Charging a 3.6v li-ion battery (ok, it's more electronics than electrics..)

[cjard]

The charger for my hitachi second fix nailer seems to have packed up. Putting a discharged battery in it and powering it up (from the wall adapter or the car charger) sees the charger clicking a relay internally, the CHARGING led blinks on, then another click and the LED extinguishes again

Looks like a new one is 80 quid (!) and used about half that, so I'm looking for another way to charge these batteries. I recalled that most mobile phone batteries are similarly specced: 3.7v and 1500mah, so I wondered about opening the hitachi charger, and soldering wires from its battery connectors to the battery connectors of a cheap phone I have lying around (got loads of old crap) and presto; the mobile phone software can charge the battery, right?

Is the 0.1v difference critical?

I also, coincidentally, have a bosch AL1115CV intended for charging the 10.8v batteries that power my screw gun, but I see adverts indicating the AL1115CV can do batteries between 3.6v and 10.8v - should I put efforts into making a small adaptor (e.g. a plug made of wood, plastic etc, and wired to the socket of the knackered charger) so I can effectively turn the knackered charger into a physical adapter that mates the hitachi battery with the bosch charger? (Pic of bosch here, can be zoomed with reasonable clarity: http://www.ebay.co.uk/itm/BOSCH-AL1...293618?hash=item2828dd73f2:g:pS4AAOSw-0xYd8bd)

The hitachi batteries have 4 terminals (+, -, L+ and S - pictured here: http://www.ebay.co.uk/itm/HITACHI-U...238580?hash=item4d520061f4:g:dlsAAOSwt5hYdTSK) - any idea what L+ would be? I'm assuming S is a sensor for temperature (?) like mobile phone batteries have

 

[Iggifer]

Doesn't even remotely answer your question, but your prices for a new charger are a bit OTT.

Here have it for £42.54 new. I'd be more inclined to open up the charger you've got and see if there's anything obviously wrong with it, if it is just a relay, it'll cost you pence to fix and there's no bodge involved

There is a 3.15A (presumably 20mm glass) fuse on the PCB so that's worth checking

 

[endecotp]

Just to confirm, this happened with multiple batteries at the same time, right? So it's definitely the charger, not the batteries?

 

[endecotp]

To answer your actual question:

No, don't try to charge it from your phone.

I don't think the 3.7V vs. 3.8V difference is significant; it's the same chemistry and the charging will be the same. The only issue might be how to detect the end of charging. If it uses the temperature it will work fine; if it monitors the voltage it could conceivably get it wrong. I wouldn't worry much.

Yes you might be able to charge it with the Bosch charger if the Bosch batteries have similar capacities (in Ah or mAh) to the Hitachi ones. Working out what the terminals do is the challenge. I've seen a 4th terminal on some smaller (e.g. camera) lithium batteries which connects to a ROM of some sort in the battery with manufacturer info. It could also be the other side of the temperature sensor (which is normally connected to battery negative).

Personally I'd try to dismantle the charger and diagnose the fault, but that would require some test equipment.

Don't leave it charging unattended. If you're safety-concious, have a bucket of sand ready!

Good web sites about battery charging:
http://batteryuniversity.com/
http://www.powerstream.com/tech.html

 

[ericmark]

There are many ways to charge NiCad and their modern replacements the lithium battery, even the manufactures get it wrong, Samsung 7, Boeing aircraft, Dell laptops to name a few. The aim is to charge the battery as fast as you can without damaging the battery, this starts simple with a trickle charge and instructions do not leave on charge more than 24 hours. The next was to fit some temperature switch, electrical energy turning into chemical energy produces very little heat, but once the converting is complete then battery (should call it a cell) will get warm, a temperature switch to stop the charging when it gets warm, and a latch to stop it trying to charge it again when it cools works well. But how do you know if there is a temperature switch built into the battery? The other method is the delta V, with most batteries if charged at a constant current the battery voltage will raise until fully charged then it will dip a bit, having a charger detect that dip means it can stop charging before the battery gets hot. Easy with a single cell, but when cells are put together it's harder to detect. So often there is some extra bits added, to first discharge the battery and have a back-up timer is one method used.

As to cameras manufacturers have fitted software in the batteries to stop fakes being used, Nikon I know did this, likely to ensure no one has a battery explode, but also clearly gives them more custom. At £2000 for the camera body, using fake batteries is not really a good idea. However with a drill which will go in the bin if you can't find a cheap battery or charger then it's a little different. I have a spare Nikon battery, all the writing on it looks correct, but how do I really know?

Read this report by BBC on the Samsung problem then decide if it's worth fiddling.

 

[Iggifer]

As to cameras manufacturers have fitted software in the batteries to stop fakes being used, Nikon I know did this, likely to ensure no one has a battery explode, but also clearly gives them more custom. At £2000 for the camera body, using fake batteries is not really a good idea

Not sure how accurate that statement is, I've used Nikon DSLRs for the past 15 years and have had no issues with 3rd party batteries (maybe they do and the replicators have copied the what they needed to from OEM batteries)

The only battery related problem I had was inserting a fully charged battery and then upon half pressing the shutter button it would shoot down to empty battery (even with 2 batteries) turned out I needed to clean the lens AF contact with isopropyl. Weird fault

 

[ericmark]

Not sure how accurate that statement is, I've used Nikon DSLRs for the past 15 years and have had no issues with 3rd party batteries (maybe they do and the replicators have copied the what they needed to from OEM batteries)

The only battery related problem I had was inserting a fully charged battery and then upon half pressing the shutter button it would shoot down to empty battery (even with 2 batteries) turned out I needed to clean the lens AF contact with isopropyl. Weird fault

There was a warning with the D7000 Nikon not to do the firmware upgrade as if you did many of the third party batteries would then fail to work, clearly the battery producers did find how to allow them to work again, so it will not stop you now buying a battery. It also affected third party battery grips.

 

[Iggifer]

There was a warning with the D7000 Nikon not to do the firmware upgrade as if you did many of the third party batteries would then fail to work, clearly the battery producers did find how to allow them to work again, so it will not stop you now buying a battery. It also affected third party battery grips.

Interesting. Yea they'll always get around it, but it's the same with all original batteries, they're ridiculously expensive - I suspect that's where the majority of their profit comes from. I think the last time I bought Nikon batteries I got 2 or 3 for the price of one original, and couldn't tell the difference in the oem/3rd party. I got similar shutter counts and re-charge times on both.

3rd party drill batteries aren't quite as reliable, there's a lot of crap, used laptop Li-ion cells being recirculated into them. My last Makita drill got burnt out by a non-makita battery. Trigger got stuck, drill bit got stuck and smoke billowed out. Apparently the OEM batteries protect against that and shut down when they detect battery or tool overheating but I'm not going to test it!

 

[stillp]

I had cheap aftermarket batteries for both my digital cameras, but the one for the Lumix expanded to the point that the spring in the camera wouldn't eject it. I managed to remove it by supergluing something to it to make a handle, but if it had expanded a fraction more that would have been a scrap camera.