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- May 19, 2009
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Given that batteries are by far the most expensive, heavy, and tricky part of an electric bike setup, it seemed to me that a good approach would be to build a battery pack incrementally, rather than just have one pack for all occasions.
Then you could:
A. Add more batteries as you could afford them, or find them for a decent price.
B. Take only the batteries that you need for any particular trip
C. Charge up some of your batteries whilst still using the bike, leaving them at some power point for a few hours.
This thread continues my introduction thread - http://www.motoredbikes.com/showthread.php?t=20392 without continually bumping and pushing out the new introductions - it seemed like there was a lot to discuss in what I was aiming to do, and was thus worthy of it's own thread.
I was very rapidly made aware that chucking more batteries in is by no means as simple as that. In fact, it borders on the impossible, by some accounts. There are many complications, firstly in mixing battery pack voltages (don't do it at all), mixing battery pack capacities, and mixing battery chemistries.
Now I don't need to be told that the safest way is to just buy the very best batteries with the capacity you need, all at once, all to exactly the same spec, and Bob's your Uncle. But unfortunately, that means:
1. Knowing exactly what capacity you need. Since my trips are not all the same length, under the same load, I don't know this in advance.
2. Taking a risk on the entire pack - you could buy thousands of dollars worth of batteries and then find they are not up to scratch.
3. Discarding or using for something else any previous batteries, which seems wasteful.
Now, this could turn out to be the most practical advice in the end anyway, but I'm not prepared to give up on the idea of incremental building just yet, for the reasons A, B and C, and 1,2, and 3. Every battery is still a source of power, and, in theory, circuits can be contrived to allow different capacities and chemistries to live together in harmony. Is it practical? That's what this thread is for.
The introduction thread has a few pages of discussion already, so make sure you check that out first, but please don't leave any more comments there.
Then you could:
A. Add more batteries as you could afford them, or find them for a decent price.
B. Take only the batteries that you need for any particular trip
C. Charge up some of your batteries whilst still using the bike, leaving them at some power point for a few hours.
This thread continues my introduction thread - http://www.motoredbikes.com/showthread.php?t=20392 without continually bumping and pushing out the new introductions - it seemed like there was a lot to discuss in what I was aiming to do, and was thus worthy of it's own thread.
I was very rapidly made aware that chucking more batteries in is by no means as simple as that. In fact, it borders on the impossible, by some accounts. There are many complications, firstly in mixing battery pack voltages (don't do it at all), mixing battery pack capacities, and mixing battery chemistries.
Now I don't need to be told that the safest way is to just buy the very best batteries with the capacity you need, all at once, all to exactly the same spec, and Bob's your Uncle. But unfortunately, that means:
1. Knowing exactly what capacity you need. Since my trips are not all the same length, under the same load, I don't know this in advance.
2. Taking a risk on the entire pack - you could buy thousands of dollars worth of batteries and then find they are not up to scratch.
3. Discarding or using for something else any previous batteries, which seems wasteful.
Now, this could turn out to be the most practical advice in the end anyway, but I'm not prepared to give up on the idea of incremental building just yet, for the reasons A, B and C, and 1,2, and 3. Every battery is still a source of power, and, in theory, circuits can be contrived to allow different capacities and chemistries to live together in harmony. Is it practical? That's what this thread is for.
The introduction thread has a few pages of discussion already, so make sure you check that out first, but please don't leave any more comments there.