Post Reply 
Lipo Ste for HP-41 battery pack
12-29-2016, 10:06 AM
Post: #1
Lipo Ste for HP-41 battery pack
Initiate by Hans-Peter I also modified some of my old HP-41 rechargable battery packs with Lithium cells.
Now I have some electronical parts for sale:

A set contains:

1x Lipo battery 250mAh
1x Lipo charger module
1x Level Booster (you can choose 5V or 6V)
2x battery connectors

You have to use your old battery packs for the modification. I also have some spare units. You can also use the 3D printer to build the battery door.

I can sell 1-2 sets for €10.


Attached File(s) Thumbnail(s)
       
Visit this user's website Find all posts by this user
Quote this message in a reply
12-29-2016, 01:55 PM
Post: #2
RE: Lipo Ste for HP-41 battery pack
Thank you, very interesting indeed.

Could you give us a glimpse at the actual wiring inside? Part numbers would also be great!

How is operation and battery life compared to a conventionally refurbished unit?

Thank you!
Find all posts by this user
Quote this message in a reply
12-30-2016, 12:29 PM
Post: #3
RE: Lipo Ste for HP-41 battery pack
As the design and specifications are from Hans-Peter I will ask him for distributing the infos.
You can also follow this thread.

Matthias
Visit this user's website Find all posts by this user
Quote this message in a reply
12-30-2016, 02:16 PM
Post: #4
RE: Lipo Ste for HP-41 battery pack
The table of all known and tested boosters with the technical details and links of the suppliers is unfortunately not finished before Christmas. As soon as I get back home, it will be one of the first work I finally want to finish.

Hans-Peter
Find all posts by this user
Quote this message in a reply
12-31-2016, 05:39 PM
Post: #5
RE: Lipo Ste for HP-41 battery pack
On the shapeways site I added some battery housings for use with LiPo batteries this morning. These are ones I used for testing.

http://www.shapeways.com/shops/wants_beer
Find all posts by this user
Quote this message in a reply
01-02-2017, 02:08 PM
Post: #6
RE: Lipo Ste for HP-41 battery pack
(12-30-2016 02:16 PM)Hans-Peter Wrote:  The table of all known and tested boosters with the technical details and links of the suppliers is unfortunately not finished before Christmas. As soon as I get back home, it will be one of the first work I finally want to finish.

Hans-Peter

Using a LiPo cell with 3.7V and a booster to 6V raises the question how to avoid destruction of the battery. I do not want to see my HP 41 go up in flames.
All rechargeable battery packs are rather picky about low voltage extracting too much energy. The booster circuit will happily boost to the target voltage even if the battery is already exhausted.
Or does the booster PCB include a low voltage switch-off? And how does the user recognize this state?
A "perfect" booster solution should probably monitor the input voltage and indicate a low voltage condition by also lowering the output voltage so that the BAT indicator come on. Maybe someone want to tackle this design problem?

Martin
Find all posts by this user
Quote this message in a reply
01-02-2017, 07:32 PM
Post: #7
RE: Lipo Ste for HP-41 battery pack
(01-02-2017 02:08 PM)Martin Hepperle Wrote:  
(12-30-2016 02:16 PM)Hans-Peter Wrote:  The table of all known and tested boosters with the technical details and links of the suppliers is unfortunately not finished before Christmas. As soon as I get back home, it will be one of the first work I finally want to finish.

Hans-Peter

Using a LiPo cell with 3.7V and a booster to 6V raises the question how to avoid destruction of the battery. I do not want to see my HP 41 go up in flames.

I have about 50 HP 41 in my home, +/-1 does not depends Wink
No, the booster serves only 5V / 6V (depends on the module). I fact, there is still the problem, that the Lipo gets empty before the BAT flag is set.
For recharching, we modified the charger with a resistor, so that the battery is loaded slower and saver.
Visit this user's website Find all posts by this user
Quote this message in a reply
01-03-2017, 12:24 PM
Post: #8
RE: Lipo Ste for HP-41 battery pack
(01-02-2017 07:32 PM)HP-Collection Wrote:  ...
I fact, there is still the problem, that the Lipo gets empty before the BAT flag is set.
For recharching, we modified the charger with a resistor, so that the battery is loaded slower and saver.

Yes, that exactly was my point - the LiPo battery would drain and you would not notice until too late. I guess if someone would develop a proper circuit it would become a best seller...
BTW: I have already two friends who had a fire in their hobby basement (R/C model aircraft) due to overcharging LiPo batteries. So be careful.

Martin
Find all posts by this user
Quote this message in a reply
01-03-2017, 10:36 PM
Post: #9
RE: Lipo Ste for HP-41 battery pack
Our used lipos have a protection circuit against deep discharge and against overcharge.
The best way to prevent a fire is a safe charge process with maximum C 0.5 or less.
Im also rc pilot and on this bisiness, there are currents between 20-80 A. And this power needs a careful work.

   

   

Hans-Peter
Find all posts by this user
Quote this message in a reply
Post Reply 




User(s) browsing this thread: 1 Guest(s)