Leisure battery power discharge ability
Comments
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Battery and cables have to provide 166 AMPS .. You will need some HEAVY DUTY Wiring to cope with the load. What are you trying to power. 100 Amp battery will give you 50 Amps usable power before you ruin the battery so thats about 20 Minutes use.
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DD the size of a battery is irrelevent to the discharge rate, they are all the same providing of course it is capable of providing the power required . The size or capacity will only determine the length of time that rate can be sustained.
peedee
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The Ah rating of a lead acid battery varies with the time over which it is taken. This is often quoted as the 100, 20 or 5 hours to discharge rate. Given the notation C100, C20 and C5.
Quoted at C100 the battery will have a much higher Ah rating than it has quoted at its C20 rating. That is the slower you dischare a battery the bigger amount you will get out of it.
See CC article:
http://www.caravanclub.co.uk/media/6552072/technical.pdf
Depending on the battery build technology the level of current draw off before doing damage varies. GEL batteries for example are excellent in many ways but taking high currents from them can cause damage to them.
"Starter batteries" are suitable for high current draw off, quality leisure batteries tend not to be; their attributes lie elsewhere.
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Generally the more expensive technology batteries will give you a lower weight/volume for the same AHr capacity and will also last longer I.e. More cycles of charge/discharge. If you stick to lead acid then heavier the better (bigger plates). Anyway, if you have a 200 Watt inverter the input current on the DC side will be about 20 amps allowing for efficiency losses. So, the battery will last no time at all ( maybe 2 or 3 hours), you need hefty cables, and a larger inverter (e.g. 2 kW as suggested) would be impossible.
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It is strange that the van manufacturer should have installed an 1800W inverter. A bit pointless if the rests of the system can't cope.
As a matter of interest as a test I boiled a full 1.7ltr 1000W kettle and I ran my wife’s 1400W hair drier for a short period. Normally it will get used set at just above 500W for about 15 minutes twice a week.
Of course this has little to do with the OP.
That's a bit baffling; I had assumed that the output was incorrectly stated and was actually 180W - 200 W. There's no arguing with the facts; 2000 W output equates to nearly 100 amps on the DC side allowing for efficiency. I am sure there is some explanation but I can't see it. How long did it take the kettle to boil?
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It is strange that the van manufacturer should have installed an 1800W inverter. A bit pointless if the rests of the system can't cope.
As a matter of interest as a test I boiled a full 1.7ltr 1000W kettle and I ran my wife’s 1400W hair drier for a short period. Normally it will get used set at just above 500W for about 15 minutes twice a week.
Of course this has little to do with the OP.
That's a bit baffling; I had assumed that the output was incorrectly stated and was actually 180W - 200 W. There's no arguing with the facts; 2000 W output equates to nearly 100 amps on the DC side allowing for efficiency. I am sure there is some explanation
but I can't see it. How long did it take the kettle to boil?Being only 1000W it takes much longer than a 3000W domestic kettle. I did not time it exactly but 7-10 mins. Afterwards the battery voltage drop, as displayed on the Waeco Inverter Control Panel, was negligible and recovered quite quickly aided by the
SP.That's a long time even for a 1 kW kettle so I suspect that whilst the maximum inverter output is as labelled they have limited it to whatever the dc side is capable of which will be significantly less. If you wanted to test it you could compare how long
it takes to boil from the inverter against how long plugged into the mains socket whilst on EHU and you can work out the power on a pro rata basis.0 -
Running 100 amps through the cables, you could boil the kettle by standing it on the wires.
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I think you have discovered free energy! I remain puzzled and was hoping somebody would jump in with an explanation. All I can say is that 12 mins to boil a kettle is a great deal longer than I would expect, even allowing for the low wattage. Maybe it is dragging the ac or dc volts down and reducing the available power.
If you look at Camperlands website they quote a 1 kW inverter as drawing 93 amps DC. The battery will last 1 hour 15 minutes but they suggest halving that because you would not want to completely discharge the battery. I think the 93 amps is a little under-estimated.
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Going back to my original question; not all batteries are born equal, how therefore is the ability and speed of a battery to discharge its power measured; surely amperage for amperage they can’t all be the same?
Batteries are certainly not born equal and it has been very difficult for a consumer to judge the quality until recently. The NCC stepped in and have introduced a quality verification scheme. There is more detail >here<
peedee
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They are all built to European standards and the capacity against a specific discharge rate (e.g C10) should be the same, however, the thickness and spacing of the lead plates (for lead - acid batteries) varies considerably and once sulphating occurs the
design of the plates will dictate very different life I.e. number if charge/discharge cycles.The other aspect is that "leisure batteries" have a different discharge requirement to cranking batteries. For leisure use you need a deep discharge battery which will give a steady low current discharge over a fair amount of time. Cranking batteries are
designed to provide high current over a short period to start an engine. The issue that Club and others have publicised is that many so called leisure batteries are cheap, car, cranking batteries and not leisure batteries and are designed to the wrong standard
so, yes, the quality can vary.Best stick to the ones recommended by the Club e.g. Banner and Varta.
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Excellent batteries which is why they cost so much. I like that they have specified the capacity at different discharge rates. Of course, you would not normally want to fully discharge them so realistically you should plan on only half the stated capacity.
But you've got two!Motorhome batteries are fitted inside so always need to be "sealed" type which is why these are Gel.
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