Help! Dc/Dc converter

Adrianlle

Finding my (electric) wheels
Aug 4, 2018
19
-1
66
Thanks for all the advice on what to do with my Wisper 906xc. In the end I have fitted a bbs01- Tony at Woosh does provide fantastic customer service. The dapu motor etc is in the Classified section now.
My question now is about lighting. The bbs01 doesn’t have a socket to provide 6v lighting. At the back of my mind is something about a dc/dc converter. Am I right in thinking that if I get one that drops from 36v to 12v that I can then wire in a 6v front and 6v back light in series? If so can anyone recommend a waterproof converter and good but good value lamps to go with it? What an amazing forum!
 

anon4

Esteemed Pedelecer
May 9, 2017
574
84
27
GB
Thanks for all the advice on what to do with my Wisper 906xc. In the end I have fitted a bbs01- Tony at Woosh does provide fantastic customer service. The dapu motor etc is in the Classified section now.
My question now is about lighting. The bbs01 doesn’t have a socket to provide 6v lighting. At the back of my mind is something about a dc/dc converter. Am I right in thinking that if I get one that drops from 36v to 12v that I can then wire in a 6v front and 6v back light in series? If so can anyone recommend a waterproof converter and good but good value lamps to go with it? What an amazing forum!
You can get lights that run off battery voltage, eBay and AliExpress are full of them. If going directly from the battery lines a fuse is recommended, in my case my controller has a light output. Many of them have switches with a horn and some even indicators which is nice, if a little overkill for a bike. Just type in 36v lights and you'll find a great selection. If you already have a 6v set then maybe your idea could work, but unless I'm wrong running 12v in series doesn't mean they get 6v each, rather you get 12 volts but less current due to resistance. The lights i mentioned are also good because they will run off anything from like 12v to 72v, hell if you had a direct drive hub like mine that will power them up too like a dynamo
 

Andy-Mat

Esteemed Pedelecer
Oct 26, 2018
504
94
72
Thanks for all the advice on what to do with my Wisper 906xc. In the end I have fitted a bbs01- Tony at Woosh does provide fantastic customer service. The dapu motor etc is in the Classified section now.
My question now is about lighting. The bbs01 doesn’t have a socket to provide 6v lighting. At the back of my mind is something about a dc/dc converter. Am I right in thinking that if I get one that drops from 36v to 12v that I can then wire in a 6v front and 6v back light in series? If so can anyone recommend a waterproof converter and good but good value lamps to go with it? What an amazing forum!
I had the same question in my head last week, and I happened to have a spare rear light fixture, (36 volt) and all they do is place a (large physical size to reduce the heating effect) resistance, calculated in value, to drop the voltage to that required, therefore supplying the correct voltage to the lamp in question.
My rear light has two of them, as it is both a rear and brake lights.
A DC to DC converter would work, but the resistance idea is far simpler!
You will have to make sure that the light is only supplied with power when your bike is switched on, as forgetting it and thereby causing a deep discharge can kill a (expensive) battery.
Also, the e-bikes I have used, cut power to everything when the battery is fully discharged, to prevent damage. Once causing me to have to ride home in the dark! So I always have battery self powered lights as well!
Regards
Andy
 

Adrianlle

Finding my (electric) wheels
Aug 4, 2018
19
-1
66
Thanks for these ideas. I had assumed everything would be 6v. I’ve now done some googling and will go for a front light that will run off 36v and which has an output for the 6v rear light I already have. There are some good ones out there that have permanent led running bulbs with the main beam operated by a day/ dusk sensor. That coupled with the on/off key on the battery should reduce the risk of draining the battery by leaving the lights on. I will splice into the plus and minus wire from the battery dock and put a fuse in. Thanks.
 

ebiker99

Esteemed Pedelecer
Feb 17, 2019
359
118
Thanks for these ideas. I had assumed everything would be 6v. I’ve now done some googling and will go for a front light that will run off 36v and which has an output for the 6v rear light I already have. There are some good ones out there that have permanent led running bulbs with the main beam operated by a day/ dusk sensor. That coupled with the on/off key on the battery should reduce the risk of draining the battery by leaving the lights on. I will splice into the plus and minus wire from the battery dock and put a fuse in. Thanks.
Sounds good, putting the 2 * 6V lights in series would have been a bad idea since they're unlikely to have the same power rating which would result in the lower powered light having more than 6V across it.
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
2,133
541
Basildon
I happened to have a spare rear light fixture, (36 volt) and all they do is place a (large physical size to reduce the heating effect) resistance, calculated in value, to drop the voltage to that required, therefore supplying the correct voltage to the lamp in question.
That's extremely inefficient. If it's a 6v bulb, you'd waste 5 times as much electricity as you use, and if its a 2v one, you'd waste 17 times as much as you use. It's much better to use a buck converter. There are loads of cheap lights on Ebay, Amazon and everywhere else that have buck converters in them so that they can work off normal ebike batteries - just plug and play.

You can buy your own buck converter for a couple of quid, but ones that can work with a 36v battery take a bit of hunting out. you need one with HV after the LM2596 designation, then check the voltages in the listing.
https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=LM2596HV+Buck+Converter&_sacat=0
 

Andy-Mat

Esteemed Pedelecer
Oct 26, 2018
504
94
72
That's extremely inefficient. If it's a 6v bulb, you'd waste 5 times as much electricity as you use, and if its a 2v one, you'd waste 17 times as much as you use. It's much better to use a buck converter. There are loads of cheap lights on Ebay, Amazon and everywhere else that have buck converters in them so that they can work off normal ebike batteries - just plug and play.

You can buy your own buck converter for a couple of quid, but ones that can work with a 36v battery take a bit of hunting out. you need one with HV after the LM2596 designation, then check the voltages in the listing.
https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=LM2596HV+Buck+Converter&_sacat=0
As its is a LED, with a far lower current usage than a conventional bulb, it is 5 times a very small amount of current, theoretically!
Even a very efficient DC to DC converter will only be a very small amount better (though I have not checked up yet, I will come back with further details if needed!) if at all, depending upon the chip used!
But a DC to DC converter will add complexity, with a far larger possibility of a fault, like a voltage spike for example, killing the chip used. Chinese designers are well known to avoid safe guards they do not feel are needed, and thereby make stuff even cheaper to produce, but more likely to fail!
The 2 watt resistors in my rear light, will handle voltage spikes all day and every day, without ANY problems, and are cheaper to use and/or replace if it finally one gives up the ghost!
I will open the lamp again sometime and read the colour bands on the resistors, when I have time, just to see what current is actually flowing, but from memory, it was only 10 ma., so they have apparently used high efficiency LEDs to achieve their aim. 10ma is fairly normal and average. Good!
Also, remember, the rear light may be on for an hour or so while riding, but the brake light will probably not exceed even one minute of that time....
So guessing a little per hour of rear light to brake light usage, if we say the ride was actually 59 minutes, and brake usage a total of 1 minute, which equals Amps x Hours = 0.01amps x 1 hour = 10ma/hours.
You are not going to ride far on that sort of power wastage now are you?
But each to his own....
I personally feel that the cheap resistor used in my rear light, is a clever alternative to any converter, and will far outlive any electronics.
Plus the DC to DC converter, will have to be designed brilliantly to save any power against the resistor in this particular case. That will not come cheap!
It is true that resistors are wasteful when the current pulled is high, but in this case not, because the current is so very low!
I hope that I have brought your thinking more into the reals of the real world, and not just the theoretical one!
I will leave the details of efficiency for you to calculate accurately, but the difference, if any, will be very, very tiny! And your factor of 5 you quoted, must be wrong, probably not taking into account and power used in the converter, as if the same rear LEDs only got a fifth of the current, that would be around 2ma, the rear light would be possibly be quite dark.
Also, remember LED have a low internal resistance, that can be safely ignored when making such calculations.
Andy
 

ebiker99

Esteemed Pedelecer
Feb 17, 2019
359
118
That's extremely inefficient. If it's a 6v bulb, you'd waste 5 times as much electricity as you use, and if its a 2v one, you'd waste 17 times as much as you use. It's much better to use a buck converter. There are loads of cheap lights on Ebay, Amazon and everywhere else that have buck converters in them so that they can work off normal ebike batteries - just plug and play.

You can buy your own buck converter for a couple of quid, but ones that can work with a 36v battery take a bit of hunting out. you need one with HV after the LM2596 designation, then check the voltages in the listing.
https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=LM2596HV+Buck+Converter&_sacat=0
He probably connects his resistor up the wrong way round ;) ;) ;)
 

Andy-Mat

Esteemed Pedelecer
Oct 26, 2018
504
94
72
He probably connects his resistor up the wrong way round ;) ;) ;)
Can you explain that?
Please remember that most resistors do not have a "way" as you call it, they work the same no matter which way round they are connected/soldered in....

Oh! I get it, that was your idea of a joke!

How poor was that then? So I guess that means you did not understand fully or exactly what I wrote, and I aimed the technical parts very low too for you be able to understand better......

Obviously not low enough eh?;);););)
Andy
 

ebiker99

Esteemed Pedelecer
Feb 17, 2019
359
118
Can you explain that?
Please remember that most resistors do not have a "way" as you call it, they work the same no matter which way round they are connected/soldered in....

Oh! I get it, that was your idea of a joke!

How poor was that then? So I guess that means you did not understand fully or exactly what I wrote, and I aimed the technical parts very low too for you be able to understand better......

Obviously not low enough eh?;);););)
Andy
OMG, it was a joke :eek::eek::eek:
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
2,133
541
Basildon
Even a very efficient DC to DC converter will only be a very small amount better (though I have not checked up yet, I will come back with further details if needed!) if at all, depending upon the chip used!
I think it might have been a good idea to check that before commenting.
The 2 watt resistors in my rear light, will handle voltage spikes all day and every day, without ANY problems, and are cheaper to use and/or replace if it finally one gives up the ghost!
The resistor might be able to, but the LED can't handle voltage spikes that the resistor won't protect it from.
 
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Andy-Mat

Esteemed Pedelecer
Oct 26, 2018
504
94
72
OMG, it was a joke :eek::eek::eek:
I guess you felt that I was actually completely right in my assessment, as you have not mentioned anything about what I wrote, or tried to correct me either.

Nothing to correct as it was accurate.

So Job done correctly by Andy!!

Your humour is as good as your electrical/electronic knowledge - Funny!

But I fail to understand why you are often SO aggressive to many of my posts, IMHO it shows a poor upbringing and a lack of knowledge in many technical matters.

I have no problem with a critique, but only when based on real accurate knowledge, so in the future (but you certainly don't have to do it, your personal choice), please do take the time to read up on technical matters before replying!

Also take a step back and look at the "big Picture", it would really help you in problem understanding and solving.

I have been teaching, but only as PART of my job in electrics, computers, and general electronics for over 50 years now.
I know most of the stuff I write about, just from my head, but sometimes I get rusty on a point, then I look it up first, before, I write a post, for example.

Please try and be more friendly to botmyself and all others on Pedelec, you will gain far more than you lose with your present attitude.....

Do have a great day. I am!
 

Andy-Mat

Esteemed Pedelecer
Oct 26, 2018
504
94
72
I think it might have been a good idea to check that before commenting.
What you wrote was just theoretical, and not real world or practical, did you check that up prior to posting?
May I ask where?
 

Andy-Mat

Esteemed Pedelecer
Oct 26, 2018
504
94
72
OMG, it was a joke :eek::eek::eek:
I guess you felt that I was actually completely right in my assessment, as you have not mentioned anything about what I wrote, or tried to correct me either.

Nothing to correct as it was accurate.

So Job done correctly by Andy!!

Your humour is as good as your electrical/electronic knowledge - Funny!

But I fail to understand why you are often SO aggressive to many of my posts, IMHO it shows a poor upbringing and a lack of knowledge in many technical matters.

I have no problem with a critique, but only when based on real accurate knowledge, so in the future (but you certainly don't have to do it, your personal choice), please do take the time to read up on technical matters before replying!

Also take a step back and look at the "big Picture", it would really help you in problem understanding and solving.

I have been teaching, but only as PART of my job in electrics, computers, and general electronics for over 50 years now.
I know most of the stuff I write about, just from my head, but sometimes I get rusty on a point, then I look it up first, before, I write a post, for example.

Please try and be more friendly to both myself and all others on Pedelec, you will gain far more than you lose with your present attitude.....

Do have a great day. I am!
 

ebiker99

Esteemed Pedelecer
Feb 17, 2019
359
118
But I fail to understand why you are often SO aggressive to many of my posts,
I rarely bother replying to your posts and when I do it's to point out your misunderstandings, for example when you were advising people to reverse the mounting of their discs, in direct violation of the instructions provided by their design engineers.
 

Tarka

Pedelecer
Jan 29, 2019
30
23
AAA LED lights are cheap and the battery lasts a very long time. Saves faffing about with wires. Even a couple of spare AAAs weigh almost nothing.
 

Andy-Mat

Esteemed Pedelecer
Oct 26, 2018
504
94
72
I find that really worrying from some of the things you've posted.
I am sure they do, you have a big ego and not a clue about electrics.

Furthermore, you feel you want tobe better than all others, but in my eyes, you have never and will never achieve it, unless you go to a college or University for at least a further 4 years.
Your problem in a nutshell.
 

Adrianlle

Finding my (electric) wheels
Aug 4, 2018
19
-1
66
I am sure they do, you have a big ego and not a clue about electrics.

Furthermore, you feel you want tobe better than all others, but in my eyes, you have never and will never achieve it, unless you go to a college or University for at least a further 4 years.
Your problem in a nutshell.
Oh dear! What a maelstrom I unleashed by a simple question about lights. I’ll stick to AAA lights in the future!
 

anotherkiwi

Esteemed Pedelecer
Jan 26, 2015
7,713
5,735
The European Union
Thanks for these ideas. I had assumed everything would be 6v. I’ve now done some googling and will go for a front light that will run off 36v and which has an output for the 6v rear light I already have. There are some good ones out there that have permanent led running bulbs with the main beam operated by a day/ dusk sensor. That coupled with the on/off key on the battery should reduce the risk of draining the battery by leaving the lights on. I will splice into the plus and minus wire from the battery dock and put a fuse in. Thanks.
I recommend. Contrary to what is written on the package they handle over 42v, I run mine at up to 50v with no overheating.
 

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