NightSun on Battery Power....Soon. Testing completed

After a lot of research and some failed attempts, I've finally got the right battery to run my NightSun away from home - preferably somewhere in the boonedocks. I wasted a little money and time on buying some Nissan Leaf EV battery modules. 180 Ah of 8S LiMn of which I used only 7S. Unfortunately, the wide Voltage discharge curve and more importantly, the high initial Voltage drop of the pack very soon had my Voltage supply to the light at below 28 Volts. The light will run on anything from 26.5 to 29 however, it is not regulated so less Voltage, less Lumens. It's spec'd at a nominal 27.5VDC. So I sold those off losing a bit of cash. But I had fun experimenting with them so it was sort of worth it. I have always wanted to go with the safer chemistry of LiFeP04 so I did a lot of research on the Plastic housed LiFeP04 Prismatic bricks. Not to be confused with the "pouch" style. There are no individually wrapped pouches inside. Just layered Anode and cathode sheets and some separators. After looking at a lot of high current discharge graphs of different brands of bricks, I settled on 9 each, 100 Ah units on Ebay. These are rated at up to 5C with 3C being rated for continuous duty. I only need 63 amps, not 300. I was hoping to get 45 minutes of run time with them being used at .63C. The graphs indicated that I could get up to 90% Depth of Discharge before the cell Voltage fell below 3.0 at a full 1C discharge. I figured I'd cut them off at 3.1 VPC or 27.9 pack Volts which is about 80 DOD. That's just about right to treat them nicely. They arrived today and I immediately charged two of them to do some testing. The graphs were not lying. I have an old Lectra-Load IIB which is an variable electronic load bank good for up to 1250 watts but at 29 Volts, it will only pull about 825 Watts (28 Amps) due to internal controls. So I tested with only two cells so I could pull the full 85 initial Amps, tapering down to 63 Amps over 45 seconds. The results:

Starting pack............29.76V - immediately dialed in 85 Amps and tapered down to 63 over 45 seconds
At 5 minutes.............28.67
At 10 minutes...........28.58
At 20 minutes...........28.49
At 30 minutes...........28.43
At 40 minutes...........28.35
At 50 minutes...........28.24
At 60 minutes...........28.06
At 63 minutes...........28.0
At 67 minutes...........27.9V - 3.1 VPC

This is at the end of the test at 67 minutes. Two cells in Series so cut the Volts in half for 3.1 or pack Voltage of 27.9




Each cell weighs just under 8lbs so the total 9 cells packs weighs a total of 72 lbs. I'm going to split them into two Pelican cases so about 40 and 32 lbs each. A single pole quick connect Anderson Power Pole terminated cable between the two packs will bring them up to the full 9S configuration. Now I just have to find the right long-distance spot to do some beam shots, undisturbed by passers-by and aircraft, hopefully.

Very great Bob! Glad to see you've tackled that pesky power supply problem!
Can't wait to see the beam shots!

At 72 pounds, why not use a generator?

Batt are quieter and don't need explosive liquids to run?

Noise and weight! My goal was to be as quiet as possible and to be able to handle all the stuff necessary to run the light by myself. It would take a 5.5KW genny to safely start and run the light and at over 250 lbs, no way could I handle that myself.

get-lit said:

At 72 pounds, why not use a generator?

Click to expand...

Ah, I didn't realize the SX-16 needed that much power for startup. That's the trade-off for nearly instant full output.

BVH said:

At 5 minutes.............28.67
At 10 minutes...........28.58
At 20 minutes...........28.49
At 30 minutes...........28.43
At 40 minutes...........28.35
At 50 minutes...........28.24
At 60 minutes...........28.06
At 63 minutes...........28.0

Click to expand...

Wow, that's some pretty stable performance over a 58 minute run, only dropping .67V

With 40 & 32lb components it does indeed make it quite portable. An awesome solution Bob!

Patriot said:

Wow, that's some pretty stable performance over a 58 minute run, only dropping .67V

With 40 & 32lb components it does indeed make it quite portable. An awesome solution Bob!

Click to expand...

Is there a "clinic" yet for dealing with the flashaholic addiction. :twothumbs
Or is "self medicating" or just admitting the "problem", our only current options ??
Join the local FA (AA) chapter ?

Who here, has a problem? I see no problems. Of what do you speak?

BVH said:

Who here, has a problem? I see no problems. Of what do you speak?

Click to expand...

They say the first step is admitting you (we) have an "issue". I guess this could be chronic, maybe even "terminal".

Of course, the other option, I could be delusional.

Nice setup. That is a lot of juice and the small loss in voltage over an hour is quite impressive.

XeRay said:

Is there a "clinic" yet for dealing with the flashaholic addiction. :twothumbsJoin the local FA (AA) chapter ?

Click to expand...

BVH said:

Who here, has a problem? I see no problems. Of what do you speak?

Click to expand...

XeRay said:

They say the first step is admitting you (we) have an "issue".

Click to expand...

I don't think we have to worry about Bob admitting that! I'm sure that he would just consider himself, "normal."

As normal an any Bob on the planet I'd say.

Here's some pics of battery unit #1. I thought a lot on how best to configure the 2 packs. I wanted them as identical as possible and for as many connections to be permanent as possible to reduce the chances of errors and sparks. I also wanted the weight to be as low as possible for my back. I bought a vertical oriented Pelican case years ago to house 4 DeWalt 36 Volt tool battery packs paralleled together. Well, these were my early days with batteries and the moment I made my last connection, sparks flew and the packs were dead - at least the electronics were dead. So the case has sat since about 2007. I knew I'd come up for a use for it eventually. These LiFeP04 cells can be used in any orientation except upside-down. In the vertical case, they are top-up which is what I wanted. Unfortunately, the next size up vertical case is humongous. It would hold just about the entire 9 cells and weigh about 90 lbs when I'm said and done. So after a few days fighting with this and not really wanting to go with a horizontal orientation, I decided to go with 3 packs. Two will be pictured as below except mirror-imaged so the two final output cables come together in the center of the two cases when placed side-by-side. I really didn't want a loose cell #9 nine but that's the way it's going to be. One of the benefits of the two, 4-cell packs is that they will be completely compatible with automotive and other typical 12 Volt systems. I could use them as jumper packs, or who knows what. So what do I do with the 9th cell? I'm going to make a simple metal strap "U" rack that will sit between the two Pelican cases when they are side-by-side. The rack will have a lip on each side to sit over the shoulder strap attachment clevis on side of each Pelican case so the rack will be firmly held in-place. Set the battery in and make a couple extra buss bar connections and it'll be a 9 in-line cell pack. I spent a lot of time thinking about not wanting to have to connect a bunch of cables whenever I want to run the light but in reality, there is a lot of set-up time involved in running this light anyway plus some driving time so what's a few extra minutes in the scheme of things. Final weight is 38 pounds.







The 8AWG Red and Black cables with Anderson Power Poles on the ends are the main charging leads and you can see the balance harness running down the center of the cells. All of these will plug into my FMA PL8 so I will get a balanced - up to 30 Amp charge rate - as recommended by the mfg.

Those cases almost look like they were made for that purpose. Seems like a good compromise with the 9th cell if the only option was to end up with a single 90lb case. As you mentioned, you've also got the added benefit of portable, high capacity, 12V power which is really kind of neat! I'll be eager to see this thing all hooked up and ready to fire up.

Very clean!

Wow. Beautiful! I get chills just imagining what its like firing that thing up. Can't wait. Thanks.

Bob, always seems to find an elegant solution to the project challenges, a real "class act". I don't think Bob has "short cuts" in his vocabulary.

Interesting cells, great housing for the powerhouse!
Any links to Ebay seller or auction? Couldn't find anything alike.

I've had my fair share of failed solutions. I just don't usually post them

I was lucky to get the last of their one-time gov't surplus purchase. They also had 200 Ah bricks but I just checked and they seem to have been sold off, too.

ww.ebay.com/itm/100-each-200Ah-3-2V-Lithium-Real-Force-Battery-Pack-EV-LiFePO4-FREE-SHIPPING-/171096755059

electriccarpartscompany dot com

They have a couple other brands available. The graphs showed they performed similar but the text specs showed lower recommended std. discharge levels.

Here's the completed setup with more pics and video here:

http://www.candlepowerforums.com/vb...-16-NightSun&p=4341912&viewfull=1#post4341912