ITTSB.EU Blog Forum
Electrical Applications | Basic Power Analysis | Accessories | PSU | UPS evaluation | Battery analysis | CCTV camera system troubleshooting => Power supply / Battery Chargers => Topic started by: Gianluca on April 21, 2020, 07:31:27 AM
-
Hello everyone, I have an old Bosch screwdriver from the 2000s. I found this battery in the house but it was disassembled and who knows where the pieces went. Now, assuming that it is impossible to buy (maybe I'm wrong?) only the piece of photo A, I have reconstructed the contacts (photo B).
I connected the contacts D and C together by inserting the temperature sensor but the charger does not charge. I am wrong, I remember when I disassembled the battery (10 years ago) that there was a small resistance inside ...
Thanks to those who can help me and thanks also to the administrator for accepting me in the forum. :)
-
Hi,
Use alcohol all over the hot-glue (make it wet) and carefully remove it by breaking it in pieces with small screwdriver.
Now extract entire connector and plates from the plastic body (battery housing).
This should look like as is in my picture.
-
Hello,
thanks for your answer, however, I no longer have the original connector that you showed me in this photo ... Unfortunately it was lost, I rebuilt the contacts and glued with hot glue. My only problem is understanding how to connect this sensor. I see resistance ... What value does it have? Where should it be connected? Thanks :)
-
The resistance this is connected at minus and to key tag = Genuine Bosch battery.
The sensor get connected at minus and front battery tag.
The resistance this is precision type, use this link to verify the bands and accuracy.
You have to use identical in specifications resistance or else the charger will reject the battery.
https://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-resistor-color-code-5-band
-
For personal use I have a modified battery box this converted to battery simulator .. I can test any Bosch charger if this is working properly, and I can data log the charging process too.
-
5 bands resistors they are tricky, here is the color code info.
Resistor this is film metal.
-
For personal use I have a modified battery box this converted to battery simulator .. I can test any Bosch charger if this is working properly, and I can data log the charging process too.
Good job
-
The resistance this is connected at minus and to key tag = Genuine Bosch battery.
The sensor get connected at minus and front battery tag.
Did I interpret well?
Thanks
-
Gianluca I will never hire you as my own assistant for an international project. :P
Contacts :
Top = sensor
Polarity Plus
Polarity Minus
Key tag
We have run out of metallic contacts. :D
-
I apologize but I am really a disaster to the limit you could hire me to put the equipment in order and clean. :-[
Have I made progress now? :)
-
Good job ! (finally) ;D
-
Thank you very much,
now I will find the resistance, make the connections as you suggest and try this new lithium battery pack.
As you can see from the photo, I made the connections wrong, the drill works but obviously does not charge the batteries .... :o
A perfect ignorant question ... I left this drill years ago because the battery packs were very expensive, now following a tutorial on youtube I found the pieces at low costs but the question is this. Are we sure that these lithium batteries are really good for my old charger which was then designed only for nicd batteries?
I don't want it to ruin my charger ... or to ignite the batteries. For example, it could happen that despite being charged, the charger continues to charge them because it does not recognize their state of charge?
Thanks
-
ROUND 1 .....
Not fake lithium 18650 they sold no less than 6~8 Euro its one.
The Bosch thermal sensor it will stop the charge at 50~55C , basically this stops from charging a battery pack this left under the hot sun in the summer.
Your BMS does not look like this having it own temperature sensor, and it should have one, because this is now their protector.
One of less important issues that you will face by using original charger, this is that at charging cut off, the charger will still deliver pulse voltage that the energy will be very low so to be used from the BMS balancing circuit (if there is one at charging mode).
Most cheap BMS they are capable at balancing due discharge.
You may add too small female banana plugs at the Bosch charger as I did too, by this way you will be able to monitor the charging voltage.
ROUND 2 ....
If you think going 100% Lithium?
I can pass one second advice only if your Bosch charger this using a real AC/AC transformer, does it?
-
My charger has this tab you see and my charger has this card you see and it is original Bosch similar to this in the photo that is not original ... I begin to think that I need to change my charger for this type of batteries .... :o
-
I need a picture of your very own charger internals.
-
Here is what is required :)
-
I have good news and bad news.
The good news ... this has a real transformer.
The bad news ... PCB this holding the metal contacts in place.
The next idea this is removing this PCB and use instead a DC/DC back converter with adjustable current (Three pots ).
Have a look here so to get some ideas.
https://www.ittsb.eu/forum/index.php?topic=1524.0
-
Thanks for the info :)
-
Thanks for the info :)
You are welcome :)
-
Good evening, I apologize these may be fine for batteries?
https://www.ebay.it/itm/LOT-DE-20-RESISTANCES-RS64Y-1-4W-0-25W-1k69-Ohms-1k69-1/181465367245?hash=item2a402dc2cd:g:9lQAAOSwMzVTw8JU
Thanks :)
-
Yes they are what you need, but try to negotiate the price by getting five of them.
This seller is very expensive.
True retail value for such resistors this is 0.10 € its one at local electronics shops.
This Italian seller has more reasonable prices and I did order from him too, just send a message if he has what you need.
https://www.ebay.co.uk/usr/computechfg?_trksid=p2047675.l2559
-
Hello,
thanks for the valuable suggestion ..
An ignorant question that I am but with so much curiosity ...
Waiting to be able to change my charger, I tried to charge the battery without this resistance and I saw that the battery is still recharged :o...
Now mine was just a small test (done unconsciously) .. I don't understand the usefulness of this resistance if it is connected only to the negative pole of the battery and to the Key tag
Thanks
-
Yes they are what you need, but try to negotiate the price by getting five of them.
This seller is very expensive.
True retail value for such resistors this is 0.10 € its one at local electronics shops.
This Italian seller has more reasonable prices and I did order from him too, just send a message if he has what you need.
https://www.ebay.co.uk/usr/computechfg?_trksid=p2047675.l2559
have I found these even if smaller ones can be fine anyway?
https://www.ebay.it/itm/25-RESISTENZE-1-69-Kohm-1-8-watt-1-strato-met-25-pezzi/230493224642
Thanks
-
I don't understand the usefulness of this resistance if it is connected only to the negative pole of the battery and to the Key tag
Thanks
BOSCH was having a wide range of chargers, slow charge speed, medium charge speed and FAST charge in just 30 minutes.
I do not know which specific model of charger this requiring such a additional confirmation due the Key tag (resistance value) so to start charging, I can only speculate that Fast Charger model this will require it at 100%.
Because non Genuine BOSCH battery this will explode under 30Min Fast charge.
BOSCH genuine battery packs was using Panasonic NiCD them able to be charged with 1.7V per cell.
Chinese NiCD they follow 1.5V max charging guideline, these at 1.7V they will run hot or even explode.
-
Thanks for this explanation, so I deduce that the size of the resistance also counts .... That is, if the manufacturer provides a 1/4 watt resistor this cannot be replaced by a similar 1/8 watt right?
-
Thanks for this explanation, so I deduce that the size of the resistance also counts .... That is, if the manufacturer provides a 1/4 watt resistor this cannot be replaced by a similar 1/8 watt right?
In theory ... there is one identical resistance at the charger PCB.
In theory ... detection is made by the two resistors acting as resistance divider (both they are set in parallel mode) and as such their total value will become half.
In theory ... the smart IC will get this compliance information and start charging.
In your case, you have the smallest available charger, and there is no clear answers of what it does apply for it or not.
If the charger it does recognize the battery pack and charging it, then do not buy any resistors.
-
Thanks a lot for the explanation, I learned a lot, I will do as you suggest. :)