Charging E-Bikes on the move

[Augusta08]

Hi all, I've just bought an e-bike for SWMBO and the charger is 240v ac thingy. So I was thinking of putting a 500w inverter on the leisure batteries to charge the e-bike battery whilst driving.

The e-bike charger is marked as 1.8a @ 240V so hence 432w, that works out at 36amps at the 12volt end, so no real problems given the wiring needs to be short and thick (bit like me?) however, what do we think about sine waves? I know not everyones cup of tea, but would modified sinewave be ok? or do I need to go for the real thing?

WDYT?

 

[Kannon Fodda]

What is the battery capacity? Many will take a number of hours to fully charge from empty. The standard 4A Bosch charger needs some 4.5 hours for their 500W battery.

Remember that inverters are not 100% efficient in their conversion. I don't know if that means a 500W inverter's output is in fact say 450W, or if to acheive the 500W you have a correspondingly higher input. But if you are charging while you are going along, you will have less available for your leisure batteries, so will they have enough for your normal other uses?

 

[Glas Robin]

I’m thinking of a 12v cccv charger connected to the leisure battery supply and not bothering with the inverter. I’ve posted a thread or two about this and had some great advice.

If you’re worried that some of the battery management electronic wizardry is in the charger not the battery, then you could open a spare charger, check the readings after the voltage has been stepped down and connect an appropriate cccv charger here and then you’re still using an OEM charger for the bike.

I’m planning on doing this for my electric scooter. Just waiting for a spare charger to arrive. Will post my findings.

Using an inverter is of course more flexible as you can use it for other purposes too. It just a much more expensive route.

 

[Augusta08]

Thanks Cannon Fodda inverters are usually quoted at their output power so to acheive 500w they're pulling 550watts. so you're right 36 amps is probably higher, 38amps ....................... however I guess the draw wouldn't be the full 1.8amps ac for very long, it will tail off rapidly. The batteries are 317whrs and are rated to charge fully in 4.5 hours.

What's an bit of an unkown is the modified sinewave.....

I've used MSW on my computer and printer to no ill effects so I'm hoping for the same with the e-bike.

 

[Kannon Fodda]

For about a year Bosch were doing a 12v "in car" cigarette lighter plug in type charger for the ebike. There are still some "no stock available" listings. It's discontinued. No idea why, but I suspect that it simply drew too much current, or the limited current was too low that batteries weren't charging.

With the modern Lithium batteries the charger and battery both have electronics to control the rate of charge and cut off on capacity. It's all too easy to kill a battery when the electronics can't detect the battery is ready. There are also very many instances (read mobile phones and even some rather large aeroplanes) that have gone up in flames when the battery has been overheated / incorrectly charged / badly designed. I'd be very wary of messing with the charger and using anything other than a manufacturer approved system.

^{_{Subscribers  do not see these advertisements}}

 

[Augusta08]

I’m thinking of a 12v cccv charger connected to the leisure battery supply and not bothering with the inverter. I’ve posted a thread or two about this and had some great advice.

If you’re worried that some of the battery management electronic wizardry is in the charger not the battery, then you could open a spare charger, check the readings after the voltage has been stepped down and connect an appropriate cccv charger here and then you’re still using an OEM charger for the bike.

I’m planning on doing this for my electric scooter. Just waiting for a spare charger to arrive. Will post my findings.

Using an inverter is of course more flexible as you can use it for other purposes too. It just a much more expensive route.

That's a thought that I hadn't had.....Thanks

The inverter is not too expensive I'm loooking at ;

https://uk.rs-online.com/web/p/fixed-installation-dc-ac-power-inverters/8160034/

 

[Glas Robin]

That's a thought that I hadn't had.....Thanks

The inverter is not too expensive I'm loooking at ;

https://uk.rs-online.com/web/p/fixed-installation-dc-ac-power-inverters/8160034/

That’s a reasonable price but still about 6 times what a cccv charger will cost you. Plus a spare charger for the bike. It just seems odd to me to use an inverter to step up to 240v for the charger to step down again to 36v or similar.

 

[Augusta08]

That’s a reasonable price but still about 6 times what a cccv charger will cost you. Plus a spare charger for the bike. It just seems odd to me to use an inverter to step up to 240v for the charger to step down again to 36v or similar.

I quite like the idea, I could get a cccv module, set it up to charge 5 amps max at 36volts capped at 38v. That would limit draw to circa 15amps but in all probability charge the battery in the same 4.5 hour run.

The cost circa a tenner, plus I can keep my good old handymains 200w unit for the computer and printer.

Like it Glas Robin!!

 

[Glas Robin]

If you get the right module and set it up correctly, then it has all the battery management wizardry needed to safely charge lithium batteries without connecting it to your existing OEM charger.

My scooter has a Bluetooth app that enables me to monitor temp and charge state of each cell. So for the first few charges I will do it outside the Moho and monitor the process to ensure it goes as expected.

 

[Glas Robin]

...plus I can keep my good old handymains 200w unit for the computer and printer.

Or use cccv modules for them too and ditch the 200w inverter too!

^{_{Subscribers  do not see these advertisements}}

 

[bobandjanie]

We charge ours on the move, and use a 600w Stirling pure cine wave inverter it will do two at the same time. Bob.

 

[Don Quixote]

Please use a pure cine wave inverter or you may damage the battery your are charging.

 

[autorouter]

however I guess the draw wouldn't be the full 1.8amps ac for very long, it will tail off rapidly. The batteries are 317whrs and are rated to charge fully in 4.5 hours.

I presume 240 volts 1.8 amps is the sudden inrush current as you first connect the charger. The power while charging will be very much less.

317 watt-hours is 317/36 = 8.8 amp-hours at 36 volts. So to charge in 4.5 hours the average current will be 8.8/4.5 = 2 amps. If the charging voltage is 40 volts, the power required is 40 x 2 = 80 watts. That's nowhere near the 432 watts suggested by the charger label.

The power from the 12 volt supply will be 80/12 = 6.7 amps in theory, but probably more like 8 or 9 amps in practice, allowing for inefficiencies. That's still a lot less than the 38 amps during the inrush spike.

You will probably find that a good quality 300 watt inverter will cope easily with a 432 watt momentary surge.

 

[Augusta08]

Or use cccv modules for them too and ditch the 200w inverter too!

Need it to run my HP inkjet printer.

 

[Jake Royd]

Prompted by this thread , I realised I could try charging my ebike battery on the move via an inverter.
I have a Giant Twist ebike with a 36v 8Ah battery
I have an inverter somebody gave to me which is 400w peak 200w continous.
The charger in put current is 1.5A at 240v, so W/IxV would give me 360w ?which seems too much.

However , cobbling it all together, it seems to work properly with no error lights.
(Using my VW Passat with engine running)
Of course it could be charging very slowly but the battery meter on the side of the battery which I'm assuming is a voltmeter definately showed a rise in battery voltage.
I ran it for about 15mins and by that time the inverter was warming up but I assume no more than usual.

So i'm going to try it when we next take the bikes away on the motorhome.

^{_{Subscribers  do not see these advertisements}}

 

[Jaws]

I gave this subject a bit of thought some time ago.
As you want to charge whilst driving, put the inverter on the cab battery.
It will handle it no probs and have direct feed off the alternator to keep everything nicely charged..
That is what I did on the Miller.. after a while paranoia set in ( worried about turning it off when we stopped ) and I put a relay on it that switched the inverter off when the engine stopped

As far as I know it is all still working ( that’s if the new owner knows it is even there ! )

 

[PeteH]

I have done this, however, In my case I had 440Ah of Hab battery, 300W of Solar, and a 40A "Smart" charger of US origin. That charged two x 25Ah L-Acid batteries on the move Via a Ring 3Kw Modified Wave Inverter. The problem that exists with modern Li-Iron batteries is the different charging regime which needs to be far more closely controlled.

 

[autorouter]

The charger in put current is 1.5A at 240v, so W/IxV would give me 360w ?which seems too much.

360 watts is the input inrush spike. The power for normal charging is about 100 watts. If the inverter doesn't trip out on the inrush spike then it should work fine for normal charging.