ST1100 Parasitic Battery Drain

I measured the current draw at the negative battery post of my '01 ST1100 ABSII with key off and got 1.94mA. Is this about normal? What have others measured? I read one post and someone mentioned that about 1.5mA was normal. Thanks for any insight.

"It's about time"... literally the clock puts a minuscule drain on the battery. Since my ST1100 sits a lot now, I thought about intercepting the power to the clock and put a switch on it. Most folks I know ride with either a GPS or their smart phone in view... both have the time available plus a watch if you wear one. When the 1100 was designed, smart phones did not exist, and GPS units were not widely used. The space occupied by the clock on the 1100 could be better utilized by a "switched" accessory of some sort.

Thanks Vinny. Thought it might be the clock but was wondering if there was anything else. Think I'll try to measure the current draw of just the clock.

This came up because my battery died after sitting for 4 days so I measured the current draw to see if I had a problem outside the battery.

Do you have USB ports on your bike? If they're on a non-switch circuit, that can drain a battery. The USB ports have to step down the voltage, so the transformers in them draw current.
How old is your battery?
The clock doesn't draw enough to drain a good battery in 4 days

kiltman said:

Do you have USB ports on your bike? If they're on a non-switch circuit, that can drain a battery. The USB ports have to step down the voltage, so the transformers in them draw current.
How old is your battery?
The clock doesn't draw enough to drain a good battery in 4 days

Click to expand...

The power for my GPS is stepped down from 12V to 5V... I'll check the current draw with and without that. Thanks for that tip.
The battery was supposed to be new as of several weeks ago. It 'looks' new but not 100% sure. Will have to look for a mfg. date code on it.
Agreed, the clock shouldn't cause a problem after only 4 days, thus the reason I'm digging into this. I put it on the tender overnight and it was a nice steady green light this morning, cranked over just fine.

kiltman said:

so the transformers in them draw current.

Click to expand...

Just FYI... transformers do not work with DC voltage.

T_C said:

Just FYI... transformers do not work with DC voltage.

Click to expand...

I sit corrected

1.94mA shouldn't take down a good battery in weeks let alone four days.

Let us know what reading you get went you repeat without your GPS connected. USB ports step down voltage from 12V to 5V but I didn't think they did it with no load. I've got one on my ST and I haven't noticed any parasitic loss. I'll have to give that a look.

Anyway why would your GPS do that? And would it do that in the Off state? It just seems odd.

paulcb said:

The power for my GPS is stepped down from 12V to 5V... I'll check the current draw with and without that.

Click to expand...

Methinks that's your culprit right there... see that you feed the active GPS cradle (and any other powered devices) from a switched source.
The clock alone wouldn't draw more then like 0.3mA (IIRC...)

My guess would be that the "new" battery was never fully charged. Now that you charged it up with your tender try letting it sit for a few days again to see if it repeats.

ST1100Y said:

Methinks that's your culprit right there... see that you feed the active GPS cradle (and any other powered devices) from a switched source.
The clock alone wouldn't draw more then like 0.3mA (IIRC...)

Click to expand...

My GPS connection is temporarily directly to the battery. I did that so I could use it on my trip back from CA where I bought the bike. Like on my previous ST11, I'll permanently connect it to the switched power in the accessory harness that's just rear of the battery.

Note that when I checked my current draw and measured 1.94mA, the GPS/cradle was connected to power but not turned on.

schlep1967 said:

My guess would be that the "new" battery was never fully charged. Now that you charged it up with your tender try letting it sit for a few days again to see if it repeats.

Click to expand...

I did ride it home 1500 miles from California two weeks ago. My charging system is working well so I think that would have fully charged it, although I know how good the battery tender is so maybe that will work better. I'll put it on the tender overnight for a week or so.

paulcb said:

Note that when I checked my current draw and measured 1.94mA, the GPS/cradle was connected to power but not turned on.

Click to expand...

Do you have a fully separating (additional) switch in the 12V feed to the cradle, or are you referring to some push-button featured on the the device?

If its the latter, forget it... the push-button might switch the outgoing 5V, but the converter site will still draw on the 12V supply provided...

The GPS forums are flooded with complaints about active Satnav cradles draining MC batteries...

Your 2001 ST features a switched 5A ACC circuit, located behind the regular fuse-box; for peace of mind tap your accessories into that.

paulcb said:

I did ride it home 1500 miles from California two weeks ago. My charging system is working well so I think that would have fully charged it, although I know how good the battery tender is so maybe that will work better. I'll put it on the tender overnight for a week or so.

Click to expand...

1500 miles should have been more than enough to fully charge it.

ST1100Y said:

Do you have a fully separating (additional) switch in the 12V feed to the cradle, or are you referring to some push-button featured on the the device?

If its the latter, forget it... the push-button might switch the outgoing 5V, but the converter site will still draw on the 12V supply provided...

The GPS forums are flooded with complaints about active Satnav cradles draining MC batteries...

Your 2001 ST features a switched 5A ACC circuit, located behind the regular fuse-box; for peace of mind tap your accessories into that.

Click to expand...

It is the latter but again, my current setup was only meant to be temporary until I could get back home and wire it correctly.

Thanks for the comment about the GPS forums... will likely hasten me to get it wired correctly. In the mean time, I'm just pulling the GPS out of the cradle when not in use. That doesn't
eliminate the converter draw so I'm going to measure the drain with and without the cradle connected. If there's a significant difference, I'll just disconnect the cradle completely. Don't really need my GPS to go to work.

Yep, that's the circuit I used before and plan to again. Thanks again for the tips and comments.

schlep1967 said:

1500 miles should have been more than enough to fully charge it.

Click to expand...

+1

If it sat at the dealership for a few months without being ridden the battery could be on its last leg. Not knowing the age/history of the battery makes it a prime candidate for replacement based on your leakage current measurements.

edit: I'd do the leakage current measurement one more time, making sure you're getting good contact with the meter leads and not artificially limiting the current flow with a poor connection.

Mystery solved. As Kiltman and ST1100Y suggested, the major drain was from the GPS cradle. It pulls ~80mA, without the GPS in it! That surprised me.... 80mA in and 0mA out... I guess it's being converted to heat at the 12V to 5V converter. Also, my 1.94mA cradle measurement this morning was wrong, must have had a bad connection. Without the cradle connected, the bike pulls 1.46mA. And, as a side note, I'm getting a constant 14.05V from idle up to 3000 rpm. Thanks again for all the comments and suggestions.

glad you were able to solve the problem quickly, and for no cost.

paulcb said:

...80mA in and 0mA out...

Click to expand...

Yep, only secondary side of the voltage regulator IC switched, primary keeps nibbling on your battery...
At least an easy fix.