DIY Portable Battery Pack-Update

puffing billy · Post by **puffing billy** » Sun Feb 11, 2007 1:19 pm

I wanted a portable battery pack and decided to make my own.
Using 20 AA size nickel metal hydride batterys and standard parts this is what I made.

I calculated that with standard usage it should last me for nearly seven hours.
The reason that there are two pack is that the universal charger I have will only charge 10 at a time.

Billy

drbandage · Post by **drbandage** » Sun Feb 11, 2007 5:09 pm

If that thing is safe and works, then Eureka! Thanks for sharing the wealth, Puffin' Billy.

Where the Lab Rat award??!

Guest · Post by **Guest** » Mon Feb 12, 2007 12:10 am

Looks great! Can you give us more details on the parts used and any construction hints.

pedroski · Post by **pedroski** » Mon Feb 12, 2007 4:01 am

Well done Bill. Good effort mate.

Peter

puffing billy · Post by **puffing billy** » Mon Feb 12, 2007 7:38 am

The parts are as follows
1. Case is 100 x 76 x 41 made from ABS
2. Battery Holder is 10 AA size (2 rows of 5) with snap connector.
3. Snap connector (PP3 type)
4. Fuseholder 20mm + 3 Amp fuse.
5. Connectors are Tyco/Amp CPC series 4 way (a crimp tool is required).
6. Cable is 19/0.15 (22 AWG) PTFE covered (aircraft grade).
7. Shrink wrap tubing
8. Power connector for PB420e CPAP is a 2.1mm plug long series (+ on middle pin).
9. AA size Nickel Metal Hydride rechargeable battery.

The 2 packs are wired in parallel giving 12V @ 5.6A.

I have not put part numbers as I live in the UK.

Warning - If you make the battery pack you must have it checked by a qualified person before using it.
This battery pack may also invalidate your warranty.
I also make no claims to the performance of the battery pack and that making one is at your own risk and any risk to your equipment.

Billy

sleepingBear · Post by **sleepingBear** » Mon Feb 12, 2007 11:05 am

Have you tried it for a night yet?

Let us know how well it stands up to the usage test.

biggziff · Post by **biggziff** » Mon Feb 12, 2007 7:08 pm

http://www.cyberpowersystems.com/CP800avr.asp

$70 and should give you a long runtime. I use this when power failure could be an issue.

puffing billy · Post by **puffing billy** » Wed Feb 14, 2007 2:57 pm

Sorry for the long time in replying.
The answer to the question have I tried it for a full night is no, but I hope to this weekend. I will let you know.
My other reason for making the pack was to see if I could use it on long flights.
I know this will open a can of worms, but from my initial investigation, the rules state that battery terminals must be double insulated, which they are.
The batteries are the same as are found in portable music players.
Can anyone lay there hands on the FAA or possibly the TSA rules for batteries.

Billy

WillSucceed · Post by **WillSucceed** » Wed Feb 14, 2007 3:34 pm

Biggziff wrote:

http://www.cyberpowersystems.com/CP800avr.asp

I use an uninterrupted power supply at home. One thing to check out BEFORE you buy is whether or not your CPAP/APAP/Heated Humidifier can tolerate a modified sine wave power supply or, must it have a pure sine wave power supply.

I have not found any of the lower end/lower priced uninterrupted power supply devices that have a pure sine wave. Usually, the pure sine wave power supplies are significantly more expensive.

Electricity, as it comes out of the wall socket, is a pure sine wave and your CPAP equipment may REQUIRE this. I spoke with the tech folk at PB before I bought a uninterrupted power supply and found out that my heated humidifier wants a pure sine wave whereas the 420e, because of the external transformer, does not care.

If you fry your equipment because of a modified sine wave power supply, you might find yourself without a warrenty.

billbolton · Post by **billbolton** » Wed Feb 14, 2007 6:13 pm

puffing billy wrote:My other reason for making the pack was to see if I could use it on long flights.

Keep in mind that when using xPAP in flight, you are dealing with an ambient cabin pressurisation equivalent to about 2400 metres (~8000 feet)above sea level.

You need to set your xPAP machine to this (its the maximum altitude setting on most xPAPs). To get your sea level tritation pressure setting at that altitude, your xPAP machine has to work significantly harder... which means it uses more energy.

So, even if you get an effective duration of ~7 hours at "sea level" (which I think you my find is not actually achievable in practice with 2600mA AA cells) you may find that you get considerably less duration when using it in flight!

Cheers,

Bill

Snooter · Post by **Snooter** » Wed Feb 14, 2007 6:44 pm

puffing billy wrote:My other reason for making the pack was to see if I could use it on long flights.
I know this will open a can of worms, but from my initial investigation, the rules state that battery terminals must be double insulated, which they are.
The batteries are the same as are found in portable music players.
Can anyone lay there hands on the FAA or possibly the TSA rules for batteries.

Billy

Billy sounds like a good idea. Please tell us when you plan to fly so I can watch the nightly news.....Man escorted from plane believed to be a terrorist wearing a breathing apparatus and battery packs.

...Just kidding. Last time a flew a red eye I had the lady next to me joking about my snoring. At least she was good humored about it. It would have been fun to pull out my CPAP..hehehe

Tired_in_NC · Post by **Tired_in_NC** » Wed Feb 14, 2007 8:40 pm

Couple of questions/comments for you.

What is the current draw that you measured? Your numbers seem a little low from what I have measured....

With 10 charged cells you will get 14+V. What is the max voltage allowed for your equipment? I measured 12.28V open circuit from my PS and 11.98 at max load, a decent 12V supply. One must wonder if 14V may damage your unit.

I have thought about doing something similar using either D cells of 3 banks of AA. I would use 10-12 cells and put in some type type of regulator. Li cells would work, but two issues. One is the swing in voltages, the second is charging issues + the Dell/Sony effect....

Guest · Post by **Guest** » Wed Feb 14, 2007 10:03 pm

I doubt it would do any damage to the machine. The reason thease machines are rated at "12V" is so that they can be plugged into a vehicle. But in all reality a vehicle puts out between 13.8v and 14.4v your little battery pack isnt going to hurt anything.

I just wouldent be the one trying to get it past security at an airport.... that homade battery pack looks too much like the makings of a bomb as opposed to a comercialy built pack. Not saying they wouldent let you take it on, but if I were a TSA person I would be certianly questioning it. I know its just radio shack parts, but you know how the world is post 9/11

Peterau · Post by **Peterau** » Thu Feb 15, 2007 12:59 am

I notice you use a PB machine. Just in case you aren't aware the PB requires 13 volts DC input. I run mine off a 12AH sealed lead acid battery which puts out 13.5 under the 11 watt load my PB CPAP places on it. When my battery drops to 12 volts under load it is 65% flat. Your voltage when flat would be well below 12 volts and this may be to low for the machine to cope with.
Don't want you to damage your machine. A change to your battery config would help fix this(add 1 more battery to each pack). FYI a NiMH battery's charged voltage is 1.2 volts.

Goofproof · Post by **Goofproof** » Thu Feb 15, 2007 8:37 am

Peterau wrote:I notice you use a PB machine. Just in case you aren't aware the PB requires 13 volts DC input. I run mine off a 12AH sealed lead acid battery which puts out 13.5 under the 11 watt load my PB CPAP places on it. When my battery drops to 12 volts under load it is 65% flat. Your voltage when flat would be well below 12 volts and this may be to low for the machine to cope with.
Don't want you to damage your machine. A change to your battery config would help fix this(add 1 more battery to each pack). FYI a NiMH battery's charged voltage is 1.2 volts.

FYI: Lead Acid battery cell are 2.1 volts, 12.6 volts is the normal state of a 6 cell vehicle battery, If you are getting 13.5 volts, it's overcharged (surface charge) or on charge, or your meter is incorrect. Electric devices are designed for a tolerance of + or - 10% voltage.

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