Bafang Voltage/Amp

sacko · Jul 10, 2012

I have order the following;

Bafang 36v 500w Motor
KU123 Controller
26" wheel

I had intended using a 44.44 2s2p lipo (Turnigy 6s 5000) but have the opportunity to run 55.5v (Hyperion 5s 4200mah).

Would anyone recommend this? Or too much for the nylon gears?

There is a 1km hill which is reasonably steep (Pic below shows half the hill)

Stick with 48v or go with 55.5v?

d8veh · Jul 10, 2012

You'll go 25% faster with 15S, but hill-climbing won't be much better. When you go faster, you use your battery a lot quicker. 15S2P will give 55v and 8.4aH, so you need to think about whether that'll give enough range for your journeys.

If it were me, I'd go with 12S first, and then, if I found I wanted more speed, I'd buy a couple of matching 3S packs to add.

I wouldn't worry too much about the nylon gears. They're pretty durable as long as you stick to about 25amps most of the time and maybe 40amps for short hills.

sacko · Jul 10, 2012

Thanks for the input Dave, was going to PM you on Pedalecs but you dont seem to frequent there as much.

If I went down the 55.5v route, I will go 3s3p; 55.5v 12.6Ah

My total journey is 20 miles.

Both options are around the same cost, but the 55.5v pack will be a lot better quality.

Jeremy Harris · Jul 10, 2012

I'd second the comment about the gears in the Bafang. Mine's been running on around 15 to 20 A a lot of the time, 30 A maximum, for around two years now. It's slightly noisier now than it was when new, but nothing to really worry about.

sacko · Jul 10, 2012

Many thanks for replies.

As you an probably tell, I'm leaning towards the 15s setup as the cells are excellent quality, in the UK and cheap.

dogman dan · Jul 10, 2012

I wouldn't sweat the gears if you keep the stock controller. Assuming it's a 12 amp or 15 amp version, you won't have the wattage to strip the gears even at 15s voltage. Most of the gear strippers I recall ran well over 1000w, like 30 amp controllers.

15s is borderline for 63v caps in the controller. If you are concerned about that, get 14s, or charge the 15s to 4.1v. 4.2 x 15 =63v. But in practice, you will drop to 62v in about a block of riding, and be in the meat of the discharge in a mile or so, closer to 60v. If you are going to bulk charge, just set the charger to 61v or so.

sacko · Jul 10, 2012

I'll be parallel charging on a CellPro PL6, will set each cell at 4.1v.

I thought the KU123 was a 30amp controller?

sacko · Jul 10, 2012

I'm presuming the KU123 comes with the 36v 500w kit?

Just seen this below, 30a to 40a it would seem.

http://www.pedelecs.co.uk/forum/electric-bicycles/10296-bmsbattery-controller-amps.html

d8veh · Jul 10, 2012

I used the KU120 with 10S lipo and it gave 30A, but when I changed to 12S it gave 40A. It was a 36v or 48v controller, so I don't know whether the software was clever enough to detect the voltage and adjust parameters accordingly. 40 amps was too much for me, so I went down to KU93s with shunts solsered to 25 amps. I never tried the KU123, but I see they are voltage specific so might not behave in the same way.

sacko · Jul 10, 2012

I may try the KU123, but try and add a KU93 to my order just in case.

Or remove some solder from the shunts on the KU123?

sacko · Jul 14, 2012

Ended up adding a KU93 to my order via email, may do the shunt mod to that first; if it isn't enough I will fit the KU123.

I also ended up adding two 3s 5000 packs to my ever increasing Hobbyking order!

Bafang Voltage/Amp

sacko

10 kW

d8veh

1 GW

sacko

10 kW

Jeremy Harris

100 MW

sacko

10 kW

dogman dan

1 PW

sacko

10 kW

sacko

10 kW

d8veh

1 GW

sacko

10 kW

sacko

10 kW

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