Electric or Petrol when weight is an issue

[SteveR]

Hi all,
We are motorhomers and carry bikes and find we always seem to be at the bottom of a hill when we set of on our bikes, plus fitness is not what it should be.
We bought some electric small wheel shopper type bikes some time ago and found them useless as the geometry was wrong for pedalling. Now there seem to be propper electrics about it seems worth looking again. The problem though is charging while on the road. We do not often stay on sites with electric and I don't think chargers like Inverters.
The other point is that the bikes will not be used every day, sometimes perhaps only once a month. So I wondered whether one of the small petrol motors from China or I believe Germany and Holland might be a better option as it is much easier to get petrol than 36volt electric while on the road. Or are there special chargers that can work off 12volt?
I hope I am not asking about a taboo subject here but would like any suggestions I can get. I don't want to spend a fortune but weight is a major consideration.
I am about 5-5 and 13stone and my wife only 5ft and 9stone so she needs a lower cross bar as she seems to have short legs.
We live in the South of France and will be travelling to the UK in April so would like to perhaps be able to make a decision by then.
Thanks for any help.
Steve

 

[eddieo]

There are a few of us motohomers on here...What I have picked up on the motorhome forums is that some manage OK with a solar panel and a couple of leisure batteries and an inverter and charge that way....

we stay on a mixture ofAires/sites/municipals (we have twin batteries but no solar) and if I can get a charge 2 or 3 of times a week that is fine. We have bikes with a decent range.

petrol? noisy horrible things, check that they are legal. In France they have small mopeds don't they? would these not be better

 

[Old Timer]

Hi all,
We are motorhomers and carry bikes and find we always seem to be at the bottom of a hill when we set of on our bikes, plus fitness is not what it should be.
We bought some electric small wheel shopper type bikes some time ago and found them useless as the geometry was wrong for pedalling. Now there seem to be propper electrics about it seems worth looking again. The problem though is charging while on the road. We do not often stay on sites with electric and I don't think chargers like Inverters.
The other point is that the bikes will not be used every day, sometimes perhaps only once a month. So I wondered whether one of the small petrol motors from China or I believe Germany and Holland might be a better option as it is much easier to get petrol than 36volt electric while on the road. Or are there special chargers that can work off 12volt?
I hope I am not asking about a taboo subject here but would like any suggestions I can get. I don't want to spend a fortune but weight is a major consideration.
I am about 5-5 and 13stone and my wife only 5ft and 9stone so she needs a lower cross bar as she seems to have short legs.
We live in the South of France and will be travelling to the UK in April so would like to perhaps be able to make a decision by then.
Thanks for any help.
Steve

Hiya Steve

I have to charge some prety heafty gear up from my van at times and an inverter should be fine (check the output) mine is working from the battery rather than the cigar plug for safety. either fit cables and run them into the van or just decent croc clips will do. Not sure what size inverter you will need, I`ll check.

Those petrol motors are OK for a bit of fun when around the home but E bikes will be a better bet.

Have Fun

 

[Old Timer]

I think you will need at least a 1000watt inverter to be on the safe side( I think that`s about right) and definitely not through the cigar lighter. Actually it might be best to charge up when on the move cos that amount might have an effect on your van battery if running for 6 hrs. I learnt that lesson when transmitting on the radio when I first started to do it mobile and running high power and landed up with a flat battery on a remote hilltop but luckily facing the right way to bump start

 

[onmebike]

Ohms law?

You can work out your charger and inverter requirements using ohms law as follows. Voltage of charger multiplied by the input current[amps] = watts.
So if your charger runs on 240volts and the input current is 1.8amps the watts will be 432
In this example you would need an inverter with a very minimum capability of 500watts, bigger as Dave says will be better.
The next equation will tell you how many amps your charger will draw via the inverter from your vehicle's battery?
Watts divided by the voltage = current[amps]
So in this case 432watt[charger] divided by 12volts[vehicle] = 36amps per hour.
This would appear to be impractical as 4 hours charging time would take in access of 140amps from the batteries. Thats nearly 4 times the headlights on mainbeam would draw.
Heres a link to advice on inverters and a calculator to work out your requirements Inverter FAQ - DonRowe.com - Frequently Asked Questions about Power Inverters

Example from site, 500watt invertor at full capability can be run for I hour on a 100ah battery.

 

[Fecn]

So if your charger runs on 240volts and the input current is 1.8amps the watts will be 432
...
So in this case 432watt[charger] divided by 12volts[vehicle] = 36amps per hour.
This would appear to be impractical as 4 hours charging time would take in access of 140amps from the batteries. Thats nearly 4 times the headlights on mainbeam would draw.

The current rating printed on the bike's charger will be the 'peak' inrush current, and not the continuous rating. When the charger is first plugged in, there's generally a fairly large capacitor on the circuit board charges up in a few milliseconds. Once this initial inrush has happened, the charger's requirements are far more modest.

For example, I have a lead-acid charger on my desk right now. It says it takes 240V, 0.8A, which would equate to 192 Watts of power. However, the output from the charger is 36V, 1.8A... which is 54 watts of power. Most switchmode battery chargers are around 85% efficient, so in reality, we're pulling 58W/0.85 = 63Watts from the mains.

In general terms, pretty much every inverter out there will be able to run pretty much every bike charger out there. I have a 75w cigarette lighter inverter which runs my Kalkhoff charger fine. (I also have 150W, 500W and 2KW inverters which are also all fine). Bike battery chargers (particularly the ones with worldwide voltage support 100-240V) will run on pretty much anything.

 

[Old Timer]

Good info (seems quite low) but if your doing it then great.

So! I could charge any of my E bike batteries from my cigar socket using a 300W inverter?

Dave

 

[eddieo]

remember you can always charge via the inverter when driving and alternator replenishing battery......

I have a Maplin 600 watt inverter hard wired via a 20 amp fuse to the twin leisure batteries.

 

[strider]

We too are motorhomers and having tried a 125cc motorbike for a year we sold it and bought a couple of good quality electric bikes. My bike is a Giant which I love and my wife doesnt and hers is a Khalkof agutu which she loves and I dont. So its better to try and find a bike that suits you personaly , we dont all like the same thing. Just remember, Cheap no good- Good no cheap.
Strider

 

[onmebike]

The current rating printed on the bike's charger will be the 'peak' inrush current, and not the continuous rating. When the charger is first plugged in, there's generally a fairly large capacitor on the circuit board charges up in a few milliseconds. Once this initial inrush has happened, the charger's requirements are far more modest.

For example, I have a lead-acid charger on my desk right now. It says it takes 240V, 0.8A, which would equate to 192 Watts of power. However, the output from the charger is 36V, 1.8A... which is 54 watts of power. Most switchmode battery chargers are around 85% efficient, so in reality, we're pulling 58W/0.85 = 63Watts from the mains.

In general terms, pretty much every inverter out there will be able to run pretty much every bike charger out there. I have a 75w cigarette lighter inverter which runs my Kalkhoff charger fine. (I also have 150W, 500W and 2KW inverters which are also all fine). Bike battery chargers (particularly the ones with worldwide voltage support 100-240V) will run on pretty much anything.

I can see where my mistake was in calculating the current draw, I took the figure's at maximum output capacity as per, 3000w Kettle at 240volts draws 12.5 amps.
On checking this against the calculations of the attached website's calculator and advice, it also quote's at maximum output rate's eg, 500watt inverter running at full capacity would run for 1hour on a 100ah battery leaving enough in reserve to start the vehicle.
Thanks for pointing this out, I should have used the charger output, rather than input in my calculation.
Would the initial surge at switch on affect safety trips where fitted?

 

[Fecn]

Would the initial surge at switch on affect safety trips where fitted?

Most inverters offer a peak of at least double their rating for many tens of seconds, and usually an absolute peak (for inrush currents) around triple their rating for about a second.

Fuses and circuit breakers are all designed with a delay incorporated so they're not triggered by inrush currents.

 

[piotrmacheta]

You can get 12V chargers for both NiMH and Li batteries. I have a Bantam 902 which can charge a 32 cell NiMH/NiCd. Not sure about the Li battery max volts but it might be 37V.
The advantage in using a 12V charger is that the inverter is only about 80% efficient but it is useful for powering other things. Buy one that has an auto-sensing system where it goes to a low power sleep mode when not being used - you can just leave it on without draining the batteries - my Steca has this feature. Hope this helps.

 

[Fecn]

I have a Bantam 902 which can charge a 32 cell NiMH/NiCd. Not sure about the Li battery max volts but it might be 37V.

Funnily enough, I have exactly the same unit, which right now is charging a 30-cell NiMH pack on my desk. It will charge pretty much any battery pack of any technology up to 50V. (12-series for Lithium batteries).

 

[onmebike]

Most inverters offer a peak of at least double their rating for many tens of seconds, and usually an absolute peak (for inrush currents) around triple their rating for about a second.

Fuses and circuit breakers are all designed with a delay incorporated so they're not triggered by inrush currents.

Just monitored charging on 36v pack. Charger output rated at 42v 1.8ah.
Maximum according to my equipment is 97watts. As you say almost any inverter will cope.

 

[rog_london]

I think you will need at least a 1000watt inverter to be on the safe side( I think that`s about right) and definitely not through the cigar lighter. Actually it might be best to charge up when on the move cos that amount might have an effect on your van battery if running for 6 hrs. I learnt that lesson when transmitting on the radio when I first started to do it mobile and running high power and landed up with a flat battery on a remote hilltop but luckily facing the right way to bump start

That's probably way over the top, IMO. The top mains power consumption of most e-bike chargers is around 150 watts though the power factor can be somewhat poor. A 300 watt inverter should be plenty. What those inverters don't much like is a big starting surge (no damage, they just refuse to start with a rapid ticking noise due to the cut-out operating repeatedly) but as most of the e-bike chargers are 'soft start' this is unlikely to be a problem either.

Keep an eye on Maplins - they often do promos on inverters, and if you're patient you can expect to pay £30 or thereabouts for a 300 watt one. They have a clearance at the moment on a 750 watt Black & Decker inverter for £39.99 which I think is a very good price.

Rog.

 

[Schwinnfan]

Petrol or electric

We do it the opposite way, we live in England and motorhome to France. I gave all the same thought to which bikes to buy to replace a couple of normal bikes. To be fair we would go out on normal bikes and do 25 miles anyway but like you say all campsites are at the bottom of hills.

50 cycles post seems about right. We have the same make as he sells but sold under another brand which the manufacturer owns, ironically Raleigh. 50 Cycles sell the same unit as a Khalkoff Tasmin. We use two batteries each and sometimes go out for 70 and 80 mile days, changing batteries at about 45 miles.
I have two 130 watt solar panels and can normally draw with normal inverters the same as the panels put in to charge the batteries. Charging whilst the engine is running is another option and is really easy.

Am going through France in May will wave on our way to Sardinia.

Phil

 

[Scatty]

I am about 5-5 and 13stone and my wife only 5ft and 9stone so she needs a lower cross bar as she seems to have short legs.
We live in the South of France and will be travelling to the UK in April so would like to perhaps be able to make a decision by then.
Thanks for any help.
Steve[/QUOTE]

Hi steve i would recommend looking at Powered and Electric Bikes Largest Range In UK & look at either the City Runner or the City Pioneer for your wife as she is short, most other makes are made for 5ft 3 + whereas these two are perfect for that height as for you, you can have any bike you like & they are on M1 aswell.

 

[Old Timer]

I am about 5-5 and 13stone and my wife only 5ft and 9stone so she needs a lower cross bar as she seems to have short legs.
We live in the South of France and will be travelling to the UK in April so would like to perhaps be able to make a decision by then.
Thanks for any help.
Steve

Hi steve i would recommend looking at Powered and Electric Bikes Largest Range In UK & look at either the City Runner or the City Pioneer for your wife as she is short, most other makes are made for 5ft 3 + whereas these two are perfect for that height as for you, you can have any bike you like & they are on M1 aswell.[/QUOTE]

Are there no E bike dealers in France then? although I don`t follow the advice re:" buying from somewhere local with a good back up" I think if I lived in another country I`d be looking to buy more local if at all poss.

 

[Scatty]

Qoute Old Timer.
Are there no E bike dealers in France then?
I'm sure theres plenty of e-bike dealers in France tho i did not say there werent ?????? & i did not see where he had asked that .
What i did say tho was the height of his wife is only 5ft & most e-bike's are made for taller people in mind so have a look at the suggestions i put.

 

[eddieo]

Matra are a large French company that sell E Bikes using the BionX system.

but if you want a bike with a throttle then you would have to buy in the UK.

I would get a bike locally, as E Bikes can be problematic so nothing like local back up

Matra Sport, I-step runneur, Magasin velo electrique, I-step city, Xs, tidal force