Di2 battery draining

matomp9

Morning all,

I purchased a new bike with Di2 c. 6 months ago. It’s last years TCR advance 0.

I’m finding that the battery is draining very quickly. Im charging it up, taking it out for a ride and then 2 days later, it’s empty. Nowhere near the 1000s of kms it’s meant to do per charge.

I’ve read online that you shouldn’t leave it in the largest cog so don’t do that.

I’ve also read that you should charge from a laptop as opposed the wall. I’ve done both without any difference.

I took the bike for the LBS and he charged it up with his charger. 2 days later still at 100%. Took it for a ride that day - 2 days later, no charge.

Does anyone have any idea what might be up or how I might go about finding out? There’s so many things I’ve read it could be: the battery, the mech, the junction boxes etc. I’d prefer not to have to send off each piece individually else I’ll be without the bike for months.

Thanks.

Matt

surfercyclist

Mine lasts for months between charge and I leave in big ring and no issues. Simple check I'd do would be to disconnect junction box below stem(assume this is set up you have), so gear shifters are disconnected and see if battery still drains. Then if no better try disconnecting front and rear mech(separately) to see if that sorts it. Basically a process of elimination that can be easily done without stripping all wiring out etc.

I charge mine from mains and have no issues, this only charging from laptop etc seems a bit of red herring to me.

matomp9

Thank you. I’ll try that. It seems as though it’s fine until I ride and then it’s like it doesn’t ‘disengage’ if you get me. I’ll charge it up full then take it for a spin then disconnect the junction box first.

pilot_pete

Check the limit screw adjustments for front and (more likely) rear derailleur. If a limit screw is too far ‘in’ it can stop the derailleur shifting properly and if you are unlucky it can be constantly trying to re-adjust into the gear when you leave the bike, thus draining the battery. That’s where the ‘don’t leave it in the big cog’ advice comes from.

The other thing to check is all the connections - a loose one can cause battery drain, so dig your di2 tool out and undo and remake all the connections and ensure you get the ‘click’ to seat each one.

PP

surfercyclist

Pilot Pete wrote:

Check the limit screw adjustments for front and (more likely) rear derailleur. If a limit screw is too far ‘in’ it can stop the derailleur shifting properly and if you are unlucky it can be constantly trying to re-adjust into the gear when you leave the bike, thus draining the battery. That’s where the ‘don’t leave it in the big cog’ advice comes from.
PP

Would you not hear the motor though trying to shift in this case? Just wondering?

gezebo

Sounds like a possible false earth somewhere or faulty battery. Can you borrow a battery and see what happens as that’s the easiest thing to remove?
After that it’s a little bit of trial and error. How good are you with a multimeter?!

StillGoing

gezebo wrote:

Sounds like a possible false earth somewhere or faulty battery. Can you borrow a battery and see what happens as that’s the easiest thing to remove?
After that it’s a little bit of trial and error. How good are you with a multimeter?!

Same thoughts; something shorting out or a duff battery. Mine also goes months between charges and is left in the big ring.

paulwood

Happened to me, battery needed charging every second or third day.

Defective battery replaced under warranty, been fine since

drexel1975

I had this recently with a bike where I had to replace the frame and the shifters. Battery drained 10% every night and after lots of investigation it turned out to be one of the new shifters which was causing the drain. Swapped over under warranty and now all is good.

k3vinjam3s

Im having similar problems. Had battery replaced under warranty and still draining. Ive checked my rear mech limits and all good. Really dont want to have to check every connection as i know the junction box in frame will be a pain to get too. Gonna go thru the process of eliminating parts. Starting with rear mech as its took a knock from fall. Although problems started 6 months after this.

matomp9

Thanks for your help, all.

I've charged it up fully, updated all firmware and am ready to begin testing tomorrow. Will take it out for a ride and see how long the battery lasts with everything connected first. Assuming the issue remains, as opposed to the 1 in 10000 chance that the firmware update has resolved the issues, I'll charge it again, take it for another ride but disconnect the junction box before leaving it for a few days.

The parts I am going to disconnect one at a time are: Junction Box A, Rear derailleur, Front derailleur, R shifter, L shifter.

Would you guys suggest disconnecting anything else?

If I eliminate those without luck, would it be fair to assume it's the battery?

david7m

Think I'd fully charge it, disconnect and measure voltage twice a day. If it goes down fast then there's your problem. If it appears ok, then eliminate one part at a time like you suggested.

matomp9

Thanks, David. Good idea to disconnect the battery first (as that is the most likely problem).

I'm not so good with technical things so apologies for the (probably inane) questions. I'm willing to learn as I'm loathed to have the LBS undertake these tests for me as I may well have to give the bike over to them for a long while. I can at least still ride it if I'm testing it myself.

Am I right in thinking the battery is 7.4v? If so and the battery were flat, would the meter read 7.4v?

What should a fully charged battery read?

david7m

I don't have DI2 so unsure about battery spec. But, normally good batteries are over there listed voltage and it won't be classed as flat 0.1v under.

matomp9

Battery didn't seem to be losing charge after 36 hours when isolated (voltage remained constant) so I don't think it's that. Full drain normally only takes 36-48 hours for me.

So, I've reconnected the battery to the system and disconnected the rear mech - just pulled the plug out of it so to speak. After 24 hours of that, the junction box light is still solid green indicating full, or 75%+ at least, battery charge. Whilst this isn't yet long enough to say with certainty, I am starting to suspect it might be the rear mech. This has led me to wondering what the issue with the rear mech might be so I returned to PP's post.

Pilot Pete wrote:

Check the limit screw adjustments for front and (more likely) rear derailleur. If a limit screw is too far ‘in’ it can stop the derailleur shifting properly and if you are unlucky it can be constantly trying to re-adjust into the gear when you leave the bike, thus draining the battery. That’s where the ‘don’t leave it in the big cog’ advice comes from.

I never leaver the bike in the big cog for this very reason, it's in the 3rd largest cog at the moment. Common sense suggests that it would need to be in the big cog to cause issue i.e. touching the limit screw to cause issue. But, I did wonder if my assumption was wrong and the limit screw being set incorrectly might still be the problem, even though the bike is on the 3rd largest cog and this there is significant daylight between the limit screw and the limit plate on the rear mech? Does anyone know if it is possible that this might still cause the rear mech to constantly be searching for the gear and therefore draining the battery ... or would it need to be on the largest cog to cause issue?

StillGoing

matomp9 wrote:

Battery didn't seem to be losing charge after 36 hours when isolated (voltage remained constant) so I don't think it's that. Full drain normally only takes 36-48 hours for me.

So, I've reconnected the battery to the system and disconnected the rear mech - just pulled the plug out of it so to speak. After 24 hours of that, the junction box light is still solid green indicating full, or 75%+ at least, battery charge. Whilst this isn't yet long enough to say with certainty, I am starting to suspect it might be the rear mech.

Struggling to see how you fathom it is the rear mech, when it reads that you've disconnected it, yet have still lost charge? That would indicate something else is draining power.

matomp9

philthy3 wrote:

matomp9 wrote:

Battery didn't seem to be losing charge after 36 hours when isolated (voltage remained constant) so I don't think it's that. Full drain normally only takes 36-48 hours for me.

So, I've reconnected the battery to the system and disconnected the rear mech - just pulled the plug out of it so to speak. After 24 hours of that, the junction box light is still solid green indicating full, or 75%+ at least, battery charge. Whilst this isn't yet long enough to say with certainty, I am starting to suspect it might be the rear mech.

Struggling to see how you fathom it is the rear mech, when it reads that you've disconnected it, yet have still lost charge? That would indicate something else is draining power.

It hasn't.

Step 1: I isolated the battery. It didn't lose charge. So i don't think it's that.

Step 2: I plugged the battery back in and unplugged the rear mech. The rest of the system is connected. As far as I can tell, it hasn't lost charge i.e. the constant green light is still on the junction box after 36 hours.

Alejandrosdog

have you got or can you get access to a DC current clamp meter? see if theres a measurable drain on a cable which would indicate the location of the problem.

Try and get a meter with a hold function
measure and record the current passing through each of the wires, measure each wire 3 times at least to get an average since the current is likely to be very small indeed.

you should see higher readings in the wire leading to the battery and the wire or wires leading to the component drawing power. make sure you set the Amp scale to the smallest one. and make sure you zero before use.

using a DC current clamp meter in this way is less than ideal BUT should give an indication (thats why multiple readings should be taken and averaged out for each wire.) and wont require you to cut the wire anywhere.

matomp9

Alejandrosdog wrote:

have you got or can you get access to a DC current clamp meter? see if theres a measurable drain on a cable which would indicate the location of the problem.

Try and get a meter with a hold function
measure and record the current passing through each of the wires

you should see higher readings in the wire leading to the battery and the wire or wires leading to the component drawing power. make sure you set the Amp scale to the smallest one. and make sure you zero before use

Thank you. That's very useful. I don't have a clamp meter but might no someone who does. I'll check with the LBS too although that may be beyond their tool set.

Alejandrosdog

matomp9 wrote:

Alejandrosdog wrote:

have you got or can you get access to a DC current clamp meter? see if theres a measurable drain on a cable which would indicate the location of the problem.

Try and get a meter with a hold function
measure and record the current passing through each of the wires

you should see higher readings in the wire leading to the battery and the wire or wires leading to the component drawing power. make sure you set the Amp scale to the smallest one. and make sure you zero before use

Thank you. That's very useful. I don't have a clamp meter but might no someone who does. I'll check with the LBS too although that may be beyond their tool set.

Cool let us know if it works. I was just thinking it through. if i had my own Di2, id be in the garage seeing if i could measure current changes in the wires when i depressed the shift lever. and if there was residual power, and then seeing if after a period of time the system went into shut down.

for no other reason than just seeing. Im not an electrician but i bought a meter recently for finding a fault in my house elctrics its basic one but seems to work well chineese and good enough for my use. a uni-t ut210E

Alejandrosdog

heres a youtube review of the meter by some american guy who seems to think its pretty good https://www.youtube.com/watch?v=0WLpc0mfYi0

StillGoing

matomp9 wrote:

Battery didn't seem to be losing charge after 36 hours when isolated (voltage remained constant) so I don't think it's that. Full drain normally only takes 36-48 hours for me.

So, I've reconnected the battery to the system and disconnected the rear mech - just pulled the plug out of it so to speak. After 24 hours of that, the junction box light is still solid green indicating full, or 75%+ at least, battery charge. Whilst this isn't yet long enough to say with certainty, I am starting to suspect it might be the rear mech. This has led me to wondering what the issue with the rear mech might be so I returned to PP's post.

matomp9 wrote:

philthy3 wrote:

matomp9 wrote:

Battery didn't seem to be losing charge after 36 hours when isolated (voltage remained constant) so I don't think it's that. Full drain normally only takes 36-48 hours for me.

So, I've reconnected the battery to the system and disconnected the rear mech - just pulled the plug out of it so to speak. After 24 hours of that, the junction box light is still solid green indicating full, or 75%+ at least, battery charge. Whilst this isn't yet long enough to say with certainty, I am starting to suspect it might be the rear mech.

Struggling to see how you fathom it is the rear mech, when it reads that you've disconnected it, yet have still lost charge? That would indicate something else is draining power.

It hasn't.

Step 1: I isolated the battery. It didn't lose charge. So i don't think it's that.

Step 2: I plugged the battery back in and unplugged the rear mech. The rest of the system is connected. As far as I can tell, it hasn't lost charge i.e. the constant green light is still on the junction box after 36 hours.

Your post said that the battery was at 75%+ when you reconnected the battery. If it was fully charged when you started and have done nothing, that is a power loss. Incidentally, the green light doesn't mean the battery is charged or at 75%, it just means there is sufficient charge for operation, ie over 50%.

matomp9

philthy3 wrote:

Your post said that the battery was at 75%+ when you reconnected the battery. If it was fully charged when you started and have done nothing, that is a power loss. Incidentally, the green light doesn't mean the battery is charged or at 75%, it just means there is sufficient charge for operation, ie over 50%.

I was advised by the LBS, and another post on here indicated similarly, that full green light meant 75%+. Your post suggests that might be wrong.

Nevertheless, on that premise I stated that the battery was 75%+ as the full green light is showing. I didn't want to mislead in stating it is 100% because I have no way of knowing what the precise % is without taking the battery out and connecting a multimeter. All I know is that the full green light is still showing.

@Alejandrosdog Thank you. I'll look into purchasing one should the LBS not have one themselves. They seem reasonable value.

GraemePH

Just wondered whether you ever sorted the problem out. I have the exact same problem. The rear mech is draining the battery. The system stays fully charged if I unplug it and drains within 36 hours if the mech is connected - new battery too. I'm pretty sure it isn't the limit screws as previously it all worked fine and nothing has changed. Also I never leave the bike on either the lowest or highest rear gear, so the limit screws never come into play anyway. Am I looking at a new rear mech or is there something I can do to fix it? Any advise appreciated!

mazwmb

I’ve been experiencing battery drain for a while, I unplugged the battery and derailleurs one at a time to eliminate them.
I unplugged the right hand shifter and connected the cable back into the di2 system using another wire and the dfly wireless dongle and set it up to use synchro mode using the left shifter, the battery has since been ok so it must be the 6870 right hand shifter somehow causing the battery drain, new shifters on order, luckily they are currently reduced.
I’ve posted this in case it helps someone else or maybe someone else has had this?

mazwmb

New right hand shifter fitted and battery drain solved.

k3vinjam3s

Ive narrowed my drainage problem down to the bluetooth adapter and the cable attached to that. Need to rule out the cable before i put the blame wholely on the bluetooth thingy. Problem is i dont know anyone that can spare a cable just to test it and dont want to buy a new one if i dont need it. Any lovely bike folk here local to teesside lol.

Problem got worse though and had to remove bluetooth completely, draining 100% in less than 48 hours