discharging NIMh batteries

[musicbooks]

Following lots of discussion ( sometimes heated) about battery shelf-life. Is there any way to fully discharge an ezee NiMh battery (as recommended by Flecc) without doing it on the move? In other words, is there an alternative to the smart charger, as sold by 50cycles, that can't fully discharge the battery ( and charge it too!) in the comfort of your own home (rather than emptying the battery while going up a steep hill!)

 

[aroncox]

Good question, I'm wondering exactly the same thing. If it needs to be done every 10 charges or so than that's pretty much every week for me. I'm also hoping someone can come up with an easy way to do this (I suppose turning the bike upside down and taping the accelerator on may have to do).

Following lots of discussion ( sometimes heated) about battery shelf-life. Is there any way to fully discharge an ezee NiMh battery (as recommended by Flecc) without doing it on the move? In other words, is there an alternative to the smart charger, as sold by 50cycles, that can't fully discharge the battery ( and charge it too!) in the comfort of your own home (rather than emptying the battery while going up a steep hill!)

 

[aaannndddyyy]

I put my bike on a speaker so the wheel is off the floor and lean the bike against the wall so the throttle will stay open, then connect a volt meter to the battery so I can keep an eye on the voltage until its down to 33 volts. (On a 36 volt NiMh).

 

[flecc]

Not really. These should never be discharged completely using bulbs or resistors since that damages them, preventing further charging.

The minimum voltage per cell should be no lower than one volt and preferably 1.1 volts for safety, and the bike's cut out looks after that requirement, so watching the voltage shouldn't be necessary.

The discussion elsewhere I don't view as heated, just resulting from the impossibility of simple and easily accessible details not being appreciated. The subject raised here illustrates the difficulties in part, since I posted this information elsewhere in response to this question only yesterday I believe.

That's how it is, painting the Forth Bridge as the saying goes.
.

 

[aaannndddyyy]

I ment place the bike on a speaker not connect it up to one, you could use a stall or anything the right hight .

 

[Ian]

I ment place the bike on a speaker not connect it up to one, you could use a stall or anything the right hight .

I'm glad you clarified that Andy, I was thinking that perhaps the speaker made a sound when the battery was discharged.

 

[prState]

Is it necessary the bike be under load before the auto cut off? Or can you just let it freewheel on a stand until it cuts off?

 

[flecc]

Freewheeling is fine, but it can take ages as the consumption under those conditions is incredibly low.
.

 

[musicbooks]

The discussion elsewhere I don't view as heated, just resulting from the impossibility of simple and easily accessible details not being appreciated. The subject raised here illustrates the difficulties in part, since I posted this information elsewhere in response to this question only yesterday I believe.

That's how it is, painting the Forth Bridge as the saying goes.
.

Sorry Flecc,
I probably meant 'animated' .. getting carried away with the battery analogy..sorry too for asking the same question again. I thin there's so much on the forum at the moment, as you say, it's difficult to keep track of it. So there's no other charger available ( or can be modiied) to do the job? Sounds like a business opportunity for you!!
Tom
musicbooks

 

[flecc]

No problem Tom, my mention was not a criticism and all questions should be asked when an answer is needed.

There are chargers available with the discharge function, but they might not match the battery's thermistor (thermal resistor). This raises another oft raised issue.

The charge cut-off with NiMh is temperature based and the charger reads that from a thermistor in the battery. The charger cut-off circuit has to match the fitted battery thermistor, so any old charger won't do.

Researching a suitable alternative charger is a very time consuming business and can be costly, so I only ever do it when original chargers are no longer available or far too expensive.

I might try for the eZee batteries sometime though.
.

 

[prState]

Freewheeling is fine, but it can take ages as the consumption under those conditions is incredibly low.
.

Here's a crude idea someone could probably improve on. Take an old bicycle wheel, fix it to a shaft (so the shaft turns) and on the ends of the shaft attach old fan blades, or maybe easier, big hunks of Styrofoam cut in a rough shape. Put that on a simple fixed stand.

Then just roll your bicycle wheel (off the ground on a stand or something) up to that wheel and get it turning with the wind resistance helping.

Or if you have a big fan blade, cut up an old bicycle tire and wrap it around the outside of the blades, and put it (unattached) to rotate around a shaft and let the wheel turn that on a fixed stand.

 

[Ian]

Here's a crude idea someone could probably improve on. Take an old bicycle wheel, fix it to a shaft (so the shaft turns) and on the ends of the shaft attach old fan blades, or maybe easier, big hunks of Styrofoam cut in a rough shape. Put that on a simple fixed stand.

Then just roll your bicycle wheel (off the ground on a stand or something) up to that wheel and get it turning with the wind resistance helping.

Or if you have a big fan blade, cut up an old bicycle tire and wrap it around the outside of the blades, and put it (unattached) to rotate around a shaft and let the wheel turn that on a fixed stand.

Thats's OK in warm sunny Nevada, here in England we can't afford unnecessary draughts at this time of year. A friction brake generating heat would be more appropriate here.