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wind friend

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Joined: 01/05/2007
Location: Australia
Posts: 39

Posted: 08:58am 16 Mar 2011

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#@*&ing large puddle(australias' largest isp), had a heap typed out, pressed post and lost connection. all gone to the big bucket o bits.

for some reason i placed a large neo next to the cables twixt battery and inverter. i was expecting a push or pull. cable is 16 mm square lugged both ends and is only 300 mm long. at only 10 Ah at 12V.

but no! there was much pulsing going on. me thinks it's the instant load on my pure sine wave inverter (that's what is says on the label, must get a scope to see how many steps there are in a pure sine wave?)

what does this kind of load look like to a battery? is there happiness inside the battery. or will it shorten it's life?

has anyone else done this? can anyone shed a little theory?

thanx

windfriend/hans

RossW
Guru

Joined: 25/02/2006
Location: Australia
Posts: 495

Posted: 10:09am 16 Mar 2011

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wind friend said #@*&ing large puddle(australias' largest isp), had a heap typed out, pressed post and lost connection. all gone to the big bucket o bits.

for some reason i placed a large neo next to the cables twixt battery and inverter. i was expecting a push or pull. cable is 16 mm square lugged both ends and is only 300 mm long. at only 10 Ah at 12V.

but no! there was much pulsing going on. me thinks it's the instant load on my pure sine wave inverter (that's what is says on the label, must get a scope to see how many steps there are in a pure sine wave?)

what does this kind of load look like to a battery? is there happiness inside the battery. or will it shorten it's life?

has anyone else done this? can anyone shed a little theory?

The effect is purely a function of the current, not the volts.
I have several large split ferrite cores over my cables, and I can certainly feel them carry on (or hear them if they don't snap together hard enough).

A CRO might make interesting viewing, but I think what you're describing isn't unusual or uncommon.

Alasdair
Regular Member

Joined: 12/01/2011
Location: Australia
Posts: 62

Posted: 08:59am 18 Mar 2011

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Hi there
I have noticed the same thing with my inverter, and the current
stepping does turn the pure dc load into an inductive load, even
the cable will have more loss, albeit very small. I placed a big
low ESR capacitor across the DC terminals of the inverter which
does work to lower the source impedance and take the hammering
off the batteries. Some argue that the staircase current load is
good for battery life as it helps stop sulfation, but I've never seen
any evidence of this myself, I still prefer a dc load. PS the cap I used
was 20000 uf / 35 Vdc ex junkbox,
Regards Alasdair.

Amc-elec

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