Defective Charger Spoiled Li-ion Battery In This SARIGAMA CARAVAN SC-03
This belonged to my school classmate and was brought to me with the complaint that there was no backup, though it worked very well. I have handled a similar set, a link of which is given below to avoid sharing another set of images, as the internal construction of both is same: https://jestineyong.com/saregama-caravan-sc-04-usb-fm-music-player-survived-floods/ I opened the set and found that the inside was very clean.
The battery had a built in charger. The outer blue layer should be peeled off to view the battery with its charger. Let us have a look.
The battery was almost dead. The charging was not taking place when checked connecting it to the board and the USB charger adaptor. Probably that is what caused a battery drain. I tried charging the battery externally using my Li-ion battery charger. It took charge but did not give necessary back-up.
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So, fetched a better rated cell and a similar charger PCB and bonded it using my recently acquired battery spot welder, which has a foot-switch to operate. I also provided the protective tapes on three sides as how it was on the original battery. (Now all these are available to buy):
The set was found working very well, which I ensured trying all its modes such as playing from internal storage of over 5000 songs, which can be selected artist-wise and type-wise (live classical, devotional etc.) from the front panel, FM Radio, USB and Bluetooth pairing.
Mission accomplished with satisfaction getting collected to the bag!
(Special note to keen observer expert: The battery was fully charged using its adaptor before giving delivery to the customer. The second pic above is taken before that!)
This article was prepared for you by Parasuraman Subramanian from India. He is 76 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
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Albert van Bemmelen
April 25, 2026 at 4:34 pm
Thanks for sharing another well fixed charger problem with the DW01 and its 2 mosfets pcb. Previously you already mentioned the satisfying use of the here also used 8000Watt portable spotwelder, why I recently decided to acquire that same welder too. Because it also got many positive reviews. Hopefully it will work much better than my previous rather worthless and quite heavy and much higher priced supercapacitor digital display spot welder and my other also disappointing working welders.
I however wonder if we need to make both tips of the copper welding probes pointier to make them perform better, or are we always able to use them as how they are (with diameter of 1.92mm) ? Because until now I only did grind of the top layer a bit when they are rather blackened to make the electrical contact better, so the current flow is higher.
Parasuraman S
April 25, 2026 at 8:58 pm
Many thanks for your expert comments and sharing your experiences again. The tip should be maintained well to have proper contact. Just cleaning it with IPA would do. Only occasionally, we need to use zero emery paper.
Waleed Rishmawi
April 25, 2026 at 4:59 pm
Good fix my friend. Thanks for sharing and have a great blessed day
Parasuraman S
April 25, 2026 at 8:59 pm
Glad to see your comments, dear friend! Many thanks!
Yogesh Panchal
April 25, 2026 at 5:01 pm
Good Job!Sir
sometime Battery showing good working voltages but because of degradation it cant hold Current for longer time.
Investment in good Tools like battery spot welder makes work easier.
Parasuraman S
April 25, 2026 at 8:59 pm
Many thanks for your comments, Yogesh Bai!
Mark J
April 26, 2026 at 2:27 am
I am thinking about purchasing one of those battery spot welders. Once again great job on the repair Parasuraman.
Parasuraman S
April 26, 2026 at 8:21 am
Yes, it is worth its money for sure! Many thanks, dear Mark!
Imoudu.O
April 26, 2026 at 3:59 am
I wonder what you mean by backup? I remember in the past I once repaired a bluetooth player with li ion battery having built in charger, which refuse to charge after repair...you know what, I just remove it from battery and charging system started working perfectly.Thanks for sharing.
Parasuraman S
April 26, 2026 at 8:23 am
By backup, what I meant is DC battery supply when the mains fail. Many thanks for your comments and sharing the experience!