Invertor question from an electrical numpty

[knokinonabit]

Our new MH is on order (since January) and I have specified 2x120watt solar panels with 2x95A batteries, which will be the standard AGM that the factory supply. I know Lithium are better, but that is for the future for now, and will be upgraded accordingly.
I would like an invertor to power a few 230v appliances, hairdryer, induction hob, kettle etc., which are all less than 1000w, but the coffee machine is 1500w as is our air fryer.
The feeling I have is that a 3000w invertor would be best as the load may increase later if we buy other gadgets. We aren't looking to go total electric, just reduce our reliance on gas to give us a bit more leeway. Can anyone give me recommends for a particular make please. Don't go all technical as I haven't a clue and will just glaze over.
This is what I have been looking at. https://uk.renogy.com/3000w-12v-to-...MI4NP_5PmBggMVWpGDBx1zuw5LEAQYASABEgL6TfD_BwE

 

[Andy MacD]

Others will come with the calculations later but I think you’ll struggle to do what you want with a couple of AGMs. With what you’re spending , and if not too late, I’d cancel the AGMs and either get lithium specified or add it when you get the van. I have a Fogstar 280ah and use 3% to boil a 1000w kettle. Not worked out what the air fryer uses but it takes a big chunk out of the battery as it would be on for longer than a kettle.

 

[headlight]

Agreed, I think you will struggle to use the mains items you've listed from 2 x 95AH AGM batteries and will kill the batteries pretty quickly.

 

[knokinonabit]

Others will come with the calculations later but I think you’ll struggle to do what you want with a couple of AGMs. With what you’re spending , and if not too late, I’d cancel the AGMs and either get lithium specified or add it when you get the van. I have a Fogstar 280ah and use 3% to boil a 1000w kettle. Not worked out what the air fryer uses but it takes a big chunk out of the battery as it would be on for longer than a kettle.

Thank you for the advice.
I will check with the dealer and see about changing the batteries, as long as the MH system can support lithium.

 

[OldCodger]

Oops wrong thread

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[knokinonabit]

Agreed, I think you will struggle to use the mains items you've listed from 2 x 95AH AGM batteries and will kill the batteries pretty quickly.

Thank you. See above

 

[DBK]

The inverter you have linked to should be fine. You can spend a lot more on a Victron but I have a £150 1500W one which has worked fine for several years.

You will be able to run the coffee machine on your current batteries as it won't take power for very long, ditto the hairdryer but I would forget the kettle and airfryer, not least because I think your solar panels will struggle to replace the energy used. There is only so much they can generate even on a very sunny day in say Spain.

 

[headlight]

It's not how long the appliances run for that is the problem it is the amount of the amp draw for the time they are running for.

 

[Speve]

I have just installed a 300a Fogstar battery with a Victron Multiplus 2000a inverter which works really well and will automatically switch your mains sockets to either use mains or battery. In my view a future proof option so worth paying a little more for the right kit
I did also install Victron smart dc-dc charger and an extra 240w of solar on the roof giving me 400w in total. What I like with the Victron kit is you can read all the information on one app From several items

 

[knokinonabit]

It's not how long the appliances run for that is the problem it is the amount of the amp draw for the time they are running for.

I've just re-read my post and it looks like I'm saying I would be running them all at once . Hopefully that's not how it's been interpreted.

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[knokinonabit]

I have just installed a 300a Fogstar battery with a Victron Multiplus 2000a inverter which works really well and will automatically switch your mains sockets to either use mains or battery. In my view a future proof option so worth paying a little more for the right kit
I did also install Victron smart dc-dc charger and an extra 240w of solar on the roof giving me 400w in total. What I like with the Victron kit is you can read all the information on one app From several items

I think it may be a case of wait until I get the MH to see exactly what I need before I buy anything. I don't want to jump in and then find out I've spent loads on something that isn't up to the job, or is more than is required.

 

[headlight]

I've just re-read my post and it looks like I'm saying I would be running them all at once . Hopefully that's not how it's been interpreted.

No I didn't interpret it as you were running them all at once but one at a time.

 

[Speve]

I think it may be a case of wait until I get the MH to see exactly what I need before I buy anything. I don't want to jump in and then find out I've spent loads on something that isn't up to the job, or is more than is required.

I think that’s the right thing to dojust to add that we have tried out the use of microwave, kettle and Remoska Grande and they have all worked without problem of course at different times.

 

[paddymcc]

I tend to agree with the ' wait and see ' approach but it might be worth contacting the dealer to find out how lithium ready it will be. You may be able to specify at this stage without much extra cost.

 

[knokinonabit]

I have just installed a 300a Fogstar battery with a Victron Multiplus 2000a inverter which works really well and will automatically switch your mains sockets to either use mains or battery. In my view a future proof option so worth paying a little more for the right kit
I did also install Victron smart dc-dc charger and an extra 240w of solar on the roof giving me 400w in total. What I like with the Victron kit is you can read all the information on one app From several items

Sorry to be a nuisance.
I've been looking at Fogstar batteries and it would seem that there is more than one 300a type, ie Drift, Drift heated and LiFePO4 etc.
Can you tell me which one you have and why you chose that type please.
I am also concerned about adding too much weight as I already have plans for up-plating.

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[knokinonabit]

I tend to agree with the ' wait and see ' approach but it might be worth contacting the dealer to find out how lithium ready it will be. You may be able to specify at this stage without much extra cost.

I am emailing them as we speak, but I know they are at the NEC and are a small family run business, so may have to wait for a reply. All the brains of the outfit are in Birmingham

 

[headlight]

I am emailing them as we speak, but I know they are at the NEC and are a small family run business, so may have to wait for a reply. All the brains of the outfit are in Birmingham

As a generalisation here your 2 x 95AH AGM's don't want to be discharged at more than 19 amps per hour each or 38 amps per hour total for the 2.
A 1000 watt appliance at 12v draws 83 amps per hour plus some amps for inverter and cabling inefficiency so let's say 100 amps per hour for round figures.
Even though that 1,000 watt appliance is not running for an hour, while it is running it is drawing at 2.5 times what the batteries are comfortable delivering.
If you do this occasionally you might be OK, assuming the inverter doesn't cut out due to low voltage.
Do it regularly and you will greatly reduce the life of the batteries and kill them.
FYI generally a 100AH lithium is rated at delivering 80-100 amps per hour (depending on make).
So 200AH of lithium will cope fine with a 100AH draw.
Lithiums are generally about half the weight of lead acid batteries so 200AH of lithium will weigh about half what your 2 x 95AH AGM's will.
The above are only rough estimates to give you an idea.

 

[knokinonabit]

As a generalisation here your 2 x 95AH AGM's don't want to be discharged at more than 19 amps per hour each or 38 amps per hour total for the 2.
A 1000 watt appliance at 12v draws 83 amps per hour plus some amps for inverter and cabling inefficiency so let's say 100 amps per hour for round figures.
Even though that 1,000 watt appliance is not running for an hour, while it is running it is drawing at 2.5 times what the batteries are comfortable delivering.
If you do this occasionally you might be OK, assuming the inverter doesn't cut out due to low voltage.
Do it regularly and you will greatly reduce the life of the batteries and kill them.
FYI generally a 100AH lithium is rated at delivering 80-100 amps per hour (depending on make).
So 200AH of lithium will cope fine with a 100AH draw.
Lithiums are generally about half the weight of lead acid batteries so 200AH of lithium will weigh about half what your 2 x 95AH AGM's will.
The above are only rough estimates to give you an idea.

Thank you, that is very helpful. It looks like Lithium are the way forward.

 

[Googlebot]

When I installed an inverter, I found the bigger you go, the more complicated the install. You need more batteries, thicker cable and have to think about it much more.

My 1000 watt one uses just under 100 amps on full. 3000 watts will use nearer 300amps, which is huge and needs lots of batteries and cables or a big one that will take the draw.

150 amps or a 1500w inverter will be just about fine on 2 lithiums if they will take a 100amp draw each. Putting the power back in however, is the main challenge outside the summer months.

For a comparison, my batteries have gone up by 10% or 20AH in the last 2 days with no usage, that’s with 350w of solar. If I tried cooking on a hob or air fryer this time of year, I would empty them easily.

There is a thread in my signature of an inverter install, lots of people gave great advice. Good luck.

 

[headlight]

Thank you, that is very helpful. It looks like Lithium are the way forward.

Yes if you want to run high draw appliances from an inverter then lithium is the way to go

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