Author Topic: A 12v battery is a 12v battery, right? Riiiiiight?  (Read 540 times)

T42

  • Old fool in a hurry
A 12v battery is a 12v battery, right? Riiiiiight?
« on: December 29, 2019, 09:34:15 am »
This Christmas MrsT gave me a 12v Bosch Professional cordless circular saw. Bosch, wily buggers that they are, sold it unbundled, with battery and charger not included, and I ended up with the right charger and the wrong battery.  Ultimate insult, the battery fits the charger but not the device, so I ended up buying the right one myself.

Nar then: the batteries look almost identical, but one is from Bosch's 'hobby' range (green) and the other is from the 'pro' range (blue).  The hobby one is rated 12v 2.5 ah and the pro one 12v 2.0 ah.  The only visible difference is in the lugs that hold the battery in the device: on the hobby battery they're squarish and on the pro they're squarish minus a corner.  I could Dremel off a corner from the hobby one and it would fit.

Question: why shouldn't I?
I've dusted all those old bottles and set them up straight.

Re: A 12v battery is a 12v battery, right? Riiiiiight?
« Reply #1 on: December 29, 2019, 09:50:39 am »
12v ?
is this old (very very) old stock.  modern li-ion batteries are normally multiples of 3.6v, so it should be 10.8 or 14.4v

Re: A 12v battery is a 12v battery, right? Riiiiiight?
« Reply #2 on: December 29, 2019, 09:58:42 am »
Li-Ion batteries are quite often labelled as 4 volts per cell these days, because moor = betterer. The cells are the same.

The lower capacity rating on the “pro” model probably indicates that’s its rated for higher current and longer lifespan. The hobby version probably won’t catch fire or anything silly but you may be working it harder than intended if you plan to use it a lot, which will knacker it.

T42

  • Old fool in a hurry
Re: A 12v battery is a 12v battery, right? Riiiiiight?
« Reply #3 on: December 29, 2019, 10:17:57 am »
@Rowan: yes, I was a little underwhelmed at seeing 12v but since it's an item I don't need I'm not that bothered. At most it'll be used for shortening stock so that it'll fit the car, although other uses might emerge later.

@grams: That sounds like a cautious 'suck it and see', so I think I'll try it.  I'm not going to bother reselling a 30€ item.
I've dusted all those old bottles and set them up straight.

Re: A 12v battery is a 12v battery, right? Riiiiiight?
« Reply #4 on: December 29, 2019, 10:39:08 am »
Li-Ion batteries are quite often labelled as 4 volts per cell these days, because moor = betterer. The cells are the same.

The lower capacity rating on the “pro” model probably indicates that’s its rated for higher current and longer lifespan. The hobby version probably won’t catch fire or anything silly but you may be working it harder than intended if you plan to use it a lot, which will knacker it.
indeed, a quick search reveals it is a 10.8 li-ion (so a nice little saw).  In fairness a 3.6v battery is nearly flat at 3.6v and fully charged it will be about 4.2v so claiming 4v is not that daft but very confusing all the same.

T42

  • Old fool in a hurry
Re: A 12v battery is a 12v battery, right? Riiiiiight?
« Reply #5 on: December 29, 2019, 10:57:57 am »
Re old stock: yes. Bosch no longer admit that it exists. Aye well.
I've dusted all those old bottles and set them up straight.

T42

  • Old fool in a hurry
Re: A 12v battery is a 12v battery, right? Riiiiiight?
« Reply #6 on: December 29, 2019, 02:55:51 pm »
OK, it works. Looks a bit funny since it has a slightly different butt end, but it latches in OK. I'll keep it as back-up only.
I've dusted all those old bottles and set them up straight.