Rechargeable battery packs for the Meg

mbelair · 5th October 2006, 23:42

I was reading Joe Radomski's new student book for the Meg and was wondering if anyone has tried to weld rechargeable batteries in series to replace the home made "Duracell" packs that seem to be popular to power the handsets.

It seems to me that it would be more practical then having to reassemble new packs all the time.
If not, why not?

Skipbreather · 6th October 2006, 02:04

Quote: (Originally Posted by mbelair)

I was reading Joe Radomski's new student book for the Meg and was wondering if anyone has tried to weld rechargeable batteries in series to replace the home made "Duracell" packs that seem to be popular to power the handsets.

It seems to me that it would be more practical then having to reassemble new packs all the time.
If not, why not?

Hi Marc-

Reasons are pretty straightforward. Has to do with how batteries die.

First is that alkaline batteries have a very gradual decline in output voltage. Nonrechargable lithiums are not all that different. You get enough warning before the start of the dive to not do something stupid like dive with a nearly flat battery. Rechargeable batteries, comparatively, fall off a cliff. They die rather abruptly. The consequences in terms of a dive would be starting w/ all looking good and then having handset die mid dive w/ little or no warning.

Other reason is that rechargeables do not hold a decent charge for a long time. In dive terms that would translate to needing to charge your battery pack before every series of dives. Stated another way: Just because you charged your cells immediately after your last dive a month ago does not mean there are enough electrons still stored for today’s dive.

I actually did use a rechargeable battery pack (my own design) w/ my Smithers-Jurgensen Gen 1 MK15 digital electronics in my previous rig. Thing ate 18 cell alkaline AA cell battery packs at the rate 1 per 20~25 hours!

There it made sense. In the Meg a 2 C cell lithium pack will easily last 1 to 2 YEARS. Very different story.

Hope this helps,
Ken

mbelair · 6th October 2006, 02:31

Quote: (Originally Posted by Skipbreather)

There it made sense. In the Meg a 2 C cell lithium pack will easily last 1 to 2 YEARS. Very different story.

Hope this helps,
Ken

Crystal Clear

Ken

I can live with assembling a pair of packs a year.

Thanks

***jradomski*** · 6th October 2006, 13:01

Quote: (Originally Posted by Skipbreather)

Hi Marc-

Reasons are pretty straightforward. Has to do with how batteries die.

First is that alkaline batteries have a very gradual decline in output voltage. Nonrechargable lithiums are not all that different. You get enough warning before the start of the dive to not do something stupid like dive with a nearly flat battery. Rechargeable batteries, comparatively, fall off a cliff. They die rather abruptly. The consequences in terms of a dive would be starting w/ all looking good and then having handset die mid dive w/ little or no warning.

Other reason is that rechargeables do not hold a decent charge for a long time. In dive terms that would translate to needing to charge your battery pack before every series of dives. Stated another way: Just because you charged your cells immediately after your last dive a month ago does not mean there are enough electrons still stored for today’s dive.

I actually did use a rechargeable battery pack (my own design) w/ my Smithers-Jurgensen Gen 1 MK15 digital electronics in my previous rig. Thing ate 18 cell alkaline AA cell battery packs at the rate 1 per 20~25 hours!

There it made sense. In the Meg a 2 C cell lithium pack will easily last 1 to 2 YEARS. Very different story.

Hope this helps,
Ken

A small correction..

There are many types of lithium cells.. The 3.6v type (LiSOCl2) has a predictable discharge curve, while the 1.5V types have a flat discharge curve then immediate failure.. At list a NiMH cell has some discernable voltage loss..

If you wanted to make a reasonable rechargeable pack use Li-Ion, these start with a Float voltage of 4.2v and decay down to 3.0v (can actually be drained to 2.4v but a rapid drop occurs around 3.0-3.5v (depends on discharge current, lower current draw means voltage stays higher further out before rapid drop) ), so a 2 cell Li-Ion pack would give some predictability

Skipbreather · 6th October 2006, 14:16

Quote: (Originally Posted by jradomski)

A small correction..

There are many types of lithium cells.. The 3.6v type (LiSOCl2) has a predictable discharge curve, while the 1.5V types have a flat discharge curve then immediate failure.. At list a NiMH cell has some discernable voltage loss..

If you wanted to make a reasonable rechargeable pack use Li-Ion, these start with a Float voltage of 4.2v and decay down to 3.0v (can actually be drained to 2.4v but a rapid drop occurs around 3.0-3.5v (depends on discharge current, lower current draw means voltage stays higher further out before rapid drop) ), so a 2 cell Li-Ion pack would give some predictability

Hi Joe-

Thanks for the info re 1.5 V Lithums. I’ve always viewed them as sort of neither fish nor fowl and so have no actual experience w/ them. I’m genuinely curious about where you have used them & found them to be either cost efficient and/ or superior electrically to a quality AA alkaline. The packages make all sorts of claims, but I value your real world experience.

I looked closely at Li-Ion rechargeables when searching for a solution to 18 cell alkaline AA packs. The energy density & discharge characteristics are indeed the best of the commonly available technologies, but without exception all the sources I consulted referenced how fussy they are when charged- essentially do it right w/ a Li-Ion specific circuitry charger or risk a fire. The clincher for me turning to NiMH was how ugly a flood to the battery compartment would have been w/ Li-Ion. All rechargeables are nasty when shorted, but LI-Ion are particularly so.

Best,
Ken

***jradomski*** · 6th October 2006, 14:29

Quote: (Originally Posted by Skipbreather)

Hi Joe-

Thanks for the info re 1.5 V Lithums. I’ve always viewed them as sort of neither fish nor fowl and so have no actual experience w/ them. I’m genuinely curious about where you have used them & found them to be either cost efficient and/ or superior electrically to a quality AA alkaline. The packages make all sorts of claims, but I value your real world experience.

I looked closely at Li-Ion rechargeables when searching for a solution to 18 cell alkaline AA packs. The energy density & discharge characteristics are indeed the best of the commonly available technologies, but without exception all the sources I consulted referenced how fussy they are when charged- essentially do it right w/ a Li-Ion specific circuitry charger or risk a fire. The clincher for me turning to NiMH was how ugly a flood to the battery compartment would have been w/ Li-Ion. All rechargeables are nasty when shorted, but LI-Ion are particularly so.

Best,
Ken

Li-ion charging technology has come along way... There are many ICs that do all the work for you... I have built a few chargers.. I recommend using ICs from linear technology... they are easy to work with and are readily available.. You can even get one of their "development" kits and easily turn it into a charger..

see this link
http://www.linear.com/pc/downloadDoc...1,C1003,D11357

or

http://www.linear.com/pc/downloadDoc...2,C1185,D10777

Asto flooding, its not as bad as you think.. most current Li-Ion packs have built in short circuit and over/undervoltage protection.. so shorting the pack externally wount be a big deal... Many packs are also sealed, but some extra protective sealing might be a prudent idea...

the 1.5v lithium cells are good for devices that can't deal with a declining voltage well.. (like somethingwith a motor ex. cassette player).. these will work perfectly until they just die.. They also work well in flashes where the constant volatges keeps the cycle time fast..

For devices that depend on a lower voltage as a warning the cells are getting low, you must avoid them.. I recommend against them in my HH manual for this reason.. I did some testing... It works perfectly, then all of a sudden the handset is totally dead...

Outlaw · 12th October 2006, 19:11

[quote=Skipbreather;71007]Hi Marc-

Reasons are pretty straightforward. Has to do with how batteries die.

First is that alkaline batteries have a very gradual decline in output voltage. Nonrechargable lithiums are not all that different. You get enough warning before the start of the dive to not do something stupid like dive with a nearly flat battery. Rechargeable batteries, comparatively, fall off a cliff. They die rather abruptly. The consequences in terms of a dive would be starting w/ all looking good and then having handset die mid dive w/ little or no warning.

Other reason is that rechargeables do not hold a decent charge for a long time. In dive terms that would translate to needing to charge your battery pack before every series of dives. Stated another way: Just because you charged your cells immediately after your last dive a month ago does not mean there are enough electrons still stored for today’s dive.

I actually did use a rechargeable battery pack (my own design) w/ my Smithers-Jurgensen Gen 1 MK15 digital electronics in my previous rig. Thing ate 18 cell alkaline AA cell battery packs at the rate 1 per 20~25 hours!

There it made sense. In the Meg a 2 C cell lithium pack will easily last 1 to 2 YEARS. Very different story.

Hope this helps,
Ken[/quote ]

what do you mean in " in the Meg a 2 C cell lithium pack? which ic the best way to make the meg batteries. did anyone have an article of how to connect the 5 1.5 batteries in series? if yes, what equipment did you use? it would be good to see some pictures of the process as well.

Thanks for sharing information guys.

Safe diving,

Spyros

Skipbreather · 13th October 2006, 02:24

[quote=Outl

what do you mean in " in the Meg a 2 C cell lithium pack? which ic the best way to make the meg batteries. did anyone have an article of how to connect the 5 1.5 batteries in series? if yes, what equipment did you use? it would be good to see some pictures of the process as well.

Thanks for sharing information guys.

Safe diving,

Spyros

[/quote]

Spyros-
See http://www.rebreatherworld.com/megal...s-30-each.html

5th October 2006, 23:42	#1 (permalink)
mbelair New Member Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Jan 2006 Location: Montreal Posts: 81	Rechargeable battery packs for the Meg I was reading Joe Radomski's new student book for the Meg and was wondering if anyone has tried to weld rechargeable batteries in series to replace the home made "Duracell" packs that seem to be popular to power the handsets. It seems to me that it would be more practical then having to reassemble new packs all the time. If not, why not? __________________ Marc
(Offline)

6th October 2006, 02:04	#2 (permalink)
Skipbreather Reads the fine print Current Rebreather/s: Megalodon Home Build Other Rebreather/s: Not Bought Yet MK 15.X Home Build Join Date: Mar 2005 Location: Chicago, Illinois, USA Posts: 544	Re: Rechargeable battery packs for the Meg Quote: (Originally Posted by mbelair) I was reading Joe Radomski's new student book for the Meg and was wondering if anyone has tried to weld rechargeable batteries in series to replace the home made "Duracell" packs that seem to be popular to power the handsets. It seems to me that it would be more practical then having to reassemble new packs all the time. If not, why not? Hi Marc- Reasons are pretty straightforward. Has to do with how batteries die. First is that alkaline batteries have a very gradual decline in output voltage. Nonrechargable lithiums are not all that different. You get enough warning before the start of the dive to not do something stupid like dive with a nearly flat battery. Rechargeable batteries, comparatively, fall off a cliff. They die rather abruptly. The consequences in terms of a dive would be starting w/ all looking good and then having handset die mid dive w/ little or no warning. Other reason is that rechargeables do not hold a decent charge for a long time. In dive terms that would translate to needing to charge your battery pack before every series of dives. Stated another way: Just because you charged your cells immediately after your last dive a month ago does not mean there are enough electrons still stored for today’s dive. I actually did use a rechargeable battery pack (my own design) w/ my Smithers-Jurgensen Gen 1 MK15 digital electronics in my previous rig. Thing ate 18 cell alkaline AA cell battery packs at the rate 1 per 20~25 hours! There it made sense. In the Meg a 2 C cell lithium pack will easily last 1 to 2 YEARS. Very different story. Hope this helps, Ken
(Offline)

6th October 2006, 02:31	#3 (permalink)
mbelair New Member Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Jan 2006 Location: Montreal Posts: 81	Re: Rechargeable battery packs for the Meg Quote: (Originally Posted by Skipbreather) There it made sense. In the Meg a 2 C cell lithium pack will easily last 1 to 2 YEARS. Very different story. Hope this helps, Ken Crystal Clear Ken I can live with assembling a pair of packs a year. Thanks __________________ Marc
(Offline)

6th October 2006, 13:01	#4 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Home Build Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Home Build Join Date: Mar 2005 Location: "Da" Bronx Posts: 2,898	Re: Rechargeable battery packs for the Meg Quote: (Originally Posted by Skipbreather) Hi Marc- Reasons are pretty straightforward. Has to do with how batteries die. First is that alkaline batteries have a very gradual decline in output voltage. Nonrechargable lithiums are not all that different. You get enough warning before the start of the dive to not do something stupid like dive with a nearly flat battery. Rechargeable batteries, comparatively, fall off a cliff. They die rather abruptly. The consequences in terms of a dive would be starting w/ all looking good and then having handset die mid dive w/ little or no warning. Other reason is that rechargeables do not hold a decent charge for a long time. In dive terms that would translate to needing to charge your battery pack before every series of dives. Stated another way: Just because you charged your cells immediately after your last dive a month ago does not mean there are enough electrons still stored for today’s dive. I actually did use a rechargeable battery pack (my own design) w/ my Smithers-Jurgensen Gen 1 MK15 digital electronics in my previous rig. Thing ate 18 cell alkaline AA cell battery packs at the rate 1 per 20~25 hours! There it made sense. In the Meg a 2 C cell lithium pack will easily last 1 to 2 YEARS. Very different story. Hope this helps, Ken A small correction.. There are many types of lithium cells.. The 3.6v type (LiSOCl2) has a predictable discharge curve, while the 1.5V types have a flat discharge curve then immediate failure.. At list a NiMH cell has some discernable voltage loss.. If you wanted to make a reasonable rechargeable pack use Li-Ion, these start with a Float voltage of 4.2v and decay down to 3.0v (can actually be drained to 2.4v but a rapid drop occurs around 3.0-3.5v (depends on discharge current, lower current draw means voltage stays higher further out before rapid drop) ), so a 2 cell Li-Ion pack would give some predictability __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
(Online)

6th October 2006, 14:16	#5 (permalink)
Skipbreather Reads the fine print Current Rebreather/s: Megalodon Home Build Other Rebreather/s: Not Bought Yet MK 15.X Home Build Join Date: Mar 2005 Location: Chicago, Illinois, USA Posts: 544	Re: Rechargeable battery packs for the Meg Quote: (Originally Posted by jradomski) A small correction.. There are many types of lithium cells.. The 3.6v type (LiSOCl2) has a predictable discharge curve, while the 1.5V types have a flat discharge curve then immediate failure.. At list a NiMH cell has some discernable voltage loss.. If you wanted to make a reasonable rechargeable pack use Li-Ion, these start with a Float voltage of 4.2v and decay down to 3.0v (can actually be drained to 2.4v but a rapid drop occurs around 3.0-3.5v (depends on discharge current, lower current draw means voltage stays higher further out before rapid drop) ), so a 2 cell Li-Ion pack would give some predictability Hi Joe- Thanks for the info re 1.5 V Lithums. I’ve always viewed them as sort of neither fish nor fowl and so have no actual experience w/ them. I’m genuinely curious about where you have used them & found them to be either cost efficient and/ or superior electrically to a quality AA alkaline. The packages make all sorts of claims, but I value your real world experience. I looked closely at Li-Ion rechargeables when searching for a solution to 18 cell alkaline AA packs. The energy density & discharge characteristics are indeed the best of the commonly available technologies, but without exception all the sources I consulted referenced how fussy they are when charged- essentially do it right w/ a Li-Ion specific circuitry charger or risk a fire. The clincher for me turning to NiMH was how ugly a flood to the battery compartment would have been w/ Li-Ion. All rechargeables are nasty when shorted, but LI-Ion are particularly so. Best, Ken
(Offline)

6th October 2006, 14:29	#6 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Home Build Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Home Build Join Date: Mar 2005 Location: "Da" Bronx Posts: 2,898	Re: Rechargeable battery packs for the Meg Quote: (Originally Posted by Skipbreather) Hi Joe- Thanks for the info re 1.5 V Lithums. I’ve always viewed them as sort of neither fish nor fowl and so have no actual experience w/ them. I’m genuinely curious about where you have used them & found them to be either cost efficient and/ or superior electrically to a quality AA alkaline. The packages make all sorts of claims, but I value your real world experience. I looked closely at Li-Ion rechargeables when searching for a solution to 18 cell alkaline AA packs. The energy density & discharge characteristics are indeed the best of the commonly available technologies, but without exception all the sources I consulted referenced how fussy they are when charged- essentially do it right w/ a Li-Ion specific circuitry charger or risk a fire. The clincher for me turning to NiMH was how ugly a flood to the battery compartment would have been w/ Li-Ion. All rechargeables are nasty when shorted, but LI-Ion are particularly so. Best, Ken Li-ion charging technology has come along way... There are many ICs that do all the work for you... I have built a few chargers.. I recommend using ICs from linear technology... they are easy to work with and are readily available.. You can even get one of their "development" kits and easily turn it into a charger.. see this link http://www.linear.com/pc/downloadDoc...1,C1003,D11357 or http://www.linear.com/pc/downloadDoc...2,C1185,D10777 Asto flooding, its not as bad as you think.. most current Li-Ion packs have built in short circuit and over/undervoltage protection.. so shorting the pack externally wount be a big deal... Many packs are also sealed, but some extra protective sealing might be a prudent idea... the 1.5v lithium cells are good for devices that can't deal with a declining voltage well.. (like somethingwith a motor ex. cassette player).. these will work perfectly until they just die.. They also work well in flashes where the constant volatges keeps the cycle time fast.. For devices that depend on a lower voltage as a warning the cells are getting low, you must avoid them.. I recommend against them in my HH manual for this reason.. I did some testing... It works perfectly, then all of a sudden the handset is totally dead... __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated. Last edited by jradomski : 6th October 2006 at 14:36.
(Online)

12th October 2006, 19:11	#7 (permalink)
Outlaw In search of Law breaking Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Aug 2006 Location: Cyprus, Nicosia Posts: 627	Re: Rechargeable battery packs for the Meg [quote=Skipbreather;71007]Hi Marc- Reasons are pretty straightforward. Has to do with how batteries die. First is that alkaline batteries have a very gradual decline in output voltage. Nonrechargable lithiums are not all that different. You get enough warning before the start of the dive to not do something stupid like dive with a nearly flat battery. Rechargeable batteries, comparatively, fall off a cliff. They die rather abruptly. The consequences in terms of a dive would be starting w/ all looking good and then having handset die mid dive w/ little or no warning. Other reason is that rechargeables do not hold a decent charge for a long time. In dive terms that would translate to needing to charge your battery pack before every series of dives. Stated another way: Just because you charged your cells immediately after your last dive a month ago does not mean there are enough electrons still stored for today’s dive. I actually did use a rechargeable battery pack (my own design) w/ my Smithers-Jurgensen Gen 1 MK15 digital electronics in my previous rig. Thing ate 18 cell alkaline AA cell battery packs at the rate 1 per 20~25 hours! There it made sense. In the Meg a 2 C cell lithium pack will easily last 1 to 2 YEARS. Very different story. Hope this helps, Ken[/quote ] what do you mean in " in the Meg a 2 C cell lithium pack? which ic the best way to make the meg batteries. did anyone have an article of how to connect the 5 1.5 batteries in series? if yes, what equipment did you use? it would be good to see some pictures of the process as well. Thanks for sharing information guys. Safe diving, Spyros __________________ CMAS - IANTD - TDI Kamikazi Instrustor Trainer DIRRebreather Team Member ---------------------------- "Once an Outlaw, always an Outlaw"
(Offline)

13th October 2006, 02:24	#8 (permalink)
Skipbreather Reads the fine print Current Rebreather/s: Megalodon Home Build Other Rebreather/s: Not Bought Yet MK 15.X Home Build Join Date: Mar 2005 Location: Chicago, Illinois, USA Posts: 544	Re: Rechargeable battery packs for the Meg [quote=Outl what do you mean in " in the Meg a 2 C cell lithium pack? which ic the best way to make the meg batteries. did anyone have an article of how to connect the 5 1.5 batteries in series? if yes, what equipment did you use? it would be good to see some pictures of the process as well. Thanks for sharing information guys. Safe diving, Spyros[/quote] Spyros- See http://www.rebreatherworld.com/megal...s-30-each.html
(Offline)

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode