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Old 08-06-2013, 14:24   #1
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Battery - Charge & High Load Question

Hi there,

just a theoretical question we discussed today and I wonder if you can bring some clarity: The discussion was about DC vs. AC and Genset etc. etc. At the end following was not clear to us:

A) Assuming you running a high power device (12 V) or put a high load on your inverter (like Waterheater, Washing Machine, Aircon etc.) Using somewhere between 100 - 200A/12V.
B) On the same time you generate the similar amount of Amps (either charger/Alternator or whatever)

So in theory you just use the energy you produce. But is this not putting an enorm stress on the batteries or is there just a "flow trough"? Are there any other drawbacks?

Thanks for any ideas on that!
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Old 08-06-2013, 14:55   #2
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Re: Battery - Charge & High Load Question

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Originally Posted by swisscraft View Post
... so in theory you just use the energy you produce. But is this not putting an enorm stress on the batteries or is there just a "flow trough"?
In any electrical system, the sum of the currents flowing into a given point must be equal to the sum of the currents flowing out of that point. Part of Norton's theorem I believe.

So, in the given situation, simplified, let's say we have current being demanded by the load (let's call it L), and we have the current supplied by a generator (G). The current (B) going to the battery bank will be G - L, so if G and L are about equal, there will be little current going to or coming from the battery. So, no stress to the battery.
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Old 08-06-2013, 15:38   #3
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Re: Battery - Charge & High Load Question

oops - Kirchoff's law, not Norton's
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Old 09-06-2013, 09:39   #4
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Old 09-06-2013, 22:19   #5
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Re: Battery - Charge & High Load Question

just make sure all the wiring can handle everything. there will be voltage drops across everything when it's all high current.

but yes. if say you have a 200a alternator and you're running the engine. and you're pulling 150a off your inverter, you could still have +50a going to charge your batteries. or if you pulled 200a off the inverter. the battery current is 0 and would just stay at the same state.


get a battery monitor.
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