Will "A" work in the diagram ??

collectors

collectors

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Hi, will "A" work in the diagram. I know "B" is ok & a good way to boost the 12v amperage, but wasn't sure if the "A" diagram would feed back on the controller/charger. I was looking to make up some smaller 12v packs & join them together for more amperage if needed.
bat wiring 3s.JPG
 
Both of the above should work, provided you are using BMS (Battery Management System) boards, rather than just boarded sold as 'protection'.

I would prefer A, as each cell is individually being monitored.
In B, one failing cell, could cause the other one in parallel with it to be over-stressed, and also fail.

PhilP
 
PhilP said:
Both of the above should work, provided you are using BMS (Battery Management System) boards, rather than just boarded sold as 'protection'.

I would prefer A, as each cell is individually being monitored.
In B, one failing cell, could cause the other one in parallel with it to be over-stressed, and also fail.

PhilP
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Good point Phil. If needed, would it be ok to link 3 or 4 in parallel using "A". wasn't sure if something like a diode on each one might be needed to stop one feeding back on each other. ? & yes it would be a BMS.
 
Just out of interest what type of batteries are they? Not declared on tne question.
 
PhilP said:
The 'dreaded' Lithium..
Quick! Sacrifice a chicken.. ;):D:D:D
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Out of curiosity, why the dreaded Lithium??. Manufacturers like Dell & many more have used them in their 41 million laptops for years without problems & hate to think how many billion are in use around the world.







.
 
collectors said:
Out of curiosity, why the dreaded Lithium??. Manufacturers like Dell & many more have used them in their 41 million laptops for years without problems & hate to think how many billion are in use around the world.







.
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Another debate that seems to be never ending. I think the general feeling is that they need slightly more care to charge, and if it all goes pear shaped, the results are pretty spectacular. But as you say there's millions out there so the debate goes on, and on etc
 
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collectors said:
Out of curiosity, why the dreaded Lithium??. Manufacturers like Dell & many more have used them in their 41 million laptops for years without problems & hate to think how many billion are in use around the world.
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He was being amusingly ironic about my hatred off all but NiMh batteries.
 
collectors said:
Out of curiosity, why the dreaded Lithium??. Manufacturers like Dell & many more have used them in their 41 million laptops for years without problems & hate to think how many billion are in use around the world.
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A bit like track vs battery power; track has analogue vs DCC, battery has lithium vs NiMh :)
 
collectors said:
Out of curiosity, why the dreaded Lithium??. Manufacturers like Dell & many more have used them in their 41 million laptops for years without problems & hate to think how many billion are in use around the world.







.
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I think the others have covered it..
Jon is slightly risk-averse, where battery chemistry is involved..
 
collectors said:
Out of curiosity, why the dreaded Lithium??. Manufacturers like Dell & many more have used them in their 41 million laptops for years without problems & hate to think how many billion are in use around the world.







.
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Not strictly true. A company I worked for had a deal to use Dell laptops and in the first 12 months we had multiple cases of batteries failing and overheating - in my case the battery case distorted and cracked. Unnerving, to put it mildly, especially as many of us used laptops on long haul flights. Agree that the technology has matured these days but personally I steer clear of anything from Dell and, like Jon, I prefer to use NiMh for my battery projects.
 
Sigh!
Every battery technology has the potential (pun intended) to present problems, of some sort:
Zinc-carbon; Will leak, have a low energy density, and will self-discharge in storage.
Lead-acid; Are heavy, there is a (slight) danger of electrolyte leakage, and most do not like light use, and being stored charged for long periods.
NiMH; Unless you choose wisely, they will self-discharge in storage. A lesser risk of leakage, but it does happen.

ALL battery technologies store energy.. If you have a short-circuit (without some form of protection) then there will be damage to the wiring, battery, whatever houses the battery (your model) and possibly you and the surroundings.
ALWAYS! Fit a fuse, as close as possible, to the battery. In this respect Lithium packs with protection boards, are 'better' as the protection is built into the pack. Do still fit a fuse.

PhilP
 
I echo what Phil says. I've had a thermal runaway with a li-ion 18650 cell (I accidentally shorted it when soldering up a pack) and it got a bit warm, hissed and fizzed but that was all. I accidentally shorted a NiMh pack and the wiring harness melted - if that had happened inside a loco it would have made a heck of a mess and maybe caught fire.

And no, I don't make a habit of shorting out battery packs - it's because I've handled and made quite a few over the years.

So, as Phil says - you need to take care whichever technology you use and, had I installed fuses right at the start of creating the packs, neither scenario would have occurred. They say you learn from experience..... ;)

Rik
 
Early laptop packs did not monitor individual cells, but worse, their charging electronics were poor.

Ralph/Phil: what year was this in, and MOST importantly, was that company using refurbished Dell laptops? I worked for a company where I mandated Dell equipment and worked for them for about 13 years. We did not have any batteries burn up, but premature battery failure was evident from a number of models.

Please tell me the years of your bad experience, I am curious if they line up with mine.

Greg
 
Greg Elmassian said:
Early laptop packs did not monitor individual cells, but worse, their charging electronics were poor.

Ralph/Phil: what year was this in, and MOST importantly, was that company using refurbished Dell laptops? I worked for a company where I mandated Dell equipment and worked for them for about 13 years. We did not have any batteries burn up, but premature battery failure was evident from a number of models.

Please tell me the years of your bad experience, I am curious if they line up with mine.

Greg
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will pm you
 
ge_rik said:
I echo what Phil says. I've had a thermal runaway with a li-ion 18650 cell (I accidentally shorted it when soldering up a pack) and it got a bit warm, hissed and fizzed but that was all. I accidentally shorted a NiMh pack and the wiring harness melted - if that had happened inside a loco it would have made a heck of a mess and maybe caught fire.

And no, I don't make a habit of shorting out battery packs - it's because I've handled and made quite a few over the years.

So, as Phil says - you need to take care whichever technology you use and, had I installed fuses right at the start of creating the packs, neither scenario would have occurred. They say you learn from experience..... ;)

Rik
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I welded my wheel nut spanner to the chassis in my mini when it slid across the boot and shorted the +ve to the chassis.
Not fun as everything stopped as I was crossing a 3 track railway crossing that joined the 2 halves of a marshalling yard and I was stuck across the tracks with a diesel bearing down on me.
 
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