Ebike Chargers running too hot -- a solution .

RoadieRoger

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Nov 8, 2010
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These Chargers run hot if they are not fitted with a cooling fan and I have usually placed them on a bean can or similar metal to let air circulate and allow the heat to be absorbed . A neater solution would be to place the Charger on a wire bird feeder to get nearly perfect air circulation all around . They are described as a Fat Cake Holder and hold one suet block . The wire is coated in a green plastic finish and measures 130mm x 130mm x 45mm thick , a good size on which to place the Charger body . They range in price from £3- £5 on Amazon , Ebay or in Pet Shops .
 

Nealh

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Aug 7, 2014
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Andy-Mat

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These Chargers run hot if they are not fitted with a cooling fan and I have usually placed them on a bean can or similar metal to let air circulate and allow the heat to be absorbed . A neater solution would be to place the Charger on a wire bird feeder to get nearly perfect air circulation all around . They are described as a Fat Cake Holder and hold one suet block . The wire is coated in a green plastic finish and measures 130mm x 130mm x 45mm thick , a good size on which to place the Charger body . They range in price from £3- £5 on Amazon , Ebay or in Pet Shops .
For the reasons you have already mentioned, I bought a relatively cheap charger (2 amp, as more runs the risk of a shortened battery life!), but with a built in tiny ventilator. On ebay I believe.....
It was no more expensive than the ones without, and it basically runs for hours "stone cold"..... I am sure that the ventilator will also improve the life of the charger electronics too!
Also, do please remember, that with the cheaper chargers, even if the LED has gone green, a tiny amount of charging continues, to the long term detriment of the battery life.
Once you have a good idea as to how long your charger needs, why not buy a cheap mechanical 24 hour time switch, and modify it so that it "switches itself off", by just move the Phase supply wire to the synchronous motor from the power in, to the power out!
That alone will extend the battery life extensively.....for a couple of quid, and a tiny mod!
regards
Andy
 

lightning

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Mar 26, 2022
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The charger won't be harmed by running hot so long as it's not too hot to keep your hand on.

The problem is the cheaper ones where they use poor quality components, specifically capacitors which eventually fail due to heat.

Use branded 105 deg C working components and the power supply will last for years.
 

lightning

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Mar 26, 2022
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lf the charger is a good one, such as a branded Shimano or Cube etc the heat won't harm it, many are encapsulated in resin. The resin draws heat away from the components and because of this the casing will get warmer than you might think is "normal"
 

Bonzo Banana

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Sep 29, 2019
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Is this just an issue with higher current chargers as I have 4x 2A chargers, 3 x48V (2 the same model) and one 36V and they seem to only get luke warm or maybe its related to the size of the battery or how much current the BMS allows. I think I saw a warning previously that if you carry your charger with you to charge lets say at work you should get a sealed unit so condensation or liquid can't enter the unit. In which case the laptop cooling pad would seem a good solution. I think the battery doctor on youtube has given a few warnings about fan assisted chargers too because of dust and debris getting into them over time and reducing the cooling but I guess this depends on the design.
 

guerney

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Sep 7, 2021
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Is this just an issue with higher current chargers
My 42V 2A charger gets very hot (19.2ah battery) - the laptop cooling pad looks a good solution, although I might swiss-cheese my charger casing like @Nealh . I did consider using large freezer ice packs, but I worried those could cause condensation to form within the charger. Plus I'd have to replace those every hour or so. I'll just point my big desk fan at it...
 
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Bonzo Banana

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Sep 29, 2019
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My 42V 2A charger gets very hot (19.2ah battery) - the laptop cooling pad looks a good solution, although I might swiss-cheese my charger casing like @Nealh . I did consider using large freezer ice packs, but I worried those could cause condensation to form within the charger casing. Plus I'd have to replace those every hour or so. I've got a big desk fan I can point at it...
I don't have any battery packs at 19.2Ah or more, 2 are 48V 13Ah (624Wh I think) and another is 48V 15ah. Fairly low end generic batteries, 2 have the Samsung 2500mAh cells, the other pack is Littokala with 21700 cells. I've just realised stupidly that I may only touch the charger at the end of the charging when the charging rate has reduced a lot so my comments sadly may have been pretty pointless as at the beginning it would still be cool and at the end probably cool too. You probably have to test the charger heat in the middle of charging which I don't think I've done. If I remember I'll check next time, hopefully I won't be in for too much of a shock regarding how hot they get..
 

guerney

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Sep 7, 2021
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I don't have any battery packs at 19.2Ah or more, 2 are 48V 13Ah (624Wh I think) and another is 48V 15ah. Fairly low end generic batteries, 2 have the Samsung 2500mAh cells, the other pack is Littokala with 21700 cells. I've just realised stupidly that I may only touch the charger at the end of the charging when the charging rate has reduced a lot so my comments sadly may have been pretty pointless as at the beginning it would still be cool and at the end probably cool too. You probably have to test the charger heat in the middle of charging which I don't think I've done. If I remember I'll check next time, hopefully I won't be in for too much of a shock regarding how hot they get..
It takes about 10 hours to charge my LG MH1 celled battery from near flat, and I was shocked at how hot it was when I happned to touch my charger about four hours in... If charges get that bloody hot, they should be housed in aluminium cases (at the very least), which would act as heatsinks, not heat-insulating plastic! A ploy for early charger demise/repeat purchases methinks...
 

lightning

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Mar 26, 2022
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As long as you're not running the charger over it's rated capacity it will be fine. lf it needed a cooling fan, the manufacturer would have installed one.
 

Nealh

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The airation holes I drilled in mine means it now barely gets luke warm, the heat just has no escape route.
 
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guerney

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The airation holes I drilled in mine means it now barely gets luke warm, the heat just has no escape route.
I like the sound of that! I'll deffo be reaching for the drill tomorrow to swiss cheese my charger case...
 

lightning

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Mar 26, 2022
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Be careful when randomly drilling holes in the case! Taking the casing apart to drill the holes would be better, but also be aware that by drilling holes in the casing, you are compromising the insulation of the device.

Make sure it's not possible to touch anything inside the casing when handling it. And don't ever let any liquid make contact with it.
 

Andy-Mat

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Oct 26, 2018
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I myself only buy chargers that are SMPS or Swiched Mode Power Supplies, as they are usually high(er) efficiency, with only a very low level of wasted power, so the tend to run comparitavely cool anyway. Chargers that get very hot, will probably NOT be SMPS types..
For anyone wanting to know more abpout Power Supply efficiency, this is a simply and easy to understand explanation:-
For chargers (remember, it's simply another form of power supply!) with a built in fan, use a piece of open weave cloth over theair input side to catch dirt and dust, replace when dirty.
I take the casing off once a year and blow out any dust with an airline.
If taking any supply with you on the bike, place it in a plastic bag with a clip to keep the bag sealed. Water in the supply/charger, as many will already know, is a huge NO NO!
Best wishes
Andy
 

lightning

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Mar 26, 2022
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Transformers are actually very efficient, IRO 95-98% as opposed to a SMPS which is 85-90%

Switch Mode power supplies can get very warm in use, but as long as you can keep your hand on the casing it's most likely okay


With any power supply, the best thing is to derate it, for instance if you need to draw 2A, use a 3A power supply.

Easier said than done though.
 
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WheezyRider

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Apr 20, 2020
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I have two Sans chargers, one gets hot, the other doesn't. The one that gets hot takes 85W from the mains and outputs 65 W to the bike battery, so 20W of heat dumped into the charger. I don't think the Sans chargers are great for efficiency.

On the one that does get hot, I did have it fail at one point. The soldering on one of the transformers wasn't great and one leg was only making intermittent contact. I've also had poor soldering on some other PSUs, typically on the large capacitors. If you have your PSU open, it's worth checking the quality of the soldering.
 

lightning

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Mar 26, 2022
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Cheap and poorly designed SMPS can have an efficiency of 50-60%

A good one would be 80% efficient

Also the better ones will have plated through holes in the PCB so you shouldn't get issues with poor solder joints.