Lithium battery dropped to 10v !

[Roger S]

Hello,

We had a sneeky few days away wild camping to test our new Lithium 230ah battery and our new 500w microwave, all went very well until I got up this morning and there was no power ! The Alde heating wouldnt work, I looked at the three way fridge and noticed it had switched from gas to battery ! I tried to light the gas hob with no joy, turned on the spare bottle of gas the hob then worked as did the fridge when I reset it to gas. I assume the gas bottle ran out and then the fridge switched to battery and fairly quickly flattened it, does this sound feasable ?

Thanks Roger

 

[Emmit]

It's possible.

Ive told this tale before.
When we were tugging and long before I knew anything, (don't know much now?)
about electrics, we boarded the Santander ferry towing our van.

In the boot/back (Audi Est.) we had a two way cooler box. I left it plugged in and when we
got to Spain 24hrs later, the battery wouldn't light a Naffi candle.

What made it all the more embarrassing was that I had to wait for everyone else to get off
and we were jump started by the scruffiest battered Ford Fiesta brought onto the ferry
from shoreside.

Fridges/Freezers are electric greedy.

 

[Roger S]

Oh that wasn't not good, one does loose confidence ( in the battery ) when you have something like this happen.

I will try to remember when wild camping to put the fridge on the gas setting rather than the auto select, then when our gas ran out the fridge would have bleeped rather than flooring the battery.

Thanks Emmit

 

[The Artilleryman]

This is the reason we're glad that our fridge is manual switching, as several times we've had the gas run out overnight.
Fridge is still cold enough in the morning and the leisure battery OK.

More so this year, as we knew the leisure battery was on its last legs and did not have time to sort the LiFePO4 upgrade till the winter.

 

[GeoffnDee]

If it is a Swift Motorhome with a Sargent Electrical system I would not expect the fridge to be connected to the leisure battery , except for its 12v controls , with the fridge only to operate from the starter battery with 12v cooling when the engine is running . When you ran out of gas it should not have drained your leisure battery but just given out an alarm signal. (unless your fridge has been wired to run from the leisure battery , as well or instead of the starter battery ,for 12v cooling)

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[Roger S]

It is a Swift as it happens, with a Sargent EC600 control unit, I understand what your saying with starter battery and the engine running, but it's a bit of a coincidence!

And if it wasn't that what's happened to my new lithium battery !

 

[Ingwe]

Assume that your new 230ah lithium battery was fully charged when you set off? How much use did the 500w microwave get over the period? If my memory of Ohm’s Law is correct a 500watt oven will draw 41.6 amp with 12v. Quite a heavy user.

 

[Roger S]

Yes the battery was pretty much full, the microwave was probably used for 10 or 12 minutes over the couple of days, I looked at the lithium app and it showed it still having plenty of power after the last use.

The app showed at 4.28am something started using the battery with fairly heavy use until it flattened.

 

[Roger S]

 

[Ingwe]

Puzzling indeed as normally a fridge isn’t connected to the leisure battery. I’m sure knowledgable posters such as autorouter or Lenny HB or Raul will be along at some point with good suggestions. There are others too so apologies if not mentioned.

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[Roger S]

It is a Swift so it wouldnt be a surprise if it is different

 

[Lenny HB]

As you have a Swift I'm surprised it switched to battery can happen on some German vans.
If its one of the bigger fridge freezers according to the spec 4.2kw per 24 hour that's 330 amps.

 

[Kannon Fodda]

How is your inverter wired to connect to the 240V systems in the van to power the microwave? If it powers all the sockets then the inverter would also try to power the fridge as if you were on mains EHU assuming the inverter was on in it's standby mode overnight.

 

[Hoovie]

Assume that your new 230ah lithium battery was fully charged when you set off? How much use did the 500w microwave get over the period? If my memory of Ohm’s Law is correct a 500watt oven will draw 41.6 amp with 12v. Quite a heavy user.

a 500W Microwave will draw a lot more that 41.6A with a voltage of 12V - because a 500W Microwave will NOT be a 500W microwave as far as input power goes - more like 800W. Then add in Inverter overhead for the battery draw - expect more like 90 Amps.

 

[Ingwe]

a 500W Microwave will draw a lot more that 41.6A with a voltage of 12V - because a 500W Microwave will NOT be a 500W microwave as far as input power goes - more like 800W. Then add in Inverter overhead for the battery draw - expect more like 90 Amps.

There you are- I knew someone knowledgable would be along in a moment.

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[Roger S]

As you have a Swift I'm surprised it switched to battery can happen on some German vans.
If its one of the bigger fridge freezers according to the spec 4.2kw per 24 hour that's 330 amps.

Ooh well that would do it. I can't imagine what else may have eaten the capacity although I did put the heating on but again that would be wire to the battery.

 

[Roger S]

The invertor is wired to two seperate sockets I fitted so no connection with the existing 240v circuit.

The microwave was converted down to 500w from the Microwave Service Company near Ashford so wether that would be 500w or higher on start I don't know.

 

[autorouter]

How is your inverter wired to connect to the 240V systems in the van to power the microwave? If it powers all the sockets then the inverter would also try to power the fridge as if you were on mains EHU assuming the inverter was on in it's standby mode overnight.

That happens to us regularly. I have quite a large lithium setup (600Ah equivalent) and a 3kW inverter. I usually run the fridge on auto when I'm travelling, and switch the inverter off. So it switches between gas and 12V as you expect.

But when we stop and turn on the inverter, I have to be careful to switch the fridge to gas (manual setting) otherwise it switches to 240V and runs off the leisure battery through the inverter. Even with 600Ah a 3-way fridge won't last very long on 240V.

 

[Lenny HB]

That happens to us regularly. I have quite a large lithium setup (600Ah equivalent) and a 3kW inverter. I usually run the fridge on auto when I'm travelling, and switch the inverter off. So it switches between gas and 12V as you expect.

But when we stop and turn on the inverter, I have to be careful to switch the fridge to gas (manual setting) otherwise it switches to 240V and runs off the leisure battery through the inverter. Even with 600Ah a 3-way fridge won't last very long on 240V.

I'm surprised at you Mr. autorouter not wiring your van correctly so the fridge is not in circuit when the Inverter is on.

 

[Hoovie]

The invertor is wired to two seperate sockets I fitted so no connection with the existing 240v circuit.

The microwave was converted down to 500w from the Microwave Service Company near Ashford so wether that would be 500w or higher on start I don't know.

Just to clear this microwave question up .... so when you are cooking food, do you use times quoted for a 500W microwave (Or adapt from say a 700W one - use 7/5ths more time?). A microwave power is always quoted as its "cooking power". A Microwaves INPUT power is always considerably more - and not talking about startup power or some oft-quoted apparent "surge" power, but CONSTANT power.
A microwave just has an input power of 500W will take approximately 2 times longer than a "600W Microwave" to cook food. Also, the amount of power drawn will not be any different, it is just slower to draw it.

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[Hoovie]

I'm surprised at you Mr. autorouter not wiring your van correctly so the fridge is not in circuit when the Inverter is on.

You sometimes want the the Fridge to use Inverter power, though
I supplied a setup for someone with a Transfer Switch and an SSR controlled by a Victron BMV-712 Relay. He runs the 3-way AES Fridge on Battery until the battery bank drops to a set SOC and then switches over to Gas automatically. When in Portugal over last winter, allowed him to stay parked up and off-grid for much longer before he had to get more gas.

 

[Lenny HB]

You sometimes want the the Fridge to use Inverter power, though
I supplied a setup for someone with a Transfer Switch and an SSR controlled by a Victron BMV-712 Relay. He runs the 3-way AES Fridge on Battery until the battery bank drops to a set SOC and then switches over to Gas automatically. When in Portugal over last winter, allowed him to stay parked up and off-grid for much longer before he had to get more gas.

But that situation was controlled by the SOC.

I run mine part of the time on 12v controlled by my Votronic solar regulator via the AES output so it only runs on 12v when plenty of power avaliable.

 

[Jev88]

Cant you set the battery BMS to turn off when it reaches 20, 15% etc?

 

[Roger S]

Just to clear this microwave question up .... so when you are cooking food, do you use times quoted for a 500W microwave (Or adapt from say a 700W one - use 7/5ths more time?). A microwave power is always quoted as its "cooking power". A Microwaves INPUT power is always considerably more - and not talking about startup power or some oft-quoted apparent "surge" power, but CONSTANT power.
A microwave just has an input power of 500W will take approximately 2 times longer than a "600W Microwave" to cook food. Also, the amount of power drawn will not be any different, it is just slower to draw it.

When we cook with the microwave we cook with times for a 500w oven and this seems to be correct with the end cooking result.

 

[autorouter]

I'm surprised at you Mr. @autorouter not wiring your van correctly so the fridge is not in circuit when the Inverter is on.

Unlike a lot of motorhomers, I'm not looking to go 100% off-grid all the time. On the last trip, for example, we mostly used CampingCarParks sites in France, which all seem to have a 6A supply. In that situation I can keep the Multiplus inverter on, with the EHU limit set to 5A, and still run everything I want when I want it - kettle, microwave, rice cooker, slow cooker etc. The fridge stays on 240V, through the inverter. The heating/hot water still runs on gas, as does the hob and oven.

We usually park up for two or three days, and explore the area with our scooters. Autoroutress can't walk for miles these days, but has no problems with the scooter.

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[Gaston aires]

These sort of battery threads are common in the winter months. Not much input from solar at this time of year. Unless you are on the move daily, it’s all output not much input.
Heavy users are microwaves, heaters, and fridges ( because they are on 24/7
Phil

 

[Hoovie]

When we cook with the microwave we cook with times for a 500w oven and this seems to be correct with the end cooking result.

It must be drawing a lot more than 500W then.

 

[Hoovie]

But that situation was controlled by the SOC.

But indeed it is controlled by the SOC (as I stated )

I run mine part of the time on 12v controlled by my Votronic solar regulator via the AES output so it only runs on 12v when plenty of power avaliable.

240V is more efficient than 12V for cooling.

 

[Lenny HB]

240V is more efficient than 12V for cooling.

A slightly bigger element I agree but uses more power than just the bigger element due to inverter efficiency.

 

[funflair]

But indeed it is controlled by the SOC (as I stated )

240V is more efficient than 12V for cooling.

More efficient or more effective?