New, Quicker Charger for 18V Batteries???

[sae]

[member=2085]Henrik R / Pingvinlakrits[/member]

From what I've been told/read of the lithium manganese cobalt cells (and most lithium cells in general), the greater enemy actually isn't the charge/discharge rate itself, but the heat associated with high amperage inputs/outputs that causes the cell the break down (80 C/176 F being the absolute limit the cells should reach). Tesla's new P85D has a mode that allows it to dump huge amount of amperage for a short period of time, something equivalent to ~800 hp, and the challenge there was not the cells themselves, but optimizing the liquid cooling for the cells.

With carefully ramped and monitored charging, it's possible to turbocharge the beginning of the charge cycle without adding a bunch of heat, and taper the amperage as the cells get more full. Add active cooling as Makita and Metabo have, and you can push even higher amperages without cell degradation.

 

[jonny round boy]

Despite that I am not too sure on super fast charging of batteries - seems that it would shorten the life span and/or make them less potent pretty quick. They would probably have a faster cut off time (in percentage of capacity drain before safety cut off) to enable fast charging. There aren't too many free lunches in the battery world.

Watched a video yesterday about a Bosch Professional cordless electric lawnmower. It uses 2x 36V, 6Ah batteries, and they charge, from empty, in 20 minutes.

 

[Kev]

Despite that I am not too sure on super fast charging of batteries - seems that it would shorten the life span and/or make them less potent pretty quick. They would probably have a faster cut off time (in percentage of capacity drain before safety cut off) to enable fast charging. There aren't too many free lunches in the battery world.

Watched a video yesterday about a Bosch Professional cordless electric lawnmower. It uses 2x 36V, 6Ah batteries, and they charge, from empty, in 20 minutes.

[member=1725]jonny round boy[/member]

The 36V Stihl gear comes with a choice of 3 chargers (with three corresponding costs!). I got the faster of the 3 and it charges the batteries a lot faster than I can use them up!

I think the cordless gardening market is going to seriously push battery and charger tech along .. a lot of the current cordless tool manufacturers have got a bit lazy IMO.

 

[pingvinlakrits]

[member=2085]Henrik R / Pingvinlakrits[/member]

From what I've been told/read of the lithium manganese cobalt cells (and most lithium cells in general), the greater enemy actually isn't the charge/discharge rate itself, but the heat associated with high amperage inputs/outputs that causes the cell the break down (80 C/176 F being the absolute limit the cells should reach). Tesla's new P85D has a mode that allows it to dump huge amount of amperage for a short period of time, something equivalent to ~800 hp, and the challenge there was not the cells themselves, but optimizing the liquid cooling for the cells.

With carefully ramped and monitored charging, it's possible to turbocharge the beginning of the charge cycle without adding a bunch of heat, and taper the amperage as the cells get more full. Add active cooling as Makita and Metabo have, and you can push even higher amperages without cell degradation.

I am not that worried about fast discharge but I am not that confident in very fast "forced" charging of batteries. It will generate heat and even if tapered down towards the end heat is the enemy for long term stability. I think.

 

[pingvinlakrits]

Despite that I am not too sure on super fast charging of batteries - seems that it would shorten the life span and/or make them less potent pretty quick. They would probably have a faster cut off time (in percentage of capacity drain before safety cut off) to enable fast charging. There aren't too many free lunches in the battery world.

Watched a video yesterday about a Bosch Professional cordless electric lawnmower. It uses 2x 36V, 6Ah batteries, and they charge, from empty, in 20 minutes.

Yes, but when they are "empty" I am sure they still have a lot of juice left in them. Seems they have a limiter / cut off with room to spare to allow for fast charging. Bosch are touting the "Cool Pack" with more air and more air flow to compensate for high heat when charging. Bosch own literature states that batteries will wear out fast when stored or exposed to temperatures higher than 50 degrees (Celsius) if I remember right. Charging batteries outside on a hot summers day building a deck comes to mind as a high drainage and forced charging situation.  In the next few months I am not worried, I can throw the batteries in a pile of snow and force charge it in five minutes and keep the pack Cool.

 

[Des Darsey]

90 minutes is fine, I'll put one on to charge over lunch!! [drooling]

90 min lunch???
If you have 30min t break at 10 and 3 as well, can I come and work for you? ?
My current boss doesn't let me stop for breaks, I have to eat while working [crying]
PS, I'm self-employed

90 mins, your obviously not self employed or on price work. Give it up 45 should be max, just bought the TSC55, did less than 20 mtr flat two batteries. (MDF 18mm).
I hope that the tool will bed in and get better life.
Any comments welcome

 

[Rip Van Winkle]

Ironically, given that Lithium batteries are an "upgrade" over previous battery systems, the older NiCd batteries could usually be charged in 15-20 minutes, or sometimes less,  with high amperage "Ultra-Rapid" chargers, and the batteries supposedly would last thru 2 to 3 times as many charging cycles over using regular "1 hour" chargers.

 

[semenza]

I think charge times have increased due to higher Ah batteries taking more time to charge. But Festool has introduced Airstream that should considerably reduce charge times.

Seth

 

[antss]

Maybe our resident EE [member=191]Rick Christopherson[/member] can give us some insite on all this voltage amperage temperature timing stuff ?  [unsure]

 

[Rick Christopherson]

Maybe our resident EE [member=191]Rick Christopherson[/member] can give us some insite on all this voltage amperage temperature timing stuff ?  [unsure]

Ironically, given that Lithium batteries are an "upgrade" over previous battery systems, the older NiCd batteries could usually be charged in 15-20 minutes, or sometimes less,  with high amperage "Ultra-Rapid" chargers, and the batteries supposedly would last thru 2 to 3 times as many charging cycles over using regular "1 hour" chargers.

Well there's your first clue. Lithium batteries are an upgrade only as it pertains to the weight of the battery, but NiCd and NiMH actually have higher amperage densities. Each new technology is in high demand only because some marketing department (many companies) convinces people they need it.

It's not unique to just batteries. Most industries are this way. I've been saying for decades that the sanders you all own are not the best for the purpose, but are simply what marketing had driven.  [tongue]

 

[Rick Christopherson]

Maybe our resident EE [member=191]Rick Christopherson[/member] can give us some insite on all this voltage amperage temperature timing stuff ?  [unsure]

Actually, to answer your question, yes, different battery technologies require different charging profiles. That's the reason why intelligent chargers utilize microprocessor control. It is no longer just a matter of giving a battery a voltage above discharge in order to charge. Each battery chemistry requires a specific charging profile as it passes from dead, half dead, half charged, to charged.

Depending on the battery type, some charging phases are based on voltage, then the next phase is based on a specific amount of amperage injection, and so on, until that particular battery type reaches full charge. It is no longer just giving it juice until the battery is charged. [cool]