Inverter vs powerbank

[aitcheeboy]

I have a newish Adria Twin with one 110 ah leisure battery and a solar panel. Up till now that has been fine, but I am (in spring) making a 2 month tour of the Balkans and with 2 e-bikes on board, I'm looking at keeping them topped up when off-grid. So. . I am looking at (a) Buying a 2nd battery and hooking up an inverter, although this will need some carpentry and professional fitting - or (b) Buying a big powerbank that on the face of it seems to be the same as (a) but in an easier to manage package, and possibly cheaper? My understanding is that the unit can be charged from a 12v power outlet from my leisure battery which is topped up either by solar or driving, my electrical knowledge is thin so any advice welcome on this. Essentially I am looking at recharging to big e-bike batteries occasionally when stationary

 

[LesW]

Some info here aitcheeboy

Post in thread 'Swytch conversion questions' https://www.motorhomefun.co.uk/forum/threads/swytch-conversion-questions.255225/post-4831186

 

[suavecarve]

I have a newish Adria Twin with one 110 ah leisure battery and a solar panel. Up till now that has been fine, but I am (in spring) making a 2 month tour of the Balkans and with 2 e-bikes on board, I'm looking at keeping them topped up when off-grid. So. . I am looking at (a) Buying a 2nd battery and hooking up an inverter, although this will need some carpentry and professional fitting - or (b) Buying a big powerbank that on the face of it seems to be the same as (a) but in an easier to manage package, and possibly cheaper? My understanding is that the unit can be charged from a 12v power outlet from my leisure battery which is topped up either by solar or driving, my electrical knowledge is thin so any advice welcome on this. Essentially I am looking at recharging to big e-bike batteries occasionally when stationary

2 ebikes will take up your battery and some more.
I would start to look at where you were going and looking at how they charge their ebikes there. For example if you have Bosch batteries they provide chargers and electricity in some areas. Holland have ashtrays turned into charging points in railway stations. Cycle paths in france often have lockable rechargable stations.
Unfortunately I have no knowledge of the charging habits of Balkan countries, but I suspect you may well need them as part of your battery management for 2 ebikes

Best of luck

 

[aitcheeboy]

Some info here aitcheeboy

Post in thread 'Swytch conversion questions' https://www.motorhomefun.co.uk/forum/threads/swytch-conversion-questions.255225/post-4831186

I do have one of these but it gets hot and also drains my leisure battery overnight. . hence the power bank option

 

[LesW]

I do have one of these but it gets hot and also drains my leisure battery overnight.

Yes it would, I only use it during the day or when on the move. No problems with the heat though, I do keep an eye on it.

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[autorouter]

my electrical knowledge is thin so any advice welcome on this. Essentially I am looking at recharging to big e-bike batteries occasionally when stationary

Here's some info to help with your calculations. You need to know how energy capacity of a battery is described. Typically an ebike battery capacity will be given in watt-hours (Wh), probably 300 to 500 watt-hours.

A typical 12V leisure battery capacity will be given in amp-hours (Ah), and to convert that to watt-hours you need the voltage, ie 12V. The energy capacity of a 12V 110Ah battery is 12 x 110 = 1320 watt-hours.

So you can see that charging two 500Wh ebike batteries from a 1320Wh leisure battery is not going to leave much left. And that's assuming the charging process is 100% efficient.

In terms of solar power, a 100W panel will give you about 30Ah (= 360Wh) on an average day, maybe up to 40Ah (= 480Wh) on a good day. Many motorhomes have 300W of solar panels, which will have a good stab at keeping a couple of ebike batteries full. Of course there's the old problem: who wants to sit around charging batteries while the sun is shining?

You could fit more leisure batteries, charge them during the daylight sunshine, then use the stored energy to charge the ebike batteries overnight.

The alternator produces maybe 20 or 30 amps while driving. If it's 30A then each hour will produce 30 x 12 = 360Wh, so you can see it's going to take three hours or so at least to charge two ebike batteries.

 

[aitcheeboy]

Here's some info to help with your calculations. You need to know how energy capacity of a battery is described. Typically an ebike battery capacity will be given in watt-hours (Wh), probably 300 to 500 watt-hours.

A typical 12V leisure battery capacity will be given in amp-hours (Ah), and to convert that to watt-hours you need the voltage, ie 12V. The energy capacity of a 12V 110Ah battery is 12 x 110 = 1320 watt-hours.

So you can see that charging two 500Wh ebike batteries from a 1320Wh leisure battery is not going to leave much left. And that's assuming the charging process is 100% efficient.

In terms of solar power, a 100W panel will give you about 30Ah (= 360Wh) on an average day, maybe up to 40Ah (= 480Wh) on a good day. Many motorhomes have 300W of solar panels, which will have a good stab at keeping a couple of ebike batteries full. Of course there's the old problem: who wants to sit around charging batteries while the sun is shining?

You could fit more leisure batteries, charge them during the daylight sunshine, then use the stored energy to charge the ebike batteries overnight.

The alternator produces maybe 20 or 30 amps while driving. If it's 30A then each hour will produce 30 x 12 = 360Wh, so you can see it's going to take three hours or so at least to charge two ebike batteries.

That is the answer I was hoping for, and, explained with clarity. . Thank you 'autorouter'