Alternative nimh Thor power...

What if you were to take 12 NiMH AA's, wire in series = 14.4 votls. Now take that pack and x 3. You get ~ 6ahr. If you used 4, you'd have 8ahr.

This wouldn't be that expensive, and you'd have 14.4 (bright!) correct voltage, and close to same runtime as the stock battery. Would this be able to be charged with the stock charger?

Just an idea, but it' would be a simple non-brainer to get the "correct" voltage to the bulb.

Would this work, or be a bad idea???

It certainly would work

I would recommend 12 'D' size cells instead...about $6 each on-line for 9 AH cells, plus the packaging would be easier

the wieght of NiMH is about 40% less than equiv SLA's

not to mention the obious advantage of easy voltage boosting

Chargers....you MUST use NiMH chargers...anything else will ruin the batteries..or worse

Check out the RC / hobby suppliers on-line ...they have real nifty smart chargers that auto-adjust for the battery voltage and type

my ballast must be safe to use with over 17 volts
because my 12 c cell nimh pack in my hid vector has not ruined it yet

Javaman: Hmm. I see my idea would work, and shave a few lbs while being brighter, but with extra complications...
The D cells would offer more amp per dollar than AA.
Good idea on the RC chargers. It seems though that this project would end up costing more than NewBie's boost upgrade (price tba) /ubbthreads/images/graemlins/frown.gif

markdi: if the ballast is made for cars then yes it should tolerate voltages over 12. I wouldn't push it much past 15 though.. 17-18 is danger zone for car electronics.

11 nimh c cells ends up being over 16 volts at end of charge

I had assumed the Thor in question has a hot-wire bulb. Boosting the input of a ballast beyond spec is a bad idea unless you have lots of spares laying around

Ok, then once again /ubbthreads/images/graemlins/twakfl.gif to markdi!! Ok now that that's out of the way... /ubbthreads/images/graemlins/grin.gif

java_man: I am talking about a stock thor, hot-wire bulb. Instead of using a boost circuit, just use a different battery source to supply the correct voltage (~13.8-14.4v) that the H4 bulb would see in a car with a running alternator. I assume markdi has put a HID in his Thor? Not sure what he is talkign about exactly... No one really does... J/K /ubbthreads/images/graemlins/smile.gif /ubbthreads/images/graemlins/wink2.gif

I guess that the cost of NiMH and a special charger is going to cost more than the voltage boost cicuit, allthough if you didn't have access to that then this would be the way to go. Unless someone else has another idea of making higher voltage to the bulb in a simalar way???

BTW, how many amps does this thing pull at ~14v? I bet you'd need a big wall wart adapter if you wanted to shine it off of your deck for a long time!!

Regarding the stock Thor bulb....

The issue is that even the NiMH will sag.

If you put in an extra battery for the sag, you risk flashing the bulb on startup.

Keep in mind the stock Thor bulb will draw 7-8 amps at 13.2V, and more at 14V.

Plus the cost. Though it is alot beter for cost than Li-Ion....

I posted this chart in another thread



this is based on a 100 W 12 V bulb

Newbie, Java, very good info. thanks! Seems like 13.6 would be a good comprimise for brightness/runtime/life.

Newbie: is the boost circuit user adjustable and do you have an approx cost yet? Thanks.

Isn't the Thor's bulb actually rated a little over 13V anyways?

The Thor bulb is a much higher end bulb, only the top end Narva, just barely able to beat it, and that could have been just lot to lot variation. If you blow your Thor bulb, Don's Bulbs has the Narva.

Not sure where that chart came from, but it must be for a regular bulb, not what is in the Thor.

And it will long be slag before 19V. It is also a much higher kelvin temperature than a regular H4 headlight. Probably why it is considerably brighter than a regular H4.

Got to thinking, and if you used several "banks" of 12 NiMH AA, then it should sag less than just using 12 D cells. Because you'd have the current demand spread over more cells instead of all into one bank, so the internal voltage won't be so bad... Is this correct assumption?

On another thought, is that H4 bulb illegal to use in your car since it's more watts than the standard 55/60watt bulbs?

my brain was thinking hid sorry

I will try using brain before posting

I looked at Panasonics data sheets for the AA and D cells and the D cells had only .002 ohm vs .02 for the AA, so the sag due to cell impedance would be much less for the D's

how about using nimh f cells ?

Generally speaking, bigger is better

Humm, 0.002 ohms * 12 cells = 0.24 ohms

0.24 ohms * 7 amps= 0.168V sag

Not too bad.

How does the cell voltage hold up under a 7 amp load?

Good cells always have data plots at various load currents.

here is a link to Panasonics D cell

D NiMH

Those Panasonic nimhs look good current wise.
www.battlepack.com may hold even more answers for this kind of application.
I have 9 of thier nimh 500mah N cells that can put through 1.3-1.6 amps with no problem.