I have a ? about residual current drain with ignition key OFF

[Ed U. Cator]

RE: 2006 Mastiff 117 S&S

My question is: with the ignition key off, is there considerable, residual current draw in the bike's OFF state (esp. my year & model)? This past weekend, I installed a new, well charged AGM battery and noticed small sparks when connecting just the 40A fused wire to the battery, which got me suspecting too much current draw in an OFF state that would eventually drain the battery.
So I connected a DC ammeter & it initially showed 370 milliamp draw for 3 seconds then it dropped to a steady 2.7 milliamps (with ignition key OFF). Repeated that test a few times & the same results (as if a capacitor is charging -- perhaps in the Gen 1 EHC RIP kit?). The flowchart in the service manual shows a normal steady state draw of 1.4ma (ignition key OFF) which is an insignificant amount. I know that if the bike is not connected to the BatteryMinder after a few days, the charger indicates a "somewhat" discharged battery and requires a few hours to top it off. Kind of strange if just 2.7ma over a few days is all that's drawing from the battery. Do I have cause for further troubleshooting?

 

[Mr. Wright]

Yes there is a current draw on the Gen 1 EHC. I've never tested to see what it is. Nor do I know yet, about the new ones out. I just know that after a couple weeks of sitting, a full battery will be down enough to make the bike hesitate when starting. I just got in the habit of topping off the battery before a ride, if it has sat for a couple weeks. I do not keep them on a trickle charger all the time. I may throw the trickle charger on it the night before the ride. In the winter time I put my big charger on them, once a month. It is my belief the batteries will last longer this way. Most of my batteries last between 3 to 7 years.

 

[Ed U. Cator]

So despite the ignition, lighting, etc. being "OFF", it's an active electrical system that draws a tiny residual amount of current, much the same as a vehicle with a security alarm or keyless remote entry. I know the previous AGM battery had been left for dead at least a couple of times while the bike was for sale at the dealership. It would charge to a relatively useable output but not enough for my comfort. It's near impossible to revive an abused battery and expect good reliability, hence why I bought a new one.
I have the top model BatteryMinder 128CEC1 w/ ambient temp sensor/ desulphator & selectable 2/4/8 amp + battery type. I trust it.

 

[PROFLYER]

I think most of us keep them on 'life support' when they're parked. Part of my routine now. Took the bikes out this weekend after being parked/covered all winter. Both were 'green' on the battery tenders and fired right up no problem. I have noticed that I'll hear the tenders 'click' while I'm in the garage messing with something else, which I assume is them putting in a float charge of some sort as needed. A good tender IS designed to be left plugged in. Mine said something about cycling the battery so it stays in top shape. Seems to work. I've gotten 5+ years out of every battery I've had. When they die, they die quick.

 

[Jersey Big Mike]

So despite the ignition, lighting, etc. being "OFF", it's an active electrical system that draws a tiny residual amount of current, much the same as a vehicle with a security alarm or keyless remote entry. I know the previous AGM battery had been left for dead at least a couple of times while the bike was for sale at the dealership. It would charge to a relatively useable output but not enough for my comfort. It's near impossible to revive an abused battery and expect good reliability, hence why I bought a new one.
I have the top model BatteryMinder 128CEC1 w/ ambient temp sensor/ desulphator & selectable 2/4/8 amp + battery type. I trust it.

Plus there is nominal discharge just of a lead acid battery sitting by itself of apprx 5%/month (not sure the current that equates to) https://batteryuniversity.com/learn/article/elevating_self_discharge

 

[Sven]

Figure a battery looses 1% a day, so in a month it's 30% down.
12.6v-12.8v the battery is fully charged.
12.4v better hit the charger on it.
Black box is more a processor and lives in a 0-5v world.
Key on,12v heads to the integrated chip (IC )in the black box, and the chip steps down 12v to 5v.

I could meguyveer a remote toggle switch on the hot wire going into the black box. I cut the current draw off from the battery.
I now toggle off the black box, note my current draw is still there.
I then begin to pull connectors off one at time and keep checking for the phantom draw till found.
I, oh shit, this box needs it too. Where is the hot wire going in? Hand me another toggle.

Signed,
NOLTT (new old limping toggle trick)

 

[Ed U. Cator]

LOL @ Sven!
I understand battery charge/discharge characteristics be it SLA, AGM, etc. given I work with them often on the job, in my lab. I thought it was almost pointless for Big Dog to indicate in their svc. manual about the measly 1.4ma current draw! But then that would further prove the electrical system isn't truly in a zero current state, even with key removed. I was surprised at the current draw of the air ride system. Starts out at 2-3 amps and draws 12+ amps at 100psi for such a small DC motor.

 

[Mr. Wright]

LOL @ Sven!
I understand battery charge/discharge characteristics be it SLA, AGM, etc. given I work with them often on the job, in my lab. I thought it was almost pointless for Big Dog to indicate in their svc. manual about the measly 1.4ma current draw! But then that would further prove the electrical system isn't truly in a zero current state, even with key removed. I was surprised at the current draw of the air ride system. Starts out at 2-3 amps and draws 12+ amps at 100psi for such a small DC motor.

Very few understand Sven

 

[Jersey Big Mike]

if you have EFI, the controller is constant power to remember the learned settings (instead of using static ram which would not require constant power).

 

[Jwooky]

The new Thunder Heart based control module systems (RIP, ESC etc) do not have an ignition off current draw issue.

If there is anything, its negligible.

 

[Ed U. Cator]

if you have EFI, the controller is constant power to remember the learned settings (instead of using static ram which would not require constant power).

No EFI- it's the Super G carb. According to BDM website I have the Gen 1 RIP and the carburetor version ignition module.

 

[Nukeranger]

None of my carburetor bikes draw current with the ignition off including the Big Dog with Wire Plus. However, my Triumph Daytona 675 with EFI and computer system draws current when off so it stays on a battery tender. So, I too like others rotate a tender around or put it on a tender the night before a ride if I can remember. It’s pretty much hit or miss for me and maybe I should consider a timer of some sort in the future to take care of the normal battery discharge process. I use a Genie charger on the Big Dog and it has a maintenance mode of some sort that I like. It only charges when needed, so I could leave it hooked up and have from time to time.

 

[Sven]

However, my Triumph Daytona 675 with EFI and computer system draws current when off so it stays on a battery tender.

Like here, I'm trying to school myself with these black boxes. Before I was kicked off some tri site, I did notice a relay from black box to battery. There is where I [self] learned the box is timed off a 555 timer (my guess) in the box to turn off the current draw after the learn process is over via relay. The box still has to draw current to save the new RAM. Now here BD wise, I don't see a relay as per learning, but if there is a drop? Not that I'd put it past man that he could turn the relay obsolete and let the box switch it off 555 timer wise and still draw to save the volatile (RAM).

if you have EFI, the controller is constant power to remember the learned settings (instead of using static ram which would not require constant power).

Here is where the head bang occurs and basically what you are saying. If you have EFI, the crank cuts in the throw, it might be sequence fire (emission induced-saves last cylinder fired so no raw gas is wasted with so many revolutions before it fires off). Whereas, the first black box on the early Harley is where the RAM is lost with key off. The bike starts at 0000. That's my thinking of learned RAM vs static RAM.

So one way the OP could have the question answered is to have another dog with the same box and work the phantom draw as a short somewhere or they match draws and no problem found. What would the ma drop be but another learn process in the making. Only your multimeter knows for sure.

Signed,
NOLTT (no one likes testing transistors)

 

[Jwooky]

EFI’s do not draw current either. It was the original EHC that did so.

The reason they need battery feeds is so they can do a proper shutdown after key off. (Write learned MAP , set IAC etc. )

 

[Jersey Big Mike]

EFI’s do not draw current either. It was the original EHC that did so.

The reason they need battery feeds is so they can do a proper shutdown after key off. (Write learned MAP , set IAC etc. )

Well looking at the wiring diagram I know of no other reason for constant power other than an active circuit/memory protection.
I've never thrown the meter on it but I'd bet it is drawing some current, maybe not much but some.

 

[FrankBDPS]

You guys are close to entering the world of over technologicalasation. Good thread though.

 

[pknowles]

You guys are close to entering the world of over technologicalasation. Good thread though.

new big word for the day technologicalasation thanks Frank, I had to look it up

 

[Nukeranger]

Thanks Sven,

So, it’s just the computer on my Triumph Daytona 675 drawing current. Cool

 

[Th3InfamousI]

Well looking at the wiring diagram I know of no other reason for constant power other than an active circuit/memory protection.
I've never thrown the meter on it but I'd bet it is drawing some current, maybe not much but some.

I think the reason for the current draw on the OEM EHC was because it kept vehicle history logs. Run Time and RPM ranges, something BigDog needed to implement to have a chance at warranty claims due to owner negligence. However, this is why the aftermarket don't have current draw is because they don't need to track the history because what the hell is a warranty now? LOL

 

[Jwooky]

Well looking at the wiring diagram I know of no other reason for constant power other than an active circuit/memory protection.
I've never thrown the meter on it but I'd bet it is drawing some current, maybe not much but some.

As I stated, the aforementioned items occur after you key off. Without bat feed you would not have power to do so.