Bosch IXO hand electric screwdriver..what's the charging circuit?(Solved!) - Page 1
Forum section: electronics / repair

author: SuzyC
author_rank: Frequent Contributor
timestamp: December 01, 2019, 10:48:18 pm
content: Someone gave me a Bosch IXO 3 electric screwdriver, but no charger for it. I know I can build a charger circuit if someone could tell me what the original charger station voltage and current is.Can anyone please help me and let me know if the charger base supplies AC or DC at what voltage/current..regulated or not?The battery is 3.6v Li-Ion and I can easily solder wires to the contact pins on the bottom of the handle to charge this thing.

author: pigrew
author_rank: Frequent Contributor
timestamp: December 02, 2019, 12:00:30 am
content: Based on web searches for similar screwdrivers, it appears that similar models use 7V/250mA DC, with the charging circuitry likely in the driver itself. If this is true for your's, I don't know.See:base disassemblyanda plug.Maybe take it apart to see if it has a charger inside?

author: andy3055
author_rank: Super Contributor
timestamp: December 02, 2019, 12:06:03 am
content: It might be a 3.6 volt unit.https://www.ebay.com/c/1527741243

author: SuzyC
author_rank: Frequent Contributor
timestamp: December 02, 2019, 01:14:18 am
content: Thanks to All!I unscrewed the screwer an saw whats up in its innards.Pigrew,your spec sounds just right, the charger circuit is internal and feeding it 7V DC at 250mA should be the ticket.It's my guess that the 7V DC is unregulated, the base unit is supplied by a wallwart, but the voltage output to the handle should be around 7V DC more or less at .25A load and I doubt that Bosch would go to the trouble and cost of regulating this voltage into the handle because the handle has a charger chip of some type to carefully charge the LI-Ion cell.I will construct a LM317 circuit that will be current regulated to offer the handle a cur limit of .25A at 7V and see which way the smoke blows!Andy3055, I thank you for your input, but I don't think your guess is correct for the charger base voltage, since the internal regulator chip in the driver would need some voltage overhead to function at all. My educated guess is the regulator inside the handle would charge the 2000mAH battery to full charge at a cutoff voltage around 4.0 to 4.2V and at a constant current of around .25A, so 3.6V into the handle would therefor not work without exotic boosting circuitry.

author: andy3055
author_rank: Super Contributor
timestamp: December 02, 2019, 03:52:22 am
content: You must be correct. I think it is being referred to as a 3.6 Volt unit because the battery is 3.6 Volts and that will of course need a higher voltage for charging.You may need to monitor it and make sure not to have too much of a voltage as that can destroy the battery-not to mention other components.

author: notsob
author_rank: Frequent Contributor
timestamp: December 02, 2019, 04:52:23 am
content: Here's a photo of the IXO wallwart

author: andy3055
author_rank: Super Contributor
timestamp: December 02, 2019, 05:31:17 pm
content: By courtesy of DigiKey:https://www.digikey.com/en/articles/techzone/2016/sep/a-designer-guide-fast-lithium-ion-battery-charging