I have a Bosch BCS210 4 amp charger on a Bosch BBS276 500W battery (Cube Bike BTW) and this thing gets VERY HOT when it is first connected and pushing to get the battery up. I am talking about a 5 bar display on the battery down to maybe 3 bars. There is no fan for the charger. I called the dealer where I bought the bike and he said it was "normal" for those chargers to get hot. I think this is not normal, so I am wondering if any of you here have the same situation as described and can comment on the heat? I am thinking I should also email Bosch directly about it to ask? I can't imagine how hot this charger would get if the battery was down to 1 bar ????
Hot Charger ??
- Thread starter Beacher
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6zfshdb
Well-Known Member
- Region
- USA
- City
- Northeast Pennsylvania
Many factory battery chargers are designed poorly with low cost being the driving factor. All the chargers I've had experience with get warm to some extent but shouldn't get too hot to touch or emit an odor.
I have three chargers that came with my bikes and all get fairly warm when charging at 4 amps. After a year of use, one of the chargers began to overheat badly to the point where it began to smoke. It turns out the cooling fan failed along with the thermal cutout switch. Eventually, the charger would have caught fire had I not been there to unplug it.
The manufacturer replaced the charger at no cost but to me, it was a wake up call. I invested in one of the many quality aftermarket chargers on the market. They range in price from around $50 to over $300. Since I often charge my batteries unattended, I bit the bullet and got the best charger I could find. I bought a Grin Satiator which is fully programmable. It barely gets warm by comparison even when charging at 6 amps.
I also adopted some safety measures when charging my batteries. I do so in an open area of my garage on a fireproof surface and away from anything flammable. I also keep a working Co2 / smoke detector nearby.
I'm not sure if this helps much.
Anyway, welcome to the forum!
I have three chargers that came with my bikes and all get fairly warm when charging at 4 amps. After a year of use, one of the chargers began to overheat badly to the point where it began to smoke. It turns out the cooling fan failed along with the thermal cutout switch. Eventually, the charger would have caught fire had I not been there to unplug it.
The manufacturer replaced the charger at no cost but to me, it was a wake up call. I invested in one of the many quality aftermarket chargers on the market. They range in price from around $50 to over $300. Since I often charge my batteries unattended, I bit the bullet and got the best charger I could find. I bought a Grin Satiator which is fully programmable. It barely gets warm by comparison even when charging at 6 amps.
I also adopted some safety measures when charging my batteries. I do so in an open area of my garage on a fireproof surface and away from anything flammable. I also keep a working Co2 / smoke detector nearby.
I'm not sure if this helps much.
Anyway, welcome to the forum!
rich c
Well-Known Member
I’ve never tried to contact Bosch directly, but I’ve read where others have tried. They don’t respond to individuals. They let dealers handle the situation. What temp is the charger at? Lay a meat thermometer on it. The charger will not get any hotter because the battery is lower. It will only charge at a certain rate. How old is the bike? One thing is for sure, Bosch stands behind warranty claims if there is a claim. I will be charging a battery this morning, I’ll lay a thermometer on it for you. Do you have other Bosch chargers that you know this one is not normal?
"VERY HOT" is a relative term, mine gets fairly warm but not too hot to touch. It is warmest during the 0 to 90% charging phase (CC - Constant Current) like most other Lithium chargers/batteries. eg. It takes about 6 hours to get to 90% from 0 and another hour & half to get from 90% to 100% with a 500Wh & 4A charger.
It has no fan, and unfortunately you cannot use a Grin Satiator, it's Bosch.
The electronics inside Bosch chargers look very sophisticated in design, component choice & manufacture compared to other cheaper lithium chargers.
It has no fan, and unfortunately you cannot use a Grin Satiator, it's Bosch.
The electronics inside Bosch chargers look very sophisticated in design, component choice & manufacture compared to other cheaper lithium chargers.
Did it get cooler at all on the last bar/10%?
rich c
Well-Known Member
It did go back to 95, but I don't know the percentage. 4 bars were solid, 1 flashing, but when I unplugged it, 5 bars were lit.
Bosch chargers are compact, simple, cheap chargers. Because there is no fan and very little room for heat dissipation they run hot.
Up to around 85 percent these chargers will push maximum possible current, after 85 it switches to constant voltage and the charge slows down significantly. So it is safe to assume that until the 5th bar the charger will run hot and should be cooler while charging the last bar.
Original poster here .... I think my specific problem may have been due to the power bar that I originally plugged in to when using the charger for the first few times? Since then, I have been plugging directly in to the wall socket and the charger, although warm when charging, does not get extremely hot as it did in the beginning.
6zfshdb
Well-Known Member
- Region
- USA
- City
- Northeast Pennsylvania
Another way to reduce the temp of your battery and charger is to provide some air circulation. I have a small fan on the "charging bench" I set up in my garage. It's just an air circulating fan from an old computer case. It's only a few watts but moves enough air to significantly reduce the temp of the charging equipment.
Not sure what chargers you're comparing the Bosch to but i've had a look inside the 2A Compact & the 12V Travel charger and they are far from simple, have you looked inside a Bosch charger?
And by 'cheap' do you mean, design, component choice, manufacture or a combination of the above?
A charger that needs a fan means it creates too much heat, this is wasted energy, this means it's inefficient and imho means it's cheap.
The Bosch 2A Compact has 2-3 times the amount of volume in space (air) to electronics.
They have a micro-controller & all sorts in them.
The Yamaha might be just as sophisticated or more, not sure about Shimano or Brose or other brands but i don't think any of these have fans.
The Bosch 2A Compact is a minimum 85% efficient @ 240AC which is not the best, the 4A might be about the same which explains the heat generated.
The Grin Cycle Satiator is 95% efficient at full load (which is large) with a PF of 0.99, this is amazing and if true (from all reports it is) then this would have to be the most efficient, sophisticated charger out there, and is watertight and no fan.
And as far as charging Lithiums the following generic chart show's that the heat dissipated by a charger (power) GRADUALLY reduces during CV (Constant Voltage):
That graph shows what I told in my post, Lithium chargers are CC CV, in the CV state the charging current (hence power) decreases significantly so the charger is expected to run cooler in that state. That is why it takes way more time to charge the last 10 percent and it is in most cases not worth it.
A "sophisticated" charger is capable of charging batteries of different chemistry, different cell counts and they are capable of quite high power outputs (1.5kw+). These chargers also handle the balancing of the cells etc. For example in RC vehicles people have been using these chargers for a long long time, the high power ones are quite pricey. In most cases you also need an independent power supply for these chargers.
I don't know how familiar you are with circuit design, if you are not it may look complex to you when you open the box but that is not really a valid argument here.
The chargers like Bosch, Yamaha etc are simply low powered (around 150W output) chargers with limited functionality(they can only charge a predefined voltage battery). That is why I am calling them simple. The reason of not including additional cooling solution is to cut the cost and since they are low power chargers so they will be "fine" in most circumstances in terms of handling the heat.
A charger needing a fan does NOT mean that it is cheaply made or it is NOT well designed. There is a limit to how efficient a charger can be and you will need cooling at higher power outputs. That is why high end chargers always come with a good cooling solution. Even the computer power supplies rated >500W, including the most efficient and expensive ones come with fans, grills etc that cool them efficiently.
Cycle satiator seems to be a well designed charger. It is way better than any cheap bundled chargers from Bosch, Yamaha, Shimano etc. The %95 efficiency is impressive(I don't know if it is true) but still, it is only rated 360W max and that is why it can get away with passive cooling.
Btw no company is going to add a $300+ charger for just charging one battery.
If you need more power the charger will get much more expensive and heavier. At least for now there is no way around it.
Last edited:
Hectors Ghost
Active Member
I use a Grin Satiator and dry my gloves on it when charging.
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