Running additional circuits off main battery

[Scimitar]

I agree that's the impression, but correctly sized, installed and protected they are more reliable than you would think. Often though, I agree that they are installed poorly and will fail.

Rubbish. They are inherently flawed in their design and fit only for bodgers and back-street artists.

 

[103Alex1]

It important to understand that 1A at 36v is the same amount of power as 10A at 3.6v - Both = 36W

When you are considering the amount of energy in the battery, you will probably talk about it as Ah - eg 20Ah. So, if you are using 1A at 36v, you are using 1/20th of your available energy for the lights. if those lights were running through a 100% efficient buck converter, at 3.6v, you would be able to pull 10A through them (assuming you converter were capable)

At 1A from the battery, I would imagine the effect on performance to be negligible, since the controller/motor will be the limiting factor in current draw. Only the range will be affected (1/20th less).

Hope that makes sense.

The dimmer light is beginning to move up the brightness curve

It's quite linear - if you draw 1A for your lights you'll deplete your main battery by a third of what you would if you draw 3A. The lights don't suddenly get greedy, unless you mean that you've read that some LEDs at full power will draw a disproportionate amount of current compared to half-power, say. I'd not worry about that - simple rule is not to run any LED at full power anyway, as it will blow itself up in short order as most heatsinking is inadequate.

OK this is starting to make sense now. I've been reading that Marwi site and looks like an answer to all prayers ... except that the driver board option doesn't seem to come with an "on only" option (lights would be switched on sequentially via the handlebar switch opening the circuit to them - am trying to get away from those wretched on/off switches on the lamps lol .. albeit it looks like there is a 'last setting' memory function which might be a light in this very dark tunnel !!

This is the page I've been reading trying to work out the options for using them :

2800ma Multi Mode Driver Board

Puzzled by the current readings on there ... am also wondering how bright the single LED would be run at less than 2.8A. I think the board may only work for 3.7v power input too so maybe a different board would need to be found

 

[Alan Quay]

To make things a bit easier:

As far as I can make out, a Cree t6 runs at about 3v, 1A. So if you had two in parallel, you would draw 2A at 3v (6w). Assuming some losses in the DC-DC converter, I would guess you would be drawing 0.2A at the battery. Even with 50% efficiency, it would still only be 0.32A

Another approach may be to use a DC-DC converter for each lamp (thus reducing current to 1A each) which would build in a some redundancy. You could even then run two rear lights (one from each converter), giving you a fair amount of redundancy.

 

[Scimitar]

albeit it looks like there is a 'last setting' memory function which might be a light in this very dark tunnel !!

This is the page I've been reading trying to work out the options for using them :

2800ma Multi Mode Driver Board

Puzzled by the current readings on there ... am also wondering how bright the single LED would be run at less than 2.8A. I think the board may only work for 3.7v power input too so maybe a different board would need to be found

Yes, the last option memory function would be ok if it remained reliable - drop him a line asking him if he does one that can be a simple on/off. Failing that, it would be worthwhile digging through some of the flashlight parts suppliers' sites from China because I've definitely seen simple on/off driver boards for T6s and P5s and pretty cheap, too.

 

[Gdread]

I agree that's the impression, but correctly sized, installed and protected they are more reliable than you would think. Often though, I agree that they are installed poorly and will fail.

These are very good:

http://www.ebay.co.uk/itm/Scotchlok-Connector-Dropwire-2A-Jelly-Gel-Filled-Telephone-Cable-Connectors-x-10-/271075939814?ssPageName=ADME:L:OC:GB:3160

 

[103Alex1]

To make things a bit easier:

As far as I can make out, a Cree t6 runs at about 3v, 1A. So if you had two in parallel, you would draw 2A at 3v (6w). Assuming some losses in the DC-DC converter, I would guess you would be drawing 0.2A at the battery. Even with 50% efficiency, it would still only be 0.32A

Another approach may be to use a DC-DC converter for each lamp (thus reducing current to 1A each) which would build in a some redundancy. You could even then run two rear lights (one from each converter), giving you a fair amount of redundancy.

Aha ... by the sounds of it then, the limiting factor is the DC-DC convertors not being happy with more than 1-1.5A (probably where I got the 0.75 from by halving that without logic !) ... thing is a decent converter with heatsinks is pretty chunky from what I can see and I'm going to need a stack of 'em if I start running every light off its own converter from 36v. They're about £10 each delivered so not cheap either. Nervous about the cheapie £2 ones to be honest as they seem to keep blowing up on people

One like Haku posted above but which is good for a 36v input rather than a 35v max and is also OK with up to 3A output seems more sensible for a 3-CREE + tail light setup. Wonder if there are any like that.

Yes, the last option memory function would be ok if it remained reliable - drop him a line asking him if he does one that can be a simple on/off. Failing that, it would be worthwhile digging through some of the flashlight parts suppliers' sites from China because I've definitely seen simple on/off driver boards for T6s and P5s and pretty cheap, too.

He says he definitely only does lights which run off 3.7v battery packs at up to 2.8A and has no other designs available. So would I still get the actual LED from him along with the housing and heatsink even if I sourced the driver elsewhere ? I really need a 1-mode driver ... on if current reaching the board (rather than a 2-mode on-off) ... presumably an on-off would most likely be without a memory function so would default to off until switched on manually at the lamp every time the power was cut and thus bring me back to the very same problem I'm trying to work around ???)

It's like trying to force a square peg in a round hole. Why doesn't someone just make T6s to wire in to a circuit ?

 

[Old_Dave]

Why doesn't someone just make T6s to wire in to a circuit ?

But they do...

Over complicating what you want to do has over complicated the task, I refer back to what I and d8veh both said... Keep it simple



Sent from my iPhone using Tapatalk

 

[Haku]

I just ordered a new dc-dc converter today:

LM2596 DC-DC Step Down Adjustable Power Supply Module Buck | eBay

I hope you aren't planning on putting many amps through that, I finally got round to wiring up my 2 near identical multimeters which can measure volts+amps and display watts (the VA number) with plugs on so I can measure the efficiency of a DC-DC converter.


First the Dimension Engineering 25watt converter, 30v input with output set to 12v:

After 10 minutes of dissipating 2.2 watts the converter gets up to 50 degrees celcius.



Now the LM2596 board, 30v input with output set to 12v:

After 10 minutes of dissipating 3.4 watts the LM2596 IC gets up to 60 degrees celcius!



You can buy 20x of those LM2596 DC-DC converter boards from China for the same price as 1x Dimension Engineering DC-DC converter from America, I know which I'm going to use

 

[tillson]

Aha ... by the sounds of it then, the limiting factor is the DC-DC convertors not being happy with more than 1-1.5A (probably where I got the 0.75 from by halving that without logic !) ... thing is a decent converter with heatsinks is pretty chunky from what I can see and I'm going to need a stack of 'em if I start running every light off its own converter from 36v. They're about £10 each delivered so not cheap either. Nervous about the cheapie £2 ones to be honest as they seem to keep blowing up on people

One like Haku posted above but which is good for a 36v input rather than a 35v max and is also OK with up to 3A output seems more sensible for a 3-CREE + tail light setup. Wonder if there are any like that.



He says he definitely only does lights which run off 3.7v battery packs at up to 2.8A and has no other designs available. So would I still get the actual LED from him along with the housing and heatsink even if I sourced the driver elsewhere ? I really need a 1-mode driver ... on if current reaching the board (rather than a 2-mode on-off) ... presumably an on-off would most likely be without a memory function so would default to off until switched on manually at the lamp every time the power was cut and thus bring me back to the very same problem I'm trying to work around ???)

It's like trying to force a square peg in a round hole. Why doesn't someone just make T6s to wire in to a circuit ?

Alex, you seem to be going around in circles asking the same questions on different threads.

This DC to DC converter will take an input voltage of anything between 8 and 50 volts and output 9 volts, which is perfect for the Cree T6 lights, at a maximum of 3 Amps. That's a max power of 27 Watts. No adjusting, just a straight 9 volt output. It even has a heat sink. I have run this on the bench with 5 x T6 LED lights and it got warm, but not hot. It even has clamp type terminals, so no soldering or crimping. I have been using it for some time now and it is fine.

And, as I and others have already pointed out in other threads that you have started, with your battery, running a few lights is not going to cause any significant reduction in range.

I'm not sure what you are trying to achieve, but if you aren't careful, I think it might be a fire. Keep it simple.

 

[103Alex1]

Hi tillson ... OK if you've tested the converter and are sure it only runs warm I am more reassured on that point. I keep dead-ending with no understanding asking things from one angle so sometimes the only way is to go at it from another and another until you can get to the understanding you're looking for.

How many amps do those T6 lights you recommended draw (there are various modes on them so the amps must vary considerably ?) ... if it's 3A at the converter then what does that correspond to at the battery ? ... and do I need a converter each for 2 ?

I keep coming back to the same point as I still can't see why what I want is so complicated. In my head it should actually be just as easy and far more sensible for this particular bike and user (other solutions might be preferred by others and suit them better, but that's the whole thing about designing stuff yourself I guess). Single mode gives controlled amps draw output with handlebar control, lights mounted on front forks and not on handlebars. This is a compact dashboard so rather not have it cluttered up with lights when I can mount them lower on a bracket and free up space... but don't want to be fiddling with on-off switches down there if I can do it from the bars.

Thing is, to me what I'm trying to achieve should actually be easy but everyone is telling me I am wanting something complicated lol. I cannot understand that yet. I simply want to by-pass the clicky switch modes on the T6s and turn them on/off via my handlebar switch by either opening the supply to them or shutting it off without having to fiddle with a light switch on the front of my forks in the middle of riding my bike... the setup is akin to every factory-supplied built-in motorbike and car light setup there is.

So can't understand why wanting that is over-complicating things ... it's just that the T6 lamp units have been set up to be driven like torches on multi-mode operation and I want them with on / off and remote switching with a single brightness setting (if dimmers don't work well on CREE LEDs).

In the end, to use an analogy, all it boils down to is switching your lamp on at the wall rather than switching it on via the flex cord that's dangling behind the cabinet and you have to fish out and fiddle with .. only difference here seems to be that you can leave your lamp set to "on" when you cut the mains power to them but the CREE lamps have a "memory" and demand being switched on and their brightness chosen via the back button every time they are used. It's the lamp units which are over-complicated surely, rather than my lighting plan

I'm not good with compromising until I understand why I have to o). It may be too much work, too much money, safety, not possible or something like that but once I understand the reasons thoroughly I'll happily move on. I don't understand the reasons yet ... only that the products can't seem to be picked up off the shelf without modding for the installation.... and as a freely admitted novice to all this, isn't that pretty much exactly the same as everything else on a self-build rather than a "fit kit" bike

Will happily make trade-offs and compromises - but once I've weighed everything up and investigated rather than just settling for the easy route.

I am very grateful for the input and have made huge progress so far (if not there with the final decision yet). Have just joined MTBR forum and put a post up on there too about the T6 clicky switch drivers to try to find whether there is a simple fix for by-passing them as no-one seems to know. It does seem like very few people have actually tried to install this way - mainly I am guessing because MTBR users are not working with the power of eBike batteries and so just want to remove the flash mode or alter brightness sequencing with their portables.

Those who have eBikes seem to be simply looking to tap the main battery in place of the portable ones rather than install a motorbike-style switching system - or else use different lo-power single mode light units rather than T6 units, which to me is missing a big opportunity. There is logic in my quest ... somewhere !

 

[Geebee]

If you are going to use more than one light why not just switch off 1 for low mode?

 

[103Alex1]

That is exactly what I'm planning Geebee. I actually want 4 lights hooked up ideally :

Setting 0/1 : Tail light on and 1 x T6 (comes on when lighting isolator switch turned on as default)

Setting 2 : An additional T6 comes on

Setting 3 : The final T6 comes on

In each mode the previous lights all stay 'on'. The switch is near the thumb throttle. Bosh. Simples.

It would work with those lights you got off DX (I ordered 3, posted out Friday) ... but I want to do this with T6 power rather than 250lm lights, that is all.

The T6 units are causing the problem - they are multi-mode and when you disconnect the battery or cut power to them you have to press a button on the back of every light to select the brightness level you want. All I want to do is exterminate that functionality so that they come on when power is opened to them via the handlebar switch and go off when you switch it down.

I looked at a dimmer - but was causing problems with how LEDs react to voltage drop (non-linear) so I simplified the plan to using multiple lamps. However I am being told the simplified plan still means I am over-complicating things. I'm struggling with this mate !

 

[Old_Dave]

However I am being told the simplified plan still means I am over-complicating things. I'm struggling with this mate !

But your getting better

If the dedicated T6 drivers are causing an issue, then just use bog standard (suitable voltage & current) drivers

Dimmers as you have found are a pita so if for example you have 3 lamps on the front bar... use 1 set at a lower angle and 2 higher (or 2 low 1 high or even 1 low 1 mid 1 high).

The answer to the problem you will have when trying to wire the switch as 1+Rear, 1+2+Rear, 1+2+3+Rear is to add two diodes

May even be a decent idea to have 1+Rear on permanently as running lights which will make it even simpler'erer

 

[tillson]

When I ran the 5 x T6 LEDs (two lamp units containing 1 LED and one lamp unit containing 3) the DC-DC unit was outputting 2.4 Amps at 9 Volts. Assuming that the converter is 80% efficient, this makes each of the 5 LEDs about 3.5 Watts. They were running at maximum brightness mode.

This handlebar light dipping idea / bypassing the mode switch on the lamp unit is possible, but it isn't necessary. As I have said before, if you adjust the angle of the lights properly, they will light the path ahead sufficiently, but will not dazzle oncoming drivers. I have 4 x properly aimed Cree T6 LEDs on the front of my bike and it is not necessary to dip the beam, reduce the brightness or any of the things that you are striving to achieve. They give good illumination without dazzling anyone. To switch them all on, it's a total of three button presses and this takes 1.5 seconds out of my day.

Unless you want to do the light mode modifications and dip switching from a handlebar mounted device as an academic exercise, it really isn't worth bothering with. There is simply nothing to be gained. Making a simple setup to provide power to the lights from the bike battery is worthwhile as it saves messing around with individual battery packs for each light.

 

[Alan Quay]

I hope you aren't planning on putting many amps through that....

No, In my case <1A at 5v (5w), so I hope it will just about cope.

Interesting results though. Your 25 Watt unit is about 85% efficient, and the LM2596 is about 80%.

(edited, I had the figures the wrong way around)

 

[103Alex1]

But your getting better

If the dedicated T6 drivers are causing an issue, then just use bog standard (suitable voltage & current) drivers

Dimmers as you have found are a pita so if for example you have 3 lamps on the front bar... use 1 set at a lower angle and 2 higher (or 2 low 1 high or even 1 low 1 mid 1 high).

The answer to the problem you will have when trying to wire the switch as 1+Rear, 1+2+Rear, 1+2+3+Rear is to add two diodes

May even be a decent idea to have 1+Rear on permanently as running lights which will make it even simpler'erer

Ooh ... now I'm getting all excited lol. AND .... my first ever DC-DC converter just turned up in the post. It's one of these ... and it's 1/10 the size I thought it would be (read mm as cm ) so I'm no longer bothered about how many I have to have and hang the cost lol !!




Now then ... wot's a diode, where does it staple to and how many capacitors, resistors and MOSFETs do I need to order from China to put it in ?

and ... which bog do I find these standard drivers in that would fit in the housing of either the lights tillson kindly linked me to (or if you can't pull those apart and swap the driver, then those marwi ones Scimitar unearthed at the ship & bottle store)

 

[Geebee]

What about just buying the t6 led without the driver and wiring them in place of the 3.5w ones, it would be worth tying one and see if the driver is up to the job, as then no converter is needed and wiring is a snap.

I think I will just wire all three of mine to a single switch, I have even half considered just wiring them permanently on when the battery is connected as I store the bike without the battery in it, and the added visibility can't really hurt.
Then the tech in me thinks an auto on light switch activated by reduced light level.

 

[Old_Dave]

Then the tech in me thinks an auto on light switch activated by reduced light level

Hmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm

 

[Old_Dave]

Now then ... wot's a diode, where does it staple to and how many capacitors, resistors and MOSFETs do I need to order from China to put it in

Diodes are cheap.. nothing else needed apart from your chosen switch, don't have to bother with China

I'll do you a little circuit diagram as soon as I go to the pub and get a beer mat

Its possible to use even cheaper 3A ones but here is something suitable

4X P600A General Purpose Rectifier Diode 6A /50V @@@FAST DELIVERY@@@ | eBay

 

[103Alex1]

What about just buying the t6 led without the driver and wiring them in place of the 3.5w ones, it would be worth tying one and see if the driver is up to the job, as then no converter is needed and wiring is a snap.

I think I will just wire all three of mine to a single switch, I have even half considered just wiring them permanently on when the battery is connected as I store the bike without the battery in it, and the added visibility can't really hurt.
Then the tech in me thinks an auto on light switch activated by reduced light level.

Got a feeling if you go and push 36v at a T6 LED it will simply go bang but what do I know ... except never seen them run at more than 9v.

Yeah with lights of that spec I would have them on all the time - they will use next to nowt in power.

When I ran the 5 x T6 LEDs (two lamp units containing 1 LED and one lamp unit containing 3) the DC-DC unit was outputting 2.4 Amps at 9 Volts. Assuming that the converter is 80% efficient, this makes each of the 5 LEDs about 3.5 Watts. They were running at maximum brightness mode.

This handlebar light dipping idea / bypassing the mode switch on the lamp unit is possible, but it isn't necessary. As I have said before, if you adjust the angle of the lights properly, they will light the path ahead sufficiently, but will not dazzle oncoming drivers. I have 4 x properly aimed Cree T6 LEDs on the front of my bike and it is not necessary to dip the beam, reduce the brightness or any of the things that you are striving to achieve. They give good illumination without dazzling anyone. To switch them all on, it's a total of three button presses and this takes 1.5 seconds out of my day.

Unless you want to do the light mode modifications and dip switching from a handlebar mounted device as an academic exercise, it really isn't worth bothering with. There is simply nothing to be gained. Making a simple setup to provide power to the lights from the bike battery is worthwhile as it saves messing around with individual battery packs for each light.

I see your point tillson. Guess it's a case of wanting things to be one way when they are designed a different way. Perfectionist preference reflexes kicking in which have to be controlled on a regular basis.

I have dazzled oncoming vehicles and pedestrians using a single 1200lm CREE T6 when if I tilted it down it doesn't light far enough or wide enough ahead. So I am well open to hearing but not (yet) believing and only real way to see for myself is to spend £60-odd on lights and play with the mounting adjustment.

PS - I ordered the converter a few days ago but held off the lights whilst I explore all this to death as they are UK-sourced and fast to get hold of.

The magicshine rear light looks a bit more than it's worth to be honest. 1W is likely more than enough as it's oncoming vehicles where having cars see my light throw long before I'm in view is what I'm trying to achieve. When you drive in far SW at night you can see 'beam up' car headlights on the windy lanes often a good 15 seconds before you see the car. The head-ons often occur when people crawl along with their beam down - as no-one is expecting to come up on them and so are driving too fast. In short, everyone knows to slow down to a virtual stop for each other way ahead of time if a pull-in is near (to avoid having to back up in pitch black) and so everyone drives reacting to that expectation. I'd like to have a light setup on my bike where cars will react to my presence in the same way. Will adjusting these CREE T6s like you suggest throw enough light up to have this effect ? Serious question this.

Might just use a SmartLunar battery powered light for brightness as I have one already and batteries last an age without being recharged. A low-powered built-in one would just be an auto-backup in case the batteries died on the clip-on one when you're out with it so doesn't have to be anything mega-expensive.