Maximum battery for BBSHD

[Thomsontouring]

Eight years ago I put together a BBSHD build for cruising the rural back roads on weekends. I scored a V1 Ludicrous controller from a friend's second hand Luna bike. I put in a 17Ah Em3ev battery running a nominal 52v. It's been running fine but after 9000 miles I was noticing a lot of voltage sag. It could easily drop 7-8 volts when given a lot of throttle, but I surprisingly never tripped the BMS. It was just sluggish, especially in the winter. The motor should have been drawing 60A and the BMS in the triangle battery was rated at 35A continuous / 51A burst.

So early this year I ordered an e-moto battery from Amorge, after carefully mocking up the size and shape to prove that I could really squeeze it into my small frame triangle. It took a full 8 weeks to arrive by sea, but the packaging was superb. I got a 35Ah 52V battery because the early Ludicrous can't take anything over 60V. But to ensure I never ran out of amps, I specified a 340A BMS and 14s7p EVE 50-PL tabless cells.

Long story short - I got the battery into the bike and it's a whole different animal. If I'm not careful it will wheely or scratch out on every start. It never exhibited close to that kind of behavior before. It's as if the battery is now pouring in amps where before it was dribbling them. I haven't tested the max speed but it's geared for 43mph unloaded in top gear. With a full battery it should be putting out 3400 watts.

 

[mrmojorising]

Massively excessive battery love it. How much does that thing weigh?

I've got a much smaller custom 20S5P Amorge 72V on my BBSHD and that is heavy enough. At least you have the metal battery box for added safety

Be interested to see some range test results

 

[Thomsontouring]

It weighs 22 lbs. My 17Ah battery weighed 13 and I sometimes carried a 13Ah shark battery as a spare. That gave me 30Ah which together weighed about the same as the Amorge. So I knew that the bike could handle it. The longest ride I managed with 30Ah was 72 miles. I think 35Ah will get over 80 and maybe I can push it to 100.

 

[mrmojorising]

It weighs 22 lbs. My 17Ah battery weighed 13 and I sometimes carried a 13Ah shark battery as a spare. That gave me 30Ah which together weighed about the same as the Amorge. So I knew that the bike could handle it. The longest ride I managed with 30Ah was 72 miles. I think 35Ah will get over 80 and maybe I can push it to 100.

Oh I had a brain fart moment and forgot this is only 14S, so my 20S pack is actually more cells, just a bit lighter due to not opting for the metal case. I think it weighs closer to 8kg (17-18Lbs)

Awesome range, do you get any Wh/Mi and avg power stats from your controller? Based on what you've said, 21.6 Wh/Mi is pretty solid efficiency. Pretty similar to what I get with 72V, averaging about 800-1000W

 

[Thomsontouring]

My controller doesn't do the calculations but I've done enough rides to know that if I consciously conserve the motor I get about 22Wh/mi. With this new battery there's the temptation to just open it up and ride at 30mph, which drops the efficiency to over 25Wh/mi. That's fine if I'm only planning to ride 30 or 40 miles and want to have fun in "motorcycle mode". But if I'm pushing for long range I'm going to be pedaling more on uphills and coasting more on downhills. I live in a very hilly area.

I once did 52 miles on my 17Ah battery by itself (16.5Wh/mi) just by being frugal with the throttle.

This is what the bike looked like with both 14s6p and 14s5p batteries from Em3ev on it. The center of gravity is now lower with the single larger battery.

 

[mrmojorising]

For sure, I wouldn't want to ride faster than that on the small tires and brakes you have going there either

 

[OlderGiantFan]

I'd be checking the spoke tension too, regularly!

 

[Thomsontouring]

For sure, I wouldn't want to ride faster than that on the small tires and brakes you have going there either

In that old picture I had standard V-brakes in the rear, because there were no disk brakes lugs on the frame. Now I have Magura hydraulic rim brakes and they're much more positive. In the front I have hydraulic 203mm disk brakes.

I'm using Schwalbe Energizer Plus tires with a ECE-R25 rating for Ebikes. They have a 3mm puncture resistant insert. In 9000 miles I've never had a flat. Heavy but super reliable.

I'm not such a huge guy - 163 lbs - so I figured an extra 9 lbs of battery mounted low and center wouldn't affect handling much. It doesn't.