300W Inverter, what happens if moderately overloaded?

[Viktorgeorge]

I am embarrassed to admit that my electrical knowledge is poor, and many others' will be far better. Hence this question.

I use the 240v 300w inverter often for devices below that wattage.

What I am wondering is would it damage the inverter to attach a higher wattage (say 450w) device to it (I accept the battery will drain fast), or will the device simply underperform or not work at all; without the inverter suffering?

 

[Stu@rt]

I suspect that it will just blow the fuse. A quick search on here suggests that its a green 30amp under the seat for when you do! Because it sounds like you just might!

 

[Viktorgeorge]

I suspect that it will just blow the fuse. A quick search on here suggests that its a green 30amp under the seat for when you do! Because it sounds like you just might!

Thank you @Stu@rt. I looked up the fuses here:

2022 Volkswagen California fuse box diagram - StartMyCar

www.startmycar.com

the closest I can get is F38 rated 25A, which reads:

"Onboard supply control unit: Exterior lighting, Interior lighting, Internal supply"

Might that be the fuse that will blow, if the inverter has a wattage overload?

I also asked Grok:

https://grok.com/share/c2hhcmQtMg_a358713d-f621-4210-aa21-aa856ca97a37

Which says it is Fuse 7 rated 30A, but then according to the above link Fuse 7 is 25A.

Perhaps I am over worrying. It is just that I bought a 300 watt kettle - i.e. there is no margin on the load - and before I use it I wanted to know the recovery procedure if required.

 

[Wannabecamperman]

Thank you @Stu@rt. I looked up the fuses here:

2022 Volkswagen California fuse box diagram - StartMyCar

www.startmycar.com

the closest I can get is F38 rated 25A, which reads:

"Onboard supply control unit: Exterior lighting, Interior lighting, Internal supply"

Might that be the fuse that will blow, if the inverter has a wattage overload?

I also asked Grok:

https://grok.com/share/c2hhcmQtMg_a358713d-f621-4210-aa21-aa856ca97a37

Which says it is Fuse 7 rated 30A, but then according to the above link Fuse 7 is 25A.

Perhaps I am over worrying. It is just that I bought a 300 watt kettle - i.e. there is no margin on the load - and before I use it I wanted to know the recovery procedure if required.

If you want an electric kettle, you really need a powerbank. Our 600w one takes around 6 mins for two mugs' worth of water to boil, so Lord knows how long a 300w one will - I've never even heard of that low a wattage other than a 12v element you drop in a mug that the lorry drivers love.

Having a powerbank also then means that toaster and hair straighteners, etc are available and the costs are getting lower by the month. Just avoid NMC and buy LiFePO4

 

[Viktorgeorge]

If you want an electric kettle, you really need a powerbank. Our 600w one takes around 6 mins for two mugs' worth of water to boil, so Lord knows how long a 300w one will - I've never even heard of that low a wattage other than a 12v element you drop in a mug that the lorry drivers love.

Having a powerbank also then means that toaster and hair straighteners, etc are available and the costs are getting lower by the month. Just avoid NMC and buy LiFePO4

Only came today, but from initial tests it takes 8 minutes from full, that is 500mm, which makes my wife and I two cups of tea; and 5 minutes for a single hot drink:

https://amzn.eu/d/eXtThm2

Hair straighteners are not for us (seen them but don’t really know what they are, to be honest) and we positively hate toasters never have or use them - they always smell as does the room where they are used, can’t imagine what they do to a California, a bit like a ‘smokers car’… urgh.

This 300 watt kettle is ideal for us for both the California and also the Santander ferry to Spain where we like to make tea in our cabin, and can’t always get the Club or Commodore without which no kettle is provided.

I am not keen on a power bank, it is another thing to avoid certainly until I specifically need one.

I do understand and respect that others love them and, in the right circumstance, I do not doubt they are brilliant.

 

[Wannabecamperman]

Only came today, but from initial tests it takes 8 minutes from full, that is 500mm, which makes my wife and I two cups of tea; and 5 minutes for a single hot drink:

https://amzn.eu/d/eXtThm2

Hair straighteners are not for us (seen them but don’t really know what they are, to be honest) and we positively hate toasters never have or use them - they always smell as does the room where they are used, can’t imagine what they do to a California, a bit like a ‘smokers car’… urgh.

This 300 watt kettle is ideal for us for both the California and also the Santander ferry to Spain where we like to make tea in our cabin, and can’t always get the Club or Commodore without which no kettle is provided.

I am not keen on a power bank, it is another thing to avoid certainly until I specially need one.

I do understand and respect that others love them and, in the right circumstance, I do not doubt they are brilliant.

Good reviews, and great price for a stainless steel kettle, however several reviews state it draws a consistent 325 - 352 watts from Jackery, etc, so I strongly doubt that the Cali 300w inverter will suffice, sadly. Interested to hear if you do manage to get it to run over capacity for many minutes per boil...

 

[Viktorgeorge]

Good reviews, and great price for a stainless steel kettle, however several reviews state it draws a consistent 325 - 352 watts from Jackery, etc, so I strongly doubt that the Cali 300w inverter will suffice, sadly. Interested to hear if you do manage to get it to run over capacity for many minutes per boil...

Thank you, @Wannabecamperman; yes this little kettle seems really well made but I did fear - as you kindly found out - that it might approximate to over 300 watts and challenge the inverter. I wonder what tolerance there is on the 300 watts on the inverter?

If anyone can confirm the correct fuse, in case the kettle does blow it, I would be grateful. I suppose Grok’s suggestion of fuse 7* is the mostly likely. I am imagining that a blown fuse under the passenger seat would not be obvious without working through them one by one?


*A search, which I should have done before, shows @calikev confirming this:

Inverter socket fuse

Does anyone out there know which fuse operates the inverter socket behhind the passenger seat please?

vwcaliforniaclub.com

 

[sidepod]

Or just use the gas hob and a pan of water. Why make life unnecessarily complicated!

 

[Viktorgeorge]

Or just use the gas hob and a pan of water. Why make life unnecessarily complicated!

Fair point, @sidepod; and we do use our Outwell folding kettle a lot. The main reson for the travel kettle was for situations when we are travelling - ferry cabins in particular - but the idea appealed to me, when I saw the 300 watt descriptor, to try using it off the inverter, though not if it might blow the fuse, hence my original post.

 

[Viktorgeorge]

Here is some Grok feedback for anyone interested:

"Thanks for sharing the order details—that confirms it's the Emooncn (sometimes listed as Emoon) 500ml stainless steel travel kettle, a popular compact model for campers and RVers. Based on the product page and hundreds of user reviews, you can absolutely use this on your 2022 VW California Ocean's 300W inverter without worry. It's designed for exactly this kind of low-power setup, and real-world feedback shows it performs reliably even at the slight overload some measure. I'll break it down with specifics to give you that reassurance.

Key Specs for This Model​

• Power Rating: Officially 300W at 240V, which matches your inverter perfectly. Reviews with watt meters (e.g., Fluke or Victron) consistently measure steady draw at 300–352W, with peaks only during initial heating (under 10–20 seconds). The "360W" from earlier reviews aligns here—it's not sustained, so it falls within the inverter's typical surge tolerance (up to 150% or ~450W briefly).
• Capacity and Boil Time: 500ml max (enough for 2 mugs). Claimed under 5 minutes, but users report 6–9 minutes for a full boil on mains or inverters (e.g., "6 minutes 16 seconds for 360ml" or "9 minutes for 500ml from cool water"). Your mentioned 8 minutes is spot-on and normal—it's slower than a home kettle but safe and efficient on battery power.
• Features: Auto shut-off, quiet operation (no loud boiling), and stainless steel build for durability. No voltage drop issues reported on 240V inverters.

What Users Say About Inverter Use​

With a 4.3/5 rating from over 300 reviews, this kettle gets praise for travel setups like yours. Folks with caravans, vans, and power banks (similar to your leisure battery) confirm it works seamlessly:

• "Works well. I am using it off power packs and the draw is as stated 300W." (No shutdowns mentioned.)
• "At 240V from UK mains or from my inverter, it was pulling 352 watts... tested with both my Fluke multimeter and a Victron SmartShunt." (Boiled fine without tripping.)
• "Draws just over 300W from our power bank but it's worth it." (Extended boil time, but no damage or fuse issues.)
• Multiple campers note 7–10 minute boils on 300W systems, with zero reports of inverter overload shutdowns, overheating, or permanent damage. One van owner: "Boils water in 4 minutes and enough for 2 cups—perfect for the road."

The consensus? It's forgiving on marginal loads—the inverter's protection will handle any brief spike by throttling or pausing if needed, but it rarely does for this kettle. No fuse blows or failures in similar VW California threads either.

Quick Tips for Your First Use​

• Test Run: Fill to half (250ml) for a 3–5 minute boil to start—monitors the dash for any warnings (unlikely).
• Battery Check: Ensure your leisure battery is at least 70% charged; it should sip ~25–30A from the 12V side.
• If It Pauses: Unplug, wait 20 seconds, restart—harmless and common on exact-match loads.
• Backup: Your gas hob is always there for speed, but this kettle's a game-changer for quiet, fume-free mornings.

You're good to go—thousands of similar setups run this without a hitch. Brew that first cup with confidence; if you notice anything off (super rare), VW's warranty covers inverter checks. Safe travels! If you try it and want to share how it goes, I'm here."