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Discussion Starter · #1 ·
Has anyone tried using 2nd gen Prius modules ? They are 7.2 v 6.5 Ah NiMH and if so is there any advice on charging them. I have been given a bunch of them all showing about 7.2 volts.
 

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I rebuild the packs for customers. We deal with Priuses primarily.
I suppose they are usable for EV use. The issue is they are heavier and lower
capacity than lithium cells. They need to be bound together to minimize bulging.
A standard pack has end caps and threaded rods to keep them from bulging or
exploding. (They do not explode like other cells might but it can happen.)
And, of course, you need a BMS.
They could be used for testing purposes.
 

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Discussion Starter · #3 ·
ok thanks, Im thinking of building a small pack about 48 volts for an electric bike,according to the interweb each module has a built in charge controller and relay, any advice on charging this setup and would a BMS designed for Li work
 

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I am pretty certain there is no charge controller or relay in the modules. The hybrid pack has relays and the bms. I have been into some cells that have burst and have popped some by overcharging when not paying attention. 6 modules would get you there. You can get something to monitor the balance without getting too crazy.
 

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Nimh is a robust chemistry and hobbiest chargers will charge it right up but a 6Ahr pack is pretty small 300whr at best 3 miles

20+ ahr would be more like it
 

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On an E-bike...

To travel about 12 mph (20kmph) you'll need about 100 watt-hours. So, 312 watt-hours will get you about 3 hours travel time, 36 miles.

But at 20mph (30kmph), you'll need about 300 watt-hours. So, you'll only get about 20 miles.

At 30mph (50kmph), you'll need about 750 watt-hours. So you'll run out after about 12 miles.

You'll be able to go damned near highway speed (50-55mph) to use enough power (6000 watts) to run out in 3 miles. So, I don't think that advice is correct.

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You don't need a BMS for NiMH. They have a feature where they self-balance by bleeding excess energy off as heat. Skip the BMS, you won't find one on just about any NiMH devices for a reason.
 

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On an E-bike...

To travel about 12 mph (20kmph) you'll need about 100 watt-hours. So, 312 watt-hours will get you about 3 hours travel time, 36 miles.

But at 20mph (30kmph), you'll need about 300 watt-hours. So, you'll only get about 20 miles.

At 30mph (50kmph), you'll need about 750 watt-hours. So you'll run out after about 12 miles.

You'll be able to go damned near highway speed (50-55mph) to use enough power (6000 watts) to run out in 3 miles. So, I don't think that advice is correct.

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You don't need a BMS for NiMH. They have a feature where they self-balance by bleeding excess energy off as heat. Skip the BMS, you won't find one on just about any NiMH devices for a reason.
I was think more of a motorcycle, a bicycle you pedal is all over the map but I still wouldn’t expect more than 10 miles off that pack without a lot of pedaling.
Those I’ve known with ebikes and 10ahr lithium packs never got anywhere near the figures you state
10wt/hr per mile basically means 100% pedalling with no assistance
 

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I was think more of a motorcycle, a bicycle you pedal is all over the map
I was using figures presuming no pedalling. Of course any amount you pedal would be above this.

10wt/hr per mile basically means 100% pedalling with no assistance
- wt is not an abbreviation for "watt"
- It's not watts/hour per mile.
- I presume you're trying to say "Wh/mile"?

Human cardio is about 100 watts continuous. That pushes a bike about 12mph.

A motor will do the same thing (minus additional efficiencies).

But no one with an e-bike would be happy going only "normal" pace so it feels slow.
 

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- wt is not an abbreviation for "watt"
True.

- It's not watts/hour per mile.
- I presume you're trying to say "Wh/mile"?
True, but given your earlier post, this might not be a good day for you to be correcting anyone else's units, Matt...

To travel about 12 mph (20kmph) you'll need about 100 watt-hours. So, 312 watt-hours will get you about 3 hours travel time, 36 miles.

But at 20mph (30kmph), you'll need about 300 watt-hours. So, you'll only get about 20 miles.

At 30mph (50kmph), you'll need about 750 watt-hours. So you'll run out after about 12 miles.
This whole thing is a pile of confused energy and power units, because a time period is assumed and not stated.

Did you mean that to travel about 12 mph (20kmph) you'll need about 100 watts of power, or and energy consumption of 8 Wh/mile? That would correspond to three hours and 36 miles for 312 watt-hours of energy. Then at 20mph (30kmph), the power requirement might be about 300 watts (15 Wh/mile), resulting in about 20 miles for 300 watt-hours. Similarly, at 30mph (50kmph) power might be about 750 watts (an energy consumption of 25 Wh/mile) and range of about 12 miles.
 

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True, but given your earlier post, this might not be a good day for you to be correcting anyone else's units, Matt...
Whoops.

Yeap.

Considered explaining it in terms of power or energy, settled on power and forgot to change energy terms to match.

Did you mean that to travel about 12 mph (20kmph) you'll need about 100 watts of power, or and energy consumption of 8 Wh/mile? That would correspond to three hours and 36 miles for 312 watt-hours of energy. Then at 20mph (30kmph), the power requirement might be about 300 watts (15 Wh/mile), resulting in about 20 miles for 300 watt-hours. Similarly, at 30mph (50kmph) power might be about 750 watts (an energy consumption of 25 Wh/mile) and range of about 12 miles.
All correct, yes.

Or, to travel 12 miles you need about 100 watt-hours of energy. Which is how I started saying it. But then I didn't like using energy when I was going to multiple it again to get to the 312 so I changed distance to speed and didn't swap the watt-hours out for watts.
 
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