A week without EHU

[funflair]

As per the title, a week in a field" without hook up well that's not difficult you are thinking and you are right of course especially with LiFePO4 batteries and 520watts of solar BUT this was a week using electric at 240v from the inverter as if we were plugged in, the weather was good and sunny most days but my solar is currently underperforming until I get the MPPT regs back on but thats another story.

So we have been using electric kettle, microwave and coffee machine and of course a hair dryer for Mrs funflair, on top of this I have fitted an induction hob outside so that has had a bit of use as well, when we make tea or coffee it is usually for at least 4 and cooking on the induction hob for 6 or 8 but not every night.

We are finishing the week with about 40% battery capacity but that would soon go if we had a day without sun, we are having another battery fitted anyway so that will see us through "no solar" days.

We have harvested around 1000ah from the sun and used around 800ah via the 240v inverter, I now wish I had kept better figures I will do it again when I get the solar sorted out a bit better and if it is hot enough we could throw in some air conditioning to really make it work.

In conclusion

 

[paddymcc]

That's impressive Martin, how big is your battery bank? ( I'm hoping to manage with a little less when going lithium!)

 

[funflair]

That's impressive Martin, how big is your battery bank? ( I'm hoping to manage with a little less when going lithium!)

At the moment we have 320ah LiFePO4 but going to add another 160ah to that so should have some good reserve capacity.

 

[IanRJ]

funflair
Just out of interest, what size (power) of kettle and induction hob do you use? I think you have a 3kw inverter?

Your post is really useful and hope you get to detail it further.

Thanks for the info.

 

[Raul]

If 1k ah that’s a approximate 12kwh, or 2kwh per day over six days. Easily doable with 500w solar this time of year. The other day I harvested 2,17kwh and we don’t use the van to it’s full. Is parked on the farm where we do some roofing work and just charge batteries, eat wash washing up etc. Haven’t used gas in the last 3 weeks as the solar can cover well, all the energy needs.

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[Geo]

As per the title, a week in a field" without hook up

So we have been using electric kettle, microwave and coffee machine and of course a hair dryer for Mrs funflair, on top of this I have fitted an induction hob outside so that has had a bit of use as well, when we make tea or coffee it is usually for at least 4 and cooking on the induction hob for 6 or 8 but not every night.

We are finishing the week with about 40% battery capacity but that would soon go if we had a day without sun, we are having another battery fitted anyway so that will see us through "no solar" days.

We have harvested around 1000ah

In conclusion

Possibly used the most expensive electricity we will ever use

 

[Wissel]

Nice to read your system is all working as you want it too
(albeit with a MPPT issue)

This last week has been the first we have been able to properly test how our elecs perform. Sat in the New Forest without moving for 9 days so far, battery would have been full when we arrived, using around 1.6kwh per 24 hours (around 125Ah) and solar is keeping up nicely.

The resting voltage of our cells is 3.3v when full and I've been taking a load of readings at 10pm each night (power in, power out, voltage, etc) to try and get an idea over time how everything is working. So far I've had readings of between 3.29v - 3.3v every night while battery is under a load of around 6a. Very happy so far.

Starting to adjust the MPPT voltages very slightly now (by 0.01v per day) trying to fine tune the system.

Thought I'd add this as our system is quite close in spec to yours. We have 400Ah of LiFePO4, but set at 80% capacity to protect them (so 320Ah usable) and 540w of solar. We also run an inverter 24/7 (Victron 1600VA). Camped next to another Funster with an identical system apart from a little less solar and he is getting similar results. Have to love LiFePO4 if you use a lot of power

Hope you get your MPPT issue sorted,
David

 

[funflair]

Nice to read your system is all working as you want it too
(albeit with a MPPT issue)

This last week has been the first we have been able to properly test how our elecs perform. Sat in the New Forest without moving for 9 days so far, battery would have been full when we arrived, using around 1.6kwh per 24 hours (around 125Ah) and solar is keeping up nicely.

The resting voltage of our cells is 3.3v when full and I've been taking a load of readings at 10pm each night (power in, power out, voltage, etc) to try and get an idea over time how everything is working. So far I've had readings of between 3.29v - 3.3v every night while battery is under a load of around 6a. Very happy so far.

Starting to adjust the MPPT voltages very slightly now (by 0.01v per day) trying to fine tune the system.

Thought I'd add this as our system is quite close in spec to yours. We have 400Ah of LiFePO4, but set at 80% capacity to protect them (so 320Ah usable) and 540w of solar. We also run an inverter 24/7 (Victron 1600VA). Camped next to another Funster with an identical system apart from a little less solar and he is getting similar results. Have to love LiFePO4 if you use a lot of power

Hope you get your MPPT issue sorted,
David

Hi David

Yours is working well and thanks for sharing I will get the MPPT thing sorted but in an effort to nail down where the issue lies I went back to the original PWM regs, parked next to jongood using Votronic MPPT but both seeing the same sun I should have been getting 24amps as a pro rata to what he was putting into nearly full gels but I was only seeing about 19amps peak on the PWM so if I hadn't already been convinced about MPPT that would have sealed it.

 

[funflair]

funflair
Just out of interest, what size (power) of kettle and induction hob do you use? I think you have a 3kw inverter?

Your post is really useful and hope you get to detail it further.

Thanks for the info.

Yes we have 3kw inverter, the kettle is 2.2kw at 240v and the induction is 2kw but fluctuates between 0.2kw and 0.8kw when on a low power 3/10 but still enough to heat a big pan of chilli for 6 without burning on.

The recently installed power meter confirms the power used on screens both inside and outside the van and includes an alarm set at 2.75kw.

Thats the kettle usage, so yes the induction would be OK with it on low and the microwave and coffee machine will run together

 

[Wissel]

Hi David

Yours is working well and thanks for sharing I will get the MPPT thing sorted but in an effort to nail down where the issue lies I went back to the original PWM regs, parked next to jongood using Votronic MPPT but both seeing the same sun I should have been getting 24amps as a pro rata to what he was putting into nearly full gels but I was only seeing about 19amps peak on the PWM so if I hadn't already been convinced about MPPT that would have sealed it.

Having had Votronic and Victron MPPT's, I'd say they are both fantastic bits of kit

I swapped to the Victron when I added more solar as I wanted to run my panels in series (I know, a lot don't like series ), but the Votronic(s) always performed as well. I do like being able to change settings via my phone though.

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[ManTheVan]

Yes we have 3kw inverter, the kettle is 2.2kw at 240v and the induction is 2kw but fluctuates between 0.2kw and 0.8kw when on a low power 3/10 but still enough to heat a big pan of chilli for 6 without burning on.

The recently installed power meter confirms the power used on screens both inside and outside the van and includes an alarm set at 2.75kw.

View attachment 488725

Thats the kettle usage, so yes the induction would be OK with it on low and the microwave and coffee machine will run together

That’s a useful looking meter! What’s the system and is it straightforward to install?

 

[funflair]

That’s a useful looking meter! What’s the system and is it straightforward to install?

Dead easy with this one, thread here

https://www.motorhomefun.co.uk/forum/threads/mains-energy-monitoring.238192/#post-4432932

 

[funflair]

Having had Votronic and Victron MPPT's, I'd say they are both fantastic bits of kit

I swapped to the Victron when I added more solar as I wanted to run my panels in series (I know, a lot don't like series ), but the Votronic(s) always performed as well. I do like being able to change settings via my phone though.

So on the Victron you can set the charge level down to protect the batteries

 

[jongood]

Possibly used the most expensive electricity we will ever use

But worth their weight in gold when it makes the difference of being able to stop in a wonderful wild spot, similar to a bigger tank or extra cassette.

 

[dabhand]

Martin, don’t you ever just get pissed and forget to check the LiFePO4 batteries and 520watts of solar, using the electric at 240v from the inverter as if we were plugged in, or the currently underperforming solar because the weather was not too good and you haven’t got your MPPT regs back, I know that’s another story and I’m eager to hear it, but in the meantime after you’ve done a bit more sun harvesting promise me you’ll put your feet up and get legless! I get very tired just reading about what your doing next!

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[two]

All very interesting.
In terms of energy consumption (power X time), I'd be interested to know how much solar you manage to harvest by day and where you are harvesting (Lattitude). Of course, the amount harvested will be capped as soon as the battery bank is restored but it's an indication of what's achievable with your panel size.
Also of interest is the typical power consumed per day (kW). Many of us will be using less than this, so would not need such capacity.
Clearly, if you can harvest more than your needs, you can survive for much longer than just a week.
I remain frugal with use of electricity but can manage three days without EHU (never tried longer), without solar. I remember my early caravan days when the battery was in a little wooden box, about 40Ah and it would last a long week-end (so long as you didn't watch telly). The primary use was lighting, no electronic gizmos to power in those days!

 

[funflair]

All very interesting.
In terms of energy consumption (power X time), I'd be interested to know how much solar you manage to harvest by day and where you are harvesting (Lattitude). Of course, the amount harvested will be capped as soon as the battery bank is restored but it's an indication of what's achievable with your panel size.
Also of interest is the typical power consumed per day (kW). Many of us will be using less than this, so would not need such capacity.
Clearly, if you can harvest more than your needs, you can survive for much longer than just a week.
I remain frugal with use of electricity but can manage three days without EHU (never tried longer), without solar. I remember my early caravan days when the battery was in a little wooden box, about 40Ah and it would last a long week-end (so long as you didn't watch telly). The primary use was lighting, no electronic gizmos to power in those days!

Next time I will do the numbers properly honest.

 

[two]

I'm not expecting that to be easy!
It's not straightforward to apply good experimental method...

 

[jongood]

I'm not expecting that to be easy!
It's not straightforward to apply good experimental method...

You ve not met funflair then? he's unlikely to pass that challenge by