Elemental electrical question time again.... amperage

[Turbogus]

Hi gang, I've been running H4 headlight shells in my Jeep and my van for a few decades now but with the intrusion of substandard parts filling the inventory of the auto parts places in my area I'm taking steps to address a problem I've been having. When I intorduced these headlight shells to my rigs I also updated the wiring from in some cases 16 gauge to 10 gauge with relays (one for each headlamp) and new sockets. A problem in recent years is when running higher watttage Wagner H4's (145/100) they would only last about 8-12 months. I've seen the argument the bulb that burns brightest burns half as long but I'm not fully convinced this is the reason for my issue.
With this in mind I just received a pair of Flösser H4's in the hopes that German engineering may be better than China and this may be the issue.
So, at 12V 145W I'm trying to wrap my head around how many amps I'd be pulling. Any ideas?
I sent a bilingual email to Flösser but hoping to resolve this question soonest.

Thanks in advance anda lift of the lynch lid.
Gus

 

[wwch99tj]

http://www.powerstream.com/Amps-Watts.htm
145÷12
=12.0833333333...?
Or
145÷13.8
=10.5072463768...?

 

[JPNinPA]

With 145W lamp on a 12V system you will draw 12Abut when idling it would be more like 10.5A per light.

 

[jfrabat]

Watts = Volts X Amps

Therefore,

Amps = Watts / Volts

Amps = 145W / 12V = about 12A for high beam per light

Keep in mind that 14V systems typically run at 13.8V in real life... But use 12V to get the higher amperage for your calculations (call it a cushion if you will).

As for the cable, the gauge will depend on the length you need to run it. The longer the ddistance, the thicker the wire. i took the following chart from here:

Length (feet)	Current (amps)
5A	10A	15A	20A	25A	30A	40A	50A	60A	70A
15	16	12	10	10	8	8	6	6	4	4
20	14	12	10	8	8	6	6	4	4	4
25	14	10	8	8	6	6	4	4	2	2
30	12	10	8	6	6	4	4	2	2	2
40	12	8	6	6	4	4	2	2	1	1/0
50	10	8	6	4	4	2	2	1	1/0	1/0
60	10	6	6	4	2	2	1	1/0	2/0	2/0
70	10	6	4	2	2	2	1/0	2/0	2/0	3/0
80	8	6	4	2	2	1	1/0	2/0	3/0	3/0
90	8	4	4	2	1	1/0	2/0	3/0	3/0	4/0

Now, since you are runing non DOT lights (stronger than I recall you can run), why not upgrade to HID lights? They consume less than the lights you are currently running, and light as well (or better).

For my type of wheeling (mud down in tropic trails), the strength of the light is not as important as the electrical consumption (it is a PITA to have to shut your lights off everytime you winch), but different styles of wheeling have different requirements (like deser running, where you need to see as far ahead as possible).

 

[Turbogus]

Thanks for your detailed response jfrabat. This light system is actually for my other rig 'Easy Bake'. The Hella H4 shells have been on 'er since 1995 and since they've been working fine (except for those Wagner bulbs I was referring to) I'll stick with them until they become untenable, rather than pitch 'em for the HID.