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Electronics => Repair => Topic started by: connectTek on May 07, 2020, 01:42:10 pm

Title: Repair lithium ion Vacuum
Post by: connectTek on May 07, 2020, 01:42:10 pm
Trying to repair my parents Hoover Stick vacuum.
It has 6 x 18650 li ion cells, yet the charger only outputs 21.6v, wtf!.
The unit never charges fully from day one.
I have charge on test bench to 25.2 v, (4.2v x 6).
Why would they supply a charger
That would only charge each cell to 3.6v ( 21.6 ).
Can some one help me with this problem.
Cheers.
Title: Re: Repair lithium ion Vacuum
Post by: Miti on May 08, 2020, 08:12:22 am
Are you sure it is Li-Ion? Li-Fe only changes to 3.65V max. Pictures of the battery pack?
Title: Re: Repair lithium ion Vacuum
Post by: Kilrah on May 08, 2020, 10:40:13 am
Yup, sounds like LiFe. 3.6 for Li-ion would be almost empty.
Title: Re: Repair lithium ion Vacuum
Post by: connectTek on May 08, 2020, 12:04:01 pm
Definitely Li ion.
Hoover 5221.
I have bench charged each cell to 4.2v.
At 3.6v they are flat,
Title: Re: Repair lithium ion Vacuum
Post by: connectTek on May 08, 2020, 12:16:12 pm
A Pic
Title: Re: Repair lithium ion Vacuum
Post by: xavier60 on May 08, 2020, 12:27:43 pm
That's really odd. I just had a look at my Dyson DC59.  It's charger is specified as 26.1V for 6 cells. It measures 26.12V unloaded.
Title: Re: Repair lithium ion Vacuum
Post by: Miti on May 08, 2020, 12:32:44 pm
Yeap, that’s weird. I wouldn’t expect to change to 4.2V for safety and extending the life time, but 3.6?
How did you measure the charger voltage? Measure the battery when the charger shows full.
Title: Re: Repair lithium ion Vacuum
Post by: xavier60 on May 08, 2020, 12:40:47 pm
I see on ebay they describe the Hover battery as "22.2V-21.6V".
I don't know about the 22.2V but 21.6V is the nominal voltage for 6x Li-ion cells witch is 3.6V per cell.
Maybe the charger just happens to be set to 21.6V and the charge circuitry in the battery pack is supposed to boost it to a higher voltage.

https://www.ebay.com.au/itm/Battery-Pack-For-Hoover-22-2V-21-6V-Ultra-Light-5221-Vacuum-Cleaner-5221BP-AU-/264409929485 (https://www.ebay.com.au/itm/Battery-Pack-For-Hoover-22-2V-21-6V-Ultra-Light-5221-Vacuum-Cleaner-5221BP-AU-/264409929485)
Title: Re: Repair lithium ion Vacuum
Post by: xavier60 on May 08, 2020, 01:38:20 pm
This replacement charger is specified as 26V,
https://www.amazon.co.uk/POWER-Adapter-SiriusXM-Portable-144D2427/dp/B071ZR5YZL (https://www.amazon.co.uk/POWER-Adapter-SiriusXM-Portable-144D2427/dp/B071ZR5YZL)
Title: Re: Repair lithium ion Vacuum
Post by: connectTek on May 08, 2020, 01:54:06 pm
Charger says 21.6v, I measured 21.9v.
As I said before, at 3.6v per cell the battery is almost flat.
I have input 25.2v from bench power supply and it charges
fine.
Weird.
Looks like a major design failure as I have read that many people
have replaced batteries, mmmmm I wonder why?
Title: Re: Repair lithium ion Vacuum
Post by: xavier60 on May 08, 2020, 02:05:08 pm
Maybe the charger's manufacturer made a mistake, setting the voltage to the marked nominal voltage instead of to the proper charge voltage.
Title: Re: Repair lithium ion Vacuum
Post by: Miti on May 09, 2020, 03:11:02 am
Yes, nominal is one, fully charged is something else.
Can the charger be adjusted?
Title: Re: Repair lithium ion Vacuum
Post by: connectTek on May 09, 2020, 05:10:23 pm
No, it's just a plug pack 21.6v