Havis Shields HID - some imperical data

[JimH]

I tried running my HS HID on one of these. It worked well for about 7 seconds.

I measured the current. The current started out at about 3.5A and rapidly rose to around 5.5A before the lamp shutdown. The batt pack is rated at 4A.

I then hooked up the HS HID to a 2ah SLA battery and measured the current. The current started at about 3.5v then rapidly rose to over 6A as the HID warmed up. Once reaching a peak of about 6.3A, the current subsided and stabalized at about 3.79 amps. The cycling of current took about 20 seconds.

Conclusion: Althought a Li-Ion batt rated at 4A should, in principle, run a HS HID, The warm up current far exceeds the capacity of the Li_Ion batt. If a circuit could be designed to pulse the current until the HID is warmed up, the 4A batt pack would be a very good choice.

A simpler, but more expensive, solution would be to run 2 batt packs in parallel. This would give 8Ah capacity and 8A current draw capacity.

 

[MaxaBaker]

Interesting-- /ubbthreads/images/graemlins/rolleyes.gif

Glad I didn't choose to buy one of those to run mine. I'll stick with the $29 6ah 12v battery that Phaserburn suggested /ubbthreads/images/graemlins/happy14.gif

 

[twentysixtwo]

Any thoughts on using some big a$$ capacitors to buffer the initial surge?

A bank of supercaps might give you close to a farad of charge without being larger than a couple of AA cells.

 

[JimH]

[ QUOTE ]
twentysixtwo said:
Any thoughts on using some big a$$ capacitors to buffer the initial surge?

A bank of supercaps might give you close to a farad of charge without being larger than a couple of AA cells.

[/ QUOTE ]

Sounds great - how, exactly, would an electrically challenged person go about implementing such a plan. I would need someone to supply a detailed design. I can work a solder gun with the best of them, but that's about the extent of my electrical knowledge and skills.

 

[Phaserburn]

Great observations, JimH.

 

[markdi]

I would not have thought a 6 or 7 amp 30 second load
on a 4 amp hour lithium ion pack would be a problem.

capacitors will not help - at least caps small enough
to be practical - the over current situation lasts too long.
caps may help an overload situation of a second or less.

I bet that there is a over current protection circuit
in the battery.

I would mod the protection circuit.

are you sure the battery has a full charge ?

 

[unnerv]

Hey Jim, if you wanna try it, I have a .5 farad cap sitting in my closet from my car audio days. Dunno that it will help, and it is probably the size of the water bottle.

 

[JimH]

[ QUOTE ]
markdi said:
are you sure the battery has a full charge ?

[/ QUOTE ]

Fresh off the smart charger that came with it.

Patrick, thanks for the offer, but, for the size of a water bottle, I think I'll go with another lithium batt pack and run them in parallel. This should give me a very nice 8Ah energy source with a 8A capacity that is lighter than a 2Ah SLA. This is the batt pack I've always wanted any way - perfect for my other plug in HID (you know the one).

 

[Phaserburn]

I believe the Vector SLA I found for 29 can handle a 10A draw before the fuse kicks in.

 

[JimH]

[ QUOTE ]
Phaserburn said:
I believe the Vector SLA I found for 29 can handle a 10A draw before the fuse kicks in.

[/ QUOTE ]

SLA's are no problem, except for the fact that they are heavy. I have a 2Ah SLA which works with both my HS HID and my 50 watt HID plug in. Run time isn't that great on 2Ah (approx 15 min), but current is not an issue.

I have a 7Ah SLA that gives lots better run time, but considering the weight, I'd rather carry around my X990.

 

[Phaserburn]

[ QUOTE ]
JimH said:
[I have a 7Ah SLA that gives lots better run time, but considering the weight, I'd rather carry around my X990.

[/ QUOTE ]

The 6Ah unit I have weighs 4lbs. Not a lightweight, but with a decent shoulder strap, not all that noticeable. It's a good mix of light weight (for an SLA) and capacity/current availability.

 

[Turd_Ferguson]

It'll be interesting to see what that Vector 6Ah really weighs. I haven't been able to find any data on it. The 5Ah Vector that The Sportsmans Guide sells for $14.97 (on sale) is supposedly 4.75 pounds. I'm curious to see if the 6 Ah actually weighs less.