External charge points for dive can light

[Packhorse]

Im thinking of using external charging points for my dive light project.
The problem is how to avoid the points being active while not charging.

Option 1. Use diodes to block the current out of the battery pack.
This seems like the easiest way to do it. Only problem is that there is a voltage drop accross the diodes of .6 volts each or 1.2 volt total. When connected to a "smart charger" how will the charger react?
Do the chargers calculate the number of cells according to voltage? will the diodes effect this?
I could always use a "dumb charger" and put up with slower charge times.

Option 2. Use relays triggered by a reed swich and externally used magnet.
This requires a little more hardware.

The Solus SU 1250 seems to not use option 2. Does it use option 1 or perhaps option 3?
If so what is option 3?

 

[RyanA]

Inductive charging would be interesting.

 

[Echo63]

Inductive charging would be interesting.

i dont see why it wouldnt work, my electric toothbrush does it
the magnetic field from trying to charge a large battery at a reasonable rate may have some interesting effects though

 

[Doh!Nut]

I really like the reed swich idea.
I am banned from rummaging inside my wifes Kowalski but they have two unmarked banana plugs as charging points.
Unmarked because it does not matter which way round you plug the leads. oo:

I dont know how Kowalski do it but I was thinking of a circuit that opened a gate between positive battery and posative charge socket when an external voltage was supplied.

Nick

 

[SUBjohan]

I really like the reed swich idea.
I am banned from rummaging inside my wifes Kowalski but they have two unmarked banana plugs as charging points.
Unmarked because it does not matter which way round you plug the leads. oo:

I dont know how Kowalski do it but I was thinking of a circuit that opened a gate between positive battery and posative charge socket when an external voltage was supplied.

Nick

I just "pimped" a old kowalski with a P7 and kowaslki does it with a bridge rectivier.

Greetz Johan

 

[Doh!Nut]

Interesting about bridge rectifier.

I think that a good NiCd charger, like one that will do 4-10 cells should be able to properly detect the dip in voltage to stop charging.

I was planning on Li-Ions which rely on accurate voltage detection for charge termination, a diode or two in the way would really screw up the charging ( it would be under charged but at least safe)

Johan
How did you find the beam with the P7 in a Kowalski reflector?
I am using and oceanic host that is basically a Kowalski copy. I was trying to find the focus point and it was 10 or 15mm inside the reflector so half? of the (P4) LED output did not even see the reflector.
I have ordered a P7 today to see how it looks.

N

 

[SUBjohan]

Johan
How did you find the beam with the P7 in a Kowalski reflector?
I am using and oceanic host that is basically a Kowalski copy. I was trying to find the focus point and it was 10 or 15mm inside the reflector so half? of the (P4) LED output did not even see the reflector.
I have ordered a P7 today to see how it looks.

N

Hmmz, could be better.
I also have made a maglite with a P7 and used the KD P7 reflector wich in my oppinion is much better. When my extra reflectors from KD arive the kowalski will get one :thumbsup:

Greetz Johan

 

[Packhorse]

I just "pimped" a old kowalski with a P7 and kowaslki does it with a bridge rectivier.

Greetz Johan

Interesting. I notice the Solus charging points do not seem to be marked so perhaps thats the same.

Now is a smart charger is only looking for the delta V and not actully looking at the voltage I cant see a problem. May have to do some research and testing.

 

[RyanA]

i dont see why it wouldnt work, my electric toothbrush does it
the magnetic field from trying to charge a large battery at a reasonable rate may have some interesting effects though

the new rechargeables from pentagon light use it with l-ion batteries.

 

[Packhorse]

I just "pimped" a old kowalski with a P7 and kowaslki does it with a bridge rectivier.

Greetz Johan

What sort of charger does it use? Is it a specific Kowalski one or just a normal transformer or is it a smartcharger?

 

[SUBjohan]

What sort of charger does it use? Is it a specific Kowalski one or just a normal transformer or is it a smartcharger?

Standard its a kowalski charger. But the guy how I made it for is using a ultramat 14 smartcharger from Gaupner.
Only the other day he called my to tell me that his battery's where getting hot, so I will need to go there to find out whats happening.

Greetz Johan

 

[markus_i]

No experience with dive lights, but a suggestion for option 3:

put the charger intelligence in the light (and connect the external contacts via any type of switch/diode/.... you like) and just use any old power supply.

Bye
Markus

 

[SUBjohan]

Only the other day he called my to tell me that his battery's where getting hot, so I will need to go there to find out whats happening.

I just found out what went wrong, he acididentely set the charger at the Li-ion program at 2,5A :green:. So the bridge rectivier is dead

Greetz Johan

 

[Packhorse]

Putting the charger in the can will make the can too BIG and then there is also the heat to deal with.
Good idea though, thanks for your input.
Am awaiting a DX mystery charger so will do some testing when it arrives.
Will make sure its set to NiMH

 

[mpf]

Putting the charger in the can will make the can too BIG and then there is also the heat to deal with.

I have used a Maxim DS2715 inside a torch. Very small. Needed only one FET TO-220 to control the charge current. Heat should not be a problem if you set the input voltage only as high as necessary. Use the case as the heat sink. Also use Schottky diodes, you only need one if you polarise the input plugs. Voltage drop <0.4V at 2A.

Edit. I don't trust deltaV cut off for changing NiMH. If the batteries are almost fully charged there is no deltaV and you end up with very hot batteries leaking their guts out. The DS2715 uses delta T cut off which is much more reliable.

 

[Packhorse]

Fair enuf.
But im really looking for a KISS approach. So smart charger may giveway to "dumb"charger.
Put in 1/10 C or even as high as 1/5 C and heat and off gas should be kept to a minimum.

 

[Fluor]

What about using a diode on the input and adding the extra 0,6V on the outside? Simply add a 0,6V powersupply in series with the charger.

I was thinking about the same thing. No need to open the light at any time(except modding). If you use the housing as the negative port you will only need one terminal. Anyone seen a good terminal with o-ring protection?

 

[DM51]

The Solus SU 1250 seems to not use option 2. Does it use option 1 or perhaps option 3?
If so what is option 3?

I dived with a prototype Solus SU 500, the 1250's predecessor. It used diodes (your option 1), however I wasn't happy with the 3x18650 cells having no balancing taps for charging, so I opened it after every 4 dives and charged the cells individually. I stress that was a prototype, and the battery was still WIP, so the set-up has probably improved.

The SU 500 was a very nice light indeed, BTW, so I should think the SU 1250 is excellent.

 

[wes_wall]

Not to sound like a gushing newbie or anything, but you guys are challenging me. Thank you. I am a dreamer.

Here's the deal: I have a degree in engineering, and a disposition of constructive discontent. (For reference, I am an electrical engineering buffoon -I worked very hard and conned a professor to scrape out a C in the one EE course I had to take. I really 'earned' an F at best in that course.)

You guys are challenging me to get more electrical knowledge. Particularly DC low voltage.

Can you guys recommend any reading geared at maybe a smart 10th grade level as a place for me to start?

 

[Packhorse]

I dived with a prototype Solus SU 500, the 1250's predecessor. It used diodes (your option 1), however I wasn't happy with the 3x18650 cells having no balancing taps for charging, so I opened it after every 4 dives and charged the cells individually. I stress that was a prototype, and the battery was still WIP, so the set-up has probably improved.

The SU 500 was a very nice light indeed, BTW, so I should think the SU 1250 is excellent.

I was on a trip a few months ago where there was aSU100 and SU1250.
Build quality was fantastic. Light output was so disappointing though. Way to floody for my liking.