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#1 Terrence Wilkins

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Posted 29 May 2015 - 07:38 AM

So I've just brought a litepanel astra 1x1, I'm looking at the price of the V-lock plate as well as a battery with a charger, the minimum cost will be £300+
 
So, I've come up with a DIY solution,
 
12v 110amp leisure battery deep cycle
300watt pure sine wave inverter
12v 10 amp charger
 
Then using this calculator to figure out the amp draw:
 
According to my rough calculations of it drawing 9.16 amps at full power per hour, so it should give me 10 hours of use easily 
 
(based on a 12 volt source, 110 watt max power draw)
 
This setup only costs around £213.97, and should provide more power than any v-lock battery could.
 
Has any one had experience with this at all? Am I completely wrong?

Edited by Terrence Wilkins, 29 May 2015 - 07:40 AM.

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#2 Terrence Wilkins

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Posted 29 May 2015 - 08:03 AM

Could also be worth adding a Surge protector:

http://www.amazon.co...b_title_kitchen

 

any ideas?


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#3 Mark Dunn

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Posted 29 May 2015 - 09:03 AM

You wouldn't get the full rated capacity and inverters tend to shut down when the voltage drops. It's a feature intended to protect the car from a flat battery-ours will not run a laptop unless the engine is running.


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#4 JD Hartman

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Posted 29 May 2015 - 09:25 AM

You wouldn't get the full rated capacity and inverters tend to shut down when the voltage drops. It's a feature intended to protect the car from a flat battery-ours will not run a laptop unless the engine is running.

 

It's a deep cycle battery, 300w is the continuous output of the inverter.  Yes, better inverters have a voltage monitor and alarm to keep the user from killing their auto battery.  No you won't be able to draw all the power out the battery that you put in through the charger.  I'd have two batteries available and switch midway.

 

Don't know about your experience/issues, but I run chargers off my 200w inverter all the time without the engine running and my truck never fails to start.


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#5 Phil Rhodes

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Posted 29 May 2015 - 09:26 AM

The deep cycle leisure batteries are rather better in that regard - they don't droop out too much under heavy load. I'm intending to use two sets of this sort of equipment on Thursday on a field location that's literally in the middle of a field. It works fine.

 

There are two principal problems. 300 watts at 12 volts represents a load of 25 amps, so if you want to use the inverter at anywhere near its maximum performance, you'll need to ensure that the cabling and connectors are... well... adequately specified, by which I mean huge. Don't rely on crocodile clips; avoid wasting power heating up the cabling by using proper battery terminal clamps and wiring containg lots and lots of copper. Beyond a couple of hundred watts, many inverters start to accept higher voltage inputs, so you can string two 12V batteries together, in series. Doubling the voltage halves the current, of course, so everything becomes a lot less stressful and difficult (your inverter needs to be built to handle this, of course, which that one isn't). At 100W or so, you should be fine, if you make sure everything's nice and heavily built. 

 

The other problem is that lead-acid batteries are generally specified at rather low discharge rates, which means that you'll actually only get 110 ampere-hours if you draw, say, five amps for for twenty-two. A lot of Yuasa sealed lead-acid batteries (which are not quite exactly the same technology, but related) are rated at the 20-hour rate, so if you have a twenty ampere-hour battery and you draw an amp, you'll get twenty hours. Draw twenty amps and you won't get anything like a full hour - you'll get something like ten minutes. The shortfall can be quite extreme. On some types I've seen, if you draw half the capacity in current - say, 55 amps for your proposed 110Ah design - you can end up with half the stated capacity. Your proposed load of about 100W works out at 8 amps or so, which isn't in any sense extreme, but you probably won't get all 110 ampere hours out of it. 

 

In general though this should work fine. Some inverters don't like loads with a poor power factor, which can be a problem with many types of switching power supply, including those supplied with Litepanels, but you can only work that out by trial and error.

 

P


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