Power Draw through coils

[salty_monk]

Do you think there's enough available overhead to tap into on the SIGNALS circuit to run a 3 amp draw for a wideband oxygen sensor and not pop the fuse?

Yep should just about be... If you think about the total load of what's on that circuit.... Maybe 85w (20w x 4 bulbs incl the brake light plus 5w for the gear change) if lamps if all are on (if you don't have 4 way flashers as that could add another 40w).

(I don't know what your KOSO draws for gear change & dash flasher indicator but I suspect it's very small so I didn't include anything for the dash light).

P=IV so your 3amp x 14v = 42w.

Say 127w / 14 = 9.1 amps. Of course that figure could rise if the voltages are off (i.e. lower voltage = more amps). It would only be intermittent but you always brake with a turn signal going at some point!

You could consider making more room on the circuit with low power LED bulbs, you should be able to free up 40w easily that way I would think.

Failing that... an inline fuse or accessory fuse block would work fine. Use the signal circuit to switch a relay.

[posplayr]

This is a figure for my GS1100ED with Accel coils (3 ohms) and a stock ignitor.
The legend says 2.47 A average with 2.6 amp RMS and a 3.1 A high.
The scale is 1A per division but the base is at about 1.9 divisions.


2019-10-11_18-18-52_OW_Ignition_2p5RPM.jpg

[posplayr]

This shows the OG 1.) key On, 2.) Crank engine 3.) apply blinkers.
The scale is changed to 5 amps per division.

Channel 1 is Current, Channel 2 is Voltage (scales are shown at the bottom)

After seeing these plots you can certainly understand why going LED for signal lights would help the whole electrical situation.

LED signal is typically about 1/6 current draw of incandescent bulbs.
LED headlamp is closer to 1/3.


2019-10-11_18-27-10_OG_Signal_Statup_thenBlinker.jpg

[posplayr]

Dan,
You can see in the plots above how much the OG varies. Just turning ON the ignition on gives a 5 Amp load on OG (60 watts). With blinker it jumps between 5-10 amps.
If I was going to put the WBO2 on OG I would certainly switch to LED signal bulbs. Even though you don't see that much variation on the battery voltage, the large current excursion could have a significant effect on the voltage going to the WBO2. Depending on that device, it may or many not have an effect on O2 readout accuracy. No reason to tempt fate.

If it is a temporary setup i would go direct to the battery with a fuse.

[Steve]

Well, I was a bit surprised.

I wouldn't be.. Jim (Posplayr) is a very skilled Electrical Engineer. If he says it's so it usually is!

For the record, I was not surprised at his results. I was more surprised that the reality shown on the meters (his and mine) were not what I expected, based on simple calculations.

Jim and I have gone round and round on a few items. Yes, he is very skilled, but not (yet) perfect. I believe there was a point or two that I made that might have adjusted his viewpoint a bit, but he is usually correct AND well-spoken.

The scope graphs are interesting, as well. They definitely confirm the lower readings on the meter, which are average readings that are incapable of showing the sharp peaks and valleys in the trace.

I was going through some stuff in storage a few days ago and saw my old dwell meter. I'll have to hook it up to see what the dwell angle is. I have a feeling that it's going to be smaller than I am currently envisioning.
(Feel free to interpret that as another "surprise".)

.

[80GS1000]

Thanks for doing the math Dan.

Yep should just about be... If you think about the total load of what's on that circuit.... Maybe 85w (20w x 4 bulbs incl the brake light plus 5w for the gear change) if lamps if all are on (if you don't have 4 way flashers as that could add another 40w).

(I don't know what your KOSO draws for gear change & dash flasher indicator but I suspect it's very small so I didn't include anything for the dash light).

P=IV so your 3amp x 14v = 42w.

Say 127w / 14 = 9.1 amps. Of course that figure could rise if the voltages are off (i.e. lower voltage = more amps). It would only be intermittent but you always brake with a turn signal going at some point!

You could consider making more room on the circuit with low power LED bulbs, you should be able to free up 40w easily that way I would think.

Failing that... an inline fuse or accessory fuse block would work fine. Use the signal circuit to switch a relay.

[salty_monk]

For the record, I was not surprised at his results. I was more surprised that the reality shown on the meters
.

My reply might have sounded "arsey" when typed - it wasn't meant to be

PJ - no probs on Sums. Jim's reply above is actually for you.

[steve murdoch]

For someone who is electrically challenged (like me) this conversation is incredibly interesting -

--interesting - yet being spoken in a language I do not know -

Learning is constant

Glad i am not the only one.