Sur-Ron - New Mid drive Bike

In attempt (along with riding slow around people) to keep the Karens at bay. Also has anyone experienced the loud motor noise with the bac4000 and 72v battery? This motor is loud as hell. You can hear it around the 2min mark.

https://www.youtube.com/watch?v=6tPVFBzcnSI

[youtube]6tPVFBzcnSI[/youtube]

Your 420 chain primary drive is making the noise,it needs a shim to make the motor/ jackshaft gears align.

Looking for some help with a tech issue (power cutting out):
All sensors have been removed. All bone stock electrics and battery, I only have the fisher fab house light installed. Bike has 3900km's on it... bike and battery was well taken care of, not ridden excessively hard. Everything worked flawless until now...
Sometimes, if I turn the ignition, it won't turn on. Sometimes I get just the speedo and no battery, sometimes everything turns on but it will hesitate and the speedo flashes....sometimes it will go but while riding it will cut out power to rear wheel, but the speedo stays on and battery % gauge goes out.

I have an X controller in the mail, the plan is to swap that and see if that solves the issue, if it doesn't, then I'll move onto the battery. Unfortunately I don't have anyone close by that wants to do a quick battery swap to help troubleshoot things...that would be super helpful..


*side question: The way it's reacting, I'm also leaning toward this being a BMS issue. I always would charge to ~ 80-90% over the past 3 years.., with full charges every now and then. If I understand correctly, the charger will perform cell balancing after it's reached 100%, but does the BMS in the battery actively seek to balance the cells also? what if it's been sitting for a long time? can it do this while outside of the bike?
My theory is that I may have a weak cell and it's causing the BMS to trip, or the BMS is just dead and that weak cell is only balanced during the 100% charge cycle. I'm not the best with electro gizmo's so I'm sure their are some experts on here that will be able to chime in on this.
Thanks!

It sounds like a battery/BMS problem. You might want to open the top of the battery and try to reseat any connectors. You might also be able to check individual cell group voltages. It's packed pretty tight around the BMS and it would be easy to short something, so be extra careful. If you could find someone with a battery for testing it would be great.

I have the same hunch also. I'm waiting to hear back from Luna support to see what they say, I don't think I'll open anything up yet before then. When the new X controller arrives, I'll give that a try, atleast that will allow me to rule out the controller :thumb:

One other thing I would check is the screws on the main circuit breaker. A loose connection could cause all sorts of random problems.

It sounds like the battery not getting the last string of 16( total voltage) voltage.In the Luna thread they have a easy fix for that one that you can do your self.I have had to do it to 3 batteries so far for my friends bike and they had the same symptoms.I think they call it the B16 fix.

Hawaiiguy said:

It sounds like the battery not getting the last string of 16( total voltage) voltage.In the Luna thread they have a easy fix for that one that you can do your self.I have had to do it to 3 batteries so far for my friends bike and they had the same symptoms.I think they call it the B16 fix.

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Can you point me to this thread or tutorial? I just swapped out my controller for a brand new X controller and it's still doing it, so it's obviously the battery, I've ruled everything else out...
Also, a quick shout out, if there is anyone in the Ottawa/Gatinea/Montreal area that can work on and repair Surron batteries, I'll gladly pay for it. DoctorBass is from MTL no?

Did you check the breaker screws? It's very easy as you can access them from the top. Worth checking since it's easy.



The next step would be open up the top of the battery and try to unplug and re-plug the BMS board. This will reboot everything. There is glue on the connectors, so may be a bit challenging.

fechter said:

Did you check the breaker screws? It's very easy as you can access them from the top. Worth checking since it's easy.

Breaker screws.jpg

The next step would be open up the top of the battery and try to unplug and re-plug the BMS board. This will reboot everything. There is glue on the connectors, so may be a bit challenging.

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Yeah I did most of the initial troubleshooting stuff, in fact, I was just able to replace the controller with a brand new X controller and the issue persists. I also did Seb G's battery pre-load test (Youtube troubleshooting video) and it dropped from 61.9V to 60.8V so something is up with the BMS. I've opened a support ticket with Luna so hopefully we can get this sorted. I'll probably in fact have to crack the battery open or something...I'll update the post with the fix once we figure it out. :thumb: :thumb:

If you hardwired around the breaker that'd be a check. I'm with Fechter that it sounds like a weird short, most likely the breaker being torqued or just bad.
Keep us posted.

I guess there are some known issues with the BMS that can cause this. The breaker itself is very robust and I haven't seen any reports of them failing.

I've ordered what I need to go full solar for the Sur Ron.

Got solar cells, MPT controller and a continuous 2KW inverter so I can run my computer and Starlink from practically anywhere and during the just announced preemptive "extreme fire danger" blackouts.

Of course, it also means I will have indefinite range once I build a little solar cart.

I'll post some pics of my setup and a bit of a "review" when I have the system together.

To plug a charger into the Sur Ron battery, is there anything else that needs a connection other than + and - DC? And same goes with the inverter being plugged in.

Anyone know what the X160 battery pack BMS current limit is? Put a Nuc24F on the kiddo's bike and am figuring it out experimentally Was tripping on me going up a big hill riding at a friend's house. I don't have a hill that big around here to tweak it further.

3DTOPO: FWIW, the Nucular controller lets you charge w/ the converter straight from a battery source. You can skip the inverter inefficiencies. Not sure if other aftermarket converters can do this. I'm still needing to add some connectors so I can charge our SurRons from the 24V 'house' battery in my RV/van and not use the inverter. I still need to get a 240V inverter solution to charge the KTM E though.

smdub said:

FWIW, the Nucular controller lets you charge w/ the converter straight from a battery source. You can skip the inverter inefficiencies. Not sure if other aftermarket converters can do this. I'm still needing to add some connectors so I can charge our SurRons from the 24V 'house' battery in my RV/van and not use the inverter. I still need to get a 240V inverter solution to charge the KTM E though.

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I got the inverter to run 120V AC from the battery.

Understood (for your "computer and Starlink"). Just saying there may be a more efficient charge method if you ever need to go that route. I'm in the business and bought one of the higher eff inverters (Cotek.) I only have ~500W of solar on the van and ~5kWh of storage. Trying to run efficient as possible. If you can charge direct, will likely save 15%+ efficiency by cutting one part out of the conversion chain. I haven't measured the Nuc charger efficiency yet though, but I suspect its not terribly different from the SurRon charger.

smdub said:

Understood (for your "computer and Starlink"). Just saying there may be a more efficient charge method if you ever need to go that route. I'm in the business and bought one of the higher eff inverters (Cotek.) I only have ~500W of solar on the van and ~5kWh of storage. Trying to run efficient as possible. If you can charge direct, will likely save 15%+ efficiency by cutting one part out of the conversion chain. I haven't measured the Nuc charger efficiency yet though, but I suspect its not terribly different from the SurRon charger.

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I don't understand what the inverter has to do with charging? It is for taking electricity out of the pack.

The MPPT controller is for direct charging. All it does it stop charging when it reaches the set voltage if I understand how it works correctly.

MPPT charges your storage battery. In my case thats a 24V pack. (I could also theoretically charge this from the vans alternator when its running using a converter.) For the sake of discussion here, once the energy is in the storage battery it doesn't really matter how it gets there.
Inverter runs from the storage battery to make 120Vac. Ballpark 85% efficient.
SurRon charger converts 120Vac to 60Vdc to charge the bike. Lets say that 90% efficient for sake of argument.
So energy from your storage battery to the Surron has 85% * 90% = 76.5% efficiency. For every Wh of energy put into your SurRon, you have to draw 1Wh/76.5%=1.3Wh of energy from the storage battery. Make sense? If you can get a charger that avoids the DC to AC to DC conversion, you can improve efficiency.

People have even modified their Starlink power supplies to run straight from DC to increase efficiency a little. When you live off solar (or any limited power source) every little bit helps.
https://www.tuckstruck.net/truck-and-kit/geekery/modifying-the-starlink-power-supply-to-run-on-ac-and-dc/

Edit: What may be confusion is that the Nuc controller has a mode that can charge the SurRon battery if you simply connect another (lower) DC voltage. I can connect my 24V van house battery and use the Nuc controller to charge the SurRon battery w/o an AC inverter or oem SurRon AC powered charger. I guess not many people know this is possible.

smdub said:

Inverter runs from the storage battery to make 120Vac. Ballpark 85% efficient.
SurRon charger converts 120Vac to 60Vdc to charge the bike. Lets say that 90% efficient for sake of argument.

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I'm not planning on using the Sur Ron charger.

It's like this: Solar Cell -> MPPT Controller -> Sur Ron battery

Not like this: Solar Cell -> Battery Bank -> Inverter -> Sur Ron Charger -> Sur Ron battery

smdub said:

People have even modified their Starlink power supplies to run straight from DC to increase efficiency a little. When you live off solar (or any limited power source) every little bit helps.
https://www.tuckstruck.net/truck-and-kit/geekery/modifying-the-starlink-power-supply-to-run-on-ac-and-dc/

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Thanks, the thought occurred to me that I can run stuff DC. Pretty much everything is DC, my computer, battery/device chargers, yes Starlink etc.

Got it! Where did you find a 60-70V MPPT and inverter? 12/24/48V are pretty common but not higher LiPo voltages.

Edit: The SurRon BMS open circuits when it reaches full. You're going to have to be really careful if running an inverter from it also.

smdub said:

Got it! Where did you find a 60-70V MPPT and inverter? 12/24/48V are pretty common but not higher LiPo voltages.

Edit: The SurRon BMS open circuits when it reaches full. You're going to have to be really careful if running an inverter from it also.

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https://amzn.to/3N6lvee

The Sur Ron charges to 67.2 VDC. If you set the MPPT to 66V it will stop before cell-balancing (from what I've read).

Here's my complete system, everything works!



I charged the battery with the solar for the first time yesterday. 8)

I just have one 100 watt panel for now - going to get another. It weighs 5 pounds and 16x16 inches. The harness is wired for three panels (and the MPPT I got supports 300 watts).

My inverter is putting out 220V that can be split to two 110V outlets (going to use GFCIs).

Un-limted range (given some time to soak up some photons) and actual broadband just about anywhere now!

Oh - the only thing is, when I connect the inverter to the battery I get a big spark - even when the inverter is off. Anyone know what connection or signal needs to go to the battery to disable DC power out?

Handy 3-n-1 machine and very nice optical(?) table.

The spark is the inverter's bulk filter capacitors charging up. You need to precharge them or use something like an anti-spark connector (AS90) to do so.

Fuse your battery connection as close to the battery as practical. That MPPT has to be a POS for the price but as long as it works, it works. If something goes wrong you want the fuse to blow and not start a fire. If the failure draws current that is lower than the BMS trip limit it can set the wires on fire. 300W MPPT / 60V = 5A max. So w/ the 1.25x UL fuse derate, look for a 6.5-10A fuse and size wire accordingly. Do similar calcs for the inverter (though it needs ~2x sizing due to the high RMS current on the DC side)

Is your 220V inverter center ground referenced/balanced? Not many cheap ones are. Be careful trying to run to separate 120V circuits from it. It likely wont like unbalanced phases either.

2kWh/100W = 20H of charging for a full charge. (~4days w/ good sun) Wife/kiddo/I can't wait that long Its clever doing what you are doing w/o intermediate storage and having it portable though. Kudos!

The inverter has a large capacitor on the input that wants to charge instantly on connection. Best to precharge it through a resistor first. I use a 4.7k 1W to do that for a few seconds before connecting.

smdub said:

Handy 3-n-1 machine and very nice optical(?) table.
The spark is the inverter's bulk filter capacitors charging up. You need to precharge them or use something like an anti-spark connector (AS90) to do so.
Fuse your battery connection as close to the battery as practical. That MPPT has to be a POS for the price but as long as it works, it works. If something goes wrong you want the fuse to blow and not start a fire. If the failure draws current that is lower than the BMS trip limit it can set the wires on fire. 300W MPPT / 60V = 5A max. So w/ the 1.25x UL fuse derate, look for a 6.5-10A fuse and size wire accordingly. Do similar calcs for the inverter (though it needs ~2x sizing due to the high RMS current on the DC side)
Is your 220V inverter center ground referenced/balanced? Not many cheap ones are. Be careful trying to run to separate 120V circuits from it. It likely wont like unbalanced phases either.
2kWh/100W = 20H of charging for a full charge. (~4days w/ good sun) Wife/kiddo/I can't wait that long Its clever doing what you are doing w/o intermediate storage and having it portable though. Kudos!

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Actually, the MPPT seems quite nice - has a decent size inductor - allows 0.1V increments - shows the voltage of the battery and other stats.

Thanks for the tips. I have a fuse for the MPPT and the inverter has one built-in. Not sure why I would need anything else other than something to precharge or preferably just turn the power off coming out of the battery?

I used 8-gauge wire for connecting the battery to the inverter. Based on my research it should be fine.

Yes, as I said I'm definitely going to add more panels but you got to start somewhere. 2-3 panels should get most of charge in a day, I never really run my battery below 20-30%.

Thanks, indeed it is a good old optical table.

Edit: yes the inverter must be ground balanced it wouldn't work split :wink: