Cheap/small charger for Bosch Pro 18v packs?

Batteries, Chargers, and Battery Management Systems.
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Cycloslalomeur   1 µW

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Cheap/small charger for Bosch Pro 18v packs?

Post by Cycloslalomeur » Mar 08 2018 6:43am

Hi everybody,

I just joined this forum as I´m building a 12v system for my recumbent (bike) and had had trouble finding a cheap and compact charger for Bosch´s BAT612 or third-party equivalent battery pack. I´ll be using these packs just to power e-bike lights, a navigation device and occasionally a phone with the aid of Bosch´s own step-down converter (model designation GAA 18V-24) that´s designed to power heated jackets and gadgets.

Obviously this is a fairly low-drain application, so I have no need for a bulky fast charger. I´ll be touring with a couple of spare battery packs anyway.

Firstly, I need to know the chemistry of the cells. Bosch´s website is scarce on technical specifications, but I think I saw a marketing blurb that mentioned iron phosphate, which means the pack has five LifePO4 cells in series, correct? Indeed, a reviewer on Amazon.fr reports that Bosch´s own AL 1820 CV charger is rated at 18v, which probably means a tad above that figure. But the rating on a third-party charger (link below) is 21v, suggesting it´s for polymer packs.

https://www.plus.parts/nl/compatibele-s ... ccu-s.html

So could somebody confirm what the guts of those packs are and point me toward an affordable and above all compact trickle charging alternative in the 0.5 to 1A range? I´m willing to simply time the charge with a multimeter using a mains adaptor with a suitable voltage and current rating.

Also, assuming the pack is iron phosphate, would I do much damage to the pack with a 21v/1A mains adapter as I found one of those (see link below)? I would be monitoring and/or timing the charge.

https://www.amazon.de/PowerSmart%C2%AE- ... C3%A4t+21v

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marty   10 MW

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Re: Cheap/small charger for Bosch Pro 18v packs?

Post by marty » Mar 08 2018 9:38am

Why not charge Bosch BAT612 batteries with a charger like this?

BC660 18V Lithium-Ion Charger
Image
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Cycloslalomeur   1 µW

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Re: Cheap/small charger for Bosch Pro 18v packs?

Post by Cycloslalomeur » Mar 09 2018 5:23am

Mainly because of the bulk, but also cost and the fact that I´ve always been taught that trickle charging is far better for cells than high-current charging is.

Bosch´s own charger (like the one in the photo you posted) costs about 40 dollars in your part of the world, compared with less than a tenner for a simple one-amp power supply, and is the size and weight of a common brick.

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dogman dan   100 GW

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Re: Cheap/small charger for Bosch Pro 18v packs?

Post by dogman dan » Mar 09 2018 7:54am

No less bulky to go with a low wattage RC battery charger like the B6 either. Best approach would be the stock charger.

Cycloslalomeur   1 µW

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Re: Cheap/small charger for Bosch Pro 18v packs?

Post by Cycloslalomeur » Mar 12 2018 5:03am

The Mini version of the B6 is fairly small though. Would it work with a small wall-mount DC adapter (I think I have some 12v/1A ones in the power supply bin) instead of the recommended 5A one?

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marty   10 MW

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Re: Cheap/small charger for Bosch Pro 18v packs?

Post by marty » Mar 12 2018 8:36am

Think you are thinking too much?
dogman dan wrote:
Mar 09 2018 7:54am
Best approach would be the stock charger.
Yes a Bosch charger is easiest way to charge Bosch batteries. Perhaps if you think charger is too big? You could take it apart and build a new case.

Beware - Don't know about Bosch? I did some experiments running a boom box off of Makita 18V Lithium-ion batteries. Music would keep playing till battery died. Battery drained too low and died as in dead. Dead never to work again. Without a electronic gismo to stop the music. Also called low voltage cutoff or disconnect. Lithium batteries keep working till they go so low they never come back. Good thing that humans don't work till we die. We get tired, eat and sleep.
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Cycloslalomeur   1 µW

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Re: Cheap/small charger for Bosch Pro 18v packs?

Post by Cycloslalomeur » Mar 13 2018 3:07am

The main problem with the Bosch chargers is indeed that they´re too big.

Apparently (according to a UK company who refurbish Bosch Pro battery packs) Bosch tools come with overdischarge protection circuits. In my case the "tool" would be the step-down converter that attaches on to the battery pack. Simply wiring the unprotected battery pack to the lights would indeed be a bad idea.

Is there really nobody out there who has simply used a small wall-mount power adapter to manually charge power tool battery packs?

Punx0r   10 GW

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Re: Cheap/small charger for Bosch Pro 18v packs?

Post by Punx0r » Mar 13 2018 3:20am

As long as the tool battery pack itself contains the means for balancing it and protecting it from over/under discharge then there is no reason you can't use a small CCCV PSU as a charger. However, as you've got two extra connectors on the stock charger (four when only two are needed to charge) you might find the battery won't accept a charge unless given some sort of signal from the charger. Similarly, the over-discharge protection might only consist of the battery signalling the tool to switch off.

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