Battery Charger Question...Capacitors...

Question

Hi all Maybe someone can give me some advice if anything should be done. I had this battery charger for about 1 year. The only issue that I am having is that the voltage readings are now lower then before. IE I have a battery @ 3.7V and I have 2 test meters reads as 3.7V but the charger reads it as 3.5V. The charger always was accurate to my 2 meters until now. Should I be worry as this can overcharge/undercharge batteries. I have read on other forums that replacing the caps help fix the voltage problem but not much person say which to use. One person said these should work UPW1V102MHD1TO or 35PK1 000MEFC10X20. Do y'all think its good to use for a charger? What caps do any of y'all recommend to change? Send me links on which caps to use, don't bother to fix, or just buy a new one. Picture is attached of the charger if it helps anyone. PS Related to the pix. The capacitor that is 35V 1000UF is actually 35V 670UF but the board has BOLD print on it calling for 35V 1000UF. Not sure if this could be causing it. The manufacturer installed 35V 670UF Capacitor. Remember this used to be fine until the other day. Also the charger does charge and discharge without a problem and no heat issues. Thank you for taking the time to read this.

w_justic · Answer

I hope my reply isn't too late for you. I don't spend much time on here and just saw your question.

By the look of that charger, it looks like a Li-Po charger for R/C use.

Checking or changing the capacitors would be a good place to start.

If you don't have a way to test the capacity and ESR of the caps, you might as well just

'shotgun' all of them considering that there are only three and they are cheap.

I'm not sure why they used a 680uF cap in place of a 1000uF cap. It could be a production

change because the 680 works better or they could have gotten a good deal on 680's and

decided that they would work sufficiently. Personally, I would use a 680 just so that I know that

I have returned it to it's pre-problem condition in case the problem remains or a new problem

occurs. If the problem goes away with the 680, you could always try a 1000 in there. Without

knowing exactly what that capacitor is doing, I can't say for certain what a change in value

would do. I will leave the choice up to you, but here are some part numbers you can use:

680uF-35VDC part # UPW1V681MHD1TO

1000uF-35VDC part # UPW1V102MHD1TO

220uf-10VDC part # UPW1A221MED1TD

470uF-25VDC part # UPW1E471MPD6TD

(I chose Nichicon capacitors because they are very good and not too pricey.)

Watch the polarity when installing them and use a good soldering iron/station with a fine tip.

Capacitors are quite often the weak link, and the most common place manufacturers cut cost

in products and it will only cost you a couple dollars to find out if that is the problem.

Im not sure what Newark/Element 14's minimum order is, but when I only need

a few inexpensive parts, I usually make up the difference by stocking up on

super-bright white L.E.D.'s. I buy the 5mm, 46,100mcd, Cree L.E.D.'s.

They are insanely bright and can be used to replace L.E.D.'s in small flashlights as

well as other uses. i usually buy part # C503B-WAN-CBBDB152C503B-WAN-CBBDB152

For some reason, I have an obsession for white L.E.D.'s.

Hopefully everything works out for you and you get it straightened out.

Let me know how it turns out and if you need any other help.

What kind of R/C vehicles do you have? I have planes, drones, cars, trucks, boats

and even a motorcycle.

Take care,

William Justic

-Nettle Creek Engineering

-Nettle Creek UAV

Battery Charger Question...Capacitors...

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