Cheers from San Diego/Bulls battery issues

[LRB]

I recently got back into mountain biking, I had purchased a cheap Emtb (against everyone’s advice) and yes I had to upgrade within a few months. I ended up buying a Bulls E-Stream EVO 4 with the Brose S mag and 750 watt super core battery. The bike is a beast and the battery lasts for miles, the longest I have been on was 5 hours, 3600 vertical and 40 miles. I got back to the truck with the battery just clicking down to 2 bars. But..... I recently did a short but technical climb with only one bar down. I was not going to recharge it but I was heading out the next day on a pretty long climb and thought I should recharge it. When I checked it in a few hours the battery was completely dead, not one bar. I took the battery off and tried charging it that way, no luck. I dropped it off at the bike shop I bought it from, they threw it on their charger and said ’yeah it’s dead dude’. Now I have to wait until Bulls approves the battery replacement warranty. I am concerned the bike charger is bad and that this may have damaged the motor or it’s components. The bike is less then a month old, any advice for a new (old) rider on how to approach this. I am concerned that the Bulls bike may not have been a good choice but I am waiting to see how the warranty division responds..

 

[jerry]

The only piece of advise I could give (without diagnosis), is to plug in the connector first, and only then plug the charger into ther mains. There's some indications where potentially the battery BMS gets fried because of a surcharge (or spark) when plugging in a charger under power. More advanced chargers (Bosch >4aH) will detect a battery being plugged in, you can hear a relay clicking.
All rather speculative though, take it for what it's worth!

 

[Zimmerframe]

Sounds like you've just been really unlucky. Some people have fried their batteries by charging them when they're HOT - ie, you've been using turbo then charge the battery straight away. You can get the same problem with a lot of tool batteries if you've used them on chainsaws or blowers and don't let them cool first.

In your case, you said you got back to the truck - so it should have had plenty of cool down time, so not the case in this instance.

Charging the battery if it's really cold and hasn't had chance to warm up can also wreck them.

Not sure how the bulls charges, but you also have to be really careful not to get anything metallic stuck on the charge connectors on the bike/charger or you could short something.

From what you're saying, they should just change the battery and hopefully that will be that. Just an unfortunate incident to put behind you and you've maybe learnt a bit more about batteries in the meantime

 

[LRB]

Sounds like you've just been really unlucky. Some people have fried their batteries by charging them when they're HOT - ie, you've been using turbo then charge the battery straight away. You can get the same problem with a lot of tool batteries if you've used them on chainsaws or blowers and don't let them cool first.

In your case, you said you got back to the truck - so it should have had plenty of cool down time, so not the case in this instance.

Charging the battery if it's really cold and hasn't had chance to warm up can also wreck them.

Not sure how the bulls charges, but you also have to be really careful not to get anything metallic stuck on the charge connectors on the bike/charger or you could short something.

From what you're saying, they should just change the battery and hopefully that will be that. Just an unfortunate incident to put behind you and you've maybe learnt a bit more about batteries in the meantime

The Bulls uses the magnetic charge point to make a positive connection, I have been checking the end as it does pick up anything slightly magnetic. Constantly cleaning the end. I did notice when I took off the battery to try and charge it there was a lot of dust in the battery and I had to clean off the charge outlet. Hopefully Bulls doesn’t use that as excuse to not give up a new battery. The bike had cooled off as it was several hours after the ride before I hooked it up. I am pretty careful about making sure that the battery has had time to cool off. I am a little concerned about the battery compartment having so much dirt in it. I think I will run a piece of tape across the lower crease between the battery and frame. Thanks for taking the time to respond I will be sure to take a little more care when connecting to the charger.

 

[LRB]

The only piece of advise I could give (without diagnosis), is to plug in the connector first, and only then plug the charger into ther mains. There's some indications where potentially the battery BMS gets fried because of a surcharge (or spark) when plugging in a charger under power. More advanced chargers (Bosch >4aH) will detect a battery being plugged in, you can hear a relay clicking.
All rather speculative though, take it for what it's worth!

Thanks for responding. Did not think about the charger causing the battery to short out. I will plug the bike in before I plug the charger into the wall. I am using a surge protector so that should be some protection.

 

[Zimmerframe]

The Bulls uses the magnetic charge point to make a positive connection, I have been checking the end as it does pick up anything slightly magnetic. Constantly cleaning the end. I did notice when I took off the battery to try and charge it there was a lot of dust in the battery and I had to clean off the charge outlet. Hopefully Bulls doesn’t use that as excuse to not give up a new battery. The bike had cooled off as it was several hours after the ride before I hooked it up. I am pretty careful about making sure that the battery has had time to cool off. I am a little concerned about the battery compartment having so much dirt in it. I think I will run a piece of tape across the lower crease between the battery and frame. Thanks for taking the time to respond I will be sure to take a little more care when connecting to the charger.

The specialized bikes use the same Rosenberger connector. It's generally pretty good, but the magnetic side has it's negatives with tiny particles sometimes.

If you search for the "Official Gen3 Levo" thread, in post two in mentions the silicone grease they use on the connectors now, so you could get some of that which will help keep moisture/dust out of the actual connector. I always leave mine unplugged/open after charging to make sure it's always dry.

Fingers crossed you won't have any problems, I'm pretty sure it won't be the first or the last time a battery has randomly failed. Especially at the moment with a cell shortage, a lot of suppliers seem to have lowered some of their testing standards, so there's more faulty cells sneaking through - leading to dead batteries.

 

[LRB]

Update. The bike seller stepped up and replaced the battery. The owner seemed pretty sure that Bulls USA will replace it. He could tell I was bummed out if I didn’t get to ride this weekend. The tech said it looked like one of the cells failed and it ‘Christmas tree’d’ so the bad cell drained the power out of the other cells, not common but they had seen it before. Thanks for all the input!