PSA – Maplins have hybrid AAs on offer currently. Picked some up today for this project.

Mark posted the XPEs today first class so you may have them tomorrow .

Could someone simpliy the wonderfully complex world of battery pack options for this project, assuming an external pack and aiming for say 3 hours life. Whats on offer out there? I’m getting a bit lost in all the flood of info, and im not at all familiar with the battery terminology (no idea what an 18650 is or why “protected” matters). Appreciate a simplified guide if someone has the patience.

18650 = big AA battery 3.7volt similar capacities

Protected cell = small electronic circuit stopping it over charging or dropping too low in voltage through use.

I think!!!

I’m going for AAs to start with as they are easy to get hold of and simple to understand.

Most AA rechargables are 2000mAh or there abouts. This is the capacity of energy. They are 1.2v. connect 2 in series and you get 2.4v. Connect 8 in series to get 9.6v still with a 2000mAh capacity.

If my memory serves me right the power draw of the 2 led’s and driver is about 7.5w (watts). to get the power of the battery you multiply the volts and amps 9.6 x 2 = 19.2wh.

divide that by the 7.5w to get the run time.

If you can follow that then you can see that increasing the voltage and/or capacity incrreases the run time.

You need a minimum of about 7.5v to put through the driver though.

Confused yet? 🙂

ok if building it as the spec using BCT`s driver we have 2 leds wired in series needing around 6.6 volts his driver needs 1 volt so 7.6 volts are needed 2 18650 li ions will be 8.4 volts off the charger and slowly lose their voltage and the driver will go out of regulation and the leds will be driven straight from the remaining volts and dim somewhat
on hi I have tested this config and it gave 1 hour 30 ish mins before the light went out .

so the sweet battery would be 3 18650 cells in series to give nominal 11.1 volts this will run the light untill the cells cut out and have full power for the duration .

Protected cells have a circuit to prevent over charge and discharge which is harmfull to Li IONs .

not sure what the ceiling is in Stevens driver but you can use a 14.8 volt pack like a Lumicycle battery so you can use a wide variety of packs upto around 20 volts I have used my Makita drill battery and that is 21 volts when fully charged .

Here is a good site to learn about Li Ions
http://www.batteryuniversity.com/partone-5.htm

You have a 3S battery dont you Troutie? I’ll post the charger up to you tomorrow 😉

Sorry for dropping in and out of discussions on here at the moment – I’ve been away for the weekend then have been fixing a carpet for SWMBO tonight and collecting the cats on the way back, meaning I’ve only just got in!

Unfortunately there was a problem with the Rapid order on Friday so it’s only just been despatched to me today, should be able to start mailing kits out tomorrow.

For those who have made special requests, I will reply when I get the chance.

To quickly cover the battery topic, the driver ideally needs about 8.5V to be able to give full output and run comfortably within limits. If you are attaching it to the case to give extra cooling them that allows you to drop the voltage below 8V. The upper limit is 24V.

In general, the higher the better. Efficiency is usually higher and less current is drawn from the battery so less stress is being put on it.

If using ‘standard’ NiMH rechargeables I’d suggest the type that hold their charge such as GP Recyko or Sanyo Enloop. They are slightly more expensive but you don’t need to worry about charging them up just before you go out as they don’t lose their charge quickly unlike most other NiMH cells. AAs tend to be the best for price / capacity / size. Eight would give you 9.6V nominal and up to 25Wh of power based on the capacity of the cells you choose. This will give over 3 hours at full power, about twice that at half power. Take care choosing a holder, many of the cheaper ones you buy don’t retain the cells all that well. If you don’t mind losing the ability to charge them in a standard charger you can make up a battery pack and buy multicell chargers that do the whole pack in one go. You could also use a RC car battery pack, I believe the 9.6V ones tend to use AA cells.

Lithium cells have advantages, mainly the fact they can store more charge for their size and weight. People often refer to 18650 cells – these are similar to AA but a little bit larger. You can get 14505 cells which are the equivalent to AA size and could be used in an AA battery holder. Three lithium cells in series would give 11.1V nominal and protected cells would cut out at around 8.1V. I believe that to quick-charge lithium cells you need a special charger which monitors each cell individually.

Hi BCT,
My payment to you still says unclaimed in paypal. I’m just wondering if you received it ok?

I’m waiting until the items are ready to despatch before claiming payments. I’ve not forgotten!

Thanks BCT.

Quick question about the recommendation of gp or enloops. Are these better because they exhibit less of a voltage drop curve (which is very good in this situation where we have a V. cutoff) or that they just retain their charge better (the main benefit between charging and first use, asuuming you are charging before use).
If the latter then as enloops only have a maximum capacity of 2100mah, so surely a set of std nimh 2900mah (non enloop) technology would be better and last longer?

Question about 2.9ah std nimh vs 2.0ah hybrids still stands (I.e. Does greater capacity more than compensate for increased voltage drop?)

However I’ve just been reading on t’web and if I’ve understood correctly the eneloops have a lower internal resistance which results in less of a voltage drop during usage (which is good)

Review of eneloops and another interesting 1.8v 2500mah chunky AA here:
http://www.tomsguide.com/us/rechargeable-batteries-cell,review-1525-3.html

Showdown: PowerGenix NiZn vs. SANYO eneloop NiMH

I’ve found that ‘standard’ NiMH cells can lose a lot of charge fairly quickly. The Uniross ones I used in my digital camera are next to useless 3-4 weeks after coming off the charger.

If you are disciplined enough to put your light on charge before you need it then you are likely to do better with higher capacity cells. If you want a light you can just pick up and not have to worry about charging it beforehand then Eneloop or Recyko+ would be best.

NiMHs have a low enough resistance anyway that you won’t need to worry about it. Current drain will be of the order of C/3 which is no strain at all – in RC applications you can get peak drains of many times C.

Anyone know where we are with delivery times on the parts? (not trying to hurry you guys just trying to reign in my excitment!)

Hoping to get the first ones out tonight provided I can kick some life in to my printer which has started missing bits out.

One problem, Rapid have let me down on the switches. I only have 22 and the other 25 I’d ordered they have given to someone else and more aren’t due until December… I’m working on an alternative but the last few orders may be delayed slightly while I find something…

so, if i was going to make up a pack of say 8 or 10 Eneloop NiHM AA, where do I get the best multicharger suitable for that ?

not sure which way im going to go yet but thinking about making a pack for the completeness of the whole project as a diy. its either that or a smudge special i think.

BCT: were you posting your parts to the individuals or over to Trout to mail out with the optics?

BlackCatTech i can pick up a switch from maplin, send mine without and let someone else have mine!

the leds may be here by the end of the week so will endevour to get my stuff into Pats van asap .

and as I am currently nearly buried under a pile of wires will chuck in a few stray bits in each packet .

I think Steven is mailing the other stuff direct

Here is a little light i have made for a customers young un

got another to do when I get another driver from BCT .

I was going to ask about what sort of cable we should use in these lights!

Cheers for the heasd up trout, gives me some more time to try and source a bracket for the bars and helmet. I tried to get a couple of the spacers used by Ctizen Kane for the catyeye mounts howver Zyro have told me these are now no unavailable in the uk and they cant order them from the states 🙁 Back to the drawing board I go…

Mini light looks really nice, I’m very envious of you having the craft to be able to do this sort of thing so well.

Trout.

Nice one, looks interesting.

I like the lens cap, I like the look of those screws set around the edge like that.

🙂

Cheers Lumi does look very mini dive light .

Bastard M2`s broke a 1.6 mmm drill in one hole but after an hour managed to unscrew the sod .though did think about leaving it and gluing in a screw head .

tis a cracking little light half of one of these CKs

Curly as I found 2 whole reels of the cable in the pics in a skip .
I will throw in 1 metre to each Diyer.

He’ll be pleased with those Troutie 8)

Don’t go showing too much though or you’ll be snowed under with those as well 😆

Thanks Troutie – the single LED is looking good – out of interest though does the cable terminate with a male or female end?

Good question steve

Female on the light so heres hoping you have a male on the batterys

yes – male on the batterries – just wanted to check!

Don’t panic me like that!

Update on leds and stuff

I have got the vagina reflectors today

the leds are now in Stuttgard or were at 01.50 this morning .

I also have a bit of a problem .

not enough addresses .
so please could you all send me an address which matches your name and stw name .

you weren’t the only one panicking- a mate was “showing off” his bastid and I saw they had the female plug on the battery – I obviously worry too much!

trout

Have mailed you with my address, looking forward to my little packets of joy falling through the door 🙂 If Maplins would pull there finger out with delivery that would be even better.

I have couple of questions about the assembley of the light.

You mentioned using 3/4mm screw taps, where would be the best place to get these and also the screw etc from?

Does it matter what silicon you use or does it have to be a specific type?

What glue would you recommend using, does this have to be a specifc type?

Last but not least any suggestions on mounts at all?

Aldi or Lidl sometimes have some cheap Tap and Die sets, or try Machine Mart.

The lumicycle mount looks good, or there is a cheaper Halfords alternative, the Electron mount is available on Ebay.

I have found that RC shops can be good for purchasing smaller diameter screws, in low quantities.

As for the taps. I use a local Hardware store which still sells taps seperately.
If you can’t get to such a store, try your local Engineering merchants.
Failing that, you’ll have to pick up a small set of taps, which may come with dies, then yeah, Machine Mart, etc.
If you do have to buy a small set, at least you’ll have’m around, should you choose to undertake another project….
😉

I hope you lot are going to post Pics of your new lights.
I want to see them.
🙂

If any of the no-addresses turn into no-sales let us know, I’ll snaffle a leftover set.

I have got the vagina reflectors today

Wow – are these going to cost more 😉

There are hundreds of brackets out there but its been attaching them to the light that has been puzzling me.

Im thinking of either MOUNT 1 or MOUNT 2 and removing the section that would hold the torch body. The flat part that remains could then be screwed or glued to the bottom of the Hammond box.

Just a quick question. How much sinking is required for these at full? having looked at the ape parts that trouble sent, it seems a very small light can be made. I’m thinking external battery and inline switch. so only reflectors, leds and driver inside.

Ref the mount.

Surely this:
http://www.chainreactioncycles.com/Models.aspx?ModelID=12871
Can be used ?.

Remove the bar section, and use a washer and the nut.

Drill a hole in the underside of your light (assuming you’ve cut the hammond box into two parts to make two seperate lights) towards the rear of the light where your switches will be.

Then, before you close the box by screwing on the end plate, you hold a nut and washer inside the box, then from the outside you screw through the clamp into the nut.

Would this not work ?.

Then apply a little thread-lock and maybe a bit of epoxy around the washer to stop the light rotating, and I’d hope you’re good to go.

Close the light up by attaching the end plate and I’d of thought that would be that.

Caveat: As I’m not familiar with the box or the mount, I expect I could be completely wide of the mark.

Alternatively, would this be OTT ?.
http://www.wiggle.co.uk/p/cycle/7/Lupine_Handlebar_Mount_25mm_for_Lamp_Unit/5360009560/