Off-Grid set up, not that great!

[Rabonitez]

Wondering if anyone has any experience with this….

I have a recently replaced 110ah leisure battery and run the usual things (led spots lights, phone chargers, 12v fridge) when off-grid. I get about 12-13v when fully charged and this will give me about 12-hours with above mentioned items running. After that, it starts to struggle to run the fridge etc and it won’t power on. I also have a Sealey 1500w inverter and this will shut down due to “low voltage”, when under load of 1kw travel kettle or a toaster. The battery voltage drops right down to 9-10v when under load and refuses to do anything‘significant’

I am wondering Is this expected performance and how I can improve? Bigger battery? Solar panel? Lower my expectations ??

I was thinking a leisure battery would give me decent performance for about 3-days, but that’s not the case with mine. Interested to hear about other’s performance with their respective setups.

Cheers

 

[roadtripper]

Your inverter is putting a pretty extreme load on the 12v system.

If you want to be off grid with 240v heating loads like that you need more capacity and at least double batteries, as you are finding single batteries cannot supply the current.

 

[roadtripper]

See this recent thread

https://www.t6forum.com/threads/new-conversion-power-solution.44589

 

[CAB]

Gas for kettle and toast.

Or a stack load of lithium.

 

[t0mb0]

Just to check on the fridge - it is a compressor fridge? Assuming so, your 12v loads are a pretty typical off-grid set-up so shouldn’t be an issue assuming an adequate recharging strategy (usually a DC-DC and preferably solar too).

The inverter running 240v loads is another matter, it’s difficult/expensive to make a credible off-grid setup with these and would involve a lot of lithium storage and enough engine run time through a chunky DC-DC to replenish the charge.

 

[Pete C]

You are asking too much of a standard leisure battery due to your inverter load. You need to move to a Lithium battery, or use gas.

Pete

 

[Salty Spuds]

You are asking too much of a standard leisure battery due to your inverter load. You need to move to a Lithium battery, or use gas.

Pete

Even with Lithium, running heavy 240V loads is wishful thinking. People think that Lithium is a magic pill for all their off grid needs, but unless you have a LOT of lithium, it isn’t.
Lithium is just another storage medium, it’s a reservoir of power & it’s only as good as the source(s) that keep it full. We have a typical 100Ah Lithium setup, battery/180W solar/B2B etc. And we can survive 3-4 days “off grid” in summer by judiciously managing the power consumption. Fridge, only necessary lighting, phone/iPad charging etc.
We’re in Scotland as we speak, it’s warm but not particularly sunny, so the fridge is working hard but the solar isn’t pulling any trees up. I’ll give it 3 days before I need to run the engine to top up the battery.
We did 3 days in the Alps off grid last winter, it was -20, it was also very sunny & the yield from the panel was more than we’re getting currently. After 3 days the battery was just about done, but we were using the Webasto for 6 hours a day & lights. Although the fridge had it easy

 

[t0mb0]

Even with Lithium, running heavy 240V loads is wishful thinking. People think that Lithium is a magic pill for all their off grid needs, but unless you have a LOT of lithium, it isn’t.
Lithium is just another storage medium, it’s a reservoir of power & it’s only as good as the source(s) that keep it full. We have a typical 100Ah Lithium setup, battery/180W solar/B2B etc. And we can survive 3-4 days “off grid” in summer by judiciously managing the power consumption. Fridge, only necessary lighting, phone/iPad charging etc.
We’re in Scotland as we speak, it’s warm bunt not particularly sunny, so the fridge is working hard but the solar isn’t pulling any trees up. I’ll give it 3 days before I need to run the engine to top up the battery.
We did 3 days in the Alps off grid last winter, it was -20, it was also very sunny & the yield from the panel was more than we’re getting currently. After 3 days the battery was just about done, but we were using the Webasto for 6 hours a day & lights. Although the fridge had it easy

Exactly this, long term ability to stay off-grid is more about power in vs power out than it is about Ah storage.

 

[Samro]

Even with Lithium, running heavy 240V loads is wishful thinking. People think that Lithium is a magic pill for all their off grid needs, but unless you have a LOT of lithium, it isn’t.
Lithium is just another storage medium, it’s a reservoir of power & it’s only as good as the source(s) that keep it full.

This is true but the true benefit of lithium is the speed that the battery bank can be charged, rather than this being solely a capacity thing.

The discharge curve of lifepo4 batteries means that heavy loads will work without the battery voltage diminishing until the battery is nearly dead flat. (This means that battery monitoring becomes more important, as there becomes a fine line between charged & discharged!)

I have 400w of solar, 30A DC-DC and 200Ah lifepo4.

I regularly use sandwich toaster, kettle and even have a hot water heater. I have only ever plugged in over the winter months, so for me I'd say lithium is somewhat of a "magic pill", as this wouldn't be achievable with lead acid.

 

[roadtripper]

But you have had to dedicate a lot of budget and space to do that.

It's possible but for the OP either using the existing gas installation or £30 on a briefcase type stove to boil outside when EHU isn't available might make sense while they consider if that investment is right for their use.

 

[Mocko1962]

Why not go for some PV power on the roof and use gas for kettle and toaster as I do when off grid … my 180w panel has no problems with fridge , lights , usb chargers and Erbersprecher heater use even in winter when there’s only a few hours of ‘daylight’ … I get 3 days use without having to start the van for B2B top up or anything … all depends what you want for the £ you want to pay … my so.at install done myself £300

Regards

 

[Samro]

But you have had to dedicate a lot of budget and space to do that.

It's possible but for the OP either using the existing gas installation or £30 on a briefcase type stove to boil outside when EHU isn't available might make sense while they consider if that investment is right for their use.

400W of panels is more that I really need. If I were doing the install again I'd probably go with a single 250-300W panel. Panels are not a fortune and MPPT controllers are relatively inexpensive. It's the cost of lithium batteries that made me squeak!

 

[Oceanis]

To put it into perspective, think about breakfast .... 2 cups of tea and 4 slices of toast.

Running a 1kW toaster will cause the inverter to draw around 85A from the 12V battery.

85A for 4 mins (toasting time) is around 5.66 Ah from the battery - another round of toast takes that to 11.3 Ah ....

For the tea, water heat capacity is 4.2 kJ/°Ckg. If the water temperature is 20°C, to boil 0,5 liter (2 cups) of water, you need:

E = 4.2 * 0.5 * (100 – 20) = 168 kJ

In the case of an ideal heater, to boil 0,5 litres (2 cups) of water at 20°C, the boiling time is:

T = 168 kJ / 1 kW = 168 seconds = 2.8 mins

2.8 mins at 85A is another 3.9 Ah ...

So in total you have around 15Ah for breakfast - almost 14% of your 110Ah ... and as you really should avoid discharging a lead acid battery below 50% it gets worse, you have used 28% of your available usable capacity.

... add the fridge 24/7 and your battery won't last long at all. I can understand why the fridge and the inverter are seeing undervoltage cut-offs.

 

[Rabonitez]

Great feedback - thanks all.

I’m not entirely sure why someone (previous to me owning the van) even installed the inverter, as with the existing setup, it’s pretty useless.

I like the idea of solar, maybe 150-200w. Hopefully this will allow me to keep the existing leisure battery (as it’s new) and will keep it topped up, to maintain fridge, lights, chargers etc. for a few days off-grid. I’ll probably remove the inverter and do tea and toast with gas.

 

[roadtripper]

Solar is a good thing to consider, especially if you can permanently mount on the roof. That way even if it's a modest charge it's always happening.

The inverter isn't useless, lower loads like a laptop charger are going to hit the batteries a lot less.

If you're on the way somewhere and you have a few hours driving ahead then the charge used by a quick brew is going to be replaced pretty quickly.

It's also possible to use it supported by the alternator, so if you are parked up in a layby can always have the engine on for a bit.

If you need the space to put in a decent DC-DC charger (assuming you haven't already) or a solar MPPT controller then fair enough, but I'd leave it in place if not.

 

[Salty Spuds]

This is true but the true benefit of lithium is the speed that the battery bank can be charged, rather than this being solely a capacity thing.

The discharge curve of lifepo4 batteries means that heavy loads will work without the battery voltage diminishing until the battery is nearly dead flat. (This means that battery monitoring becomes more important, as there becomes a fine line between charged & discharged!)

I have 400w of solar, 30A DC-DC and 200Ah lifepo4.
View attachment 213083
I regularly use sandwich toaster, kettle and even have a hot water heater. I have only ever plugged in over the winter months, so for me I'd say lithium is somewhat of a "magic pill", as this wouldn't be achievable with lead acid.

I rest my case. You have a hefty setup which isn’t typical of the majority. Most 12V installations are basically 100Ah battery/150W PV/ B2B/mains charger. Notwithstanding the B2B & mains charger, you probably have double the capacity in terms of battery & PV than most folk.

 

[CJW]

So many variables.

But if, as it turns out, you’re not aiming to use the inverter, adding 200w of solar panels will change your world. It did ours.

 

[Samro]

I rest my case. You have a hefty setup which isn’t typical of the majority. Most 12V installations are basically 100Ah battery/150W PV/ B2B/mains charger. Notwithstanding the B2B & mains charger, you probably have double the capacity in terms of battery & PV than most folk.

I agree that my setup is a bit OTT for a transporter which is used for short term
camping. However, a 150w- 200w panel & MPPT is reasonably cheap and will do well even if a lithium battery bank is not utilised.

 

[T6ChrisO]

I really enjoy reading these posts and the elec side of things always goes over my head with these camper builds. We have some very inteligent people on this forum

 

[Dellmassive]

upgrade the battery to a lithium,

then add more solar.



+++++++++++++++++++++


this weekend, running 1500w coffee machine, 900w kettle, twin fridges, uSB, lights etc etc etc .

400w tempory on roof. . .



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230Ah Roamer storage battery, - [Guide] Mobile Solar Panels ? . . . - How I Did It -


and a EcoFlow Delta2 - Portable Power Packs - LifePo4 Battery Boxes -- How I done It --


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