Can I run an 8Fun 36V350W hub motor at 48V?

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EbikeJamie
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Can I run an 8Fun 36V350W hub motor at 48V?

Post by EbikeJamie » Jul 30, 2017 6:37 am

Hi

My first post, after lurking for about 5 years and reading lots of useful info! But now I've got some specific upgrade questions.

My 36V battery died, and my controller isn't in the best of condition, so I'm thinking it would be a great time to upgrade my kit to something with a bit more power!

Motor is still going strong after 5 years, so I'm curious as to whether I could run it at 48V, and how it would perform?
The motor is a front geared hub labelled as: 8Fun BPM36V350W 26(13).

If i got a new 48V battery and a 48V controller, will the motor handle 48V OK at whatever maximum power the controller can deliver? Am I likely to see any significant speed and/or torque increase? At 36V I was getting sufficient torque until about 28km/h then a weaker increase up to 32km/h in good conditions (at which point power was cut off by controller). For an upgrade I was hoping to get similar torque and speeds of at least 42-45km/h.

Any recommendations for a 48V controller for this motor, if it will handle the juice?

As an alternative I'll probrably upgrade the motor to MagicPie 5, so don't necessarily want to buy controller to give it try, if there is likely to be no performance increase running the old motor at 48V.

Thanks
Jamie

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by d8veh » Jul 30, 2017 12:43 pm

You will get 33% more torque and the motor will spin up to a top speed of 33% more. if you tell us what writing there is on the motor, we can tell you what the top speed will be and the real world speed on the road.

It will run very smoothly if you use a KT sine-wave controller with an LCD. This one from PSWpower is pretty good, and it's a perfect match for the 350w BPM:

http://www.pswpower.com/peng/iview.asp? ... 33C0.50CGS

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by EbikeJamie » Jul 31, 2017 1:50 am

Thanks d8veh! Prices look very decent on that site. Assuming they are a reliable seller? How about their batteries?

The only writing on the motor (outside) appears to be 8Fun BPM36V350W 26(13) and looks like a serial number: 1207065491
The wheel size is 26".

I found what looks like the same motor on Alibaba:
https://www.alibaba.com/product-detail/ ... 1abcLjSS4A

It confirms 36/48V compatibily, though I see speed is rated at 32-38km/h and Max RPM is 285-300. Would this suggest the max speed might only be 37km/h (300rpm with 26"), or would these numbers be conservative?

Thanks

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by d8veh » Jul 31, 2017 3:04 am

Code 13 is 235 rpm at 36v, which is about 19 mph on the road with a fully-charged battery. At 48v, it'll be 312 rpm and about 23 mph on the road.

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by EbikeJamie » Jul 31, 2017 6:29 am

Pretty much exactly what I was getting at 36V and what I worked out for 48V from the specs. So not quite 33% faster.

Bit short of what I was hoping, but certainly a stepping stone upgrade to consider. But maybe I will splash out for the the Magic Pie 5. I'm assuming the higher power would make up for any loss in torque due to the lack of reduction gearing in the direct drive motor?

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by 999zip999 » Aug 01, 2017 10:33 am

Get a great battery. Heart of electronic bike.

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fechter
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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by fechter » Aug 01, 2017 12:46 pm

It could probably take 52v (14s li-ion).
"One test is worth a thousand opinions"

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by d8veh » Aug 01, 2017 5:54 pm

EbikeJamie wrote: Bit short of what I was hoping, but certainly a stepping stone upgrade to consider. But maybe I will splash out for the the Magic Pie 5. I'm assuming the higher power would make up for any loss in torque due to the lack of reduction gearing in the direct drive motor?
I doubt that the magic pie 5 will beat the BPM for torque.

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by EbikeJamie » Aug 07, 2017 8:18 am

Thanks for your comments.

Well I've decided to try the BPM at 48V, and have a battery on it's way. Not a lot of choice here in NZ, so battery ordered with sketchy details of 48V14ah with Panasonic cells in hailing/shark style pack, unsure of cell configuration or continuous rated discharge, hopefully it is reasonable.

I'm thinking of ordering a controller from BMS Battery, mainly as they have some other bits I'd like to order, and the controllers/displays seems to have plenty of support.

One question I have... it seems the S12S 500W controller is a popular choice. Is there any reason why I wouldn't choose one of the larger sine wave controllers, e.g. an 800W S12SH or 1000W S12SN model for a few dollars more? Apart from maybe some size/weight difference? Would an over-powered controller force too much power into the motor or strain a lower spec battery too much, or can this easily be adjusted for the battery/motor? I'm just thinking for the small price difference, a more powerful controller could be a worthy investment for a future motor upgrade.

I'll probably get the LCD6 display, I assume it will have the same programming features of the more commonly mentioned LCD3?

Thanks

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by Voltron » Aug 07, 2017 8:49 am

Re your last questions, yes, too much controller can force too much power thru the motor and crush a battery that can't supply the power, and do both things at the same time.

That being said, if you're a prudent user, and hit the power in short bursts with time to cool down in between, the bigger controller could be fine, and give you a little reserve for the odd short steep hill here and there.

It all comes down to your throttle discipline.... How's yours? :D

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by fechter » Aug 07, 2017 6:37 pm

Most of the larger controllers are programmable so you can set the limit lower than the max rating.
"One test is worth a thousand opinions"

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by EbikeJamie » Aug 08, 2017 3:46 am

Voltron wrote:
It all comes down to your throttle discipline.... How's yours? :D
I've never bothered with a throttle in the past, and just gone for max power with PAS acting like on/off switch. So could be a problem there, but with new controls could simply lower the PAS level. Won't have a cycle analyst to monitor how much I'm drawing to know where to dial the power down to. So maybe would be safer just to go for the 500W controller. But short power boost feature would be fun, maybe controlled by to a red button with hazard symbol and a protective tab you got to flick back first to access...LOL

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by d8veh » Aug 08, 2017 4:10 am

The 350w BPM doesn't respond to any more than 22 amps, so no point in going any higher. 48v will already give you 33% more power, so you'll probably find that 20 amps is enough. I'd go with the PSWpower 20A sine-wave one.

The speed calculaions I did earlier are theoretical based on the numbers you gave. Whatever speed you actually get with your 36v battery will increase by 33% with 48v. That applies to the no-load speed. Speed on the road depends on conditions, like weight, hills, wind, etc., but if you were getting about 22 mph, you should see a significant increase.

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by EbikeJamie » Aug 08, 2017 8:50 am

d8veh wrote: I'd go with the PSWpower 20A sine-wave one.
Any reason why? Any particular advantages of the PSWpower KT-controllers vs the BMS S-controllers?

With the KT controller can you switch between current and speed control for the PAS using the LCD, like you can with the S? I'm not convinced I'd be happy with current control, but would like to try and compare it.

Thanks

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by d8veh » Aug 08, 2017 4:09 pm

It's 20A. The only one that BMSB has is the 20A 09 Dolphin battery one, which is OK, but not as serviceable as the aluminium box one. The S12S is too big

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by EbikeJamie » Aug 11, 2017 10:41 am

My new battery arrived today in time to play with it over the weekend. :D Opened up the hailong case and appears to be 14S3P panasonic GA cells. Seems about half the size and weight of my old LiFePO4 rack battery.

Before ordering a controller, I thought I'd take a look at my existing controller. Turns out it is a Nine Continent 36/48V Infineron type 9 fet 22A controller. However it is marked as set to 31.5V LVC rather than 42V. When I bought the kit 5 years ago, I was told that the controller was only for 36V, but I guess the reference is to the hardwired LVC. I'm keen to give it a go, even if as a temporary measure until a new sinewave controller comes from China. Can I safely ignore the LVC, provided I keep an eye on my battery level?

If not, on the PCB there is an occupied point marked +48V that links off towards a cap (I think), immediately next to it is another point linked to the end of a 200 ohm resistor (only connected to the circuit at the other end). Would it be likely that a simple jumper wire between these two points will add appropriate extra resistence set it to 42V LVC?

There are also three other points in same row. One heads off in the same direction (towards cap), another links to a point alongside the other wiring points and the final one is a ground. I'm guessing these may be for an external LVC switch and I could safely ignore them?

If it works, I imagine I'll still have the artifical 32km/h limiter to try and hack. Is this linkly to be a hard wired setting, or software only? There are five programming connector points (though no pins).

Time for bed. Thanks in advanced for any suggestions before I potentially blow it tomorrow! :lol:

Will be nice to have power again!!

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by d8veh » Aug 11, 2017 5:43 pm

It's probably a good idea to show a detailed photo of the PCB in that area. I've seen PCBs that had a an optional resister that you could jump in or out to change the LVC between 36v and 48v.

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by EbikeJamie » Aug 12, 2017 11:07 pm

Quick update.

I had a closer look at the resistor in the morning light, and found it also a PCB track running back under the resistor and out towards a little black M5. So I thought I'd better not touch what I don't understand and just give it a whirl...

WOW! So much POWER!!! :lol:

Was precisely 33% faster and more torque. Doesn't see that the quoted max RPMs apply to this motor version as I'm now getting 43km/h (26.7mph) (unloaded or on road with pedelling) and about 38km/h (23.6mph) on road motor only.

So I'm extreamly happy with this result. Motor or controller don't seem to be getting hot, just warm. For not just got to watch the battery level.

Been busy reorganising all my wiring and making an brake motor cutoff out as it is too scary to ride without it now! I'll upload the PCB detail later for advice on 48V jumpers for LVC.

Thanks!

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by 999zip999 » Aug 13, 2017 2:38 pm

Plus handle bar kill switch. Off/on switch a must. Play nice with the battery and don't fun to cutoff as the rule.

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by EbikeJamie » Aug 14, 2017 8:03 am

Hi

Here is a pic of the controller board. I thought at first that the R01A point only linked off to the 2nd point in the +48V boxout, but it actually links also to D5 (the M7 diode). Anyone got any ideas on about the +48V boxout?

Excuse the corrosion, tried to clean it up a little. I actually poured water out of the controller after a cyclone hammered my bike parked outside at work. Surprised how much water got in, considering it was underneath the rack battery and had all the silicone seals intact. Battery fuse blew, which probably saved the controller. The battery was full of water too which corroded and killed the BMS. A couple of weeks later my work built a covered bike shed... just little too late.
Controller.jpg
Cheers

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by d8veh » Aug 14, 2017 9:53 am

I wouldn't bother with controller. You should get a KT one with LCD. They give really nice adjustable PAS. You can see how much power you're using on the LCD. They have current control on the PAS, so you can turn the power up and down.

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Re: Can I run an 8Fun 36V350W hub motor at 48V?

Post by markz » Aug 15, 2017 2:51 am

I gotta agree with the KT display, I love it.
I gotta book mark that website - http://www.pswpower.com
and add it to my list. Been wondering about that link for some time, wanted to see if theres something more then 40-45A cont like my Conhismotor.

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