P14 setting on SW-900 display

General Discussion about electric bicycles.
Post Reply
salex1   1 µW

1 µW
Posts: 4
Joined: Dec 03 2019 10:47pm

P14 setting on SW-900 display

Post by salex1 » Dec 04 2019 2:45am

Hi all, I am planning to put together a 1500w ebike kit that I purchased online.

It is a 48v 1500w Violamart rear-hub kit with a built-in controller and waterproof higo connectors. This will be paired with a 52v 17.5Ah Samsung-3500 cell battery w/ 40A BMS

No information was provided about the "programmable built-in-internal controller", but it seems that it is programmable through the SW-900 display.

This SW-900 display has a parameter setting P14. It is described as follows:

"P14 - Current-limiting of Controller. The original Current is 12A. Range 1-20A"

I don't really understand this. My reading of this with my limited understanding would be that if this setting was set at the max 20A, and with a fully charged battery at 58.8v, this would equal about 1176w going to the motor at max load. However, this seems really low for a kit sold as a 1500w kit.

So my question is, Can anyone tell me what this setting does and how it might affect my performance with this kit? I was thinking that this kind of setup would have at least a 35A controller in order to get the desired wattage to the motor.

Thanks,

AHicks   100 W

100 W
Posts: 271
Joined: Jul 24 2018 10:53am

Re: P14 setting on SW-900 display

Post by AHicks » Dec 04 2019 8:55am

My take, others may have different opinions. From what you say, you may have a 20a bottleneck between your motor and your battery.

As far as supplying that controller with a 1500w motor, there's no way whoever put that "kit" together might have known you were going to use a high capacity battery to feed it. This is a big piece of checking out ALL of the specs when sourcing parts for a project like the one you've taken on.

I know for sure that 20a max controller rating would be perfectly suitable for other batteries.

I also know you can get a 1500w hub motor with a good 20a feed pretty hot under certain conditions. A long 10mph climb for instance....

User avatar
E-HP   100 kW

100 kW
Posts: 1179
Joined: Nov 01 2018 9:20pm

Re: P14 setting on SW-900 display

Post by E-HP » Dec 04 2019 10:17am

salex1 wrote:
Dec 04 2019 2:45am
Hi all, I am planning to put together a 1500w ebike kit that I purchased online.

It is a 48v 1500w Violamart rear-hub kit with a built-in controller and waterproof higo connectors. This will be paired with a 52v 17.5Ah Samsung-3500 cell battery w/ 40A BMS

No information was provided about the "programmable built-in-internal controller", but it seems that it is programmable through the SW-900 display.

This SW-900 display has a parameter setting P14. It is described as follows:

"P14 - Current-limiting of Controller. The original Current is 12A. Range 1-20A"

I don't really understand this. My reading of this with my limited understanding would be that if this setting was set at the max 20A, and with a fully charged battery at 58.8v, this would equal about 1176w going to the motor at max load. However, this seems really low for a kit sold as a 1500w kit.

So my question is, Can anyone tell me what this setting does and how it might affect my performance with this kit? I was thinking that this kind of setup would have at least a 35A controller in order to get the desired wattage to the motor.

Thanks,
Well yes, the 20 amp controller is not enough to provide 1500 watts continuous to the motor, but that's probably a good thing. The motor and controller have enough of a challenge staying cool, but when the controller is housed in the motor, you wouldn't be able to dissipate the heat if you ran it at 1500 watts continuous anyway. Great battery though, which you should be able to use when you upgrade.

salex1   1 µW

1 µW
Posts: 4
Joined: Dec 03 2019 10:47pm

Re: P14 setting on SW-900 display

Post by salex1 » Dec 06 2019 2:20am

Thanks for the input guys.

Still doesn't make sense to me.

So if I am reading the user guide for the SW900 that came with my kit correctly, the default value for the P14 setting i.e. "Current Limiting of the Controller" is 12A, and the max setting is 20A.

Okay that sounds straightforward, if I put this setting on 20A, and ran my motor at full-load, I would be limited to a max current of 20A at 58.8v resulting in around 1176w going to my motor. The full potential of the motor would never be realized and I would get more range out of my batteries and life out of my motor and its internal controller, etc.

But what about in the case of a 48v 3000w kit with a 65A external controller and the same identical SW900 display?

Surely the P14 Current-Limiting of the Controller setting on the SW900 display is doing something other than creating a 20A bottleneck in any ebike running this display, right?

Here are the links I am referring to:

https://ebikeling.com/blogs/news/how-to ... parameters

https://ebikeling.com/collections/conve ... ersion-kit


salex1   1 µW

1 µW
Posts: 4
Joined: Dec 03 2019 10:47pm

Re: P14 setting on SW-900 display

Post by salex1 » Dec 06 2019 10:40am

Yep that's the one

AHicks   100 W

100 W
Posts: 271
Joined: Jul 24 2018 10:53am

Re: P14 setting on SW-900 display

Post by AHicks » Dec 07 2019 10:36am

I think the answer regarding the amperage the sw-900 is capable of might be best answered by the vendor. I think the point is a darn good one, and have to wonder why they are offering this package - unless they are OK with a 20a max output.

That said, I think you may be better served with a KT based display (LCD3 for example) and KT controller when it comes to this type of "kit".

User avatar
TommyCat   1 kW

1 kW
Posts: 369
Joined: Jan 22 2018 8:05pm
Location: North-west Illinois, USA

Re: P14 setting on SW-900 display

Post by TommyCat » Dec 07 2019 10:54am

I would be curious if the PO8 speed limiting setting would make a difference. And in the advisement, what's that about a speed limited function wire?
See my completed Magic Pie V5 rear hub E-Bike build Here!

salex1   1 µW

1 µW
Posts: 4
Joined: Dec 03 2019 10:47pm

Re: P14 setting on SW-900 display

Post by salex1 » Dec 08 2019 6:40pm

Ok I got the kit installed and powered it up. Max setting for the current limit on this SW900 is 40A, not 20A as it states in the included manual. I guess this was just outdated info.

Bike is running good.

User avatar
thundercamel   1 kW

1 kW
Posts: 330
Joined: Jul 23 2018 2:58pm
Location: Round Lake, Illinois

Re: P14 setting on SW-900 display

Post by thundercamel » Dec 18 2019 4:22pm

My ebikeling kit came with the sw900 display, and that 1-20 amp setting doesn't make a difference for me at all.
My Ebike builds - Existing bikes, affordable motor kits, self built 14s6p batteries - Now with more recumbent!

Post Reply