2023 TCU Battery - Replacement

[Acee]

Hi,

I've a 2023 "new" ("sat in a warehouse for the last 18 months") Levo Carbon Comp and twice I've got to the bike and can't turn on the Mastermind TCU, even though there's 90% in the big battery. The first time the shop replaced a cable and declared it fixed, but one week later it's dead again. They didn't change the TCU battery the first time (I suggested they maybe should - it's a cheap item) so I'm thinking I'll do it myself (the shop's an hour away). Trouble is all the online guides appear to be for an older model - the latest has a rubber door that reveals a USB-C socket (not the old USB type) and more importantly no battery / slot lurking underneath.

Can anyone confirm the latest Mastermind TCU still has a battery and does anyone know how to access it? Thanks

note - there is a way to "wake up" the bike - I plugged in a battery pack to the USB-C and the TCU sprang into life. Whether it'll turn on without the boost in an hour, a day etc. I don't know...

 

[Zimmerframe]

Can anyone confirm the latest TCU still has a battery and does anyone know how to access it? Thanks

When you say "wake up the bike" .. with the USB cable connected, does it let you turn on the bike and actually use the motor ?

 

[Acee]

Ahh, that explains the lack of an obvious battery, then. Thanks.

Re. waking up the bike - yes, I attached a mobile battery pack to the USB-C port (the one the manual says "is for Specialized retailers and service centers" ) and the TCU turned on with a press of the 'on' button. I removed the battery pack, screwed down the TCU and the bike works as intended. I now see on p17 of the manual...

"If the system does not power on after a long period of non-use, remove the MasterMind TCU from the tube and charge the MasterMind TCU via a Type C cable".

Bit of a pain if I have to do this every week, though...

 

[Zimmerframe]

Bit of a pain if I have to do this every week, though...

Hopefully, Once you've done it once and the bikes been on a while ?! it will charge itself up and be ok.

If not then there could be a fault with the rechargeable battery in the TCU, in which case they should swap it out on warranty.

 

[Mikerb]

The Bosch Smart System also uses a similar system. The controller has a rechargeable battery that is charged by the main battery when the bike is switched on. The rub is that if the battery in the controller ( for a Specialized the TCU is the controller) goes flat it cannot switch the bike on and some bikes equipped with the new Bosch Smart System have also had that problem. So you are left with 2 choices as outlined by @Zimmerframe . The first is charge the TCU battery via the USB port. You should really find out what rate it should be charged at and there is probably no way to know when it is fully charged so just try charging it from a laptop USB for about 1.5 hours. That may "wake up" the battery and you will be fine thereafter. So that is worth trying first. You will need to do a ride after charging the battery of at least 10/15 miles/1.5 hours to test if that has worked, since the TCU battery will last that long with no charge from the main battery.

It may however be that the battery is defective and if it is not replaceable it means a new TCU is required. I found out that with the Bosch controller battery, it is equipped with a thermistor and it is that which controls the charging circuit from the main battery ( otherwise there is a risk of overcharging which would be a fire hazard given it is a lithium battery). Thermistors can and do fail! The TCU battery probably uses the same system. When thermistors fail their signal ( charge/no charge) becomes erratic.

 

[Acee]

So you are left with 2 choices... The first is charge the TCU battery via the USB port... for about 1.5 hours. You will need to do a ride after charging the battery of at least 10/15 miles/1.5 hours to test if that has worked.

It may however be that the battery is defective and if it is not replaceable it means a new TCU is required.

Thanks, the bike shop initially charged it overnight, and repeated the process when I returned it (followed by it parked in my kitchen for 5 days when I again found it dead). Yesterdays investigation saw it die again a couple of hours after I got it working (albeit with no immediate ride). I'll get it going tomorrow and ride it to see if this is a fix... but I'm thinking it is indeed in need of a fresh TCU.

 

[Jase]

Please let me know how you get on, I have just gone to turn my KSL on after a long period of not riding it and no joy. Disconnected the TCU reconnect and it turned on. So unsure whether the TCU needs charging or there is another fault???

 

[Acee]

Please let me know how you get on, I have just gone to turn my KSL on after a long period of not riding it and no joy. Disconnected the TCU reconnect and it turned on. So unsure whether the TCU needs charging or there is another fault???

right... didn't manage to get out on it, so it stood for a week and wouldn't turn on yesterday. Pulled out the TCU (T10 Torx) and attached a USB C cable from a 15000mAh battery pack to the TCU. Result, TCU turns on. I noted the Zendure battery pack stopped flashing immediately, suggesting the TCU battery wasn't taking a charge - like it just needed a jump start to wake it up. Went for a ride, and experienced the TCU turning off (assistance off also) with an error message (something about "loose connections", or maybe that I'd wired in "lights" incorrectly - I haven't touched it), but pressed the on button again and it worked for the remainder of the 2hr ride. This morning the TCU still turns on... Whether it will next weekend without the faff of removing it I don't yet know... I'm still thinking it's the (now non-replaceable) TCU battery that's the issue...

 

[Jase]

I seem to be having the same snags, with it not turning on when left. I’ve given everything a thorough dry in case it’s moisture, but don’t think so. I’m pretty careful when washing and you should be able to ride a mountain bike in our uk weather. Disconnected the TCU reconnected and it turned on. Be back in the LBS again if carries on. Will try charging the TCU, but it did have a good few hours ride last time I was out on it.

 

[Acee]

Mine's not seem rain, and it's only a month old. If it doesn't turn on next weekend, I'll be back to the shop also.

 

[Ou812]

I got my Levo out yesterday for the first time in about a month, I’ve been riding my amish bikes here lately. Anyway, it’s been sitting with the battery out as I keep it inside. I popped the battery in and it fired right up with no issues. I’d definitely be getting the TCU replaced, especially if others can sit for a month and still work fine.

 

[Jase]

Mine's not seem rain, and it's only a month old. If it doesn't turn on next weekend, I'll be back to the shop also.

I had this problem when I first got the bike. They replaced the wiring harness after three visits with the fault reoccurring. My mate had the Levo SL and hasn’t had a problem. I’m happy with the Customer Support with Specialized, but not so chuffed with the reliability and electrical faults.

 

[Acee]

I had this problem when I first got the bike. They replaced the wiring harness after three visits with the fault reoccurring. My mate had the Levo SL and hasn’t had a problem. I’m happy with the Customer Support with Specialized, but not so chuffed with the reliability and electrical faults.

They replaced the harness the first time on mine. Next I'll be after a new TCU . You're right to be miffed about the flakiness of the bike. It feels a bit... unfinished.

 

[Ou812]

They replaced the harness the first time on mine. Next I'll be after a new TCU . You're right to be miffed about the flakiness of the bike. It feels a bit... unfinished.

What shop did you buy from? I ordered mine from Balfes and had it sent up to Scotland. I’ve been using the local spesh shop up here and they’ve been awesome, even though I didn’t buy it from them. These guys would bend over backwards to make sure you’re happy, especially when it comes to warranty work.

 

[Acee]

What shop did you buy from? I ordered mine from Balfes and had it sent up to Scotland. I’ve been using the local spesh shop up here and they’ve been awesome, even though I didn’t buy it from them. These guys would bend over backwards to make sure you’re happy, especially when it comes to warranty work.

The dealer's fine (Surrey)- just these little issues. Having said that and coming from a 15 year old Epic, I'm scratching my head about things like gearing ("save weight with a single front cog but add weight with a massive cassette", "have the tiniest cog on the back seeing most of the work (wear) because you've only got 34 teeth up front" - "oh, go further up the cassette and spin more"), brakes that stop okay-ish, but lack the feel of my 15 year old XT's.

Puzzling "progress". <insert pic of The Simpsons Grandpa shaking fist>

Still happy to have it, though

 

[Ou812]

The dealer's fine (Surrey)- just these little issues. Having said that and coming from a 15 year old Epic, I'm scratching my head about things like gearing ("save weight with a single front cog but add weight with a massive cassette", "have the tiniest cog on the back seeing most of the work (wear) because you've only got 34 teeth up front" - "oh, go further up the cassette and spin more"), brakes that stop okay-ish, but lack the feel of my 15 year old XT's.

Puzzling "progress". <insert pic of The Simpsons Grandpa shaking fist>

Still happy to have it, though

I’ve found that a 36 tooth chain ring works a lot better than the stock 34, I seem to use more of the cassette since swapping over to that. I agree about the brakes though, I’ve not been impressed with the code RSCs that came on my bike and everyone seems to rave about them. I’ve already swapped rotors and pads trying to get more out of them. Cascade is still having their sale and they have some callipers that look pretty interesting, they’re normally £500 but on sale for £250.

 

[Acee]

Quick update - the TCU would only last about 5 or 6 days after a ride (without jump-starting it with a charging brick), so had a new TCU fitted. Shame the '23 model has an integrated watch battery, and not the old replaceable battery...

 

[DOGBOY333!]

I had the same issue when I first bought the bike and a quick charge was enough to start the TCU and hence the bike.
However it would not turn on at all last weekend and would not take a charge, "No battery" would flash up and then off again.
So i pooped the cover off the underside of the TCU and saw a small white piece of foam stuck over 3 tiny plug connectors the battery one had come lose so gently pressed it back in place re stuck the white foam and all is fine.