Is it possible to repair a Giant Battery?

[KuRi]

Hi! I have a 625wh battery that shuts down when using high asistance levels. At the beginning is working fine, but when using 3+ assistance level for some time it shuts down. Then it will shut down even using level 1 until you let it rest for some hours.

Can it be repaired? Do you know of any well known shops that would do the job?

thanks!

 

[Dgedge]

Hi, there is a company in France who repairs batteries (Vente et réparation de batterie de vélo électrique) but I don't know if they can do anything on our batteries. Maybe you can ask them ?
So far I don't remember someone who opened the battery to check what is inside...

 

[KuRi]

I have contacted a shop here in Spain that told me that Giant batteries are "protected" and cannot be repaired easily.

Thanks, I will contact them.

 

[DaveMatthews]

I have contacted a shop here in Spain that told me that Giant batteries are "protected" and cannot be repaired easily.

Thanks, I will contact them.

Keep us informed mate, good info to have!

 

[KuRi]

They have answered that maybe the problem is the BMS and Giant does not sell BMS units as spare parts, so they can't help.

I have a working 500wh battery... I wonder if the BMS units are interchangeable... that could be a good one!

 

[Dgedge]

I don't think that the BMS is interchangeable between 500 and 625Wh because they don't have same amount of cells inside.

Did you ask a Giant shop if they can send it to their service center for repair ? They do it for motors why not for batteries too ?

 

[RustyIron]

I have a 625wh battery that shuts down

What does a battery shutting down look like?

 

[KuRi]

I don't think that the BMS is interchangeable between 500 and 625Wh because they don't have same amount of cells inside.

Did you ask a Giant shop if they can send it to their service center for repair ? They do it for motors why not for batteries too ?

The thing is that the have given me a replacement battery. A new 625wh battery that works perfectly. However they have not claimed the original battery and I would like to repair it as cheap as possible

What does a battery shutting down look like?

The battery looks like a normal battery xD, but the bike turns off frequently.

If anyone have advanced batteries knowledge and want to give it a try send me a private and we can think about a price

 

[RustyIron]

I see now... it's definitely the battery.

Since the system shuts down after periods of high assist, it could very well be heat related. When it heats up, it dies. When it cools off, it comes back to life. I'm thinking an intermittent connection.

If you can figure out how to take the battery apart, you can visually examine every connection. It could be some thing as simple as a bad solder joint. Sometimes there will be discoloration, especially on high-current connections that are faulty. It's not inconceivable that the battery has some kind of thermal protection, as well.

Right now you have a battery that is fudged up. If you take it apart and are unable to fix it, you're not out anything.

 

[KuRi]

Hmmm... y'know... a faulty battery is not the first conclusion I would jump to, but it's an easy thing to test. Find someone or a shop with a battery you can borrow. Swap batteries with another bike. If the problem follows the battery, you can be fairly certain that's your problem.

I think a pretty good clue is that the problem occurs after using a lot of assistance, and the problem resolves itself after the passage of time. This leads me to believe the problem is heat related.

So here's some random thoughts.

When you're using a lot of assistance, your system is pulling a lot of current. Current traveling through resistive circuits creates heat. If you have a connection that is faulty, there's more resistance, which creates more heat, which creates more resistance... until there is insufficient power to keep everything running, and it dies. When things cool off, there is less resistance, and you can turn the system back on. The problem could be within the battery, but that's not where I'd go to first; it's less likely and harder to test. First, just check the connectors at the battery. Then must be clean with no corrosion and no pitting. Don't use sandpaper to clean them. Use fine scotchbrite or an ink eraser. Check ALL the other connections, both high current and computer connections. Our bikes are subjected to dirt and water, so a faulty connection is not improbable.

Our bikes have thermal protection. High assist means more heat generation, and the system shuts down until it cools off. Since the sensor is going to be deep in the motor, surrounded by metal, it will take a while to cool down. It's not likely that your motor or transmission are faulty to the point of creating excess heat. This just occurred to me... our motors are protected by shrouds. Your motor isn't caked with mud and debris, is it? Unlikely, but I had to mention it.

If the system is shutting down for overheating, it could very well be a faulty sensor. I don't know for sure if your sensor is a pickup that the computer reads and shuts down if the temperature is too high. But sensors of that sort can go bad. And faulty connections in that circuit will cause bogus readings. We're back to looking for contamination. And some temperature sensors are really just an on/off overload. When it heats up, it turns off. When it cools down, it turns on.

It would be helpful if you could look through the available computer data right after the motor shuts down. Temperature data might not be available to the user, but if it is, it might provide a clue.

Thanks for your answer. I am sorry I did not give you enough details.

I already tested other batteries, they have worked all perfectly, no matter the temperature nor the assistance levels. The battery was tested at the lbs, showing no fault at the diagnosis. This same battery failed in another bikes. So yes, the problem was the battery.

Giant has already replaced the battery with a new one, that is working perfectly, not a single shut down.

My question is... how can I repair the original battery that I still have?

 

[RustyIron]

Hahaha! I typed out the original answer, then read backwards and saw you've already changed batteries, so I edited my answer.
IF the battery can be disassembled, I'd take it apart and look for something that doesn't look like everything else.

But you need to be careful. Those batteries are just overflowing with plenty of electrons that are looking for the first opportunity to burn you or blow something up.

 

[Planemo]

I've had ebike packs re-celled by Jimmy at Insat (BGA Re-Working) here in the UK although I have just seen it seems you are in Spain.

He knows what he's doing and uses good cells but if the system is canbus or uses a proprietary BMS then he's probably as stuck with a repair as anyone else unless it's an obvious solder failure or summat. The stuff I had done was real simple (older) ebike packs with basic BMS'.

 

[KuRi]

Thanks for all your comments.

Based on the symptoms... what would you think the problem is? (it shuts down when requiring some constant power). It is not directly related to temperature because sometimes it just shuts down after some meters from cool.

 

[Planemo]

Given that it's predominantly shutting down under high load conditions, it's entirely possible that one or more cells have failed and under load the pack as a whole is dipping below the low voltage cutoff. It's difficult to identify this particular problem without stripping the pack down and running a charge/discharge cycle on each string of cells to ascertain whether they are accepting the expected amount of Mah.

Even the fact that it may charge to full voltage doesn't help much - often duff cells will, but they will discharge a fraction of what they should before hitting minimum voltage.

Or it could be simply a dodgy wire or BMS. It's impossible to tell and to be frank you are completely pissing in the wind until it's stripped and at least some charge/discharge tests are done on the cells to rule them out one way or the other.

 

[Gear4beer]

Ive had Issues with battery not charging both charger and battery failure on my Giant trance 3 Ive had two different inspections independent of Giant store and its now a very expensive brick ! No other way around it but buy from Giant which is a kick in the stones !! Considering their piss poor attitude when it comes to customer service its against my better judgement to fork 650+ out on parts that they say will do a thousand charges but in reality only did 60 odd charges .