No. Please learn more about different battery chemistry and read the inverter manual before attempting to build one, this is for your safety. The reason why it won't work is because, at 12V, the inverter draws <20A (150W) and <40A (300W). The one from the link, it's max. output is only 3A. One should use #14AWG wire or larger for 15A+ draw (http://tinyurl.com/24x8hym). Inverter will beep if the voltage becomes too low. The operating voltage of Li-Ion cell is 2.7V-4.2V, Samlex's inverter minimum input voltage is 10.5V, so the minimum cell voltage is 3.5V, that means you have at least 0.5V worth of capacity which can not be used. Li-Ion/Li-Po also requires a PCM (http://tinyurl.com/2aat6hc) to prevent the cells from over-charge/discharge and over-current draw. Some circuits have built in charge-balancing function so the cells are within 0.2V of difference to extend life span of the cells. On another note, please check out the videos of Li-Ion/Li-Po exploding due to mishandle or abuse: http://tinyurl.com/22nuhcx This is the very reason I am a strong advocate of LiFePO4, which is a safer chemistry and has a stable output of 3.2V-3.3V, perfect for 12V or 24V inverters. You can see my previous setup here: http://tinyurl.com/yc6kaox
With all that said, one can still build a Li-Ion/Li-Po pack, my advice is to get a 4 cells (12V-16.8V) configuration with max. output >15A-30A, a reliable PCM and a good charger. Glad you asked here, and to everyone who wants to build one themselves-what you don't know may cause serious injury.
Thanks for all the info! and i'm definitely using this forum for research as there is a wealth of information here. I have already built two pelican packs that i'm really happy with,per your build and Gabe's, so thanks! I'm certainly not going to build anything without full research first. Thanks again!
Would the VB unit also work with a Li-ion battery?
As I'm thinking about buying a few LARGE Li-ion batteries for my continuous lights.
Are Li-ion batteries really much more powerful for size then SLA batteries?
I know they are crazy amounts more expensive. But figured It would be worth it, since I want to run my 4 continuous lights off of them, which would mean 4 batteries to lug around. So at the size of half a tissue box each battery, I wanna only bring one battery per light.
adamdewilde wrote:
Would the VB unit also work with a Li-ion battery?
As I'm thinking about buying a few LARGE Li-ion batteries for my continuous lights.
Battery chemistry has nothing to do here. You can build a serial configuration of 10 1.2V 2500mAh NiMH, and connect 10 of these together in parallel (yes, total of 100 cells=>12V 25AH), of course you can run a 12V 300W inverter of AA NiMH, it's just a messy setup. Fact is, you have to look at the spec. of the cells, I do not know the spec. for VB II. The maximum current draw of a Samlex PST 12V 300W unit is <40A (VB II shouldn't be too far off), that means you need a Li-Ion 4 cells pack that can sustain a continuous draw of >25A. Here's a rough calculation: P=VI, 300W/12V=25A, considering the inverter has 87% efficiency, 25A/0.87=28.7A. The inverter will run hot though, due to the continuous draw at max. output. Once again, I do not recommend a hi-capacity Li-Ion pack, if anything goes wrong, that's whole lot of energy to dissipate. Please have a professional to build it for you if you decided to do so, the cells should be spot welded, insulation on terminals between each cell, silicone wires/wires with fiberglass braided sleeve..etc.
Are Li-ion batteries really much more powerful for size then SLA batteries?
The term "powerful" is vague. You can compare different chemistries in several ways:
-energy (Wh)/cost
-energy/weight (kg)
-energy/volume (L)
For energy/weight or volume, Li-Ion has the best ratio when compared to SLA and NiMH. However, surge power/cost for lead-acid batteries is still unbeatable, guess how much a Li-Ion battery will cost if you want to use it on your car? Things will be changed though, as there are already many different lithium chemistries out there.
Recently bought a 600w(1200w surge) Pure SIne Inverter to try out powering a strobe. But no luck. At first I thought it was due to the old battery I first had it hooked up to, but after testing with a known good 100AH battery it still did the same thing.
The stobe power light flickers and may charge up after 20-30 seconds.
As has been pointed out (frequently ) YMMV .........
I have a "cheap Chinese crap" inverter and it powered up my 250Ws strobe just like it was connected to the mains.
However, the same inverter can not drive my 600Ws ("cheap Chinese crap") strobes.
I'm pretty sure that I understand what is happening ...........
Inverters can be designed one of two ways, voltage limiting or current limiting.
You ideally need a "current limiting" inverter, when the current draw from your (just discharged) strobe is at maximum, you need the inverter to limit the current BY DROPPING THE VOLTAGE.
This is often not done in inverters (BY DESIGN) as they try to maintain their nominal output voltage and when they cannot they shut down.
Current-limiting inverters, on the other hand, drop the voltage (on a 240v system to as low as 90v)...Which of course causes issues with devices that do not cope with such a large voltage drop.
If you have a device that could fail with a large voltage drop, a current-limiting inverter would be a BAD thing, on the theory it's better to have NO electricity then 90v in a 240v system.
So, you need to have the "right combination" of inverter and strobe, if your strobe (or other device) CAN handle low voltages, a current-limiting inverter, but if you have a strobe (or other device) that crashes at low voltages then NOT a current-limiting inverter.
Seems unless someone has the same gear you have, trial-and-error is the only way to find what works in YOUR situation.
That's how I understand it, I could be wrong and it could all be tied up in phases of the moon.
TomRittenhous wrote:
In that case you got a bad one, sent it back. Unfortunately, corporations figured out a long time back that it was cheaper to let their customers do final testing than doing it themselves. No use even getting mad about it, as it is 30 years too late for that.
Well I was hoping this Wagan failure was an isolated incident, but the Wagan 180 will blow its internal fuse the first time you turn on your strobe. I plugged in a B400 and that was it. Bummer is, it would blow the internal fuse every time you powered on the inverter unit even with nothing connected, so much for the overload circuit protection.
I could run any of these packs in series or parallel to get to a certain voltage or capacity. BUT, I have no clue what type of setup, if any, would work since I am so "dumb" when it comes to this stuff. Am I trying to get to a certain voltage or capacity? Should I be concerned about the gauge of the wire leads on these lipo batteries?
Some direction and assistance would be greatly appreciated. Thank you in advance.
PS. I understand some may shun the idea of using lipo's because they are pricey but times are changing. Many hobbyists have been dumping "older" lipo's because the technology is advancing so much as of late. The batteries I have mentioned above for example were double the cost of what they go for now just two years ago.
I could run any of these packs in series or parallel to get to a certain voltage or capacity. BUT, I have no clue what type of setup, if any, would work since I am so "dumb" when it comes to this stuff. Am I trying to get to a certain voltage or capacity? Should I be concerned about the gauge of the wire leads on these lipo batteries?
Some direction and assistance would be greatly appreciated. Thank you in advance.
PS. I understand some may shun the idea of using lipo's because they are pricey but times are changing. Many hobbyists have been dumping "older" lipo's because the technology is advancing so much as of late. The batteries I have mentioned above for example were double the cost of what they go for now just two years ago....Show more →
The specs for these cells are suspicious. Normal max continuous output for LIPO cels is 1 to 2 C. IC means a 3000mAH battery can deliver a max of 3000mA (3A). 2C would be very unusual. Most of these RC batteries come from Ryder. I won't say 20-25C from LIPO cells is impossible . . . these thing are changing rapidly.
One thing . . . the "Continuous" rating may not be long term continuous at all . . . may only be for a matter of milliseconds. 20C for a three series cell 2100mAH cell set is 42A. Cell resistance is typically about 100 mohms per cell, or 300 mohm for the three series cells. 42 amps at 300 mohm resistance equals a 12.6V drop across an 11.8V battery . . . . equivalent to a short circuit. with the cell dissipating 500 watts and blowing up real fast, with no voltage going to the inverter. Something missing in these specs. We got promises and had samples made by Ryder and they didn't work.
Also, be warned . . . a 180W inverter with 2X current limiting will draw 33A+ continuous from the battery at 12V. Ryder has a habit of making RC cells without the usual PCM boards that protect the cells from overheat and explosion. Definitely put you batteries in a closed box when you test this stuff for safety.
Wow, Mr. Buff, thank you for chiming in on my question with your wealth of knowledge. As you can probably tell, I really don't know much about batteries and the specs can be wrong of course. The brand of battery that I have are Thunder Power and Enerland. Here is a spec sheet that Thunder Power provides on their batteries. http://thunderpowerrc.com/PDF/ThunderPowerRC-Pricing.pdf
I wouldn't be surprised if companies are a bit generous with their battery specs.
On a side note, I just ordered my first pair of Alien Bees strobes with some accessories and can't wait for them to get in. I have heard so many great things about you and your products.
Lithium Polymer's are amazing, I've been using them in my electric planes since Nippon Dave's first lot of the E-Tec 1200's.
Paul - These discharge rates are for real! I think peak discharge rates are measured in 10 to 20 second bursts and continuous until they hit voltage cutoff limits inside the electronic speed controller (3v per cell?).
ehong - You'll want to go with 3-cell packs since you want ~12 volts, these cells sit around 4.2v without a load. You've also got to be careful when discharging them, just as you wouldn't keep flying your plane until it's incapable of flight. I think cell voltage isn't supposed to drop lower than ~3v, can't quite recall. Anyway, removing a couple cells from the 5ah pack is probably what I would try, just keep a volt meter handy. I'd probably try to permanently mount one of those cheapy eBay units, see auction #370445273506.
) YMMV .........