Battery pack requirements

[Crosman451]

I am new to this group. Any suggestions on using a battery pack to power a lamp that I have. It is the landing light used on Boeing 737's and other commerical jets. The mfg. tells me it is a 600W 28V lamp which draws 22 amps. I would like to make a hand held portable "flashlight" but need recommendations as to what type of battery pack might be assembled to power this lamp. Any help would be appreciated.

 

[Rifter]

are you serious?????

 

[Crosman451]

Yes I am. I take it from your post that you do not think it can be none. If so, why not?

 

[Floating Spots]

It could be done, but "portable" is going to take on a whole new meaning...
The easiest way would be to get two AGM SLAs. Thus in series, you would have ~25.2V, which should run it fine. However, as an off the wall observation, SLAs, in 12v, are usually just a bit heavier than a pound per ampere-hour. Thus for ~ 1hour of runtime, without killing the batteries, you would need ~60 pounds of batteries./ubbthreads/images/graemlins/shocked.gif

Hope this helps....

 

[Rifter]

It can be done, of that i am sure, im also sure it would require a backpack size battery pack(think ghostbusters) and would probably cost upwards of 1,000-2,000 for the cells to power it. And recharging it would probably take days. What burn time are you looking for and how "portable" do you want it? and for one thing its not going to be hand held, not the battery pack anyways.

 

[Crosman451]

Would it be possible to use Ni-Cd D cells for a battery pack? Or would NiMH or any other work better for this high amp use. It would not have to run for an hour, I was thinking more like my Sure Fire M6 15 to 20 min. Even if this pack had to be contained in a back pack that would be OK.

 

[snakebite]

[ QUOTE ]
Would it be possible to use Ni-Cd D cells for a battery pack? Or would NiMH or any other work better for this high amp use. It would not have to run for an hour, I was thinking more like my Sure Fire M6 15 to 20 min. Even if this pack had to be contained in a back pack that would be OK.

[/ QUOTE ]
sure if you can find some size m cells.
they are about the size of beer cans. /ubbthreads/images/graemlins/smile.gif
i have a homebrew light made of the same sealed beam you have.
i use 2 17 ah ups batts.
its more a silly toy than usefull tool.

 

[X-CalBR8]

I would probably go with sealed gel cell batteries if I were to attempt something so ambitious. If I recall correctly, they are capable of a very high rate of discharge, but as has been mentioned previously, you would have to carry a LOT of weight to get an hours worth of run-time out of it. A heavy-duty backpack would be a must. Believe me when I say that you DO NOT want to try making a battery pack out of rechargeable D batteries. You would probably have to buy a hundred of them to pull this off and they charge very very very slowly. A cluster of gel cells or sealed lead acid batteries are the only real options that I would seriously consider for something this grand in scope. That or a small fusion reactor. Hehe.

You will probably have to use a series parallel setup. Two 14-16V (preferably 16V to make up for the voltage drop you are almost sure to have) batteries in series to get the 28V and then several sets of these combos of 2 batteries in parallel with each other in order to get the amp output that you would need and also in order to get any significant amount of run-time out of them. You probably are looking at around 50-100 pounds of batteries to get even an hour or so of run-time out of it. Do you have a specific need for this light or are you just building it just for the heck of it? I can see it now,> “that’s not a light, THIS is a light”!!! /ubbthreads/images/graemlins/laugh.gif

LOL, and I thought that some of MY mod projects were ambitious!!! This project would put all of my puny mods to shame, even the ones that I’ve made using gel cells. You could probably signal aliens on the moon with a light that powerful. LOL. /ubbthreads/images/graemlins/laugh.gif Any idea how many candle power it’s rated for? Anyway, good luck on this and I hope you have some significant amount of cash set aside for this project because it will cost several hundred dollars to buy that many high amperage batteries plus a good quality, high output charger to feed all of those hungry batteries.

 

[highlandsun]

Just for reference - Li-Ion batteries are quoted with a volumetric energy density of 300Wh/liter. So to put that into perspective, you would need a LiIon battery pack the size of a 2-liter bottle of soda to run the lamp for an hour. That would be one hell of an expensive pack.

Let's see, I think you could get away with 7 cells in series for the 28V, and I think strings of 26 parallel cells will do for the 22A draw. Using 763048 cells (7.6x30x48mm, 900mAh) will get you right in the ballpark - 7x26=182 cells will be just slightly under 2 liters. 33gm per cell, so you're looking at 33*182=6.006kg. Plus some fudge factors for your solder connections, etc... There isn't any LiIon charger out there that will charge a pack like this, so you should use quick-disconnect plugs for some of the connections. Solder the parallel strings together, then plug them into each other in series. When it's time to recharge, unplug the strings and charge each parallel string by itself.

(26 cells, 900mAh each, gives 23.4Ah. Discharging at 22A means you're running at .94C which should be OK.)

If you order the cells direct from the manufacturer, you're looking at $2-$3 per cell.

Quite a project. Doable, and at only 13.2lbs, a lot more convenient than the lead-acid approach. But hairy, nonetheless.

 

[Deleted member 684]

Base on the cost of the batteries alone, the weight of everything, and the rechargablility of it, I think, if you are building this for fun, unless you have time and money, it's not worth it.

If you are building this for use, the above mentioned reasons would make it not so feasible either. I would propose you go with a 150 watt - 200 watt HID light. They are white, much more efficient and almost as bright as a 600 watt incandescent lamp. Not to mention you can focus them really tight. If you go this route, batteries would be reduced by 1/3 or that run time could be increase by a factor of 3-4 times. SLA batteries, 12 volts type (fully charged, will be 14-15 volts?), 20 AH, would weight like 30 pounds? (not sure), and give you a 1 hour run time on a 200 watt HID light. Charging could be done overnight. Battery would be the length of 3/4 of your keyboard, 1/3 the height of a 17 inch monitor, prolly 1/3 of your keyboard in width? (not too sure either)

A light like this would put out well over 10K lumens @ minumum. /ubbthreads/images/graemlins/bowdown.gif

Even without the visible light, using a infra red filter, you could probably barbeque food with the projected infra red from the HID! /ubbthreads/images/graemlins/icon15.gif

 

[Crosman451]

OK, thanks for all who have posted with your ideas and suggestions. Highlandsun, I like your approach so far as weight and size is concerned. This Li-Ion pack described seems to be the way to go. What are the 763048 cells and where do I purchase them?

 

[Doug S]

Crosman451 YOU ARE NUTS! A good kind of nuts. My kind of nuts /ubbthreads/images/graemlins/thumbsup.gif
I agree with the other posters with regard to use of Li-ion cells if you really want to keep the weight down and cost is no object. Depending on the spec design life of your bulb at 28V, you might wish to overdrive it a bit by using the voltage of 8 series Li-ion cells rather than 7. Under the high loads you are talking about, 7 cells will quickly droop to below 28V.
If you are really serious about the Li-ion option, you really need to study this battery technology carefully to understand their needs for charge and discharge protection. Manufacturers and their lawyers are very hesitant to sell bare cells to customers unless they have some assurance that the customers' engineering staff is competant. You might be able to source some from a foriegn source with fewer questions asked. Alternately, once you do know what you are doing, you may have some success with sucking up to a certified pack assembler.
An alternative to Li-ions if cost is a consideration and potentially even lighter weight if very short runtimes are acceptable, are NiCd cells that are specially engineered for high discharge rates. Some of these can deliver over 10A each in the sub-C size which is probably the best size for cost and availability of high rate cells.
Regards of whether you use Li-ion or NiCd cells, be sure to design in thermal protection for the battery pack. Heat build up can be an issue with large numbers of cells densely packed together.
Question: Is your need for a light that will only be used for very short periods or do you want to be able to run it continuously for a complete battery charge? Do you have a minimum runtime per charge?

 

[Crosman451]

Hi Doug S, Most of the people who know me say the same thing about some of my more "off the wall projects". With regards to the Li-Ion batteries, I do know a little about their charge and discharge quirks compaired to NiCd or NiMh. Can you elaborate a little more on the sub-C size cell pack idea? The run time of this project would not have to be long at all 15 min. to 30 min. would be nice. This light would be operated like my Sure Fire M6, short duty cycle only. Of course "firing it" for longer run times if need be would be good also if possible. Having never delt with a battery pack of this size before I am delving into the unknown so to speak. I know that discharging a 1700ma NiCd pack in 5 or 6 min. does heat up the pack a lot. And I agree, having thermal protection would have to be designed in this pack.

 

[Doug S]

[ QUOTE ]
Hi Doug S, Can you elaborate a little more on the sub-C size cell pack idea? The run time of this project would not have to be long at all 15 min. to 30 min. would be nice. This light would be operated like my Sure Fire M6, short duty cycle only. Of course "firing it" for longer run times if need be would be good also if possible.

[/ QUOTE ]

Checkout the websites of the major manufacturers of Ni-Cd cells specifically for high rate cells: Here is a link to a Panasonic example where a single cell can discharge at over 30A. From the graphs on the datasheet it looks like you could get around 3 minutes at your intended 22A load. 25 of these in series would weigh only 1.2kg so we are talking about hand held with one hand. If you doubled up with 2 in parallel it looks like you would get eight minutes.
http://www.panasonic.com/industrial/battery/oem/images/pdf/Panasonic_NiCd_P-170SCRP.pdf

If you go the Li-ion route most, are rated at a max discharge of 2C so whatever cell combo you are looking at would give you about 30 min runtime if you designed to the 2C limit. If you limited yourself to short, minute or less, usage you might be able to push this to 3 to 4C. I would experiment extensively with a single cell though before assembling a complete pack on this assumption.
Here is a link to a 1500mA [typical] rectangular cell that I have had some recent experience with:
http://sanyo.wslogic.com/pdf/pdf/UF103450.pdf
With and 8x8 array of these you could get 30 minutes or more for a weight of 2.4kg.

I am guessing that you are using a PAR64 size #Q4559 or Q4559X 600W landing light. These are rated at 100Hr life at 28V/600W.

 

[Deleted member 684]

Why not look to www.powerstream.com and their batteries? If I'm not wrong they have this battle robot battery that can discharge at 98 amps pulsed (2 seconds on, 8 seconds off). Their batteries manage to pull of 20 amps discharge continuos while maintaining a capacity of 2.18 amps which is pretty impressive. I would wager 23 of these batteries in a pack would power your 600 watt light no problem for 8 mins min. Each battery weighs 81 grams. 23 would weigh 1.8 kg. That's lightweight dude! /ubbthreads/images/graemlins/thumbsup.gif

BTW it's 1/2 D size. 2.5 AH nominal.

/ubbthreads/images/graemlins/naughty.gif
/ubbthreads/images/graemlins/eek.gif

Oh the other hand, I've notice www.powerstream.com also sells high discharge Lithium Ions. http://www.powerstream.com/LL.htm. 50 Ah batteries for 1.15 kg. Pricing unknown. Rated capacity (50 Ah) @ 15 amps discharge rate. Pulsed current @ 600 amps (/ubbthreads/images/graemlins/eek.gif) But for 28 volts, you need 8 packs... = 8 KG for 2 hours run time... cool!

For comparism, the Battle Robot battery 1/2 size ones I mention above would need 27 kg for a 2 hour run time. Size IS an issue. But with 2 hour run time on a 600 watt light, I would gladly carry around 8 KG of Lithium Ion battery packs just for the sake of blinding others.

With 600 watt HIDs........ /ubbthreads/images/graemlins/eek.gif

/ubbthreads/images/graemlins/naughty.gif

 

[Crosman451]

I've been talking and emailing to different people and companies all week. As it stands for now, I will be using the Sanyo 4000mah N-4000DRL "D" size NiCd battery for this pack build-up. The pack will be assembled by TNR in CA. It will consist of 25 cells which the Sanyo rep. in CA said should be able to handle the 28V 22amp load for 8 to 9 minutes. For longer run times another set of 25 can be used in parallel. These cells weigh 160 grams each for an approximate total pack weight just under 9 pounds. It will be a waist belt or back pack unit. I hope to post pictures soon of the mock-up of this flashlight.

 

[lemlux]

How will your packs be set up for recharging?

 

[Crosman451]

I will be able to run one or both packs and charge them separately. To start with I will be using just one pack for testing this lamp.

 

[lemlux]

I'm sorry, I should have been clearer. What sort of charger will you use to charge a 25 cell 30 V NiCad pack? I can't imagine that there are stock delta peak shutoff chargers, so I imagine that you'd drive it with 0.1 C (i.e.: 400 mA) or less for a reasonable period of time in order not to damage the cells from overcharging.

 

[Crosman451]

I have a number of battery chargers at my disposal. When I receive this pack from TNR Batteries I will probably use an SR Batteries Smart Charger. This Sanyo cell is able to be fast charged at 4A, but the first few charges will be at 400mah.