new/used battery compatability?

[SoSauty]

I've enjoyed my 48V e-bikes. They provide modest hill climbing torque, allow me to pedal assist a bit, and run as far as needed at 20mph. Love to cruise 20 as a decent crash years ago taught me that old bodies don't heal well, sometimes not at all. Yet out in AL, where I spend summers, country dogs are a small threat and then there's the occasional 850 ft. mountain climb. It'd be great to speed up close to 30mph to make the dogs have to work at it, or relax on the 850 ft climb and watch people faces as they drive by. I'm thinking 72V for my C-408 as there's a 40% used up 8.2ahr 36V Lith-ion batt just lying around and its-electric.ca has a 5.6ahr 36V batt that's caught my eye. How do think they would perform in ?parallel for 72V+ Would one or the other get relied upon for current more than the other? Do you think they would both expire roughly the same season? Any relavant thoughts would be of interest

 

[Russell]

What is your top speed now? Have you considered simply adding a booster to your 48V battery to get the extra speed? Instead of spending for a new battery how about replacing the 408 with a 9C 2806, that'll get you close to 30 mph at 48V.

-R

 

[Rassy]

How do think they would perform in ?parallel for 72V+

Hi SOS. Yeah, your question mark is well placed. Two 36V batteries hooked together to create a 72V battery is a series hook up. I really responded to mention that unless you are into battery usage and maintenance you should only parallel or series batteries of the same voltage, amperage, and chemistry. Even then you can create charging and BMS problems.

 

[SoSauty]

Russell, top speed with present 48V 25a controller is in the 21-23mph range. I generally pedal in 6th gear (of 7) at 19mph to minimally assist the motor at around 90% throttle. Oh yah yah, series or parallel, a flashlite multiplies V in series, somethin' like that, thanks, I ought to know :? Rusy, I enjoy and need the 'silence' such as the C-lite 400 motors. The country dogs can hear almost anything coming down the road and be there waiting to bite Plus I wear hearing aids, a motor whine would be annoying, so I don't consider the C9 clearly superior to the C408.

The batts have the same voltage, chemistry, and isn't extreme apart on the amp hrs, 8.2ahr for the used; 5.6ahr new. Though the batt may cost as much as a C9, it would be simple to add vs switching out the controller, wiring, and wheel. I did consider your suggestions yet want to mod my present rig while the bugs get worked out of BMCs/others before building up a completedly new e-bike.

 

[morph999]

you could try putting a 12v SLA onto your current configuration for 60v maybe. I don't know if you're controller could handle it. The problem is that 408 isn't really built for speed like 406 is. What would be even better is the new NC 2805. That would definitely get to 30 mph at 48v.

I run 60v on my Forsen and it gets to 30 mph.

 

[Russell]

Russell, top speed with present 48V 25a controller is in the 21-23mph range. I generally pedal in 6th gear (of 7) at 19mph to minimally assist the motor at around 90% throttle. Oh yah yah, series or parallel, a flashlite multiplies V in series, somethin' like that, thanks, I ought to know :? Rusy, I enjoy and need the 'silence' such as the C-lite 400 motors. The country dogs can hear almost anything coming down the road and be there waiting to bite Plus I wear hearing aids, a motor whine would be annoying, so I don't consider the C9 clearly superior to the C408.

The batts have the same voltage, chemistry, and isn't extreme apart on the amp hrs, 8.2ahr for the used; 5.6ahr new. Though the batt may cost as much as a C9, it would be simple to add vs switching out the controller, wiring, and wheel. I did consider your suggestions yet want to mod my present rig while the bugs get worked out of BMCs/others before building up a completedly new e-bike.

That 5.6Ah battery is pretty pricey ($350+shipping) and with it in series with the 8.2Ah battery gives you a 5.6Ah/72V battery. You won't want to drain the new little battery much beyond 80% so that leaves you a 4.5Ah/72V battery or 324Wh. Unless you limit your current you're also going to be running those batteries way too hard (25A is 4C). Then again you'll also likely need a new controller to handle 72V.

If you have to buy a new 72V controller then you might as well get one that can handle 84V then use your old 36V battery in series with your present 48V battery for 84V.

I think the best solution if you want to retain your present set-up is to see how much voltage your controller can handle then add a ??V/10Ah booster to your 48V/10Ah main battery, which will give you a full 10Ah at whatever voltage.

I mentioned switching to a 9C because you can reuse your old controller, wiring, etc. and just buy the 2806 in a rim. You might have to reterminate the motor connectors but otherwise it would be an easy and less expensive swap than the battery purchase. The 9C does have some noise to it but it's not really as loud or irritating as you make it out to be, besides when you get up to 30 mph all you'll hear is the wind


-R

 

[DerekG]

I mentioned switching to a 9C because you can reuse your old controller, wiring, etc. and just buy the 2806 in a rim. You might have to reterminate the motor connectors but otherwise it would be an easy and less expensive swap than the battery purchase. The 9C does have some noise to it but it's not really as loud or irritating as you make it out to be, besides when you get up to 30 mph all you'll hear is the wind

Having a 9C I can attest to that... The only time you get noticeable noise is when accelerating hard, going up a steep hill or when the motor matches the resonance frequency of the case.

Once you get up to speed the wind is much louder than the motor and even your tires make more noise

 

[dogman dan]

I agree, I doubt the motor noise is much of an issue once above about 22 mph, and it would have to be real loud at 30. Which brings you to, maybe you'd be real uncomfortable with that much wind noise in a hearing aid? At slower speeds though, I agree a silent motor is a joy. Most dd motors are silent once cruising. They just grunt some under heavy loads.

Anyway, the solution is real simple, Clyte 406 or 407 instead of the 408, which is a pretty slow motor. I belive the 407 should get you close to 30 and the 406 for sure at 48v. If you want to go up the hills no pedaling, then a BMC motor may be what you need. For me the dog issue is easy, I simply turn around and confront them psycologically, ( don't try this at home viewers) I can do it.

Nothing wrong with the idea of going to 72v though, I'm sure you'd love it on hills. It just gets expensive, heavy, etc. With a good set of contactors, you could make a boost switch to add volts when you need it, using a drill battery or such for short bursts. But again, a pain compared to just buying a faster motor.

 

[dogman dan]

As far as the series connecting, you really need to use matched batteries. Same everything. If you don't the weaker one will get murdered by 100% discharges unless you have some serious discipline about stopping in time. Fine if the batteries are freebies, but not for anything new.

 

[Drunkskunk]

Rusy, I enjoy and need the 'silence' such as the C-lite 400 motors. The country dogs can hear almost anything coming down the road and be there waiting to bite Plus I wear hearing aids, a motor whine would be annoying, so I don't consider the C9 clearly superior to the C408.

I have both a Clyte and a 9C. the 9C is noisier than the Clyte, but its a low growl, not a high pitch whine. You aren't going to get a high pitch whine from a direct drive hub motor at 20mph. 20mph with a 26" wheel is a motor rpm of 254rpm thats a frequancy of 254hz, a low bass tone at best.

But I did notoce that when filming on my bike, my camera mike picks up a very high pitch whine from the Controller. it does it on both the motors's controllers. its not a normaly audible sound, but an electronic mic is going to pick it up so your hearing aids might not react well to a brushless controller.

 

[SoSauty]

Thoughtful helpful remarks; Looked into the NC 2806. Good to know 1st hand that the noise isn't problematic. I'm guessing that without a new controller, the NC '06 would cost the same as the batt. Yet with present 25amp controller, I'd lose 2-3mph, so there's the trade off; another $110 for 35amp controller. I'm open to the NC though.

About the pricey batteries, I run both the 'Lith-ion its-electric' and the 'LiFePo4 Ping' and find both to be flawless. The Ping wins on $$value, yet I'll buy the its-electric batt next time due to smaller size allows 'em to be mounted in the frame triangle. Less weight and lower center gravity, makes a worthy difference.

Still, 72V should give some effiecent mileage at 19mph, 2X's 5.6ahr, as 27mph would only come into play for laughing at the tired cheetah dogs. For now I have to scratch the slightly mismatched 36V batts idea, at least until further study shows more plausability.

How to sound like an e-bike engineer, read the Endless-shpere forum.

 

[sprocket]

I have both a Clyte and a 9C. the 9C is noisier than the Clyte, but its a low growl, not a high pitch whine. You aren't going to get a high pitch whine from a direct drive hub motor at 20mph. 20mph with a 26" wheel is a motor rpm of 254rpm thats a frequancy of 254hz, a low bass tone at best.

I have a 9C as well and while it doesn't whine, it certainly makes noises above 254Hz. First of all, 254rmp is Revolutions per MINUTE while 254hz is Cycles per SECOND, so I have no idea what you are thinking there. Secondly, there is no reason to assume that the motor noise is a single tone at the frequency of the wheel. The noise is most likely caused by the changing force on the stators as they swing past the poles and may well be a convolution of the natural vibrating frequency of the stators, the hub housing, and the driving force (which changes with RPM).

In any case, anyone who buys a 9C should be ready for a moderate, but noticeable, electric motor sound during acceleration.