Recharge solar Li-Ion of an electric bike: solar kit

[Christophe]

Here I started the 1ers solar recharging tests of our VAE (see experience EAV-velo-electric-functional-with-trailer t7946.html for details):



A) Elements of the "solar kit"

All the products of the "solarization kit" (except the inverter that you find everywhere) come from the solar section shop :
- 2 5W amorphous silicon panels in parallel: https://www.econologie.com/shop/panneau ... p-109.html
- 1 regulator: https://www.econologie.com/shop/regulat ... p-116.html
- 2 7Ah battery (insufficient to make a complete charge but sufficient for tests)



B) Photos (this is the brothel, normal is testing, I would do a clean editing after):



From left to right:
a) LiIon 24V 8Ah = 24 * 8 = 192 Wh batteries stored
b) LiIon charger
c) 12V to 230VAC XnumXVAC Modified Sinus (XS) converter converter
d) 2 12V lead cyclic 7Ah batteries that make buffer = 2 * 12 * 7 = 168 Wh stored (I would add 2 more soon)
e) above, truncated, the solar regulator

I added 2 galvanometric ammeters to see the input amps (from the solar panels) and output (to the inverter):



We can read (full sun):
a) full deviation on the solar input is at least 7W solar input
b) A little more than 6 A in consumption say 6.2 * 12 V = 75W about out

We see immediately (power ratio of 10) that we could not recharge live unless you have 10 times more solar panel: lead-acid batteries are essential!

Depending on the amount of sunshine the input amperage obviously varies, a day without sun, cloudy but quite clear gives between 100 and 200 mA which is "always good to take"!

C) Performance and yield estimation

For the 1ere charge it's not bad I think.

Under 6A, the 2 batteries held about 2h (before the inverter would beep = 10.5 V on the lead batteries = stop to protect them), LiIon battery completely flat, it won 4 / 5 charging points.

I continued charging on other batteries. She is currently in class.

The LiIon charger used is the one supplied with the bike:



It therefore leaves (1st phase of recharging a LiIon battery = high amperage) 1.8 A at 29.4 V = 53W "in" the battery.

The inverter + charger yield is thus 53 / 75 70 =% which is very respectable because there 2 transformer in series and that goes through the 230V AC (root = 0.7 an average by transformer 84%)!

D) Remarks and questions:

a) some people will say that it is stupid to do 230V AC from CC to redo the CC ... they will be right but I have not (for the moment) charger LiIon 12V ... (if kk1 has an address ca interests me!)

b) when you plug the charger into the inverter, it "buzzes": is it good or not? Should I invest in a pure sine wave inverter (more than 2 times more expensive)?

c) this method requires the use of a buffer battery, which wears out and pollutes. Yes, but "we don't really have a choice" if we want to stay within a reasonable investment. In addition lead batteries permanently charged "12/24" have a lifespan surely more interesting than batteries heavily used. Putting several batteries also increases their lifespan (I intend to put 4 in the final assembly so as not to completely discharge them at each cycle)

Voila here!

Before we warmed ourselves with the sun, now we ride solar (well, when it's raining!)

[Christophe]

2ieme test, just as messy ...





I added an 3ieme battery of 12 Ah.
The "solar" capacity is therefore 12 + 7 + 7 = 26 Ah (or 312 Wh)

As the load consumes 6A, so it should be able to load during 26 / 6 = 4h20 min about ...

To see if it is enough to make a complete charge of the batteries of the bike (whose capacity is 8Ah under 24 V is 192 Wh) ... in theory yes since 312 Wh should compensate the 70% of yield with a small margin .. to see in practice ...

Results in a few hours.

The next test, I do it with a stopwatch.

[Christophe]

This time it took an hour of additional load on sector.

It therefore lacks "a bit" of energy.

I will add an 4ieme 12Ah battery.

[Christophe]

Here is the "almost" final assembly is done:
a) I added a battery (2 * 12 Ah + 2 * 7 Ah)
b) I found a box (transparent plastic while waiting better)
c) I removed the galvanometers (brothel)
d) everything is closable with the cover of the box (do not look at the colors of threads it is the recovery of washing machine !!)




The load is in progress, I hope to reach the end of the load of the bike (the pellets are loaded to block).

[Christophe]

The last test is conclusive:

Start: 17h
End: between 21h20 and 21h50

Duration: between 4h20 and 4h50.

It remains to reflect on the overall results of this solution: economic profitability (how many costs to make the "solution" profitable) and ecological (will gray energy be depreciable ...) ...

Finally I have to have fun a little too!

[I Citro]

I know that your lithium charger is under warranty ...
I will try to open his belly to see how he climbed ...
The idea is to see if it is possible to connect directly to the output of the tranfo of your original charger ...

[Christophe]

Mmm yes it would win 30% at least.

It is an electronic charger without ferric transformer according to the weight.

It comes out of the 29.4 V CC and from what I understand there are 2 charge sequences:
a) high amperage up to a few% of the charge end
b) low amperage on the end of charge

I do not know how it detects the sequences and end of charge, surely a delta voltage?

And I do not know if it goes through 12 or 24V ... internally.

I think finding a Li-Ion charger powered by 12 V would also be a good track.

[I Citro]

I think finding a Li-Ion charger powered by 12 V would also be a good track.

To then go up the 12V in 29.4CC
Intellectually, it bothers me ...
I would rather see 3 12V batteries in series, ie 36V,
regulated, if necessary, to 29.4V CC to get to the right place in your current charger.

[clasou]

Hello,
Just out of curiosity, there is nothing imaginable given the 4 battery converter .... on the side of a stirling mount or peltier effect module.

Yes, I know even worse when gardening, but who does not wake up does not live.
a + claude

[delnoram]

It comes out of the 29.4 V CC and from what I understand there are 2 charge sequences:
a) high amperage up to a few% of the charge end
b) low amperage on the end of charge

I do not know how it detects the sequences and end of charge, surely a delta voltage?

When I charge a Li-on battery with a lab power supply, I set the voltage to 4.2V per element and then once the battery is plugged in, I put the amperage back up to about 50% of the battery capacity.

During charging, I have to go back up the amperage until the 4.2V limit appears on the voltmeter of the power supply.

The batteries require a lot of amps at the beginning, that's why it is necessary to limit them between 1 / 2C and 1C (0.5A and 1A for a battery of 1A), but the more the charge advances month they ask for current (Ampere) and I cut the load to 0.03 A