Inverter power rating question

[Sandancers]

I have a 500W electric heater fixed in the MH. With my two 105Ah lead acid batteries I believe I could just about power that heater and still be close to the C5 figure. Obviously the heater would quickly deplete the batteries, but it would only be used on odd occasions for short times to take the chill off the vehicle.

I was looking at a 800w Victron inverter, but could I run the heater from only a 500w inverter ? Like is the 500w figure a continuous use figure ?

 

[pappajohn]

I reckon a 500w inverter to run a 500watt appliance is far too close to a constant maximum.
You also need to take into account inverter losses which may be as much as 10%.
Your batteries will last just over 2 hours to 50%

 

[LithiumConvert]

Obviously the heater would quickly deplete the batteries

As pappajohn says, 2 hours.

But more imprtant is the damage you will do to your lead acid batteries. They are not designed for constant heavy load.

 

[Sandancers]

As pappajohn says, 2 hours.

But more imprtant is the damage you will do to your lead acid batteries. They are not designed for constant heavy load.

I'd not envisage running the electric heater for more than 20 minutes, tops.

 

[LithiumConvert]

By constant, I mean anything longer that starting an engine.

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[Raul]

You don’t have batteries rated for C/5 discharge. Those are deep cycle thick plates that can take some hammering, and still long term they shed a lot of their active material of the plates. A common leisure lead acid it’s comfortable at C/10, any more you need special batteries rated for what you need. Your choice.

 

[Sandancers]

So I emailed Yuasa and asked about the batteries being able to power the 500w 240v heater, emails as shown below. I also rang them and spoke to a technical services chap just to double check and he confirmed the email was correct. So it would seem that the current draw to power the heater via the inverter (I have decided to use a 800w inverter) is fine, as long as the voltage of the battery does not go down too far and it is recharged again in a short space of time.




-----Original Message-----
From: Enquiries <info@gs-yuasa.uk>
Sent: Saturday, November 25, 2023 2:11 PM
To: Enquiries - Yuasa Sales <info@gs-yuasa.uk>
Subject: Contact Form


Comment: Hi,

I have a motorhome in which I am currently using two 105Ah lead acid batteries connected in parallel as a leisure battery.

These have been in use for 5 years and I want to replace them early next year.

These batteries are the maximum size I can fit into the space in the Motorhome, which is 353mm long x 175mm wide x 190mm high per battery.

I think that your L36-EFB batteries would be a direct replacement.

I have a 500w 240v heater fitted in the vehicle which I currently run from mains hook-up. I was considering fitting a 800w inverter from the leisure batteries to power this unit for say 20 min each evening if it gets chilly. I am aware that this would put a large current draw onto the batteries, but would like your advice as to if it would be detrimental to the L36-EFB batteries to do this ?

Thanks.


Thank you for your enquiry.
With the two batteries in parallel, you should be able to sustain the setup. What would be important is to monitor the battery voltage, so it does not discharge too deeply after reach run.

Best regards.