First 18 mile test run with S12S, 48v battery, and MXUS cassette motor.

[eHomer]

I've just returned from my first test run with my upgraded setup on my DIY Giant Trance.

I bought one of Dave's rear MXUS motor's with the cassette spline last year, and originally ran it with my 36v battery.

I've now rewired it with a BMS S12S sinewave controller and 48v lithium ion battery in a detachable bottle fitting carrier.

Unfortunately, there wasn't enough room in the Trance's full suspension frame, so I mounted the battery and controller on a backing board and fixed that inside a small 12 litre pannier bag.

The result is very stealthy, yet still reasonably secure, since the battery is locked into the carrier which is bolted through the pannier to the rack, (and out of sight). It's quite light, so doesn't throw the balance, and the weight is low well.

The range seems very good, 18 miles at an average of about 15 mph, and the GT battery meter shows only 5.5 amp/hours used up (half of the 10.5). The remaining voltage was just under 48 volts, so I'm assuming the BMS battery level gauge is fairly accurate, showing half the level left ?

 

[Deleted member 4366]

Well, how was it? Was it worthwhile upgrading to 48v?

 

[eHomer]

Well, how was it? Was it worthwhile upgrading to 48v?

Yes Dave, your advice on upping the voltage where possible has certainly made a big difference with the MXUS motor.

It was good with my 36v 10ah lithium pack, giving a max of about 18 mph and a range of about 20 miles, assisted.

With this 48v battery and the sine wave controller the difference in power is really good, and the shunt reduction mod must be ok because the motor doesn't even get warm after a high speed run (though admittedly, on the flat). I had it up to 24 mph, and it would have probably gone a shade higher. Though I still cruise at about 16 mph, to avoid wasting power against the disproportionate buildup of wind resistance.

I won't know what the max range is for sure until I run the battery to lvc on a run, but if it does actually hold 10ah, then it's going to be just under 40 miles, going by the ah used on the GT power meter.

 

[Deleted member 4366]

Thanks, so it looks like this could be a worthwhile mod on any 250w hub-motor, especially if your 36v battery is knackered.

 

[eHomer]

Yes, certainly nice with the MXUS.

The sinewave controller makes the motor quieter too.

That runs nice and cool too, even though it's in the pannier. I mounted it on standoffs, but it looks like there was no need, because of the shunt current reduction, nice and unstressed I suppose.

I do like the sinewave PAS too, a wide range of assist, with level one being quite usable for 10 to 15 mph.

I would have considered the new BMS 800 watt sinewave controller for my old direct 1000w motor that was modified down to 36v / 750 watts, but the MXUS seems plenty powerful enough, so much lighter, pretty quiet, and zero drag on freewheel. A perfect ebike setup for me really.

 

[eHomer]

I've just had another long run on this battery and motor, (well, "long" for me anyway ).

24 miles mostly at assist level 2.

The BMS LCD panel battery level was showing half, and the Power meter showed 5.5 a/h used.

The standing voltage was 47.2 though, compared to 53 volts fully charged.

Am I right in thinking that the battery was therefore quite a bit lower than half discharged ?

What would the actual LVC voltage limit be for this type of battery ?

I'm assuming there's an LVC for the battery BMS and another for the S12S controller ? If so, as the S12S is dual 36/48v, how does it auto-sense for the correct LVC ?

 

[Deleted member 4366]

The auto-sensing is errrr.... automatic. don't ask me how it works. It's a total mystery to me. My guess is that you've used about 55 - 60% of the battery based on discharge curves that I plotted using my battery tester.

 

[Tangsoo]

That battery's lating well for a 10ah.. - can I ask where did you get it from

 

[eHomer]

That battery's lating well for a 10ah.. - can I ask where did you get it from

I got it from a UK based ebay seller, and he's still listing them:

http://www.ebay.co.uk/itm/2014-Model-48V-10-4ah-bottle-holdermount-lithium-Li-ion-electric-bike-battery-/141258290667?pt=UK_Bikes_GL&hash=item20e3a675eb

 

[eHomer]

The auto-sensing is errrr.... automatic. don't ask me how it works. It's a total mystery to me. My guess is that you've used about 55 - 60% of the battery based on discharge curves that I plotted using my battery tester.

My question did sound a bit naive I suppose !

I was just thinking about auto sensing working with LVC, if there was any danger that the controller might drop to 48v LVC, and then think it's a 36v battery, and then drop to the 36v LVC, and damage the 48 v battery.

That's good news then, I'm very happy with 55 to 60% used after 24 miles, and it bears out the Power meter's 5.5 a/h used, so that's going to be a very handy "fuel gauge" while out riding.

 

[Deleted member 4366]

No, don't get me wrong. It was a very good question. I wish I knew the answer. All I know is that it gets it right.

 

[amigafan2003]

I was just thinking about auto sensing working with LVC, if there was any danger that the controller might drop to 48v LVC, and then think it's a 36v battery, and then drop to the 36v LVC, and damage the 48 v battery.

If you could confuse the controller (unlikely as a fully charged 36v battery is still lower in voltage than a discharged 48v battery) the BMS on your battery should protect it.

 

[eHomer]

Fingers crossed then.....

Call me paranoid, but there's a just a hint of "reserve parachute" about it then.


(Ok, maybe super paranoid...)