Battery charging

[Greengrass]

Hi folks,
Ive ordered a Kalkhoff Sahel with 17Ah battery. As it can take up to 7 hours to charge, I have 3 questions

1. Is it ok to leave it overnight on the charger?

2. If not, what about putting it on a timer plug set to switch the power off after the estimated charging time, but still leaving all cables attached?

3. Should I recharge after every outing?

Any suggestions gratefully received.

Many thanks.

 

[Fordulike]

1. Yes, but for absolute safety, I would charge it in the same room as a smoke detector. Plus, it's a good idea to charge it somewhere that has little combustible material nearby, or where you can remove the battery easily to a safe place. This is not meant to strike fear into you, just remind you that there is a minute risk of a battery igniting.
2. You may find that the battery will self discharge back through the charging lead, if the mains power is switched off and the charger left connected. I'm not 100% on this, so maybe someone else can clarify if this is the case.
3. Yes, just pop it on charge until the green light on the charger comes on. This means you'll be always get the full use of the battery's charge, and not get caught short if it's only half full.

 

[Danidl]

Hi folks,
Ive ordered a Kalkhoff Sahel with 17Ah battery. As it can take up to 7 hours to charge, I have 3 questions

1. Is it ok to leave it overnight on the charger?

2. If not, what about putting it on a timer plug set to switch the power off after the estimated charging time, but still leaving all cables attached?

3. Should I recharge after every outing?

Any suggestions gratefully received.

Many thanks.

The kalkoff is premium brand name of European extraction. You. Can rest assured that the engineering of safety has received proper consideration.
I would agree in . Principle with ford. But the risk of. Fire is negligible. I would reckon safer than a tumble dryer. The battery pack will disconnect electrically itself from the charger once it has charged so discharge back through the leads won't happen. My model is a Bosch but at the same price point and skies go so I would expect them to be similar. Be guided by they instruction leaflet which came with it.
And yes it is a good idea to charge the unit after use. Battery packs of two generations ago needed to be discharged fully before recharging but the chemistry is different now.
.

 

[Fordulike]

The kalkoff is premium brand name of European extraction. You. Can rest assured that the engineering of safety has received proper consideration.
I would agree in . Principle with ford. But the risk of. Fire is negligible.
.

Yes, absolutely, but I'm sure owners of the Samsung Galaxy Note 7 thought that they were using a product at the higher end of the market too.

Battery packs are quite likely to contain Samsung SDI batteries these days.

The battery pack will disconnect electrically itself from the charger once it has charged so discharge back through the leads won't happen.
.

I'm not sure this is entirely true, as I believe the charger only supplies power when it senses that the battery voltage is below the charger's working voltage.

When the battery reaches the same voltage as the charger, then the charger cuts power. If the battery voltage drops again, then the charger will switch back on. I wouldn't consider this as electrically isolated, so I still think it may discharge back through the charger, if the charger isn't switched on at the mains.

I am by no means trying to create an argument here (been enough of those lately!). It would be interesting to find out in black and white, whether the charger does do this when the mains power is off.

 

[Danidl]

Yes, absolutely, but I'm sure owners of the Samsung Galaxy Note 7 thought that they were using a product at the higher end of the market too.

Battery packs are quite likely to contain Samsung SDI batteries these days.


I'm not sure this is entirely true, as I believe the charger only supplies power when it senses that the battery voltage is below the charger's working voltage.

When the battery reaches the same voltage as the charger, then the charger cuts power. If the battery voltage drops again, then the charger will switch back on. I wouldn't consider this as electrically isolated, so I still think it may discharge back through the charger, if the charger isn't switched on at the mains.

I am by no means trying to create an argument here (been enough of those lately!). It would be interesting to find out in black and white, whether the charger does do this when the mains power is off.

We are not going to argue, but clarifying is another matter. The chargers in Li ion family will 1 read the voltage available in the battery 2 provided it is above a minimum threshold assume the battery is valid and commence charging at a fixed current .. the charger adjusts the output voltage so that the target current flows. 3 When the voltage reaches a specific value, it then supplies a much smaller current until the final designed voltage is reached. 4 On the better models e.g Bosch and I would also assume Kalkoff, the internal electronics then , whether inside the battery pack or the charger disconnects the charging circuit. Even were the mains supply to the charger interupted, and then reconnected the charger will not recommence. This I have confirmed in the case of the Bosch and the instructions for the Kalkoff read similar.

Even the lower cost chargers will have a blocking diode to prevent discharge back. It would be necessary to prevent damage to the voltage sensing , electronics in the charger. Semiconductor devices don't like currents flowing the wrong way.

In my (in this case ill-considered opinion), the Samsung battery debacle was a brilliant campaign of discrediting a competitor. Samsung provide a full 25% of the global Mobilephones , there were I understand 7 instances of spontaneous combustion in total. Thus is the power of social media

 

[Greengrass]

Thanks Folks,
Some interesting and helpful points made here.
Bottom line seems to be that it is OK to leave bike on charger overnight? That is certainly the case with Li Ion bike lights on a USB charger but it's just that I have read conflicting reports about bike batteries themselves.
And the biggest potential screw up with Li-ion batteries must have been the Boeing 787....

 

[Nealh]

Greengrass you have little to worry about.
Good e bike batteries from reputable sources have a good bms inside and this looks after the charging and discharge to keep things safe. When charging chargers get quite warm but once the charge is near the end they cool down as the bms goes in to balance mode to bleed the cells so they are equal. Once the charge is complete the charger stops charging as the bms will refuse to accept any more current.