Inverter... with 2 x 80ah batteries

[DandJ]

I've failed miserably in trying to find a previous post about what size inverter for a set up with 2 x 80ah leisure batteries. It will likely only charge 1 e-bike battery and plug in a laptop. Feasible or should I be going down the rabbithole/expense of largarer capacity Lipo type set up...in which case she'll have to ride her non battery bike....

 

[Lenny HB]

To get the best life out of your batteries you should restrict the max current draw to the C5 rate which for your batteries would be 32 amps so max size of inverter 400 watts.

 

[Kannon Fodda]

You will need a pure sine wave inverter to ensure it works correctly with the e-bike and laptop chargers. I find the Victron 12/375 VE.Direct works well which has a 300W output. Possibly you could get away with the lesser rated 12/250 model with a 200W output. This will depend on the ratings of your charger, the e-bike probably being heavier load than the laptop.

But do consider the amount of power you have stored, especially if you don't have a good means to replenish. Your standard lead-acid or AGM type leisure batteries, for reasonable longevity, should normally be discharged to only 50%. So if you arrive somewhere fully charged you only have 80Ah to play with, if your leisure batteries are still healthy (their capacity to hold charge does diminish even with normal use). So that 80Ah needs to cover your normal lifestyle such as lighting, water pump, perhaps heater fan, tv use, radio, etc. I can chew through 25-30Ah in a normal day, but then I watch a fair bit of tv in evenings.

A typical e-bike battery, such as those fitted on many Bosch bikes is say 500Wh at 36V. If your e-bike needed to be fully charged that would be pulling over 40Ah from your 12V leisure system.

The laptop again. Typically they are 90W input if running flat out (some laptops especially with bigger screens and added graphics can be higher loads). Not too bad that is 7.5A at 12V. But even so you will draw through a fair bit of power from your leisure batteries in only a few hours use.

In all cases allow a small bit of headroom for the inverter inefficiency, which means amount of power drawn will be even more. Ensure you switch the inverter off when not in use to avoid it's standby power use.

 

[DandJ]

Many thanks.
It is our first MH, had it 13 mths. We are still sussing out a) our way around the whole MoHo thing and b) whether we will stick with what we have (Off to a local show down here in SW France tomorrow so who knows) We aren't big users of electric when away, we don't have a TV and are probably on EHU 3 out of 4 nights. We are going to Scandinavia next May/June for 6 to 8 weeks and anticipate more than just 1 night off grid...we MAY well be better off in the short term buyinga 500w power bank...the e-bike is a 400w battery and will easily do 60 miles on one charge...so either one decent ride or two shorter ones on one charge. My thinking with a power bank is that if we go down the 300w inverter route, and then 18 mths down the kline we need to change the then 4 yr old batteries...we'd upgrade so would end up buying a new inverter anyway. I may be wrong? All new to us

 

[TrudeandDall]

I agree with you on forward thinking, as 18 months down the line you may very well be looking at changing your electrical system.
I found out the hard way by fitting a 600w inverter (perfect for our 2 x ebikes) for our AGM battery set up, only later on to change it for a 1200w inverter when I upgraded to LifePO4.
What I would say is that it matters not what you can get out of your batteries if you do not have a sustainable method of recharging them. Lots of people advocate turning your van into a mobile solar farm, but from experience I would say "treat solar as a bonus charger" as it is not reliable. My advice is to get a B2B that will pump amps into whatever battery system that you have every minute that you are driving.

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[DandJ]

I agree with you on forward thinking, as 18 months down the line you may very well be looking at changing your electrical system.
I found out the hard way by fitting a 600w inverter (perfect for our 2 x ebikes) for our AGM battery set up, only later on to change it for a 1200w inverter when I upgraded to LifePO4.
What I would say is that it matters not what you can get out of your batteries if you do not have a sustainable method of recharging them. Lots of people advocate turning your van into a mobile solar farm, but from experience I would say "treat solar as a bonus charger" as it is not reliable. My advice is to get a B2B that will pump amps into whatever battery system that you have every minute that you are driving.

Thanks...we are in SW France and do OK for solar. Pretty sure it has a B2B system but I'd have to take someone who speaks more than just pigeon french with me to the local camping car centre. (We'll maybe go in it to the show tomorrow and get any electrical sales bods to see what they can try to upsell...whilst telling us what we already have)

 

[9Etype]

For your setup with 2 x 80Ah leisure batteries, you should be fine with a decent inverter around 1000W. That should cover charging the e-bike battery and powering a laptop without breaking the bank. If you're only doing light use, there's no need to go down the LiPo rabbit hole unless you want a weight advantage or faster charging.

 

[LithiumConvert]

Going down the lipo rabbit hole is not recommended. They are the wrong technology for motorhomes.

However, the LiFePO4 rabbit hole is well worth investigating. Sometimes challenging, but rewarding.

 

[DandJ]

Thank you.
If I ever get to that point...I'll make sure I suss the differences between Li, Po, Fe and all the others bits of the sound of music soundtrack.

 

[headlight]

For your setup with 2 x 80Ah leisure batteries, you should be fine with a decent inverter around 1000W. That should cover charging the e-bike battery and powering a laptop without breaking the bank. If you're only doing light use, there's no need to go down the LiPo rabbit hole unless you want a weight advantage or faster charging.

A 1,000 watt inverter at max will greatly reduce the life of the batteries as they are only rated at about 32 amps continuous discharge for the pair.
1,000 watts is about 90 amps so 3 times more than the batteries discharge rating.

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[TrudeandDall]

Thanks...we are in SW France and do OK for solar. Pretty sure it has a B2B system but I'd have to take someone who speaks more than just pigeon french with me to the local camping car centre. (We'll maybe go in it to the show tomorrow and get any electrical sales bods to see what they can try to upsell...whilst telling us what we already have)

You will not be doing very well for solar today! We travelled from North of Albi to SE of Angouleme in biblical rain - and that's coming from a native of the Lake District .
But ordinarily you will definitely benefit more from solar that I do in North Cumbria...
Good luck with your systems....

 

[Lenny HB]

For your setup with 2 x 80Ah leisure batteries, you should be fine with a decent inverter around 1000W.

Only if you want to kill your batteries.

 

[DandJ]

You will not be doing very well for solar today! We travelled from North of Albi to SE of Angouleme in biblical rain - and that's coming from a native of the Lake District .
But ordinarily you will definitely benefit more from solar that I do in North Cumbria...
Good luck with your systems....

Suffice to say, we have every water butt and container full to the brim after the 50mm+ we had today.... (12 mths ago we were on severe water restrictions....we now have more than we know what to do with.....)

 

[VXman]

Only if you want to kill your batteries.

Only if he uses the 1000 watts surely. I have a 1500 watt inverter and 270AH of batteries. However I don't think I've ever used 1500.

 

[Raul]

Only if he uses the 1000 watts surely. I have a 1500 watt inverter and 270AH of batteries. However I don't think I've ever used 1500.

And whats the point on that? A bigger inverter will have very poor efficiency with small loads, and a greater stand by load. You should size the inverter to 70-80% of your largest load; and that, if the batteries can feed it.

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[StillGoing]

I’ve had a Victron 12/375 for nearly 5 years and I have no intention of upgrading. It does me fine for recharging my eBike and running my laptop. Be honest with yourself about what you are likely to use it for and don’t rush into a decision.

 

[Just smiffy]

A 500w pure sine wave would be ok and try to charge your bike batteries while driving to your next stop…

 

[autorouter]

To get the best life out of your batteries you should restrict the max current draw to the C5 rate which for your batteries would be 32 amps so max size of inverter 400 watts.

This also is true for charging the batteries, so if you are going to fit a B2B for charging while the engine is running, be sure to keep it within that limit. Many B2Bs can't adjust the charging amps, some can do half and full charging amps, and the Victron XS is adjustable in 1 amp steps up to the full 50A output.