power on board HID on Li-ion

[kanarie]

Question:
I want to reduce the weight of my power on board HID.
Is it possible to run this HID on 3 Li-ion cells total 11.1 volt (like 3x 18650 batteries) and will it still run when they are almost empty (8- 9volt)
Or do I need 4 cells (and risk of blowing the balast?)

 

[kanarie]

to give an answer to my own question:
yes you can!
I just had an idea and connected two pretty full 18650's (with a magnet)
The two of them had enough voltage/power to startup the HID (buzzing noise in the beginning though) The lightoutput was reduced with a third.
If I can start it at 7 volt (with two) I guess 8-11 volts (with three li-ions) won't be a problem...

Any ideas for a 3x2 18650 battery holder anyone?

 

[jayb79]

I was thinking something like this
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=4270
Do you know how many amps it draws of the sla battery?
I think the voltage will drop quite a bit so 4 cells should not be a problem.

 

[schiesz]

If anyone gets this working on lithium ion i'd love to hear about it. Maybe a 3sx2p config would be god for runtime? To take this monster and make it so much lighter would be incredible.

 

[Patriot]

Good link jay, and it would probably be good to get something with a bit more capacity.

Here are many packs to choose from:
http://www.batteryspace.com/index.asp?PageAction=VIEWCATS&Category=1008


EDIT:
...and yes kanarie, I'd lean toward the 11V packs with larger capacity than a small pack with higher voltage. It's safer, since I don't know if anyone knows what the voltage range of the ballast is, and the run-time will keep the light practical unlike four 18650's.

 

[Flashanator]

those batts + 4300K bulb would really make the POB the light it should have been all along.

Im gonna get a POB.

 

[jayb79]

Best bang 4 the buck would be Ni-cd
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2533
Or Ni-mh
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2052
for around $100 and you can have 7-10 ahs of bright light. Easy to charge and lots of capacity.

 

[kanarie]

I was thinking something like this
http://www.batteryspace.com/index.as...OD&ProdID=4270
Do you know how many amps it draws of the sla battery?
I think the voltage will drop quite a bit so 4 cells should not be a problem.

a 3 pack would be safer I think also 6 x 18650's at DX will cost $25
So I can make an 11,1V 5000mAh (3s 2p) pack for far less money
and a Cheap dual 18650 charger ($6)
I only need an battery holder for 18650 batteries
maybe two PVC tubes with magnets between the batteries

 

[Dead_Nuts]

I really like the 12v, 10,000 mAH battery that jayb79 shows above. A separate charging lead allows the battery to be permanently installed in the housing and charged externally. Of course taking a $28 light and modding it with a $100 battery and a $28 charger might be considered a little INSANE. But, hey, I'd love to see someone else do it.

 

[mdocod]

a 3 pack would be safer I think also 6 x 18650's at DX will cost $25
So I can make an 11,1V 5000mAh (3s 2p) pack for far less money
and a Cheap dual 18650 charger ($6)
I only need an battery holder for 18650 batteries
maybe two PVC tubes with magnets between the batteries

Just a few things I want to point out here:

1. Your 2x18650 "test" to see if it would work was probably pulling upwards of 8 amps (give or take a few amps) from the cells. That's not good for them.
2. Using cheap cells with huge variances in true capacity is never a very good idea for building battery packs, especially li-ion packs.
3. Charging a LiCo pack, especially if you are going to use a bunch of cheap mismatched cells, is going to require some special considerations, I would personally recommend looking into balance chargers and building a pack with balance taps for safety reasons.

doing a 3s2P configurations of Li-Ion cells won't really extend the runtime much if any compared with a good performing SLA, with that in mind, it would be a lot of money to spend, to have not dramatically improved anything accept for weight. I would suggest a 3S3P configuration as bare minimum li-ion conversion to say that it was worth it overall, that should extend runtime to around 2 hours.

 

[lennin]

My low-budget project. 4x3 18650 cells to my HID

 

[kanarie]

NICE!
did you do the wires already?

 

[Wattnot]

If I'm not mistaken there's a 12v 7000ma SLA in the stock POB. If you want to use 18650's, you would probably be better off with a 3S4P config. That should give you enough current draw and runtime from protected 18650s. The stock light claims 70 minutes of continuous operation so you should be able to do your rough runtime math from that.

However, this would be a good application for lithium POLYMER cells. You can buy them in almost any configuration from hobby shops online (I can hook you up). I know I recommended against these in a flashlight previously but that guy wanted to shove a lipo into a mag body. Nice flare if you drop it the right way! But in the POB, it would do fine and save a LOT of weight and current draw is not a consideration since most of these allow 50 or more amps easy. They would be terrible in the cold though. Just throwing out some ideas here.

 

[Patriot]

It would be one high performance POB but a good li-po would sure be light.

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=6322

too expensive?

 

[jayb79]

I would think a 4s pack would be ok. Here is a 3s, http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3871

And a 4s with built in protection circuit, http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=4032

 

[Patriot]

The 4S will peak at 16.8V. I'm not really sure how much those ballasts will handle.

 

[plasmaman]

My PoB runs a 50w 4200k D2 lamp on 4 x Li D in series.
Very light, very good output. A great lantern all round.
:twothumbs

 

[worldedit]

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=7346
Very cheap, light and can supply 50W no problem.

 

[Richie086]

From what I've observed in my stock POB, removed from the charger (already on float mode) the SLA battery voltage is about 13v. When turned on, the battery immediately falls to 12 volts and stays there even after the HID bulb has warmed up to full brightness. This HID requires 3.5 amps of power from the battery to run at full power and runs for easily 90 minutes on a single charge. That's as far as I went with the SLA battery.

I'd love to upgrade it on both of mine as well, so I watching this thread carefully.

 

[Patriot]

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=7346
Very cheap, light and can supply 50W no problem.

Those Rhino brand batteries are very good quality and I fly them in large 1500 Watt RC planes. That said, I personally think the 2600mah capacity is too small. The largest Rhino that Hobby City sells is a 4900mah but it only comes in a 20C which drives the price up to $65. Still a great price for those willing to sacrifice run-time but I'd still want more capacity.