2 di2 batteries?

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havana
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Joined: Tue Jan 09, 2007 5:04 pm

by havana

Silly question...

I own a second internal battery as a backup. My primary broke down one day so I want to have a backup in my cycling bag.

Can I charge the battery by unplugging the RD and hooking up the secondary battery?
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kulivontot
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by kulivontot

Don't think so. The batteries have a chip that communicates with the system, so I imagine they would conflict. In addition, the batteries would be at different potentials, so you'd effectively be shorting out the fresh one with the dead one. This is one place where the external battery mount has an advantage

glepore
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by glepore

No conflict so long as the battery has same firmware version loaded as the system.
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Tristan
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by Tristan

havana wrote:Can I charge the battery by unplugging the RD and hooking up the secondary battery?


I assume you want to use the RD wire as it's easily accessible and your primary battery is internal and thus hard to get to? Assuming you have an external junction A box you could unplug the etube wire leading to the junction B / RD / FD / primary battery and plug the secondary directly to the junction A.

I haven't tried plugging in or charging two batteries at once but this is how I charge a secondary battery.
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havana
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by havana

Thanks guys. That last solution is the easiest, it's also what Shimano recommends.
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froze
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by froze

As an added note about these LiIon batteries, you should be charging the battery when it's no more than 25% used, if you charge when it's only about 25% discharged you could double your battery life in years, otherwise these batteries are only lasting 2 to 3 years on average because people are discharging them too far.

egebhardt
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by egebhardt

It depends if you have the external or internal battery.
Every 'Etube' system (6770 ultegra and on) requires a special 'chip' on the battery.
The external batteries have the chip in the mount. The internal batteries have the chip in the battery.
Eric in San Carlos, CA

bulls604
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by bulls604

Did you try it out, how did it go?

froze
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by froze

Everywhere that I've read on the internet, and people that I know that use them, and bike shop mechanics I spoke to have all said that 3 years is about the max they will last if taken care of properly.

That is why I won't make the switch to electronic shifting, the batteries that Shimano uses are poor quality...seriously! The drain is not that heavy, the amps being drawn are very low, you only have to charge it maybe 6 to 8 times a year...compare this to other rechargeable things like my rechargeable lights that use smaller batteries than the D12 uses and I can get at least 5 years with a recharge rate of at least 200 times a year! Compare that to my cordless drills, cordless weed whacker, cordless yard blower/vacuum that all have very high amp draws and those batteries will last at least 10 years. So to have to spend $80 to $150 (depending on battery) every 3 years is a rip off! It's how Shimano makes money.

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Dan Gerous
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by Dan Gerous

froze wrote:
Wed Dec 18, 2019 4:49 pm
Everywhere that I've read on the internet, and people that I know that use them, and bike shop mechanics I spoke to have all said that 3 years is about the max they will last if taken care of properly.

That is why I won't make the switch to electronic shifting, the batteries that Shimano uses are poor quality...seriously! The drain is not that heavy, the amps being drawn are very low, you only have to charge it maybe 6 to 8 times a year...compare this to other rechargeable things like my rechargeable lights that use smaller batteries than the D12 uses and I can get at least 5 years with a recharge rate of at least 200 times a year! Compare that to my cordless drills, cordless weed whacker, cordless yard blower/vacuum that all have very high amp draws and those batteries will last at least 10 years. So to have to spend $80 to $150 (depending on battery) every 3 years is a rip off! It's how Shimano makes money.
What? I'm still using the same battery since 2014, still holds it's charge ridiculously long, same for all my friends who have been using Di2 for a long time as well, including two who are full time cyclists riding pretty much the same bike all the time. :noidea:

TheRich
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by TheRich

froze wrote:
Wed Dec 18, 2019 4:49 pm
Everywhere that I've read on the internet, and people that I know that use them, and bike shop mechanics I spoke to have all said that 3 years is about the max they will last if taken care of properly.

That is why I won't make the switch to electronic shifting, the batteries that Shimano uses are poor quality...seriously! The drain is not that heavy, the amps being drawn are very low, you only have to charge it maybe 6 to 8 times a year...compare this to other rechargeable things like my rechargeable lights that use smaller batteries than the D12 uses and I can get at least 5 years with a recharge rate of at least 200 times a year! Compare that to my cordless drills, cordless weed whacker, cordless yard blower/vacuum that all have very high amp draws and those batteries will last at least 10 years. So to have to spend $80 to $150 (depending on battery) every 3 years is a rip off! It's how Shimano makes money.
The real money is in the small parts, like those cables and housings you swap out on a regular basis.

froze
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by froze

Dan Gerous wrote:
Wed Dec 18, 2019 5:25 pm
froze wrote:
Wed Dec 18, 2019 4:49 pm
Everywhere that I've read on the internet, and people that I know that use them, and bike shop mechanics I spoke to have all said that 3 years is about the max they will last if taken care of properly.

That is why I won't make the switch to electronic shifting, the batteries that Shimano uses are poor quality...seriously! The drain is not that heavy, the amps being drawn are very low, you only have to charge it maybe 6 to 8 times a year...compare this to other rechargeable things like my rechargeable lights that use smaller batteries than the D12 uses and I can get at least 5 years with a recharge rate of at least 200 times a year! Compare that to my cordless drills, cordless weed whacker, cordless yard blower/vacuum that all have very high amp draws and those batteries will last at least 10 years. So to have to spend $80 to $150 (depending on battery) every 3 years is a rip off! It's how Shimano makes money.
What? I'm still using the same battery since 2014, still holds it's charge ridiculously long, same for all my friends who have been using Di2 for a long time as well, including two who are full time cyclists riding pretty much the same bike all the time. :noidea:
sorry man but that's been the average, note I said average, average means some last less and some last more, you're on the high side of average, but I knew and read about people only getting a year, they were on the low side of average. Also if the bike is used in milder climates the batteries will last longer, heat and cold will destroy them faster, this is true with any battery used in any other type of product. I live in cold climate where temps can drop to well below freezing, freezing temps are bad for any battery; in the summer it can get quite hot and heat is bad for any battery; so my temp variations are not battery friendly and since most of the US is like my state that would be true for a lot of people.

Speaking of idea temp range I think Shimano is wrong when they say their storage temp is from 14 degrees F to 158 degrees F, that's stupid! In fact my batteries from my drill and yard tools all say that for max battery life do not store below 59 degrees F and not above 122 degrees F. So in the late fall until late spring my tools and yard batteries are brought into the house, my bike lights are all kept in the house year round just because I have to charge them inside after a ride anyways.

The other problem is charging the batteries, never charge batteries that have been subject to heat, like a ride in the hot sun, or after heavy use like you would find with tools, in fact tool companies know now that this is extremely important and they build into their chargers a sensor that reads the battery temps and will not charge a battery until those temps drop down into the safe zone. For both NiMh and Li-ion it is highly not recommended to recharge a battery that has been setting at below freezing or above 113 degrees like you would find if a battery was inside a hot car for example.

froze
Posts: 430
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by froze

TheRich wrote:
Wed Dec 18, 2019 5:29 pm
froze wrote:
Wed Dec 18, 2019 4:49 pm
Everywhere that I've read on the internet, and people that I know that use them, and bike shop mechanics I spoke to have all said that 3 years is about the max they will last if taken care of properly.

That is why I won't make the switch to electronic shifting, the batteries that Shimano uses are poor quality...seriously! The drain is not that heavy, the amps being drawn are very low, you only have to charge it maybe 6 to 8 times a year...compare this to other rechargeable things like my rechargeable lights that use smaller batteries than the D12 uses and I can get at least 5 years with a recharge rate of at least 200 times a year! Compare that to my cordless drills, cordless weed whacker, cordless yard blower/vacuum that all have very high amp draws and those batteries will last at least 10 years. So to have to spend $80 to $150 (depending on battery) every 3 years is a rip off! It's how Shimano makes money.
The real money is in the small parts, like those cables and housings you swap out on a regular basis.
Yes, but since Shimano uses a cheap quality battery cells they got out of China for $5 and that's OUR cost! I think Shimano makes quite a bit of money on Di2 replacement batteries. There are sites on the internet that shows people how to replace the cells inside the Shimano battery pack, if you're adventurous and know how to desolder and solder your good to go to replace your batteries for around $5 and a little time.

FactoryMatt
Posts: 1014
Joined: Tue Apr 14, 2015 4:35 am

by FactoryMatt

froze wrote:
Wed Dec 18, 2019 4:49 pm
Everywhere that I've read on the internet, and people that I know that use them, and bike shop mechanics I spoke to have all said that 3 years is about the max they will last if taken care of properly.

That is why I won't make the switch to electronic shifting, the batteries that Shimano uses are poor quality...seriously! The drain is not that heavy, the amps being drawn are very low, you only have to charge it maybe 6 to 8 times a year...compare this to other rechargeable things like my rechargeable lights that use smaller batteries than the D12 uses and I can get at least 5 years with a recharge rate of at least 200 times a year! Compare that to my cordless drills, cordless weed whacker, cordless yard blower/vacuum that all have very high amp draws and those batteries will last at least 10 years. So to have to spend $80 to $150 (depending on battery) every 3 years is a rip off! It's how Shimano makes money.
lol. it's all about discharge cycles.

you should see the horror stories on older Teslas starting to crop up. dead batteries out of warranty with a higher replacement cost that residual value and/or payoff!

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TheRich
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Joined: Tue Jan 01, 2019 1:36 am

by TheRich

froze wrote:
Wed Dec 18, 2019 6:30 pm
Yes, but since Shimano uses a cheap quality battery cells they got out of China for $5 and that's OUR cost! I think Shimano makes quite a bit of money on Di2 replacement batteries. There are sites on the internet that shows people how to replace the cells inside the Shimano battery pack, if you're adventurous and know how to desolder and solder your good to go to replace your batteries for around $5 and a little time.
No, it's not your cost....and you should know that the brains of the system is in the battery, which makes the cost of the "battery" part of the battery pretty minimal.

A Di2 battery can degrade pretty far before it ever starts being an issue, and a lot of people are probably replacing their batteries because the newer ones enable newer features. I put 10K miles on my battery with no noticiable degradation, but since I wanted to get the BT module, I got a new battery. The old one was more than fine.

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