4/10/22 3:10 PM

I think I need to replace my SRAM e-tap derailleur batteries. They’re about 5 years old, haven’t been heavily used. They now run down over time, with light use. For example, I charged them near the end of last year and now, with little use but about 6 months gone by, they’re dead. Seems to me they should run down with use, not passage of time. I’m charging them now, dunno how long it will last. Don’t mind replacing them, but any thoughts? Do they lose ability to hold a charge over time? TIA

4/10/22 3:14 PM

"Do they lose ability to hold a charge over time?"

Yes, as does every battery from day one until not serviceable pretty much. All die slow death. We trade off longevity of that life for keeping a higher rate of overall charge for convenience sake.

Just like a Tesla ;)


So if you often charged to have them full frequently for use readiness, you traded off the tail end life as I understand it.

4/10/22 3:28 PM

Well I really haven’t charged this that much as I don’t ride big miles to begin with and I’ve always put more miles on a gravel/cross/commuter bike than this bike (Domane RSL). And I don’t charge unless I need to …:)

But I’ll probably suck it up and replace them. Thanks

4/10/22 3:52 PM

I'm not sure it's accurate for the first gen groups but the newer stuff is supposed to go into sleep mode when not in use. There are accelerometers in the shifters that shut everything down when the bike doesn't move. Even if you've never ridden yours, if you move it around, or bump into it, or whatever, each time you do so you're turning everything on, even if you never turn a crank or shift a gear. This might be contributing to lower battery life?

Or, yup, old batteries aren't as good as new batteries. This is also true.

This is a 3 minute read dumbed down article that doesn't really explain the "whys". Just that you're not doing your batteries any favours not using them.

https://m.greenway-battery.com/news/Do-Rechargeable-Batteries-Go-Bad-If-Not-Used-Introduction,-Charging-and-Cycle-Life-1274.html

4/10/22 4:41 PM

According to that article, the only surprising thing is that my batteries lasted this long. Just have to ride more!

Sparky mentioned Tesla (I have one). Tesla recommends basically always keeping it charged to about to about 80% (not 100% unless going on a trip).

4/10/22 8:26 PM

Same with our Bolt.

4/11/22 7:36 AM

My understanding is that lithium ion batteries are "happiest" when they're between 20% and 80% charged. Storing them at 100% charge can apparently damage them. They will lose charge over time, so if they're dead or nearly so after six months of non-use, I wouldn't assume that they're no good, though at 5 years old, they're definitely going to be somewhat worn.

Charge 'em and see how long they last in actual use; you may be pleasantly surprised. Worst case, they can serve as backup "just get me home" batteries after you get new ones.

4/11/22 8:28 AM

When we first got Elaine 2022 Bolt, the revamped model has the bigger new 'issue resolved' 66 kWh pack. Supposedly!

So I programed it to charge only to 75, and we'd charge it before 20% lowest. This promised the longest longevity outlook as far as stressing the battery overall. So on topic, a 5, 6, 8 year old car who knows what is normal lessened range from 'normal' degradation.

Then of course it turns out GM decided even the 2022 with the 'improved' pack, in other words 'ALL' Bolts will get new batteries recalled/replaced.

So GM said, don't go below 70 miles range, and not to charge over 90%. Limited the range a lot, but still as a commuter [for us] not really anything changed in use really.

If Elaine didn't love the car so much, I'd have made legal action make them buy it back honestly.

So the patched interim solution waiting for a pack change removed the low limit and it a has 'max' 80% which you can not change program limits. Gaining the 70 miles on the bottom now is better than the limits I imposed thus in a normal range use for us. 2 charges a week for 5x46 mile commutes.

I do know loosing approx 50 miles of range I'd consider a cause of action to make them buy it back. Duking it out with banks of lawyers wouldn't be fun though.

4/11/22 8:40 AM

We are in CA currently, my SIS has a 2013 Hybrid C-Max. I can see by the avg MPG the hybrid pack is not working @ near a high percentage. But no codes so no imbalances etc.

But Elaine's Honda Fit we traded on the Bolt, non hybrid 1.5 v-tec got about 5-6 MPG better than she is seeing. What is the point of it at that point? ;)

Got my youngest an old Prius that got a new pack 6 year prior, health and balance of volts in it are excellent. He gets 45 worst, and usually 49-55 mpg. Probably what the C-Max does with a less run out pack..

We are driving to Vegas in a borrowed Chevy Avalanche. It will cost about the same amount of juice my Pacifica does in a year for this trip. ;) Not if I do trips in the Van of course.

Batteries, Zed...

4/11/22 11:38 AM

Sparky, what MPG were you seeing with the Fit? With mixed weather here, and mixed driving, my 2010 with 160K on the clock to date is getting 33-35. I don't think I've ever filled the tank with <30 MPG...

4/11/22 12:45 PM

That's what I'm doing exactly - they're charged and we'll see how long they stay that way.....

4/11/22 12:47 PM

Lowest with snows was 39. 2. 2018 LX CVT.

Commonly 41.1-2 and consistent too.

6/5/22 4:44 PM

Well I recharged about 2 months ago and the batteries have been fine. I have an actual ride with people coming up this week so I just recharged as a protective measure. If I can recharge every 2 months or so that’s not too burdensome. So thus far I guess I don’t need to replace the batteries after all. :). Thanks for the advice.

6/6/22 3:09 PM

Glad to hear that they're working. I recharge the Di2 battery on my gravel bike 2-3 times per year and I've never had it go dead. I can't compare that directly with the SRAM multi-battery system, but I assume that they have some way of checking the battery charge level. I check mine so rarely that I have to look up the procedure every time. ;-)

6/6/22 4:47 PM

Yeah SRAM has an easy way to check change status but it’s also easy to recharge so I may just do that periodically.

6/6/22 7:13 PM

The only reason not to do that is that lithium batteries have a limited number of charge cycles. It doesn't matter how much they've been discharged, each charge cycle reduces the life of the battery slightly.

6/7/22 1:54 AM

Don't forget the coin cell batteries in the shifters. The derailleur batteries will need to be charged several times before the shifter batteries die. These are 2032 batteries. At 5 years of light use the derailleur batteries may be finicky, but you may be due for shifter batteries too.

At least with the derailleurs the batteries are interchangeable so if one battery dies you can put the good battery on the rear derailleur and still have some gears to choose from.

6/7/22 6:18 AM

I’m aware of them, I had to replace one early on. It was a bit cumbersome. Plus I neglected to take the transparent backing off the new battery so it didn’t work when it was installed, D’oh!

It’s easy to check them, but I don’t think that tells you anything other than they’re working at the moment.

6/8/22 2:32 AM

I have two bikes with the original Red eTap. The eTap setups on my bikes are both about four years old, and I can't say that I have noticed a reduction in the battery life. I have a data field on my Garmin that displays the battery status of all four batteries - FD, RD, and shifters - and I check it at the end of rides to see if any batteries are showing less than the max of five bars, at which point I charge/replace them if that is the case. I've had to replace the shifter batteries once on each bike over the four years, and I seem to have to charge the RD battery every two or three weeks and the FD batteries much less frequently.

The Garmin also gives a count of the number of front and rear changes for each ride. I find that the average 70-80km ride over moderately lumpy terrain results in several hundred shifts on the rear and a couple of dozen shifts on the front. I swap the FD and RD batteries occasionally to even out the usage.

As for EV batteries, I believe the Bolt uses the same LG batteries as our Hyundai Kona EV, and the batteries in our 2019 model also had a recall on them. I made a nuisance of myself about it, and the local dealership arranged for the batteries to be replaced in about September 2021.

6/8/22 3:04 PM

One of the reasons I have hybrid Di2 setup is batteries. I do have internal too, but more with external, and an extra external battery. I'd bring an extra of doing multi day or similar.

And I use the small 10speed 6770 A junctions still. Where I can trick the firmware and diddle versions etc.

I always have extra charged batteries on a bike or the extra one.

If I sell a Di2 bike I put in a new A junction and internal battery. I have lots of parts for choices.

The Boone is the 1st all modern Di2 setup, bar end A junction and internal battery etc. Being a 2021 frame I want parts balance on the build. Next newest is 2015 bike and old parts are not as value disabling.

The only time I get caught out is if I misremember stuff, like that ever happens. ;)

I sold 2 bikes this week, so I am handling my addition... ;) err I mean addiction.