He is using a 12 Ohm load as demanded by german law for approval ("12 Lastwiderstand" in the picture subtitle).
At 10 km/h I do have a charge current of 100mA into 5 cells (6V nominal) but I am not using a hub generator but a standard wheel generator. Attached are my measurements
BTW how can I inline the picture instead of attaching it?
To inline the picture: first post the content with image attached, then click on the image link, copy "link location" and edit your post to add an image URL.
Were these data collected using a full wave bridge or a single diode rectifier?
How can the "charging current" be negative, as the graph indicates for low speed?
Did the load consist simply of 5 x 1.2V (nominal) AA NiMH or other types of cells?
but I am not using a hub generator but a standard wheel generator.
Noted. The OP, of course, has the hub generator.
jremington:
To inline the picture: first post the content with image attached, then click on the image link, copy "link location" and edit your post to add an image URL.
Thanks for the hint
Were these data collected using a full wave bridge or a single diode rectifier?
Full wave bridge with Schottky diodes
How can the "charging current" be negative, as the graph indicates for low speed?
The current includes the current used by the electronics (some 74xx chips back then...)
Did the load consist simply of 5 x 1.2V (nominal) AA NiMH or other types of cells?
5 x AAA NiMH, but capacity should not make a difference here
The current includes the current used by the electronics (some 74xx chips back then...)
So, the load is NOT just the cells being charged.
I am a bit late to this discussion, but if the cells are individual cells and not in a battery pack, what about getting a regular charger that has all the charging sensing electronics already built in? I have one that is several years old and plugs into the wall or with an adapter into my car, which implies about 12vdc input.
Then all that is needed to be done is the power supply part, to produce 12vdc to the charger. Given the amount of USB stuff out there now I would be surprised if you can't find a charger designed for a 5vdc input.
Problem is: the sensing of the state-of-charge is based on the assumption that you have a stable input. It is easy then to sense temperature rise rate or minus-delta-v (voltage goes slightly down at full charge). This will not work with a bicycle generator as an input
Think you might be going a bit over the top worrying about overcharge on a $2 cell. In my experience it might get a bit warm ( when connected to mains charger) but never seemed to worry them too much. Would replace them every 2 years anyhow ( rc gear)
Use post #16 + 7807 voltage regulator +50 ohm resistor, for 6V.
Charging voltage can be 1V higher than battery voltage, in the cars charging voltage for batteries 12V is 14V.
If you want charge quickly reduce resistor value.