Running lights from Bosch gen 4 power port...

[Hardtail]

It works, kind of...

So I installed a 48v buck converter: Szwengao DC-DC Converter. 48V in 12V out. 03A, DC-DC-S-48/12V-NI-03A | Energy Solutions

I wired in a switch, which turns out is only rated to 24v...

The bike powers on no matter whether the converter and light are switched on or off, but if I turn the converter on when the bike is already on it momentarily kills power to the bike, powers down, and then restarts the system. The lights will stay on during this restart. It doesn't make a difference when switching off the converter when everything is on. Note that the converter doesn't get power when the bike is off but the converter is switched on.

Is there a way of reducing the voltage drop through the switch? by adding a relay etc??? maybe @BeBiker @All4Fun have some ideas?

I will source and add a 48v switch, one without an led as it is just too bright.

Cheers,

 

[BeBiker]

It works, kind of...

So I installed a 48v buck converter: Szwengao DC-DC Converter. 48V in 12V out. 03A, DC-DC-S-48/12V-NI-03A | Energy Solutions

I wired in a switch, which turns out is only rated to 24v...

The bike powers on no matter whether the converter and light are switched on or off, but if I turn the converter on when the bike is already on it momentarily kills power to the bike, powers down, and then restarts the system. The lights will stay on during this restart. It doesn't make a difference when switching off the converter when everything is on. Note that the converter doesn't get power when the bike is off but the converter is switched on.

Is there a way of reducing the voltage drop through the switch? by adding a relay etc??? maybe @BeBiker @All4Fun have some ideas?

I will source and add a 48v switch, one without an led as it is just too bright.

Cheers,

Strange, Switches are Current rated.
There is often also a Voltage marking, but for isolation, irrelevant here.

Most things you experienced are completely different than what I saw.
You installed the switch between +36V from the bike and the buck converter ?

The commercial page of your converter says 48V input.
Do you have specifications where they mention 24V-48V input? or 24V-80V or...

 

[Hardtail]

The commercial page of your converter says 48V input.
Do you have specifications where they mention 24V-48V input? or 24V-80V or...

Yes, it’s rated from 30v-60v.
The switch is mounted between battery and converter, which is sectioned off between battery and motor.

http://proa2427b.pic7.websiteonline.cn/upload/WG-48S1203.pdf

I guess Bosch senses the voltage drop and restarts for some ‘safety’ reason…

 

[Hardtail]

This is how I wired the led push button switch to the converter.

 

[Ebikeslife]

This is how I wired the led push button switch to the converter.
View attachment 101017

Shortly after purchasing my bike two years ago like you I attempted to access the Bosch’s 36 volts in order to power a 3600 lumen Niterider setup I already owned. I used what appears to be the identical converter you used and as expected had the same results. Ended up using the battery that came with the Niterider light but have not given up on the idea of using the bikes battery instead. I have also looked into what Supernova has to offer but am not interested in the downside of unlocking the light and power ports on the Bosch motor. Have you been able to make any progress on accessing the 36 volts while avoiding the Bosch system dropping power?

 

[Kiwimike]

This is how I wired the led push button switch to the converter.
View attachment 101017

That’s not how I wired it - you’ve taken the converter feed off the green instead of the red main motor feed. I think that’s why you have this startup issue.

 

[Hardtail]

@Ebikeslife , no success yet. I gave the bike to an electrical engineer I work with and, although he was short on time, he couldn’t see why it wouldn’t work, he confirmed it was wired correctly. He put a scope on it and could see a spike when turning the button on.
He suggested it was probably the led in the button causing this so I rewired the button and bypassed the led, no luck. I guess I will try a different converter…

@Kiwimike the feed is coming from the main battery red, it is via a switch, that is what the green line represents. I can hard wire it without the switch and it works but the. The converter is always active with a small power drain. It also means that my rear light always comes on during start up, which is sub optimal.

 

[Ebikeslife]

@Ebikeslife , no success yet. I gave the bike to an electrical engineer I work with and, although he was short on time, he couldn’t see why it wouldn’t work, he confirmed it was wired correctly. He put a scope on it and could see a spike when turning the button on.
He suggested it was probably the led in the button causing this so I rewired the button and bypassed the led, no luck. I guess I will try a different converter…

@Kiwimike the feed is coming from the main battery red, it is via a switch, that is what the green line represents. I can hard wire it without the switch and it works but the. The converter is always active with a small power drain. It also means that my rear light always comes on during start up, which is sub optimal.

It is terrific to hear that you were able to have someone with an electrical engineering background review your work and it checked out. It does look good. As you are probably aware the only electrical device located between the array of batteries in the pack and where we are attempting to tap the 36 volts is the BMS board. I think that if it weren’t for the BMS board in the battery pack this would be a no brainer. Since eliminating the BMS board is not an option the only other consideration would be to open the battery pack case and connect leads directly to the output of the battery array before it connects to the BMS board. There are obviously a number of reasons why one would suggest against this approach but it would offer guaranteed success in accessing the 36 volts. Another thing this modification would guarantee is a voided warranty. For some of us it would not be an issue either because of already being out of warranty or the desire to access the 36 volts is simply too great. It would also be suggested that someone doing a modification of this type understands the scope of the work being performed. Excellent solder connections that do not disturb the existing connections is very important. Proper gauge wires that are fused and protected from chafing internally and externally to the battery pack. My suggestion would be to have the wires exit the battery at the highest point of the pack when mounted in the bike. This choice of location in the pack combined with a weathertight seal must reduce the risk of water egress to 0%. In addition to the aforementioned a Low Voltage Cutoff is necessary to protect the battery from irreversible damage in the event the lights are left on. A Low Voltage Alarm would be optional. This is only the basic footprint of the modification as there are a number of details not covered.

 

[Kiwimike]

It is terrific to hear that you were able to have someone with an electrical engineering background review your work and it checked out. It does look good. As you are probably aware the only electrical device located between the array of batteries in the pack and where we are attempting to tap the 36 volts is the BMS board. I think that if it weren’t for the BMS board in the battery pack this would be a no brainer. Since eliminating the BMS board is not an option the only other consideration would be to open the battery pack case and connect leads directly to the output of the battery array before it connects to the BMS board. There are obviously a number of reasons why one would suggest against this approach but it would offer guaranteed success in accessing the 36 volts. Another thing this modification would guarantee is a voided warranty. For some of us it would not be an issue either because of already being out of warranty or the desire to access the 36 volts is simply too great. It would also be suggested that someone doing a modification of this type understands the scope of the work being performed. Excellent solder connections that do not disturb the existing connections is very important. Proper gauge wires that are fused and protected from chafing internally and externally to the battery pack. My suggestion would be to have the wires exit the battery at the highest point of the pack when mounted in the bike. This choice of location in the pack combined with a weathertight seal must reduce the risk of water egress to 0%. In addition to the aforementioned a Low Voltage Cutoff is necessary to protect the battery from irreversible damage in the event the lights are left on. A Low Voltage Alarm would be optional. This is only the basic footprint of the modification as there are a number of details not covered.

This is a really bad idea for a number of reasons. Do not under any circumstances try this. There is 36V accessible at the battery connector, you don’t need to hack open the case and risk fire/explosion etc. We aren’t smarter than Bosch engineers folks.

 

[Ebikeslife]

This is a really bad idea for a number of reasons. Do not under any circumstances try this. There is 36V accessible at the battery connector, you don’t need to hack open the case and risk fire/explosion etc. We aren’t smarter than Bosch engineers folks.

Although your concern is viable and appreciated a project such as this IN THE RIGHT HANDS has little to be concerned with. With the proper application of workmanship, use of quality parts and the correct circuit it is actually quite simple. Unfortunately the reality appears to be that 36 volts is NOT available outside of the battery at the accessory level because Bosch uses a CAN bus system so their devices can communicate. Tapping into the wires external to the battery upsets that system similar to what now occurs when attempting to modify some modern vehicles. The Bosch system does things such as having an awkward startup and/or no consistent power output when a load outside of its system is applied. In full disclosure I will confess that although I am very comfortable doing a modification such as this I am still considering just settling for a frame mounted battery to power the bikes lights. The added weight and appearance of a frame mounted battery is something I was trying to avoid. If I am mistaken and anyone knows of a tried and true way of accessing a reliable 36 volts outside of the Bosch battery please share.

 

[Kiwimike]

Although your concern is viable and appreciated a project such as this IN THE RIGHT HANDS has little to be concerned with. With the proper application of workmanship, use of quality parts and the correct circuit it is actually quite simple. Unfortunately the reality appears to be that 36 volts is NOT available outside of the battery at the accessory level because Bosch uses a CAN bus system so their devices can communicate. Tapping into the wires external to the battery upsets that system similar to what now occurs when attempting to modify some modern vehicles. The Bosch system does things such as having an awkward startup and/or no consistent power output when a load outside of its system is applied. In full disclosure I will confess that although I am very comfortable doing a modification such as this I am still considering just settling for a frame mounted battery to power the bikes lights. The added weight and appearance of a frame mounted battery is something I was trying to avoid. If I am mistaken and anyone knows of a tried and true way of accessing a reliable 36 volts outside of the Bosch battery please share.

I don’t understand the issue here. I’m tapping into the 36V driving a Buck converter using the main motor feeds just fine. Others I’ve met have done this too.

 

[Ebikeslife]

I don’t understand the issue here. I’m tapping into the 36V driving a Buck converter using the main motor feeds just fine. Others I’ve met have done this too.

I don’t understand the issue here. I’m tapping into the 36V driving a Buck converter using the main motor feeds just fine. Others I’ve met have done this too.

I think the issue is that I might have chosen an ‘incompatible’ buck booster. Lol. The one I attempted to use was a properly spec’d booster similar to the one Hardtail used but it seems that model doesn’t play nice with the Bosch system. Can you please share the model and source of the booster that is working for you? It would be incredible to have a safe and reliable source of power. Thank you!

 

[BeBiker]

In the mean time, my 12-80v light just runs fine.
A Buck converter with a 12v light did it well too.

 

[Kiwimike]

This one: Waterproof DC-DC Buck Step Down Volt Converter 20V-72V 24V 36V 48V to 12V 3A JP | eBay

 

[Ebikeslife]

This one: Waterproof DC-DC Buck Step Down Volt Converter 20V-72V 24V 36V 48V to 12V 3A JP | eBay

Thank you. The lighting system I intend to use requires a slightly high amp rating. There are buck boosters similar in design to the one you are using that have a higher amp rating. The one Hardtail and I tried are rated at 10 amps.

 

[Ebikeslife]

Just ordered this.
36V/48V to 12V Step Down Converter 30~60V to 12V 0~10A MAX 0~120W Adaptive DC Buck Converter Transformer Voltage Module Regulator Waterproof Power Supply(30~60V Input/12V 0~10A MAX Adaptive Output) https://a.co/d/8HoMZt9

 

[Hardtail]

This one: Waterproof DC-DC Buck Step Down Volt Converter 20V-72V 24V 36V 48V to 12V 3A JP | eBay

This is the next type I will get next , probably the 2amp version. My loom is modified so trying different types will be easy.
@Kiwimike Do you have a Bosch performance CX and is it hard wired or are you running it through a switch?

 

[Hardtail]

In the mean time, my 12-80v light just runs fine.
A Buck converter with a 12v light did it well too.

My understanding is that the unit you use is a double USB converter outputting 5v, not a traditional 12v buck converter, running on the Shimano motor, correct?

 

[Kiwimike]

This is the next type I will get next , probably the 2amp version. My loom is modified so trying different types will be easy.
@Kiwimike Do you have a Bosch performance CX and is it hard wired or are you running it through a switch?

Hardwired. I might put a switch in to turn off the rear light, which is always on

 

[Hardtail]

Hardwired. I might put a switch in to turn off the rear light, which is always on

Yes, that is how mine works just fine…
But with a switch inline it shuts down and restarts when being turned on.
Are you running. Gen 4 Bosch?

 

[BeBiker]

My understanding is that the unit you use is a double USB converter outputting 5v, not a traditional 12v buck converter, running on the Shimano motor, correct?

No, everything you mention is false.

 

[Ebikeslife]

It works! 36 volts is easily accessible like Kiwimike said. Initially I was using the same type of converter Hardtail was attempting to use. As expected I had the same results that he described. The converter Kiwimike is using gave the same successful results he described. Even better he has been powering his lights successfully for some time which proves it’s a solid solution. A switch is required to remove the additional electrical load when the Bosch system is powered on otherwise the bike will turn back off and the 36 volts is never supplied. But once the Bosch system is powered up just flip the switch for the converter on and the 36 volts is available. Thanks to everyone who has contributed to this thread but special thanks to BeBiker, Hardtail and especially Kiwimike for contributing to this discussion. Thank you guys so much!
Here’s a pic of my rats nest of alligator clips.

 

[BeBiker]

... A switch is required to remove the additional electrical load when the Bosch system is powered on otherwise the bike will turn back off and the 36 volts is never supplied...

Indeed, same effect here. When I turn the bike on I just get a short flash in that case.

 

[2WheelsNot4]

Thats interesting about the motor cutting off at 10% if lights are fitted, I did not know that.
I've an Exposure fuse i got a bit back,meaning to fit it as an extra along with the Exposure toro i run mostly.
But in light(pun) of this info I think it best I don't fit it, and maybe get a 2nd toro or maybe something a bit bigger like a six pack.

 

[Kiwimike]

It works! 36 volts is easily accessible like Kiwimike said. Initially I was using the same type of converter Hardtail was attempting to use. As expected I had the same results that he described. The converter Kiwimike is using gave the same successful results he described. Even better he has been powering his lights successfully for some time which proves it’s a solid solution. A switch is required to remove the additional electrical load when the Bosch system is powered on otherwise the bike will turn back off and the 36 volts is never supplied. But once the Bosch system is powered up just flip the switch for the converter on and the 36 volts is available. Thanks to everyone who has contributed to this thread but special thanks to BeBiker, Hardtail and especially Kiwimike for contributing to this discussion. Thank you guys so much!
Here’s a pic of my rats nest of alligator clips. View attachment 104253

Cool it worked for you. Noting I don't have a switch installed - if the bike is on, the light is on.

 

[Ebikeslife]

Cool it worked for you. Noting I don't have a switch installed - if the bike is on, the light is on.

Cool it worked for you. Noting I don't have a switch installed - if the bike is on, the light is on.

I included a switch during my testing but now am hardly even considering using one in the installation on the bike. As we discussed if the Bosch system on my bike sees any load when turned on it turns back off. Theoretically since the aftermarket lights will be off when the Bosch system is turned on there should be no load. Therefore no switch is needed to allow properly powering on. The type of voltage converter you suggested and I am now using allows this to work. The switch was only a consideration in order to totally take the lights and converter out of the equation so I did not risk the Bosch system not turning on when in an isolated area. I am now much more confident in its reliability without a switch and am very grateful that you suggested the type of converter you did.

 

[Hardtail]

Cool it worked for you. Noting I don't have a switch installed - if the bike is on, the light is on.

Yes, here in lies the issue for me. It works without a switch, but restarts the system with a switch, it can be worked around but is not ideal.
I tried another buck converter like Kiwimike's, with identical specs and shape, just that the one I was sent is the same brand as my previous one. With the same issue, the system shuts down and restarts when the switch to power the converter is turned on...
So I ordered the one from Kiwimikes supplier and asked for the specific model, I just received a refund and a message that the stock they received from the supplier was faulty and they have sent them back....
I also bypassed the LED circuit in the switch like suggested and wired it inline with the 36v power straight to the converter but it still resets the Bosch system.
@Ebikeslife can you flick the switch on and off while the system is powered without the system restarting? Sometimes it will not restart but I have realised that is only after the converter has been powered and there is some residual voltage still leaking down...
So now I will try another switch and a nother converter...

 

[Hardtail]

Yes, here in lies the issue for me. It works without a switch, but restarts the system with a switch, it can be worked around but is not ideal.
I tried another buck converter like Kiwimike's, with identical specs and shape, just that the one I was sent is the same brand as my previous one. With the same issue, the system shuts down and restarts when the switch to power the converter is turned on...
So I ordered the one from Kiwimikes supplier and asked for the specific model, I just received a refund and a message that the stock they received from the supplier was faulty and they have sent them back....
I also bypassed the LED circuit in the switch like suggested and wired it inline with the 36v power straight to the converter but it still resets the Bosch system.
@Ebikeslife can you flick the switch on and off while the system is powered without the system restarting? Sometimes it will not restart but I have realised that is only after the converter has been powered and there is some residual voltage still leaking down...
So now I will try another switch and a nother converter...

But the benefit of the switch is to prevent the converter from being energized and thus leaking voltage unnecessarily when the lights are not used. The workaround is to just turn the convertor on when the bike is off if lights are required, it's just not optimal.

 

[Ebikeslife]

Yes. Once the bike is powered on the switched for the lights can be turned on and off without disturbing the Bosch system whatsoever. The power source seems to be solid once the bike is powered on. As for power leakage I do not think it will be a problem but I have not verified that yet. My next test will be to locate the converter before the switch so the converter remains in the circuit. I will check power draw.

 

[BeBiker]

The good thing of the gen4smart is that after a few minutes of non-activity, the power is switched off.
So no risk of long power leak when the lights (and/or a converter) are still on.