Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Finding the right portable battery...

Status
Not open for further replies.

dmh187

New Member
Hello, I need some help with my portable fridge!

I am attempting to find a battery that will charge a Medi-Fridge Portable micro-refigerator. I am not sure about electronics and just going to give you all the information about the fridge.
Operates from 12V DV or 100-240V Ac outlet. The medi-Fridge MR IIx consumes 1.5 amps of 12V DC power.

I need a constant power supply or the fridge temp rises to high and my medication will be no good, fast. I need a 4 min hour power supply, that can be taken on an airplane safely, and light weight. Money doesn't matter, but the cheapest best one would do. I think it's called a portable battery, i need that because i will never be near a outlet :)

I also live in Canada, and the only stores available to me are: BestBuy, Walmart, Future Shop, Sears, Costco, Staples, Battery Boys. Though I could probably find it if you could give me the name.

Thanks,
Danielle.
 
Things weren't too bad till the aircraft and portability figured in. Since this is for meds you want a safety margin. I would be looking for a 12 volt 10 AH (Amp Hour) battery. While not gigantic or terribly heavy a pair of 12 volt 7.5 AH batteries of the SLA (Sealed Lead Acid) type would fit the bill or even a 10 or so AH SLA battery. There are also other battery types that would likely work. Additionally like a cell phone battery any battery would need charged so a charger in the luggage. Possibly with advance planning arrangements could be made for using onboard refrigeration? Years ago this would not have been a problem but anymore they are fussy about what boards an aircraft. Looking at SLA batteries as I mentioned you are looking at about just under 5kG in weight.

Ron
 
Reloadron, that would be marginal. lead acid AHr ratings are only good for room temperature and a 20Hr drain rate. at the at 1C they are down to half capacity.

Also he would need to find high drain deep cycle types.

I doubt that it requires that much continuously. refrigeration systems power drain is rated at it's peak consumption: when it is actively cooling down the unit. current readings will probably reveal it taking more like 0.5A average.

take a few measurements... you might just find that this one is plenty: https://www.batteryspace.com/Custom...ry-12.8V-1800-mAh-23Wh-4S3P-Flat-Pack-2A.aspx at 9oz
 
There is the possibility of flying with an airline with a laptop power port: https://www.seatguru.com/articles/in-seat_laptop_power.php

And then there is a Fuel Cell technology system: https://www.electro-tech-online.com/custompdfs/2012/02/XX25_Data_Sheet_09-dec-2010.pdf

It won't be cheap at all. Like really expensive.

then there is the airplane hoops to go through.

Now, I have a portable 12V battery system that uses a sealed lead acid battery. Not quite like this: **broken link removed** it sort of seems that it may charge with 100-240 V input and a lighter input. I hate product specs that aren't all there.

Doing a bit more research, I found this: https://www.batteryspace.com/portab...rwith110vacand5vusboutput---poweronthego.aspx

The medifridge is customarily used for Insulin. Remember that most insulins and other diabetic injectables are good for 28 days once opened as long as it doesn't see excessive temperature. If it's insulin, you may not need the fridge.
 
Last edited:
Ubergeek63, I agree. My initial take was 1.5 amps over a minimum of 4.0 hours. Purely a guess and I did not get into looking at LiPo batteries. I would think, with prior arrangements and inspection a passenger could arrange for on board refrigeration? Also, not being familiar with those tiny units I have no clue what the actual draw would be so went with 1.5 amps over a minimum 4 hour period? Beats the hell out of me? :(

Ron
 
Reloadron,

I was going by physics. nameplates do not include starting motors but would include the initial cool down.

base that there would be 1.5A initially and when the door was opened, at other times there would be only a maintenance level.

LiFePO4s are good for 2-3K cycles instead of 300 for lead acid and 600 for most lithiums

Dan
 
LiFePO4s are good for 2-3K cycles instead of 300 for lead acid and 600 for most lithiums
From a practical standpoint this is irrelevant. Even if it were used to depletion once a day that's a two year lifespan for standard lithiums. Given a more practical usage they should last 4-5 years as long as they're maintained.

A simple three cell lithium pack of 5-6AH should work for 4 hours or so. You can get that for less than 100 dollars from radio controlled hobby stores, even with a charger it's not too badly priced. You might have problems getting that on an airplane if you don't make it look decent though.

The commercial unit linked above is a bit expensive but not only surpases the posters needs but is a hands off total out of the box solution ready to go. The only downside is the 11.1 volts of the battery is a bit less than you'd get from a car socket so the fridge will only be good to about room temperature (72 or thereabouts) obviously not okay for a hot day.

A 4cell Lithium pack would be much better but fresh that will be near 16 volts, should be within tolerances for anything designed to run off a car but it might be pushing it.
 
Last edited:
I'm not forgetting anything Ubergeek, the price of the fridge is totally irrelevant to getting it working on battery power. The poster also explicitly stated that money wasn't an issue but that he would like to go for the cheapest solution, which is the hobby battery pack and charger that I suggested where the more proper way of doing it would be with the commercial unit that KISS linked in post #4 in this thread.
 
Before you go any further, I would check with an airline and your equivalent of TSA. LiIon batteries cannot be mailed in the US, as they are not allowed in the cargo department of airplanes. Most US airlines have an announcement that any electrical items must be turned off during take off and landings.
I would suggest dry ice, suitably insulated to protect the contents from freezer burn.
 
true

well the he can put 2 car batteries in a back pack and go hiking :)

fact remains that the fridge is probably only 0.5A average as long as you keep the door closed. based on that my $50 solution is much lighter and should run for 6Hrs
 
Ubergeek63 said:
fact remains that the fridge is probably only 0.5A average as long as you keep the door closed.

The fact remains?! That the fridge probably only averages under a specific condition what you think it does!?

If this medicine is that thermally sensitive, I would definitely not be able to trust someone that suggested that it was a fact that given two assumed variables and a set condition that their medicine would be safe if this were that important.
 
By the way JMW, you suggestion of dry ice is excellent and far cheaper, as long as a source can be found, though I'm not sure about the legalities of carrying dry ice on an airplane, cargo sure, on the airplane that's probably different.
 
On a side off topic note:

Thanks,
Danielle.

My guess is the OP is feminine and not masculine in gender. :)

Ron
 
The fact remains?! That the fridge probably only averages under a specific condition what you think it does!?

If this medicine is that thermally sensitive, I would definitely not be able to trust someone that suggested that it was a fact that given two assumed variables and a set condition that their medicine would be safe if this were that important.

i did say to put a meter on it... or contact the mfg... the name plate rating is worst case... once at temperature the power consumption GOES DOWN
 
i did say to put a meter on it... or contact the mfg... the name plate rating is worst case... once at temperature the power consumption GOES DOWN
You don't engineer for ideals, you engineer for the real world, you engineer for the nameplate. You can get away with murder outside of that, engineer on assumed specs with a medically important device and you take someone's life at stake, what power rating do you give that?

If your design doesn't keep the insulin (assumed in this case) at it's proper temperature, whom do you let know that your failure to observe the strictures of the requirements? The person that will be dead or in a coma? No one else that uses it will be around.
 
actually insulin does not need near that much temperature control in the short term.

As an engineer myself I am well aware of that....I had to tell my boss the same thing effectively.

The nameplate is NORMAL MAX conditions, such as cooling off from room temperature. Motors are listed as normal RUNNING current but draw double or triple that when starting up.

Computers draw large chunk of current that far exceeds nameplate levels to charge the filter caps. ... the list goes on and and on.
 
If the medicine is Insulin, the cartridge or the pen (300 U per cartridge or 3 ml) is a smaller quantity than the vial. The vial is 1000 U or 10 ml's. Cartridges and pens come in a box of 5 for a total of 1500 doses per box.
 
Hi all, well thank you for so many responses! Yes, it is a fact I am a girl.
So the first one by Ubergeek, https://www.batteryspace.com/Custom...ry-12.8V-1800-mAh-23Wh-4S3P-Flat-Pack-2A.aspx, I don't see how this would fit on my mini fridge, it doesn't look like it would plug into it. Sorry I may be missing something.
KISS did mention a possible one, **broken link removed**, or even https://www.batteryspace.com/portab...rwith110vacand5vusboutput---poweronthego.aspx.
I understand that my insulin doesn't need to be refrigerated all the time, and thank you for taking that into your considerations, but I have had a lot of problems arise on my last few trips. Even where the insulin froze by the time I got there and had 1 pen and 4 bottles completely useless. This is what I want to avoid. No situation is ideal and I want to be in control of my surroundings as much as possible.
Oh by the way, I can take batteries on a airplane just none that are not sealed. So those work so far!
Thank you for all your suggestions. I will see if I can get any of those from Canada (Another challenge itself).
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top