2014 Stealth Fighter Charger failure

[jammer]

Hello to the Forum,

First time post, but many years reading.
I have contacted the manufacture tech support, but have received less than stellar support and am now left with no support.
Stealth claims they do not have a suitable 5amp charger for my bike.

I am hoping someone can review the attached photos and comment on what a suitable PCB component looks to have failed.
I believe it is a thermistor. I found the following thread that indicates the RT1 component printed on my board likely is a thermistor. The component appears to have been epoxied to the adjacent transformer for thermal feedback, but this is only a guess as the component was fried.
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https://electronics.stackexchange.com/questions/261829/what-electronic-component-does-rt1-refer-to-in-the-following-diagram

RT is a reference designator(wikipedia article, with list) for thermistors.
Unfortunately there are basically no other details in that shcematic about the component, so it's impossible to tell if it's a NTC or PTC type, let alone the other details (k, β, a, b, c, tolerance etc.).

It's a thermistor and its initial (at room temperature) resistance is 10k. But I cannot determine whether it's a NTC or a PTC.
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I have a collection of components to solder into the PCB or could source from www.digi-key.com.
The charger has two leds, one red (indicating 110 power is present), and one dual color red/green(red indicating charge mode/green indicating fully charged). I shorted the contacts together and the charger appears to function normally and the battery begins to take a charge, but I do not want to operate the charger without the failed component.

Any thoughts?

jammer

 

[amberwolf]

Stealth claims they do not have a suitable 5amp charger for my bike.

The good news is that there are many suitable chargers out there, so you don't have to fix this one. You just need one that is 58.4v output, at 5A, for a lithium battery. (Li-Ion, etc).

If you don't mind the price, the Satiatior from http://ebikes.ca is a good one, and the 8A model will work for your pack; just setup a profile in it that has 58.4v final voltage, and 5A max charge current. (or alter one of the built in profiles to that).

It's useful because if you get a different bike or battery, you can set a profile in it for that one, if it's different than this one, without having to get a new charger.

It's also fanless, weather- and vibration- resistant, which means you can mount it on the bike itself or carry it with you if you need to, without worrying about damaging it (unlike typical chargers).

Ebikes.ca carries an assortment of adapters for the charger to fit many different charging port connectors on batteries.

Otherwise there are numerous similar or even identical chargers out there. I've seen ones shaped like yours called "Kingpan", among other names, so I used this search
https://www.google.com/search?q=kingpan+58.4v+5A+charger
to find a few; a search without the brand name for a 58.4v 5A Li-Ion charger will find more.

If the charger you find doesn't have the right connector, you can swap the cable (or just the connector) over from the old one.

I am hoping someone can review the attached photos and comment on what a suitable PCB component looks to have failed.
I believe it is a thermistor. I found the following thread that indicates the RT1 component printed on my board likely is a thermistor. The component appears to have been epoxied to the adjacent transformer for thermal feedback, but this is only a guess as the component was fried.

It is almost certainly just a typical ICL (inrush current limiter), which is an NTC, so that resistance goes down with temperature--it's purpose is to be higher resistance at first, when the device is plugged into the wall, to reduce inrush current into the capacitors of the device, and as current heats it up it passes more and more of the current, to allow the device to operate correctly.

If you happen to have any old computer PSUs, or any other similarly-designed and sized chargers for something you are not using, they may well have a similar-enough ICL in them to just swap in.

Otherwise, you can order an appropriate ICL from Mouser, Digikey, Farnell, etc. I would use their chat function to locate the specific part to order, given whatever the max current draw


Most likely it was not attached to the transformer, just coincidentally placed alongside in the layout procedure. Because it continues to generate heat, being next to the transformer is probably not the best place for it, as that also generates heat, and heat ages and stresses components, and eventually makes them fail. But that's where they put it, so that's the easiest place for you to install the replacement, without modifying the charger. (running wires from that location to a new one, gluing the new part in place so it won't move around, etc).

 

[jammer]

Amberwolf, thank you for the greatly detailed response!
I also apologize the delayed response. I hoped for a more expedient purchase and/or repair of my charger and life got in the way. You are correct, it is in fact a thermistor. I ended up simply shorting out the remaining burned up thermistor posts with a jumper lead and the charger has been working just fine.

After reviewing and searching numerous chargers, I ended up ordering this charger: https://www.amazon.com/dp/B09FFTVHFV?psc=1&ref=ppx_yo2ov_dt_b_product_details
I overlooked the fact that the title and description clearly stated LifePO4, but I relied on the actual photo's that showed multiple chemistries. After receiving the charger - the portion of the manufacture decal that showed Li-Ion~Lipo / LifePO4 / Lead acid actually had the LifePO4 box ticked in red. My Bad.

Unless the chemistry of LifePO4 will work for my Li-ion battery, I will return and purchase the Grin Satiator.
I was simply hoping for a turn-key solution. I believe my battery is 48V - the original charger does in fact cut off at 58.3/58.4v.
Some sites list the Fighter battery specs as a LifePO4, others Li-ion. LifePO4 cells are 3.2v whereas Li-Ion are 3.7v.
Short of dissecting the pack, unsure of chemistry.

I am unsure of the appropriate Satiator model though.
The Grin info page states there are three models: https://ebikes.ca/product-info/grin-products/cycle-satiator.html
7205 = up to 103v and 5a (72v/360w model - 36V to 84V Nominal Batteries)
4808 = up to 63v and 8a (52v/360w model - 24V-52V Nominal Batteries)
2415 = up to 36v and 15a.

48v is the nominal voltage ,so I believe either of the 7205 or 4808 will work.

Thank you again for the assistance!

 

[amberwolf]

I ended up simply shorting out the remaining burned up thermistor posts with a jumper lead and the charger has been working just fine.

It will operate, but it now has no inrush limiting, meaning full current "immediately" flows into the charger's input capacitors to charge them up, and also thru all the semiconductors in the path.

Systems use the ICL to limit the current specifically to prevent that, because it stresses those parts otherwise. Sometimes they even size those parts based on the ICL being there and doing it's job, so the stress is even worse on them than otherwise.

So...if you can, I'd recommend replacing the ICL; usually one of similar physical size will do a similar job and handle similar power. (since you can't read any markings on it to find a matching part).

A similarly-rated-wattage power supply (no longer used computer PSU, etc) may also have an ICL you can transfer over.

Unless the chemistry of LifePO4 will work for my Li-ion battery, I will return and purchase the Grin Satiator.

As long as the final voltage is the same, the charger works basically the same way. The only typical difference I've seen in them noted around the forums is that, at least back when they were posted about, some LFP chargers don't ever shut off while the LI chargers shut off output when current drops below some tiny amount. As long as your BMS is correclty working to shut off input when the cells are full, that won't really matter.

Some sites list the Fighter battery specs as a LifePO4, others Li-ion.

It depends on the age of the bike as to which pack they used. If there are no labels on your pack with any information, you'd have to directly contact the manufacturer of the bike to see if they keep track of which serial# has what specific parts on it.

If there are any labels, you could post a pic of them here and we can see if it tells us anything.

I am unsure of the appropriate Satiator model though.
The Grin info page states there are three models: https://ebikes.ca/product-info/grin-products/cycle-satiator.html
7205 = up to 103v and 5a (72v/360w model - 36V to 84V Nominal Batteries)
4808 = up to 63v and 8a (52v/360w model - 24V-52V Nominal Batteries)
2415 = up to 36v and 15a.

48v is the nominal voltage ,so I believe either of the 7205 or 4808 will work.

Either will work; depends on the charge rate you want. The 72v version cannot charge any higher than 5A IIRC, while the 48V version can charge up to 8A (as long as total power remains within the watt limit of the charger; it will automatically drop current as charger gets hot to make sure it doesn't exceed it's ability to shed heat.