Green recharging

[mithril]

Probably the height of bad manners to start a second new thread after just joining, but I know you'll forgive me

Just wondering if anyone generates their own electricity to charge up their bikes? It would be the height of Green-ness!

 

[flecc]

No problem for me, and I'm sure the administrator would say post whatever threads you need, it's a friendly site.

I don't green recharge, but A to B magazine have solar charged their Giant bike's batteries for years and previously published an article about it. The latest issue has an article on their solar panels for domestic electricity.

www.atob.org.uk

 

[rsscott]

Welcome aboard Mithril and fire away, ask as many questions as you need!!

It's a very interesting topic and definitely warrants some research and a feature article on the main site.

There aren't many things in life that don't affect the environment in some way and many electric bike companies promote their bikes as been green, zero-emission vehicles etc, which is not entirely true as you know, electric bikes need to get the electricity from somewhere!!

It would be interesting to see the costs etc of solar charging and any green energy companies.

 

[mithril]

Thanks both, for your food-for-thought replies in this thread and my max range one.

Have just taken out a subscription to AtoB mag.

I do like the idea of making my commute as clean as possible and look forward to the article you mention. As you indicate, an easy first step would be to go to a 'renewables only' electricity supplier, but my ultimate goal would be a micro-generation scheme of solar panels and even small wind turbines (if that's remotely possible in a small semi-detached garden ;->).

I do get the sense that this stuff is just starting to become viable from a price point of view (when taking into account the ever rising energy costs)... but only just.

 

[flecc]

Using solar charging

The A to B back issue that's best for you is issue 37, August/September 2003. This has a three page article on their solar charging of the Lafree batteries, plus lots of other information on the subject.

 

[oobs]

Aaaah. My fave subject. Apologies too for perhaps overindulgent posting on my first day. It is just so nice to talk Torq for a few hours!

Until a few days ago, I had a 510Wp solar PV system installed on my roof (It has come down, ready for my house move). It connected into my household supply and if it was generating, met whatever loads were running at the time. The Li-ion charger seemed to take max 60 watts and the solar was therefore often meeting all this demand. It helps that I work from home and so many of my recharges are during the day when the sun is out.

 

[mithril]

Flecc - thanks again, I'll get hold of that back issue.

Oobs - sounds good. Is that a system you had profesionally installed or did you do it yourself? Did your electricity provider pay you for the power you generated and didn't use? I'm very interested in all the details to be honest (incl. ballpark costs if that's not too rude to ask) - hopefully others on the forum would be to - it goes hand-in-hand with leccy bikes I reckon!

 

[oobs]

Hi mithril,

The system was professionally installed but I helped! It would cost about £3200 installed depending on choice of mounting sytem, difficulty of access etc. You can get a grant on that too, reducing cost to £1700. I do get paid for the power produced. In fact a cheque arrived today - a wopping £6.11p!!! (half year) Up until now, this has been @5p/unit generated. Future scheme customers (npower) will get a mini export meter and be paid on a 'net tariff' for units exported. This is good because it means you get the same benefit whether you use the units 'in house' (or in bike) or if you export them.

oobs

 

[rsscott]

We are currently in the process of moving and will most certainly be fitting a panel to the new house. Solar and wind are going to be big in the coming years as fossil fuels are not an infinite resource and I can see once everyone else gets wind (pun intended!) this will drive the price up considerably. So now is the time to invest in this technology for me.

Can you explain in more detail the process you went through ?

 

[mithril]

Thanks Oobs. That's not quite as expensive as I thought, though I do wish the price of solar panels would fall dramatically as things tend to in other hi-tech areas, but I read somewhere that the demand is likely to outstrip supply for a while yet so that's wishfull thinking.

I'll certainly go for it once my finances have recovered from Torq purchase

 

[deesee]

Solar charging

I'm wondering whether solar charging is quite so easy. The website <www.batteryuniversity.com> makes it clear that different batteries need charging in different ways. The charger circuitry should be designed to vary the rate of charge depending on the type (and state) of the battery. It's obviously not just a case of squirting in a few volts lapped up from the sun!

Incidentally, how can we be sure that chargers are correctly designed. I understand that manufacturers like Heinzmann go to great lengths to use the best batteries and compatible chargers, but how often do we see mention of charger design in bike publicity blurb?

David

 

[Ian]

Solar charging of typical e-bike batteries is far more complex than may be thought. Lithium batteries usualy incorporate charge managment circuitry that is designed to work with a specific charger which has totally different characteristics to a solar panel, and NiMh batteries don't take kindly to extended trickle charging, which is what solar chargers do.
The only batteries really suitable for solar charging are the lead acid types.

The other problem is the very small amount of power that solar panels generate, it would take a very large array of panels to fully charge a bike battery in one average British day

 

[flecc]

A to B magazine have spent large sums on suitable equipment and used solar charging on the Twist NiMh batteries but have suffered some ill effects like very uneven cell voltages which will impair battery life. These batteries when used with the correct charger never suffer that, the cells remaining perfectly aligned.

Therefore I wouldn't recommend it. The environmental saving is tiny, and the environmental cost of prematurely replacing a battery which uses rare or polluting metals also makes this approach a bad option.
.

 

[Ian]

There is another way that wouldn't risk battery damage, and that is to use a solar panel to maintain the charge in a large 12V leisure battery, and then to use that battery to power a 12-240V inverter which in turn powers the original e-bike charger. I have used the 12-240V inverter solution to charge my bike away from a mains supply, the inverter drawing about 15A while powering the Ezee charger.

Of course the cost and environmental impact of the leisure battery may well negate any savings made.

 

[oldosc]

bit late posting on this but new member and engaged in buying couple of bikes, Have motor home with solar panel (only 1.5 amp now as they are a bit old, but I have 200ah leisure batts which the panels keep full, when we are not travelling 9(even in winter) I now use an inverter to charge my bike batts with the specified charger. (most important as has been posted)

 

[ElephantsGerald]

There is another way that wouldn't risk battery damage, and that is to use a solar panel to maintain the charge in a large 12V leisure battery, and then to use that battery to power a 12-240V inverter which in turn powers the original e-bike charger. I have used the 12-240V inverter solution to charge my bike away from a mains supply, the inverter drawing about 15A while powering the Ezee charger.

I don't know if it would affect the charger, and hence the charging, but there are invertors, and there are invertors...

Expensive invertors deliver a pure sine wave a/c power profile (like the mains). These bits of kits usually cost several hundred pounds.

Cheap invertors deliver a modified sine wave profile (basically a square wave with the corners chopped off). This can affect equipment plugged in to the invertor (e.g. you might get interference or buzzing on a TV plugged into a modified sine wave invertor).

As ever, you get what you pay for!!

Also, there are lots of inefficiencies involved in charging a leisure battery, which then runs an invertor, but I guess all the power is free(ish - apart from the cost of buying/installing all the required kit in the first place!), so that doesn't matter much

Does anyone know if a modified sine wave invertor would run a bike charger properly?

Regards,

Elephants

 

[oldosc]

Does anyone know if a modified sine wave invertor would run a bike charger properly?

Flecc answered this question for me in a previous thread.

 

[ElephantsGerald]

Does anyone know if a modified sine wave invertor would run a bike charger properly?

Flecc answered this question for me in a previous thread.

Hi oldosc,

I did a bit of searching but I couldn't find Flecc's answer which you refer to. However, I did come across an answer in this thread: Charging Ebike Battery from Car 12volt System.

P.S. in previous posts where I said "modified sine wave", I actually meant "modified square wave" (doh!).

Regards,

Elephants

 

[Jeremy]

The few chargers I've looked at were all switched mode systems, so would happily work on DC if required. As such, I can't see that the waveform would present any problems at all.

One idea that might be worth exploring would be to have a bank of smaller 12V batteries charged up in parallel by a solar panel, then switched into series to drive a charger directly at a higher voltage. This would be more efficient than using an inverter. You don't need to go to 240V either, as the switched mode chargers work from about 90V to 240V with a DC input.

A stack of eight 12V batteries, together with a suitable series/parallel switch and solar panel, would seem like a reasonable approach. The batteries wouldn't need to be very big either, even very cheap 5 to 10Ah 12V SLAs would do, as the current required to run the charger isn't very high. I reckon you could build a viable solar charger using this approach for less than £100, with a bit of ingenuity.

Jeremy

 

[john]

solar charging lithium cells

I can see that charging NiMH directly from DC solar is problematic, but isn't it more of a possibility for some of the lithium technologies where most or the inteligence is in the BMS and charge termination is not so difficult to establish.

How about a strings of solar cells to charge each lithium cell individually, not using the BMS, just a simple voltage limit and the current would be limited by the solar cell capacity.