12v LED Light Drain on Leisure Battery Query

[deleted79651]

Our first weekend stay in Brunhilde after sorting out the Fridge Control Panel and wrong fuse in the drop down bed! Strong sun for most of each day and [newly fitted by Dealer] Leisure Battery showing as about 13.8v in Float State on Control Panel, having very little work to do, with Gas running of fridge and water. LED Lights are in Banks of 2 in kitchen, bathroom, and lounge 'side lights', and a group of 4 on the underside of the drop down bed. We never used more than 2 sets of 'Bank of 2' LEDs at any one time, and then only briefly, for 2 minutes or so, before dropping back to a single Bank of 2 setting. The battery capacity seemed to drop quite quickly [LEDs say 2.1w max] down to just over 11.5v on Leisure Battery, after only a few minutes use. Wee bit of panic mode in case we killed Leisure Battery so cleared off to bed to save further use of lights. The 180w Solar Panel restored the Leisure Battery to full power quite quickly the following morning [App showing 19v to 23v at the Solar Panel before 9am].

My question is how long can we safely use the lights for, without having to pray to the Scottish Sun God [I am an atheist ...] for a bright day next morning. Ideally, a maximum of 1 hour per night would be adequate [no TV usage or other power consumption, apart from occasional use of water pump and the running of the Truma Control Panel for gas heating]? We are being very cautious as we learn about Brunhilde's habits, and may be panicking without reason, but I'm not sure whether we should be thinking about a second leisure battery, 'just in case' [my mother should have called me 'Justin' ...].

Steve & Elaine

 

[pappajohn]

2.1watt is 0.175amps at 12v so ten lights is only 1.75amps.......your battery or meter is faulty.
Just because the battery is new doesn't mean it can't be faulty.

 

[Cush]

Hi. I would be interested to find out the state of charge of your newly fitted battery. I would expect it to take a while to get a battery back up to full after being so low but be careful using volts as in indication of state of charge.
I think that to take a full 12v leisure that low from just a couple of LEDs would need further investigation.
How many amp-hours is your new leisure rated?

 

[Richard n Ann]

You're being very cautious, you should last indefinitely with a 180w panel, even using TV and LED lights as much as you want. Even on cloudy days you'll get about a 3 amp charge.

 

[xsparks]

Led equipment, Gods gift to the motorhomer.

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[Gellyneck]

To get a correct reading on the leisure battery you need to wait for a couple of hours after charging (mains or solar) and measure with a multimeter over the battery terminals. Control panel readings are notoriously suspect.

 

[deleted79651]

You're being very cautious, you should last indefinitely with a 180w panel, even using TV and LED lights as much as you want. Even on cloudy days you'll get about a 3 amp charge.

Thanks, Richard n Ann. We were being very [and overly] cautious! Having arrived on site and blown the drop down bed fuse twice [wrong fuse inserted], anything electrical was spooking us, not least because we haven't owned a m/home before and we have no point of reference from which to work. 'I'll ask on the Forum' has become our watchword! Prefer this approach to doing something, encountering a problem, and then posting on the Forum, only to receive a batch of 'too late now, your controller/panel/battery etc is goosed' replies

'If you think you're in a hole, stop digging, or at least swap the spade for a small trowel until you know what you're doing' ...

Steve

 

[Cobra]

In theory, 2.1w at 12v uses 0.175a per hour (0.175ah)
I assume that each led uses this much? (You can check the rating on each bulb to confirm)
Even with 10 running for an hour you should only be using 1.75ah
With an average 100ah battery, using up to 50% of the power (50ah - as it’s not recommended to take them below 50% without recharging) this would get you about 28.5 hours of running the lights!

If you were only running a couple at a time and the battery voltage dropped to 11.5v then I would be concerned about the ‘new’ battery recently fitted.
One question, how are you measuring the leisure battery voltage?
You can buy a cheap multimeter which will give you a reasonably accurate measurement


Andy

 

[deleted79651]

To get a correct reading on the leisure battery you need to wait for a couple of hours after charging (mains or solar) and measure with a multimeter over the battery terminals. Control panel readings are notoriously suspect.

All I can remember from my Physics lessons was the Master, Roger Conibear, saying in a resigned tone at the end of Year 4, 'Don't take Physics at 'O' Level, March; you'll be wasting the Examiner's time and demoralising yourself ...'. He wasn't wrong! For matters electrical, I am the man for whom the term 'Idiot's Instructions' was coined!

It was safer at the weekend to be in the dark, literally and metaphorically, until I could check with Forum Members! A phone light to find the water pump for the 3am excursion works quite well ...

We learned quite a bit about Brunhilde by using her on a proper trip; but we also realised that we have an awful lot more to learn

P.S. Fridge Panel is all good now, thanks to Alex!

Steve

 

[deleted79651]

In theory, 2.1w at 12v uses 0.175a per hour (0.175ah)
I assume that each led uses this much? (You can check the rating on each bulb to confirm)
Even with 10 running for an hour you should only be using 1.75ah
With an average 100ah battery, using up to 50% of the power (50ah - as it’s not recommended to take them below 50% without recharging) this would get you about 28.5 hours of running the lights!

If you were only running a couple at a time and the battery voltage dropped to 11.5v then I would be concerned about the ‘new’ battery recently fitted.
One question, how are you measuring the leisure battery voltage?
You can buy a cheap multimeter which will give you a reasonably accurate measurement


Andy

Thanks, Andy. My 11.5v reading was at a slight angle [straight on view requires standing in the had door footwell] and the Control Panel also reports a pessimistic state of the vehicle battery [around 12.25v], yet the m/home fires up very strongly, so the CP is probably not very accurate. We had also been playing/learning about the Truma Control Panel during the early evening daylight so there may have been more power usage than I had realised!

Steve

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[Gellyneck]

All I can remember from my Physics lessons was the Master, Roger Conibear, saying in a resigned tone at the end of Year 4, 'Don't take Physics at 'O' Level, March; you'll be wasting the Examiner's time and demoralising yourself ...'. He wasn't wrong! For matters electrical, I am the man for whom the term 'Idiot's Instructions' was coined!

It was safer at the weekend to be in the dark, literally and metaphorically, until I could check with Forum Members! A phone light to find the water pump for the 3am excursion works quite well ...

We learned quite a bit about Brunhilde by using her on a proper trip; but we also realised that we have an awful lot more to learn

P.S. Fridge Panel is all good now, thanks to Alex!

Steve

A multimeter should be a "definite" for a motorhome toolkit. Something like this would suffice https://www.screwfix.com/p/lap-mas830b-digital-multimeter-600v/75337#_=p
Turn the dial to the appropriate setting (probably something like 20v DC), turn it on and place the +ve probe on +ve battery terminal (that's the red ones) and -ve probe on -ve battery terminal (that's the black ones). Read the voltage on the lcd screen.
Or, even better, get the brains of the outfit to do it! Oh, Elaine, darling.

 

[deleted79651]

A multimeter should be a "definite" for a motorhome toolkit. Something like this would suffice https://www.screwfix.com/p/lap-mas830b-digital-multimeter-600v/75337#_=p
Turn the dial to the appropriate setting (probably something like 20v DC), turn it on and place the +ve probe on +ve battery terminal (that's the red ones) and -ve probe on -ve battery terminal (that's the black ones). Read the voltage on the lcd screen.
Or, even better, get the brains of the outfit to do it! Oh, Elaine, darling.

Need to find out whether it's 'sarky' or sarcy' and how many 'g's there are in bugger before I reply to this, Grant . But you're in the right zone as far as my knowledge is concerned ... Or as Eric Morecambe said about Ernie Wise's 'Play what I wrote', 'Remember, Ern; there's no 'k' in 'pathetic', and only only 1 'b' in abysmal ...'

Armed with your advice, I shall purchase a multimeter, turn the dials/push the buttons as you suggest, report the readings, and then ask for an interpretation of the data from Members who understand the dark art of leccy. As for 'Elaine, darling, ...' her last words were 'Don't touch anything, I've just got it working ... [re the Truma CP]. I pressed the button, and it stopped working ... The sudden frost made me wish that the Truma CP was working ...

Steve

 

[Richard n Ann]

If you're feeling a bit more ambitious these are excellent.

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A good range of ranges including DC amps & capacitance ready for when you graduate into electrical genius in about 12 months

 

[Cobra]

Hey!
if you really want to go mad you could do something like this.

 

[Eggs]

I'm going to get one of those, mines seen better days and it's only AC on the clamp

If you're feeling a bit more ambitious these are excellent.

UNI‑T AC/DC Current Voltage LCD Digital Clamp Meter Tester Multimeter Data Hold 8852103819957 | eBay

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A good range of ranges including DC amps & capacitance ready for when you graduate into electrical genius in about 12 months

.

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[deleted79651]

If you're feeling a bit more ambitious these are excellent.

UNI‑T AC/DC Current Voltage LCD Digital Clamp Meter Tester Multimeter Data Hold 8852103819957 | eBay

Find many great new & used options and get the best deals for UNI‑T AC/DC Current Voltage LCD Digital Clamp Meter Tester Multimeter Data Hold at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

A good range of ranges including DC amps & capacitance ready for when you graduate into electrical genius in about 12 months

In my dreams! Ohm is where the Hert is, is the peak of my electrical misunderstanding ... A former neighbour was a Rolls Royce Electronics Engineer, seconded to the Submarines Maintenance Team at Gosport. When we were about to move house, Mick drew me an idiot's diagram to wiring in a socket & light for the, ahem, 'garage', spurred from the house sockets. I can remember his instruction 'Don't connect the 2 black wires, otherwise you'll never have to worry about your first mortgage payment ...'. That is the level at which my electrical understanding sits.

Steve

 

[G-RMPS]

You mentioned Truma gas heating. The fan which blows hot air around the van is electric and consumes quite a few electrons. Could that be the source?

 

[deleted79651]

You mentioned Truma gas heating. The fan which blows hot air around the van is electric and consumes quite a few electrons. Could that be the source?

Of course! Thank you so much! So the lights, solar panel and leisure battery can be eliminated from our enquiries! It all seems so obvious when the reason/solution is expressed so simply ...

Steve

 

[Newfie]

The drop down bed motor uses quite a bit of power

 

[deleted79651]

The drop down bed motor uses quite a bit of power

Thanks very much. We did blow a couple of fuses on Friday before we discovered that a 10 Amp fuse had been used instead of a 25 Amp version, and were winding the bed up and down [the access ladder only works at the higher level and the lower level is too high to use unaided because the bed extends beyond the cab raised floor area, so we start in the rear area, 13cms down!] We bought a metal caravan step yesterday on the way back from the site, and it makes a perfect, comfortable transition from step to bed! Friday night was like a scene from Goldilocks and the 3 Bears with the High setting being too high and the low setting being too high without a step!

Steve

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[Clarky]

Don’t forget that the water pump will be using a tidly bit of power too as will the fridge electronics and control panel.
Non of them use much but it all adds up.

 

[Newfie]

Thanks very much. We did blow a couple of fuses on Friday before we discovered that a 10 Amp fuse had been used instead of a 25 Amp version, and were winding the bed up and down [the access ladder only works at the higher level and the lower level is too high to use unaided because the bed extends beyond the cab raised floor area, so we start in the rear area, 13cms down!] We bought a metal caravan step yesterday on the way back from the site, and it makes a perfect, comfortable transition from step to bed! Friday night was like a scene from Goldilocks and the 3 Bears with the High setting being too high and the low setting being too high without a step!

Steve

I would think that’s what discharging your battery then. Keep an eye on it & only wind the bed down once when you want to use it.

 

[Guigsy]

The bed and water pump do pull a lot of power, but only for a few seconds at a time. In the grand scheme of things, it doesn't add up to much.

I'm betting it's the heating. The heating is gas, but the fan pulls a few amps from the battery and remains on for extended periods.

 

[pappajohn]

Bed and water pump do use power But neither will pull the voltage down to 11.5v in a couple of minutes.
Momentarily maybe, in the way a starter motor can drop a fully charged battery to 10v but as soon as the load is removed the voltage almost instantly recovers.

 

[autorouter]

My question is how long can we safely use the lights for,

LEDs use almost no power - I have an LED head torch that lasts 8 hours on 3 AAA rechargeables. Make sure the batteries have been charged up fully, it takes a few hours of charging if they are a bit flat. If the battery doesn't last forever with just the lights on, there's something wrong.

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[deleted79651]

I would think that’s what discharging your battery then. Keep an eye on it & only wind the bed down once when you want to use it.

There's wanting to use the bed, and there's being able to do so ... But that's another area where investigations await ...

Steve

 

[deleted79651]

Bed and water pump do use power But neither will pull the voltage down to 11.5v in a couple of minutes.
Momentarily maybe, in the way a starter motor can drop a fully charged battery to 10v but as soon as the load is removed the voltage almost instantly recovers.

I'm not sure that I checked the battery immediately after lowering the bed. It was dark, so little, if any solar charge, and we had the fridge running, the water pump, faffing about with the Truma CP and the blown air heating on Gas [forgot about the electric fan!], so the cumulative draw made me panic about the lights! Now that Members have pointed out all the bits of kit that were using the 12v, and I think back to the 'wasted' resources trying to get the bed and heating setup, I am more relaxed about the battery level. And it did regain its 'strength' very quickly when the sun shone next morning, and the energy usage was much lower!

Steve & Elaine