Solar and ebikes

[ToBoldlyGo]

I'm just looking at having a solar panel fitted to the roof and having a 100ah lithium battery. One of the main things I want to charge off grid is our 2 ebikes. I started thinking about charging 2 ebikes from flat, and I assumed I'd charge both at the same time.

I realised that in practice, and scanning threads here, that we're unlikely to flatten the bike batteries,. a more likely usage is running both ebike batteries down a third say and then recharging them. We're not big off-gridders, our usage may be 70% ehu aire, 10% ehu campsite, 20% off-grid.

I can arithmetically size the solar system, but I'd like to think of actual usage, for us the shower, fridge and the bikes are the main power consumers off grid, maybe heating occasionally.

Those of you with both solar and ebikes, can you tell me what wattage panel, battery and inverter you use?

 

[Lenny HB]

I have 300 watts of solar and a 1000 watt pure sine inverter, I try not to charge them from flat and try to do one each day. Last time I charged both from flat was on my last van with 200 watts of solar took 3 days to recharge the batteries fully in June.

Ours are Bosch 400 watt batteries to charge both from flat takes about 160 a/h. Realistically even with Lithium to charge from flat you really need a minimum of 200 a/h of batteries preferably 300 and around 400 watts of solar to recharge in a reasonable time and that is for mid summer with plenty of sunshine.

 

[ToBoldlyGo]

Ouch, that's zonked my simple 100ah aspiration! That's a lot of battery, I won't charge them from flat. Hmm, and I only put the fridge down too as an afterthought but I can see ... hmm, let me get my calculator out :}

 

[funflair]

I have 300 watts of solar and a 1000 watt pure sine inverter, I try not to charge them from flat and try to do one each day. Last time I charged both from flat was on my last van with 200 watts of solar took 3 days to recharge the batteries fully in June.

Ours are Bosch 400 watt batteries to charge both from flat takes about 160 a/h. Realistically even with Lithium to charge from flat you really need a minimum of 200 a/h of batteries preferably 300 and around 400 watts of solar to recharge in a reasonable time and that is for mid summer with plenty of sunshine.

How do 2x400watt batteries take 160ah to recharge, I would have thought that 40ah each would do it.

 

[Lenny HB]

How do 2x400watt batteries take 160ah to recharge, I would have thought that 40ah each would do it.

Charger takes 1.5 amps @ 240v and takes 2½ hours per bike that's 75 a/h at 12v plus 10% inverter efficency per bike.

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[Jimbohorlicks]

We have a 1000w inverter with 3 X leisure batteries,315 ah and 2 panels ,200 w.
We usually charge one battery at a time if not on the move and usually in the mornings to allow the leisure batteries to recharge ,which doesn't take long usually. We always try to alternate charging the batteries day to day ,but on really long summer days can do both easily.

 

[autorouter]

Charger takes 1.5 amps @ 240v

Does it actually take that power, or is that what's on the charger label? It does sound very high.

 

[Lenny HB]

Does it actually take that power, or is that what's on the charger label? It does sound very high.

That is what the charger is labeled but it also draws that, running from the inverter my BMV700 shows over 30 amps drawn on 12v.

 

[Richard n Ann]

When you think what a 100cc scooter will do on a gallon of liquid fuel why do we bother?