SSR to provide 12VDC power to accessory fuse block in Motorcycle , current leak draining battery

Thread Starter

gt7599a

Joined Apr 13, 2019
3
I have a small displacement motorcycle that I want to add accessories to without risking draining the battery when the bike is not in use.

I purchased an SSR thinking to avoid mechanical failure due to vibration.
The way I originally had it wired, the SSR is allowing current through even when the bike is off. I originally had L1 & T1 swapped which is may be sufficient explanation.
Motorcycle relay diagram with current leakage.png

I corrected the wiring to L1 & T1.

Motorcycle relay diagram.png
The way I have it wired now though I'm seeing voltage values which make me think that if I leave it connected it will drain the battery
New Battery reads 12.5 VCD if measured directly.

With the ignition Off (switch open), the Voltage between the Negative terminal and L1 is 1.5 VDC
With the bike On, the Voltage between the Negative terminal and L1 is 12.1 VDC

With the bike Off (switch open), the Voltage between the Positive terminal and L1 is 11.9 VDC
With the bike On, the Voltage between the Positive terminal and L1 is 0.5 VDC

So my questions
  1. If I left this connected, it would drain my battery, right? I don't get to ride the bike often so I could easily go 1-2 months without riding so even a small current leak would be problematic.
  2. If this voltage indictaes current leakage, Is there a way to rewire this to avoid battery drain or is this simply a by product of using an SSR?
  3. If I used a mechanical relay, would that avoid this leakage?
Thanks so much
Ed
 

wayneh

Joined Sep 9, 2010
16,114
I suspect you may be seeing ghost voltages, meaning the high sensitivity of the meter allows you to see the leakages you are concerned about. You could add a 10K resistor in parallel with your meter leads to introduce a small load and reduce the impedance of the meter. The voltage discrepancies might disappear.

Can your meter measure current directly? That would tell you a lot more about the current drain. It'd be worth borrowing a meter from someone.
 

Thread Starter

gt7599a

Joined Apr 13, 2019
3
Thanks
I tried measuring current putting the meter in series, but my cheap small meter wasn't showing anything. Not sure I should believe it.
I'll take my good meter down next time (which also does current) and try for new readings to see what I get.

Ed
 

Thread Starter

gt7599a

Joined Apr 13, 2019
3
Went back with the better meter, rigged it in series, and again, no current flowing. So my guess is it was the initial incorrect wiring which caused the current leakage and killed the battery.

As it is now, with the switch off, there was a voltage difference of about 1.6VDC between the fuse block (L1 above) & the negative terminal on the battery, that slowly dropped towards 0 over the course of a few minutes.

Ed

upload_2019-4-23_22-21-41.png
 

wayneh

Joined Sep 9, 2010
16,114
Your meter's input impedance is at least 1MΩ. I measured mine and I forget the number but I know it was 1MΩ or more. I gather an expensive meter will have a 10MΩ impedance. The point is, a meter is capable of measuring a voltage when there is just a tiny or phantom current. For many applications, just measuring a voltage is almost meaningless. Adding an appropriate load, anything from a 10KΩ resistor to an automotive headlight depending on the application, can produce far more useful data.

Anyway, sounds like you're good to go. :D
 
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