (for very short periods of time) unlimited current at a particular voltage, it is voltage limited. The resistance across your body is HUGE and depends more on the very final bit of the connection -- wet hands vs. dry hands etc (just a quick test on a multimeter told me 100k-2.5m ohms)

So at 12V a battery will only be able to give you 0.12mA (12/100,000) = 0.00012A. But that's still enough to REALLLY hurt you and possibly kill you. But it's the tiny amount of current that will kill you - by upsetting your heart rhythm, it won't burn you to a pile of cinders like the grid will.

People don't get killed by electricity in the way they do in the Movies:
http://gizmodo.com/5262971/giz-explains-how-electrocution-really-kills-you
 
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johnjm

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The_Traveller said:
That's a good inverter, but $$$ ... anyways to answer your question ...

you're right, to add voltage, you need to wire in series.

The advantage of a 48v over a 24 is that you will have extended backup time ... for example ...
If your load is 1000w ...
on a 24v system - 1000/24 = 41.66Ah
on a 48v system - 1000/48 = 20.83Ah

So if you using 12v100ah batteries, then on a 24v system .... 100/41.66 = 2.4 hours
on a 48v system ... 100/20.83 = 4.8 hours

ALL OF THE ABOVE IS NOT TAKING INTO ACCOUNT INVERTER EFFICIENCY, BATTERY DC CURVES ETC. JUST A QUICK LOOK AT WHY A 48V IS BETTER THAN A 24V , BECAUSE YOU HAVE MORE BATTERY.
Click to expand...
No. The benefit of using higher voltage is less amps and therefore you don't need massive wiring for batteries.

2x100Ah batteries in series is a total of 100Ah.
2x100Ah batteries in parallel is a total of 200Ah.

Therefore batteries in series do no last longer, they last the same length of time regardless of voltage and number if the same sized batteries.
 
The_Traveller

The_Traveller

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johnjm said:
No. The benefit of using higher voltage is less amps and therefore you don't need massive wiring for batteries.

2x100Ah batteries in series is a total of 100Ah.
2x100Ah batteries in parallel is a total of 200Ah.

Therefore batteries in series do no last longer, they last the same length of time regardless of voltage and number if the same sized batteries.
Click to expand...

I've already admitted my mistake , next time try reading through the entire thread, it's only 3 pages.
 
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