Car inverter for bosh charger

[Highside43]

Does anyone know what watts the bosh charger draws - I was thinking of getting a cigarette lighter inverter and can't find what wattage I need. Cheaper than the bosh car charger, and it'll come in useful for other gadgets also.

Mucho gracias.

 

[PH001]

I would guess that it is around 2-4A @ 40V so 160W max o/p which would equate to around 200W input worst case. You would be looking at an inverter in the 300VA to 500VA range I would expect.

With your engine off, even the 300VA version equates to 25-30A which is far more than you can reliably take from a fag lighter.

 

[Highside43]

Many thanks PH001, just the answer I was after.

 

[Artstu]

My 300 watt inverter doesn't supply enough for my Bosch charger, I think a 500 watt will, but that'll need wiring direct to the battery and will flatten your car battery rather quickly.

 

[Highside43]

So a dedicated car charger it is then. Why will a car one charge it but an inverter and 240v charger not?

Forgive my ignorance, I'm no electrical and it's a dark art to me.

 

[Artstu]

I forget the maths too,ohms law. There are some loses with an inverter, but I think the main one will be that the car charger doesn't deliver as many amps, so charging time will be longer, but power needs much less.

I hadn't realised they'd made a 12v charger

https://www.e-bikeshop.co.uk/eBike-Spare-Parts/Bosch-eBike-Car-12v-Travel-Charger

 

[Alan Quay]

So a dedicated car charger it is then. Why will a car one charge it but an inverter and 240v charger not?

Forgive my ignorance, I'm no electrical and it's a dark art to me.

Losses. When converting from 12vdc to 240vac there is a loss. Quite a large loss, somewhere around 70% efficient.

Then there's another loss when you convert back from 240vac to 42vdc. Probably about 80%. So, you end up with 80% of 70%, or about 50% wasted.

The dedicated charger also has losses, but they will be a lot lower.

Ultimately, your car battery (average car) is around 400-500wh of usable energy. That's about the same as your bike battery, so there's not much room for wastage.

The other problem is current. As others have said, the 12v side will need to draw a massive current, around 40a, possibly more. You lighter socket won't be happy with that.

Sent from my HTC One_M8 using Tapatalk

 

[PH001]

Yeh, efficiencies aside, the fundamental reason is that the car charger is about half the power of the mains one. Scroll down right to the bottom of this page to see...

https://www.bosch-ebike.com/en/components/charger/?setLanguage=1