Our overnight electric has shot up???

Pudsey Bear

Pudsey Bear

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the only new thing is the Ctek which I put on on Christmas day, but surely that isn't adding 40p overnight, the vans charger is turned off so only the Ctek MXS5 is running.

But my maths seems to say 5a x 230v =1150w or £9.38p which is of course wrong, and trying to explain is painful as I don't know what it is using per 24 hours.

The manual seems to say nothing helpful and I have Liz telling me to turn it off.



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The charger won't be running at 5 amps if the battery is fully charged. If you have an alarm or tracker on then that will be using power. The smart charger should just use the minimum to keep the battery topped up. Switch the charger off, leave it for an hour and then check the battery voltage.
 
It was down to 11.6V when I last checked so I don't want to turn it off for now, just an accurate current usage, just rhe van std alarm no tracker.
 
Pudsey Bear said:
It was down to 11.6V when I last checked so I don't want to turn it off for now, just an accurate current usage, just rhe van std alarm no tracker.
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Don't forget the ECUs in the van will be using power. May not be a lot but it mounts up over a couple of weeks. Letting the battery get below 50% charge which 11.6v certainly is will just wreck the battery. The smart charger should help. I have one permanently wired in so when I connect the EHU it charges the vehicle battery. The habitation is done by the solar. I can also plug the charger In to the inverter and charge the engine battery from the leisure battery it needed.
 
I thought I'd contact Ctek, they are obviously working today as they got back to me but the response has fried my brain as usual with electrical stuff.

We are @ £0.34 per kWh

Hello Kev,

Here is a simple way to find out what it costs in electricity to charge a lead battery with a CTEK charger.
I have earlier made a calculation on a 75Ah battery below like this:

Battery voltage, BV = 12V
Battery size, B = 75Ah
The battery charge level, Bl = 50%
Battery efficiency = 87%
CTEK charger's efficiency = 80%

Calculate:

Energy consumed from the grid to charge the battery to full (A)
First, how much energy we need to complete the battery?
12V x 75Ah x 50% = 12x75x0.5 = 450Wh

How much energy the charger must supply of the battery efficiency?
450Wh / 87% = 450/0.87 = 517Wh
How much energy must the grid to the charger in the light of efficiency?
A = 517Wh / 80% = 517 / 0.8 = 647Wh or 0.647 kWh.

Answer:

It takes 0.647kWh to charge the battery with the given data.

You may count on 80% efficiency for all models of CTEK chargers.

Vary the battery size (Bs) and the charge level (Bl) to count on other cases
The charger draws 1.5W of input power from the grid, on average, while in maintenance mode, (ie Mode 7 or 8.)
It makes it in one day pull 24 x 1.5 Wh = 36Wh/24h
On a 30-day month making it 30 x 36 Wh = 1080Wh = 1.08kWh/Month

It takes 1.08 kWh to keep the charger maintaining the battery with the given data.

It differs not very much between batteries of different sizes, at least until the batteries less than 150Ah.

Best regards,
CTEK Customer Service
 
QFour said:
Don't forget the ECUs in the van will be using power. May not be a lot but it mounts up over a couple of weeks. Letting the battery get below 50% charge which 11.6v certainly is will just wreck the battery. The smart charger should help. I have one permanently wired in so when I connect the EHU it charges the vehicle battery. The habitation is done by the solar. I can also plug the charger In to the inverter and charge the engine battery from the leisure battery it needed.
Click to expand...
We have an Ablemail AMT12-2 Battery Reconditioner that can be set to an almost constant stae [9 seconds in every 10 seconds] to transfer current from the Leisure Battery ['LB'] [irrespective of its state] to the Vehicle Battery ['VB'] to keep the latter topped up. The LB then recharges from the solar, and, even in the Scottish Winter, can keep the VB at 12.9v-13.1v and the LB at 13.2v-13.4v. We have only on street parking so the £65 cost of the AMT12 avoids the need to run EHU leads across the footpath, with the attandant H&S risks. The AMT12 was installed almost exactly 12 months ago and is probably the most useful bit of kit in the M/Home, and is certainly the best value for money item

Steve
 
Pudsey Bear said:
the only new thing is the Ctek which I put on on Christmas day, but surely that isn't adding 40p overnight, the vans charger is turned off so only the Ctek MXS5 is running.

But my maths seems to say 5a x 230v =1150w or £9.38p which is of course wrong, and trying to explain is painful as I don't know what it is using per 24 hours.

The manual seems to say nothing helpful and I have Liz telling me to turn it off.



View attachment 65388
Click to expand...
For a start, the 5A is the DC current, not the AC, so you don't do a 5A X 230V to get a wattage.

Assuming the use shooting up is 40p a day (is that "shooting up"? That is like putting on a small electric fire on for an hour when it gets a bit colder), that is around 1Kwh.

The CTEK does not seem to be that efficient as a charger as they quote a max 5A (DC) output and a max 0.6A (AC) input. If the charger was 100% efficient (none are of course), the AC input would be about 0.3A, not 0.6A. so the charger looks like it is just 50% efficient based on that flyer info you posted.
So if it was the charger taking that 1Kwh of power, that translates to around 500Wh into the battery. That is about right for a typical van starter battery that is half-full to get fully charged again (if your battery was at 11.6V it is below half charged).

So yes, 40 pence to charge the battery looks right. But you would not expect that on a daily basis just to maintain it once charged of course. Is this 'jump' every day or you just noticed it now and thinking it will continue?
 
wildebus said:
For a start, the 5A is the DC current, not the AC, so you don't do a 5A X 230V to get a wattage.

Assuming the use shooting up is 40p a day (is that "shooting up"? That is like putting on a small electric fire on for an hour when it gets a bit colder), that is around 1Kwh.

The CTEK does not seem to be that efficient as a charger as they quote a 5A (DC) output and a 0.6A (AC) input. If the charger was 100% efficient (none are of course), the AC input would be about 0.3A, not 0.6A. so the charger looks like it is just 50% efficient based on that flyer info you posted.
So if it was the charger taking that 1Kwh of power, that translates to around 500Wh into the battery. That is about right for a typical van starter battery that is half-full to get fully charged again (if your battery was at 11.6V it is below half charger).

So yes, 40 pence to charge the battery looks right. But you would not expect that on a daily basis just to maintain it once charged of course. Is this 'jump' every day or you just noticed it now and thinking it will continue?
Click to expand...
Thanks David, we used to see 26p first thing on the smart meter, then it jumped up when they put up the standing charge, and of course the new £0.34 per kWh we pay for for the fridge etc which are on all the time overnight this morning it was £1.43 this is added to during the day of course with the kettle oven hob etc and it's getting out of hand, we don't even put the heating on til 4pm ish as we can't afford it.
 
Pudsey Bear said:
Thanks David, we used to see 26p first thing on the smart meter, then it jumped up when they put up the standing charge, and of course the new £0.34 per kWh we pay for for the fridge etc which are on all the time overnight this morning it was £1.43 this is added to during the day of course with the kettle oven hob etc and it's getting out of hand, we don't even put the heating on til 4pm ish as we can't afford it.
Click to expand...
I posted last month that our November Dual Energy Bill [part of the month was during quite mild temperatures] was £136'ish. The December bill is £275, because of the very cold weather throughout the month, and topped off with running a 200W dehumidifier round the clock for 10 days after the pipe burst!
We were told when we had our new Combi Boiler installed 7 years ago [so guarantee has just run out ...] that it was more economical to keep the heating on constantly at around 16 degrees, and to allow the evening 4-5 hours period to rise to 18 degrees, because this consumed less gas than a huge surge from biting cold [and is more comfortable!]
We had built up a large credit balance during the Spring/Summer period when we were away in the M/Home for some 155 days in total; but another £275 bill in January will wipe out the credit balance and leave us playing catch up again. An average January temperature of 16 degrees should do the trick :rolleyes:

Steve
 
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