# Anyone seen low startup current ballast for 35w HID



## AlexGT (Jan 31, 2009)

Hi all!

I was trying to convert my HID spotlight to use Li-ions and was having a hard time getting the battery pack to ignite the HID posted over here.

http://candlepowerforums.com/vb/showthread.php?t=221224

After giving it some tought I decided to open up the spotlight to see if the ballast was drawing too much power, lo and behold! 20 amps initial burst! WTF! That is crazy!:thumbsdow







No wonder my battery pack with a 6.5 amp overcurrent limit was not able to ignite! I then went to look at ebay for ballasts that had lower start up current and saw some with 18, 15, 10, and one with less than 6 amps for startup current according to their specs.






I am sure the battery pack will ignite the 6 amp ballast but are there more efficient ballasts out there that can run from 9-16v?

Thanks!
AlexGT


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## 65535 (Feb 3, 2009)

Why not put a capacitor inline with the ballast? Surely a decent sized capacitor would supply the initial burst.


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## AlexGT (Feb 3, 2009)

Well I did put one, but didn't help ignite the HID

The one I used was 56000mfd at 25V, maybe a half farad or 1 farad would work but they are too big.

AlexGT


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## 65535 (Feb 3, 2009)

You won't find anything more efficient. I mean you're putting in just over 37watts and getting out 35 nominal. That is pretty efficient.


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## AlexGT (Feb 3, 2009)

Well I ordered the one in the lower photo with the <6amps starting current, Hope that one can ignite the with the Li-ion pack I have.

AlexGT


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## 65535 (Feb 3, 2009)

If it doesn't unless it's mislabeled or something a small cap would help. I'm guessing the reason the cap didn't work was that the 20amps lasts more than just a burst it may be a good 1-2 seconds.


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## XeRay (Feb 3, 2009)

65535 said:


> You won't find anything more efficient. I mean you're putting in just over 37watts and getting out 35 nominal. That is pretty efficient.


 

Not quite correct. The most efficient ballasts currently possible are about 92% ,that would be 38 watts in. 94-95% as you indicated is currently impossible for this HID ballast technology.

None of the ballasts he showed (photos) of are that efficient. The newest Chinese ballasts are from 80% low side to 87% at best. 

The Philips ballast (both ballasts) shown are 83% but that old Philips/Hella design is 8-10+ years old.


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## Patriot (Feb 3, 2009)

How about running it on li-po instead. No amp shortage there.


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## AlexGT (Feb 4, 2009)

I got into the LI-ion because it was rather cheap at $59 for a 11.1v 6600 mah battery pack, Currently waiting on the new ballast to see if it will work, if not I might just sell the pack and get 10 to 12Kmah Nimh "D" and be done with it.

AlexGT

AlexGT


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## Patriot (Feb 4, 2009)

AlexGT said:


> I got into the LI-ion because it was rather cheap at $59 for a 11.1v 6600 mah battery pack, Currently waiting on the new ballast to see if it will work, if not I might just sell the pack and get 10 to 12Kmah Nimh "D" and be done with it.
> 
> AlexGT
> 
> AlexGT





I've been purchasing my li-po's from hobby city.
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=6501

The price is really great and I've had excellent performance from both the Rhino and Zippy brands....as good as any expensive Flightpower pack that I've purchased. As you can see, the price is reasonable and you could always run packs in parallel to get the desired capacity. Try their battery finder engine, it works pretty well. Anyhow, I would think that would be more appealing than the NiMH option...

P.S. They also come in nearly every size imaginable. Great for projects.


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## AlexGT (Feb 4, 2009)

Thanks for sharing the link Patriot36!, that is indeed a very good price for a Li-Po pack, I will consider it.

AlexGT

Edit!
Found this 3S1P 5000mah pack for $43.26, any one have experience with this pack?
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=8579


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## Norm (Feb 4, 2009)

Hi Alex if you look at my thread on the light I built the ballast looks to be exactly the same as the slim ballast shown above except mine is painted black just did some measurements start up from cold @12 Volts 4.8 Amps runs at 3.8 Amps subsequent start up after 1 minute off 4.00 Amps.

Just did some readings at 11.1 Volts start up 5.2 amps runs at 4.2 Amps.
norm

If your going for one of these hobby packs Alex why not this one ZIPPY 5000mAh 4S1P 15C $78.39
The higher voltage will drop the current being drawn and give you longer run time. The ballast says up to 16 Volts and the pack is 14.8 Volts which I think would be better than starting at 11.1 Volts and going down from there. Very tempted to do the same to mine.


> *Spec.*
> Capacity: 5000mAh
> Voltage: 4S1P / 4 Cell / 14.8v
> Discharge: 15C Constant / 20-22C Burst
> ...


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## AlexGT (Feb 4, 2009)

Thanks Norm! That sounds about what the actual pack I have can handle! The protection circuit is rated at 6.5amps, hope it works, I will probably be recieving the ballast today, will post what happens.

Thanks!
AlexGT


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## AlexGT (Feb 4, 2009)

I recieved the new ballast today and....

 *SUCCESS!!!* 

The Li-ion pack ignites the HID with no problems at all! Can't believe how light the spotlight is now!

Thanks everyone for your help!
AlexGT


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## Norm (Feb 5, 2009)

Great News Alex  :twothumbs :twothumbs :twothumbs
Cheers Norm


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## Patriot (Feb 5, 2009)

Good deal!! Glad that worked out so well.


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## broadgage (Feb 5, 2009)

AlexGT said:


> Well I did put one, but didn't help ignite the HID
> 
> The one I used was 56000mfd at 25V, maybe a half farad or 1 farad would work but they are too big.
> 
> AlexGT


 
Putting a capacitor in parralel with the ballast and "downstream" of the switch wont help.
When the light is turned on, the capacitor will be discharged, and therefore the battery will have to supply the charging current of the capacitor, and the inrush current of the ballast, thus increasing the chance of tripping any protection circuit.

Placing the capacitor before the switch, directly across the battery would help since the capacitor would then be fully charged when the switch is closed.
The drawback would be that the leakage current of the capacitor would gradually discharge the battery when the light was not being used.

A 3 position switch could be used OFF, START (charges cap) and RUN (turns ballast on)
Probably best though to use a different battery or a different ballast, as the O/P has now done.


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## Sampolainen (Feb 5, 2009)

Just out of curiosity I measured my ballast's(the cheap chinese kind) start up amps and got the following results:
1sec 4.5A

2sec 6
3sec 7A 
4sec 7.5A
5sec 8A
6sec 8.5A at this


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## Norm (Feb 5, 2009)

Do you have a picture of the ballast?
Wow looks like the slim ballasts seem to be a newer much more efficient design. I have been thinking of building a 50 Watt but I'm so happy with the 35 I don't think I'll bother.
Norm


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## AlexGT (Feb 5, 2009)

This is the ballast used, I seen those in 50 watts too!

AlexGT


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## XeRay (Feb 5, 2009)

AlexGT said:


> This is the ballast used, I seen those in 50 watts too!
> 
> AlexGT


 
Remember 50 watts in not 50 watts out. More likely 42-43 watts out.


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## AlexGT (Feb 5, 2009)

Here is the first burntime test with the new ballast, I got lazy to wait for the 11.1V 6600mah pack to be fully charged to a voltage of 12.59V so I decided to start it from 12.48V starting voltage.

Time Voltage
7:20 12.48V
7:25 11.49V
7:30 11.31V 
7:35 11.13V
7:40 10.96V
7:45 10.79V
7:50 10.65V
7:55 10.52V
8:00 10.40V
8:05 10.30V
8:10 10.22V
8:15 10.17V
8:20 10.10V Good 1 hour!
8:25 10.03V
8:30 9.95V
8:35 9.87V
8:40 9.73V
8:45 9.44V
8:47 8.60V Light turned off!

8.55 10.19V Resting voltage

This is nice, the new ballast seems more efficient than the old one this one gave me *87* minutes and it ignited the HID!, I think If I had waited for the pack to reach 12.59V it would have given off 90+ minutes of 3200 lumen goodness!

AlexGT


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## brickbat (Feb 5, 2009)

Nice work! 

Do you suppose there will be any issues with a mostly discharged pack still being able to start the lamp? Or if, say, the battery is cold?


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## AlexGT (Feb 6, 2009)

While installing the ballast I did test it with various levels of charge, IIRC the lowest I tested it was 10.43V at rest and it did start with no problems, lower than that I don't know.

AlexGT


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