Charging Electric motorbike (Scooter) with inverter - what power needed.

[VXman]

I realise this might not be doable but what would be required? Not really technical enough to understand but just wondering if I could use the motorhome to charge at least partly in an emergency if I was off grid. I have two 95 ah batteries and a 175W solar panel.

The bike battery is a 60 volt but I cannot for the life of my discover what Ah it is. The charger has some power details on it.

So what wattage inverter and how much power would it consume in say an 8 hour charge?

 

[Riverbankannie]

You are falling off the first page of Whats New so I’ll bump it.
I am useless at electrickery but it says 3.5ah input, so in 8 hours would use 28amps from your battery?
I will let someone else come along to help out

 

[David and Sally]

240v at 3.5 a is about 840 watts. So, not far off a kilowatt.

That is mains. Depends how good your inverter is as to how much it takes out of your batteries.

 

[addoaddo]

given power factor adjustment it will take about 1000w. 240 x 3.5.
at 12v volts that’s 80A. You have 95ah of usable capacity ( can only use 50% of capacity) so you would use all your stored capacity in just over 1 hour. Not ideal

this is from the label but I doubt the psu is that inefficient. The output is only only 280W. So it might be ok to top up only

In summary your set-up does not really have enough capacity unless very sunny

 

[ToBoldlyGo]

What is the electric motorbike / scooter you use? When we use our ebikes (bicycles) we in practice tend to just run them down to about 50%; you said you'd like to know if you could at least partially charge, and it does sound doable from what others have said. Can you not access / remove the battery in the scooter?

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[funflair]

You are falling off the first page of Whats New so I’ll bump it.
I am useless at electrickery but it says 3.5ah input, so in 8 hours would use 28amps from your battery?
I will let someone else come along to help out

Good bump and good try but the one thing you got right is "you are useless at electrickery" no offence meant you have to be really careful with amps as they change relative to the voltage, the only reliable measure of power is watts, Watts=VoltsxAmps so for the same power (watts) requirement at less volts needs more amps and vice versa, as batteries are normally 12v and mains is 240v for the same mains power from your inverter you need 20 times the amps (240/12).

To run a 240v 2kw electric kettle from an inverter you need 8.3 amps at 240v but this takes more like 166amps from your batteries at 12v, for the purists there are losses and inefficiencies that have been ignored.

If that doesn't make sense I apologise, I have tried explaining it to Mrs funflair and failed dismally

And don't get me onto engine power,torque and RPM as that would need another bottle.

 

[Itsmcb]

240v at 3.5 a is about 840 watts. So, not far off a kilowatt.

That is mains. Depends how good your inverter is as to how much it takes out of your batteries.

I believe the 3.5amps will be at 100volts so that charger will actually take 350 watts max.

 

[VXman]

What is the electric motorbike / scooter you use? When we use our ebikes (bicycles) we in practice tend to just run them down to about 50%; you said you'd like to know if you could at least partially charge, and it does sound doable from what others have said. Can you not access / remove the battery in the scooter?

Lexmoto Impulse. Battery capacity and consumption is a lot higher than an electric bike - quite often run it down to nothing. Yes the battery is removable but I'm camping off grid for 10 days at Le Mans 24 hour race in June so not sure where I will be able to plug it in.

 

[VXman]

240v at 3.5 a is about 840 watts. So, not far off a kilowatt.

That is mains. Depends how good your inverter is as to how much it takes out of your batteries.

I believe the 3.5amps will be at 100volts so that charger will actually take 350 watts max.

Well - there's 2 quite different repsonses.

The charger says 100 -240 Volts but it the inverter is supplying 240 volts then it would use 240 volts - yes/no?

 

[VXman]

given power factor adjustment it will take about 1000w. 240 x 3.5.
at 12v volts that’s 80A. You have 95ah of usable capacity ( can only use 50% of capacity) so you would use all your stored capacity in just over 1 hour. Not ideal

But the solar supplies 8 amps (175W/20volt) so that could in ideal circumstances supply 64 amps back in a day.

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[Figaro]

Lexmoto Impulse. Battery capacity and consumption is a lot higher than an electric bike - quite often run it down to nothing. Yes the battery is removable but I'm camping off grid for 10 days at Le Mans 24 hour race in June so not sure where I will be able to plug it in.

Sounds like you need a generator ?
On the bright side, you probably won't be upsetting the petrol heads

 

[Jamesh]

Why not get a little kw measuring device and plug it into that. Then you can see the true input power required?

Useful around the house / MH too.

 

[David and Sally]

I believe the 3.5amps will be at 100volts so that charger will actually take 350 watts max.

I assumed 240v. You assume 100 v. TBF it is not specific so could be either or in between. Only way is to measure it in use.

 

[Hoovie]

Well - there's 2 quite different repsonses.

The charger says 100 -240 Volts but it the inverter is supplying 240 volts then it would use 240 volts - yes/no?

Two different responses, yes. But only one correct . Itsmcb has got it right.

Many transformers, especially for leisure equipment are for use worldwide and so accept a very wide voltage range. The current quoted, if only one is, is the maximum current draw of the transformer, and the maximum current will be at the lowest voltage.
If a device draws 3.5A at 100V, that is 350W. At a nominal UK 240V, it is still a 350W power, it does not suddenly shoot up to 840W.

End of the day, the current/power draw is less important than the total Wh drawn however. That will determine if it is feasible to recharge a scooter battery from a Leisure Battery, so the battery Voltage and Ah rating are both needed to know the overall Battery Capacity Wattage that needs to be put back. (The Ah of the battery on its own is unlikely to be sufficient as that Ah will be at a different Voltage to the Leisure Battery and so not comparable. Watt-Hours are a better measure as that is voltage independent)

 

[David and Sally]

Two different responses, yes. But only one correct . Itsmcb has got it right.

Many transformers, especially for leisure equipment are for use worldwide and so accept a very wide voltage range. The current quoted, if only one is, is the maximum current draw of the transformer, and the maximum current will be at the lowest voltage.
If a device draws 3.5A at 100V, that is 350W. At a nominal UK 240V, it is still a 350W power, it does not suddenly shoot up to 840W.

End of the day, the current/power draw is less important than the total Wh drawn however. That will determine if it is feasible to recharge a scooter battery from a Leisure Battery, so the battery Voltage and Ah rating are both needed to know the overall Battery Capacity Wattage that needs to be put back. (The Ah of the battery on its own is unlikely to be sufficient as that Ah will be at a different Voltage to the Leisure Battery and so not comparable. Watt-Hours are a better measure as that is voltage independent)

I stand corrected.

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[Hoovie]

I stand corrected.

The output info on the charger adds to the confusion as well ... Usually they would quote y Amps @ z Voltage, which would make it clearer, but with an OUTPUT voltage range so wide, it is hard to be sure what power the charger will actually deliver at any time!

The suggestion made on using a WattMeter to see the numbers is a good one... Run the battery flat (so worst case recharge scenario), then recharge off a standard mains socket and see how much power is pulled to recharge. Multiply that by say 1.2 (to have inverter inefficiency factored in for motorhome use) and that will be the WattHours drawn from the battery.

Rule of thumb ....
100Ah Lead Acid battery is 1200 Wh (100Ah X 12V); if you dont want to draw below 50%, a 100Ah lead can provide 600Wh of power.
100Ah Lithium is 1280 Wh (100Ah X 12.8V); If you don't want to draw below 20%, a 100Ah Lithium can provide 1,024Wh of power.

 

[autorouter]

The OP has 2 x 95Ah batteries, which have a capacity of 190Ah or 190 x 12 = 2280Wh, so 50% of that is 1140Wh. A 175W panel could maybe provide 70Ah of 12V power on a good day, so that's 70 x 12 = 840Wh of energy.

The bike batteries I've seen have been about 350 to 500 Wh, so I suppose a big one would be 600 to 700 Wh. So the arithmetic indicates there's a good chance a 175W panel can refill such a bike battery, especially if it's not completely flat. The 2 x 95Ah leisure batteries can store the solar energy so the bike can be recharged overnight.

To estimate the charging watts, chargers typically take about 3 hours to recharge a battery. For a 700Wh battery that would be 700 / 3 = 240 watts. Adding about 20% for inefficiencies makes it about 290 watts. So worth trying a 300W inverter if you can try before you buy, but a 500W would be a wiser choice if you can't.

 

[Itsmcb]

It appears that the OP has a 1500watt Scooter. That's going to take some charging.

 

[nicholsong]

It appears that the OP has a 1500watt Scooter. That's going to take some charging.

I have not followed all the calculations in the thread, but gut feeling is that if you want to charger scooters of that size and live a normal life in a MH, i.e. showers, water heating, lights etc. then the only way to charge the scooter battery would be on the move with a massive alternator and B2B, and I do not know the effect on the batteries of doing that often.

 

[Lenny HB]

But the solar supplies 8 amps (175W/20volt) so that could in ideal circumstances supply 64 amps back in a day.

20v is the off load voltage if you use the charge voltage to the battery its 12 amps. But you will only get for an hour or so either side of midday in June. Any other time or day or year it will be a lot less.

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[pappajohn]

The charger says 100 -240 Volts but it the inverter is supplying 240 volts then it would use 240 volts - yes/no?

That's a universal charger for countries using either 230v or 110v....you have no control over the input voltage

 

[Lenny HB]

So what wattage inverter and how much power would it consume in say an 8 hour charge?

I agree with autorouter a 500 watt inverter.
Assuming your charger takes 1.75 amps at 240v 8 hours running would consume 280 ah at 12v.
So as not to overload your batteries you would need to add another 3 batteries and if you don't increase your solar it will take days to recharge them from solar, in other words not practical with your set up.

If you really want to do it you probably need to fit 400 ah if Lithium batteries and at least 500 Watts of solar.

 

[autorouter]

It appears that the OP has a 1500watt Scooter. That's going to take some charging.

Perhaps it's a 1500 watt-hour battery. That is 1500 / 12 = 125Ah in 12-volt battery terms. Yes, that's quite a lot, but doable with more solar, for example if it was doubled. The battery is probably 48V, which would make its amp-hour rating at 48V to be 1500 / 48 = about 31Ah.

To charge that in 3 hours would take 1500/3 = 500 watts from the inverter, so more like 600 watts from the leisure batteries. That's a current of 600 / 12 = 50A, which is more or less OK from two 95Ah batteries.

Sorry, I wrote this earlier and forgot to post it. The battery would be equivalent to having another large leisure battery (125Ah) that needs recharging every day, so it is indeed a sizeable requirement, more than could be filled by a 175W panel. However many MHs have more solar than that, and 300W of panel would at least partly refill the battery, and could refill it completely on a good day.

 

[Lenny HB]

To charge that in 3 hours would take 1500/3 = 500 watts from the inverter, so more like 600 watts from the leisure batteries. That's a current of 600 / 12 = 50A, which is more or less OK from two 95Ah batteries.

In his OP he was saying running the charger for 8 hours, if that is the case its a no go really on the current system.

He needs to take some measurements of charging current & how long to charge.

 

[68c]

Spec for Lexmoto Impulse says it has a 60volt 24Ah Li battery. That is 1440Wh, my legal ebike (max 15.5mph) has a 36v 15Ah battery, 540Wh. Will do about twenty five miles with pedal assist without fully depleting battery. The spec for the Lexmoto suggests 40 miles! Cannot see that happening, no pedal assist and will probably be ridden full throttle at its 28mph max.

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[jumar]

Providing there is enough Solar Energy to complete the task in hand....

 

[VXman]

Spec for Lexmoto Impulse says it has a 60volt 24Ah Li battery. That is 1440Wh, my legal ebike (max 15.5mph) has a 36v 15Ah battery, 540Wh. Will do about twenty five miles with pedal assist without fully depleting battery. The spec for the Lexmoto suggests 40 miles! Cannot see that happening, no pedal assist and will probably be ridden full throttle at its 28mph max.

You sound the Ah rating - I spent ages trying to find that!

You are correct. 40 miles is pretty unobtainable. Bit like manufacturers mpg figures. It must be worked out somehow but I think you'd have to be doing a max of 15 mph on the flat, no opposition from the wind etc to obtain that.

I think 30 is doable with one person and gentle driving.

I have de-restricted it so it will do 45mph so that will bring it right down.!!!

In practice with the motorhome it will do 20 miles with 2 of us on it. Fine for popping to local towns villages when on a campsite. We usually have EHU. It is ideal as a town commuting bike for up to 20 miles round trip - plug it in at home. Also it cost £1600 which is less than a lot of electric bikes which only carry one person.

We have normal push bikes too.

 

[VXman]

Thanks for all the responses. I was expecting it not to be possible so this has been confirmed. Not worth spending considerable sums on additional batteries/lithium, additional solar.

It really was just 10 days off grid for the Le mans 24 hour I was wondering about. Would be useful to use the bike to get around to more far flung reaches of the track. I will have to find a friendly person with a electric socket to plug the battery into for a few hours. There is a site with EHU - maybe a friendly motorhomer might lend me some of their power!

 

[nicholsong]

You sound the Ah rating - I spent ages trying to find that!

You are correct. 40 miles is pretty unobtainable. Bit like manufacturers mpg figures. It must be worked out somehow but I think you'd have to be doing a max of 15 mph on the flat, no opposition from the wind etc to obtain that.

I think 30 is doable with one person and gentle driving.

I have de-restricted it so it will do 45mph so that will bring it right down.!!!

In practice with the motorhome it will do 20 miles with 2 of us on it. Fine for popping to local towns villages when on a campsite. We usually have EHU. It is ideal as a town commuting bike for up to 20 miles round trip - plug it in at home. Also it cost £1600 which is less than a lot of electric bikes which only carry one person.

We have normal push bikes too.

Then on yer bike(s)!