Hi all! I’m not very well versed in electronics, so I hope you can help me here! I’m trying to charge a 25.2V lithium ion battery. I don’t have an OEM charger for it, so I’m trying to put something together. I have a laptop charger which outputs 19.5 V, and I just bought this voltage boost converter:
I set it up to output 28V with no load. Once I plug it into the battery’s charging port the booster’s output and input voltages drop down to about 1V over about 30 seconds and keeps dropping (and, I infer, the battery doesn’t charge).
IDK if this is relevant but the laptop charger can output 130W and the battery is 4000mAh.
What am I doing wrong?
Hi Andrew
That is some laptop charger. That equates to nearly 17A.
Just had a look at one of my laptop chargers and it is 19.5V @ 2.31A or 45W.
Are you sure of these numbers or should it be 32.5W which would be 1.66A which might not be enough for your application.
Cheers Bob
SORRY!! 19.7V @ 6.7A = 130.65W. I don’t know how I suffed that up, but I’ve edited it now.
I don’t know much about how a lithium battery charges but I’d have thought it if it tried to pull more power than is available it would just max out and charge a bit slower…???
Hi Andrew
I think you are going down a very dangerous path here.
Please give up now before you have a disaster.
Don’t you watch the TV news or read the papers and see how many houses are destroyed due to the probable incorrect charging of lithium batteries. They can be very dangerous if mistreated.
Do yourself and everybody else a favour and purchase the correct charger for that battery. Don’t skimp on a Chinese knock off either. Get the correct unit.
Cheers Bob
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Hey @Andrew278117,
Would you be able to tell us a bit more about the specific battery you are trying to charge?
The SkyRC iMax B6 V2 Battery Charger may work if your battery has 6 cells or less but the more information you can provide on the battery the easier it will be to make sure you can find a suitable charger.
If you have a link to the battery that would also work.
I will echo what Bob is saying about lithium battery safety. This is something you want to be sure you are doing correctly and spending a little more for a decent charger over building your own is absolutely the safest option.
Hope this helps!
Don’t try and do it yourself !!!
Take the battery to a reputable battery supply shop and ask if they have a charger to suit.
In Australia I would visit Battery World first. Of course it may cost more than you want to pay but a DIY that burns down a house is not worth it.
regards
Jim
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