Adding Battery Capacity

[electric 2 wheeler]

I have a 2013 Empulse Standard model with 22,000 and decided to add an extender pack for more range. I tapped into the main battery pack at the most negative battery module terminal and for the positive lead to the Battery side of the contactor. I built two 10 P 14 S 18650 cell batteries using LG M26 cells so about 26 amp hours. They are installed  in boxes on each side of the bike forward of where your legs would be when stopped. They are hooked up to the main pack through a 120 amp Anderson connector that comes out on the right side just forward of the foot peg. There is also a 50 amp Anderson for connecting a battery charger. I've put a few hundred miles on them and they seem to give an extra 20 miles range in mixed driving. Great ! I also spliced into the AC charge plug and put a female plug down by the 50 amp Anderson to plug the extra charger into so now I can plug into a level 2 charger and then plug in another portable charger using the same power source. It all works fine and the % meter reads correctly. The only difference is that the KW reading on the instrument screen reads only the power going in and out of the main pack minus what is going into the extender pack. When I lug into 120 ac I usually see 11 amps but now only 8 or 9 because the rest is going to charge the extender pack. The charger is still charging the same total as always. I'm looking forward to doing some short distance touring this summer.

[siai47]

Nice work.  I like the location you have decided to use for the additional battery cells.  The lower the better.  I am glad you are getting the extra range you have been looking for.

The only question I have is what are you doing for cell balancing?  The BMS in the bike itself will balance the internal pack and it will limit the charge and discharge limits of the internal pack.  However, it has no idea of what the external pack is doing.  If it goes out of balance (and over time it will) you could overcharge or overdischarge one of your parallel strings of external cells.  The fact that you have 10 cells in parallel helps lengthen the interval that balancing will be required by supporting cells in the string that have slightly different capacities from the rest of the cells. At a minimum you need to have a way to look at the individual parallel string voltages when nearly discharged and when fully charged to make sure the external battery is within limits particularly when reaching full charge.  Then you need a way to manually adjust the voltage of each string to get the pack back in balance until you can figure out an automatic balancing scheme.  There are fairly low cost balancers out there but many will not accommodate the output current levels of your pack.

Please keep us posted as to how this is working out for you and how well the external pack is staying in balance without automatic balancing.   

[electric 2 wheeler]

Thanks for the reply. I have had quite a bit of experience with lithium batteries. I ran my Vectrix scooter for two years and 6,000 miles on Chevy Volt cells with no balancing, just JST connectors so I could check the voltage with a small RC model tester. I never balanced them and they were just a few hundredths of a volt off from each other. I use a timer on that bike and never fully charge unless I am present and watching. I am doing the same with the  cells in the extender packs but have ordered two small waterproof BMS to install in the packs so I can leave the bike to charge unattended overnight at my shop. For now I just check the balance through the JST connectors that come out where the main power wires come out. The packs are drawing about 30 amps at 70 mph and the BMS are rated at 60 amps continuous. I have a couple I bought to test and use on other projects and I have run one for 10 minutes at 50 amps and it barely got warm so should work fine. The only issue is that the BMS are set to balance the cells to 4.2 v and the Brammo charges to 4.15 per cell so the balancing will not be perfect but I'm not to worried about that and the BMS will cut power or charging if anything bad happens.

[Shinysideup]

Nice work!

[sunchaser]

Really impressive work. 

[electric 2 wheeler]

I've had some time to put miles on the new battery pack and got my new charger so here is the report. The new charger is really a 2000 watt 100v charger I had built for a Zev LRC I once owned in series with a 14.6 v charger tweaked to 15. I built an adapter using three 50 amp Anderson connectors so I can plug the two chargers together in series for a 115v 17.6 amp total. The onboard charger will charge 24 amps when the battery is low so I am charging at about 40 amps combined. The whole lash up looks a bit messy but I can charge close to 40% in an hour. It's pulling a bit under 4.9 KW out of a level 2 EVSE. Most of my rides are on rural highways and suburban main roads so 35 to 55 mph and some 60 mph stretches. I've been recording the SOC % from the dash before and after I charge during the longer rides so I can compute a miles per % figure to get an idea of what my range is. I am seeing from 0.9 to 0.85 miles per 1% SOC so a theoretical range of between  85 and 90 miles if you ran the thing till it stopped. So I'm pretty safe figuring around 80 miles of range for the kind of riding I do. I got the 0.85 figure on a 114 mile ride from 30 ft elevation where I live on the Columbia river to over a 1000 ft in the foothills of the Coast Range at Timber, then  on to Vernonia and back down. There is a small mountain range in between with a pass of just over 1000 ft so I had to do that twice but at pretty low speeds due to curves ( fun). The 0.9 figure was flat 55 mph old highway 99E to Salem and back on 99W, 123 miles. I have no way of knowing what the bikes battery pack capacity is. I would guess around 7.5 K ( 7 year old pack with over 20K miles ) plus the new battery at around 2.6K so around 10K. My Vectrix with a 10.6K pack does 90 miles.
I also got the 2 BMS installed. I had to modify the end caps to get another half inch clearance. One on each pack. Here is a pic of my Vectrix just for fun. Mine is on the left. How often have you seen two blue Vectrix riding together?? Kind of as rare as two Empulses screaming down the road together. I have actually never seen another Empulse anywhere.
 There you have it, geeking out on electric motorcycles during a pandemic. Life is good here.

[HadesOmega]

Wow cool great job

[electric 2 wheeler]

Nice to see there are still some people on the forum. Thanks to everyone for the encouragement.

[empulsefan]

good job!!

[electric 2 wheeler]

Hi All
It's been 90 degrees here in Portland OR and riding on rural highways I can get one mile per 1% on the battery % meter !

[HadesOmega]

Nice I'm about 2% per mile.  What's the longest you've gone?  Mine gets about 60 miles

[electric 2 wheeler]

I took a ride yesterday on rural roads with speeds of 50 mph or less and got back to the shop with 32% and 68.4 miles showing on the GPS and something like 72 on the trip meter. The odometer and speedometer on the bike read a little high. I never like going below 10% so about 90 miles is what I consider to be the max range. I usually ride in 4th gear in sport mode which according to some test runs I have made is the most economical combination and I use 3rd sometimes if I want to have some fun and occasionally shift down to 3rd also if I want to get a little more regen and engine braking in the twisty parts. You could certainly reduce the range with more aggressive riding. Sometime I want to do a range test at 60 mph just to get an idea of how that changes the range. What speeds and riding style do you usually use when you ride? I have found that shifting up through the gears all the time like it was a gas bike is not efficient. If you are riding in traffic and just keeping up with the flow it is much better to just leave it in 3rd or 4th. You can always drop down a gear if you need more acceleration for pulling out into traffic.

[Shinysideup]

They say for efficiency, you want to keep the RPM in the 4K to 6K range.
(Also gives maximum power, which is nice )

My approach to the gears on the Empulse is sort of a "bracket concept":

Around San Francisco in hilly parts, just keep it in 1st, trying to keep the rpm up when creeping along slowly.
San Francisco in the flatter areas, 2nd is pretty sweet.
In more suburban areas, just keep it in 2nd for normal traffic, 3rd if can get up some speed between lights.
Upshift for highways to whatever gear centers the tach around 5K rpm.

I find that "Sport" mode yields better mileage due to more aggressive regen, provided I don't hoon around on the bike with all that nice torque available.

[HadesOmega]

He I love riding my bike in SF, I don't do it often as it's like at the max end of my range.

I have a 13tooth countersprocket so it might be different.  But in the city up to 40-45mph I generally just leave it at 1st so I can rocket off the stop lights.  2nd gear is up to to 55mph.  Then 3rd  up to about 65.  Then 4th probably 70mph.

It's totally dependent on speed and yes speed will chomp up your range faster exponentially faster.  They say to keep it at the lower portion of the green zone to get the best efficiency.  As long as I'm in there it's ok for me. 

[electric 2 wheeler]

When I talk about efficiency I mean longer range at a steady highway speed. I did several tests on a 60 mile loop with speeds from 35 to 60 mph in different gears and I definitely got farther in 4th than in third. I think when Brammo recommends 5000 rpm they are talking more about power than range efficiency. Using higher gears automatically reduces the amps you can draw while accelerating, kind of an automatic ECO mode that you can change on the fly. If you are driving for performance then you will want lower gears but you will pay with amp hours used, but you will have fun!