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Building a Lithium Ion Battery Pack. Need help.

B

Bighiller

My goal is this:

To be able to power a 21W HID bulb for 3hours using AA sized lithium-
ion batteries and to charge them using one charger. Basically I am
building an underwater canister dive light, but I'm not 100% on the
battery pack and how to wire it.

I understand I can buy a bunch of batteries at ~3.7V each, but I need
to know how to wire them up to the PCM and other such niceties. If
someone could point me in the right direction, that would be
excellent!

Let me know if anyone could tell me what I'll need to make this so.

Thanks,
 
A

[email protected]

My goal is this:

To be able to power a 21W HID bulb for 3hours using AA sized lithium-
ion batteries and to charge them using one charger. Basically I am
building an underwater canister dive light, but I'm not 100% on the
battery pack and how to wire it.
Click to expand...

And you wanna trust your life to the low life yahoos on this group!?
I understand I can buy a bunch of batteries at ~3.7V each, but I need
Click to expand...

Never heard of AA 3.7V lithium ion cells. You got a link?
http://www.greenbatteries.com/libafa.html#Li-ion in AA
"Are Lithium Ion batteries available in standard sizes like AA , C or
D cell size?
No, Lithium-ion batteries are not available in standard sizes. "
to know how to wire them up to the PCM and other such niceties. If
someone could point me in the right direction, that would be
excellent!
Click to expand...

I'd point you in the direction of a diving supply store. And of you
still want to build something like this yourself, I'd point you to a
stretcher in the back of the truck driven by the men with the
butterfly nets.
 
P

PeterD

A 63 Watt hour AA sized battery would be quite a trick. You could go
voltage I suppose, and have a *lot* of batteries, but they why limit
yourself to AA sizes? That said, there is no such thing as a AA sized
lithium battery anyway.
 
J

James Arthur

Bighiller said:
My goal is this:

To be able to power a 21W HID bulb for 3hours using AA sized lithium-
ion batteries and to charge them using one charger. Basically I am
building an underwater canister dive light, but I'm not 100% on the
battery pack and how to wire it.

I understand I can buy a bunch of batteries at ~3.7V each, but I need
to know how to wire them up to the PCM and other such niceties. If
someone could point me in the right direction, that would be
excellent!

Let me know if anyone could tell me what I'll need to make this so.

Thanks,
Click to expand...

Confining a large lithium-ion pack in a pressure-tight
container is DANGEROUS. Be careful.

A safety vent's a good idea.

Best of luck,
James Arthur
 
I

IanM

Benj said:
Absolutely. My camera takes them. They are nifty gadgets! The
batteries have a tiny circuit board built right in the end that
handles all the electronic sensing and charging folerol for Li-ion
batteries too.
Click to expand...
I downloaded the data sheet for JJJ-LC14500 and it did not appear to
"handles all the electronic sensing and charging folerol for Li-ion
batteries too"
 
B

Bighiller

And you wanna trust your life to the low life yahoos on this group!?
Click to expand...

That's a nice thing to say. And useful too.
Never heard of AA 3.7V lithium ion cells. You got a link?http://www.greenbatteries.com/libafa.html#Li-ion in AA
"Are Lithium Ion batteries available in standard sizes like AA , C or
D cell size?
No, Lithium-ion batteries are not available in standard sizes. "


I'd point you in the direction of a diving supply store. And of you
still want to build something like this yourself, I'd point you to a
stretcher in the back of the truck driven by the men with the
butterfly nets.
Click to expand...

Buddy, just keep your useless comment to yourself. You know jack and
squat about what I am doing and you just want to seem like you know
something....which is doubtful.

Good luck with that.

Well, thanks for the useless comments, they've made all our lives
better.
 
B

Bighiller

A 63 Watt hour AA sized battery would be quite a trick. You could go
voltage I suppose, and have a *lot* of batteries, but they why limit
yourself to AA sizes? That said, there is no such thing as a AA sized
lithium battery anyway.
Click to expand...

I've check batteryspace.com and they have A LOT of lithium ion
batteries and chargers, but I can't make out exactly what I need. It's
a matter of wiring the batteries together and getting the right
charger. As for the size, well I don't really care, so long as they
fit into a 2"x~12" PVC tube (roughly).
 
B

Bighiller

He is probably talking about 18650 cells. They are slightly longer and
wider in diameter than AA cells.
Click to expand...

Yeah, I think I was.
Lithium-ion batteries require more attention to safety than nicad or
nimh.
Click to expand...

This is understand, hence my posting.

They will be in a sealed container, but not permanently sealed. It's a
canister dive light, using PVC, proper O-rings, etc. SS latches hold
the top on making an air-tight seal.
 
B

Bighiller

Bighillerwrote:





Confining a large lithium-ion pack in a pressure-tight
container is DANGEROUS.  Be careful.

A safety vent's a good idea.

Best of luck,
James Arthur
Click to expand...

I understand that, but it shouldn't be a problem as the pack would
only be sealed for ~2hrs MAX. It's a dive light and I don't plan on
any LOOOOOOOONG dives.
 
J

Jim Yanik

A diode on one of the terminals would probably deal with that, and
also protect against a reversed connection.

Bob
Click to expand...

how do you recharge it then? the diode would block charging current.
 
J

James Arthur

Bighiller said:
I've check batteryspace.com and they have A LOT of lithium ion
batteries and chargers, but I can't make out exactly what I need. It's
a matter of wiring the batteries together and getting the right
charger. As for the size, well I don't really care, so long as they
fit into a 2"x~12" PVC tube (roughly).
Click to expand...

CONNECTION: several cells in series, or series-parallel, to
get the voltage the HID needs.

SAFETY: you need battery pack electronics, thermal switch, + a
one-way valve (vent) for the containing vessel.

The battery pack electronics protects each cell in the series
pack against reverse voltage, overdischarge, overcharging, and
the entire thing against short-circuit. The thermal switch
(PTC, positive temp. coefficient thermistor) is built-in to
many LiIon cells' anode contact. It's a back-up short-circuit
protector.

Numerous vendors offer pack electronics configured for common
pack voltages.

CHARGER: current-limited to C/2, voltage-limited to 4.15v per cell.

You might consider the 18650 size cells--they're the standard, bigger,
stronger, and cheaper. 14500's not so much.

The dangers are many--LiIons will vent with flame if abused, sometimes
not for hours or days after the insult. I don't know how they'll like
being pressurized.

You need the one-way safety vent. They're common, and cheap.
Otherwise, you're making a pipe bomb.

HTH,
James Arthur
 
B

Bighiller

Bighillerwrote:


CONNECTION: several cells in series, or series-parallel, to
get the voltage the HID needs.

SAFETY: you need battery pack electronics, thermal switch, + a
one-way valve (vent) for the containing vessel.

The battery pack electronics protects each cell in the series
pack against reverse voltage, overdischarge, overcharging, and
the entire thing against short-circuit.  The thermal switch
(PTC, positive temp. coefficient thermistor) is built-in to
many LiIon cells' anode contact.  It's a back-up short-circuit
protector.

Numerous vendors offer pack electronics configured for common
pack voltages.

CHARGER: current-limited to C/2, voltage-limited to 4.15v per cell.

You might consider the 18650 size cells--they're the standard, bigger,
stronger, and cheaper. 14500's not so much.

The dangers are many--LiIons will vent with flame if abused, sometimes
not for hours or days after the insult.  I don't know how they'll like
being pressurized.

You need the one-way safety vent.  They're common, and cheap.
Otherwise, you're making a pipe bomb.

HTH,
James Arthur
Click to expand...

The canister will only be air-tight with no-venting as I am in the
water (max ~1hr). The pressure inside the canister will remain at
1bar, while the outside pressure on the canister will max at about
4bar. The battery pack will be housed in a air-tight/water-tight
(both) canister for the dive. The battery pack will be contained with
heat shrink wrapping. The batteries will NEVER (as long as I can help
it) come in contact with water. As for the venting, please, if you
could, explain why I need to vent this canister? The battery pack will
stay in there only while on my dive and it's not likely to create an
explosion underwater. When you say vent, do you mean out of the
battery pack or out of the canister?
 
J

James Arthur

Bighiller said:
The canister will only be air-tight with no-venting as I am in the
water (max ~1hr). The pressure inside the canister will remain at
1bar, while the outside pressure on the canister will max at about
4bar. The battery pack will be housed in a air-tight/water-tight
(both) canister for the dive. The battery pack will be contained with
heat shrink wrapping. The batteries will NEVER (as long as I can help
it) come in contact with water. As for the venting, please, if you
could, explain why I need to vent this canister? The battery pack will
stay in there only while on my dive and it's not likely to create an
explosion underwater. When you say vent, do you mean out of the
battery pack or out of the canister?
Click to expand...

I mean that if and when the battery pack catches on fire, a vent
will keep it from killing you. The excess pressure has to have
an escape all the way to the atmosphere, otherwise it'll build
up, burst and shred most any container. That throws shrapnel,
fire, and incandescent burning metal everywhere inside your car,
boat, or backpack.

It doesn't happen often, but it happens.

Vents are common in flashlights, even dive lights IIRC. They
keep external pressure and water out, but let internal pressure
escape.

One method uses a silicone rubber plug--it'll pop out under
overpressure conditions. Another is a simple seal arrangement
that compresses and seals tighter under sea pressure, but
which lets internal pressure out. AKA "check valve."


(View in Courier font)

battery
/
plug | .--..--. |
--> (== | || | |
| | || | |
| | || | | <~~container
| '--''--' |
'----------'

Cheers,
James Arthur
 
B

Bighiller

Bighillerwrote:


I mean that if and when the battery pack catches on fire, a vent
will keep it from killing you.  The excess pressure has to have
an escape all the way to the atmosphere, otherwise it'll build
up, burst and shred most any container.  That throws shrapnel,
fire, and incandescent burning metal everywhere inside your car,
boat, or backpack.

It doesn't happen often, but it happens.

Vents are common in flashlights, even dive lights IIRC.  They
keep external pressure and water out, but let internal pressure
escape.

One method uses a silicone rubber plug--it'll pop out under
overpressure conditions. Another is a simple seal arrangement
that compresses and seals tighter under sea pressure, but
which lets internal pressure out.  AKA "check valve."

   (View in Courier font)

               battery
                 /
plug   | .--..--. |
  --> (== |  ||  | |
        | |  ||  | |
        | |  ||  | | <~~container
        | '--''--' |
        '----------'

Cheers,
James Arthur
Click to expand...

That I understand. I think, so long as it doesn't pop off, I'd could
integrate a check valve. Just would suck if it popped off underwater
and then water seeped in an made a bigger mess. What I am building is
similar to one of these:

http://www.halcyon.net/?q=lights/explorer

I prefer lithium-ion as they last longer and an HID for the quality
and quantity of light. Simply need a battery setup that will fit into
a canister like the one on their page....

BTW, thanks for your input James!!!
 
B

Bighiller

Dunno.  Soiled wetsuit, that's for sure.

James Arthur
Click to expand...

Soiled dry suit! :)

There is a guy that builds these things and his says that it's not as
bad as was expected when lithium-ion batteries were first considered...
 
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