C Cab Hot Rod Power Advice

As Someone famously said..
a good man knows his limitations ..
Click to expand...
Please be aware of that And the possible consequences of overestimating your abilities and experience.
Mixing battery connections like that , and other misunderstandings about battery systems, charging, maintenance etc etc, can have dire consequences. ( fire, acid explosions, loss of property)
If in doubt, swallow your pride and seek local experienced/qualified help from someone you trust.
( internet advice can be very helpful , but is not always 100% correct and carries no responsibility ! )
 
Hillhater said:
As Someone famously said..
a good man knows his limitations ..
Click to expand...
Please be aware of that And the possible consequences of overestimating your abilities and experience.
Mixing battery connections like that , and other misunderstandings about battery systems, charging, maintenance etc etc, can have dire consequences. ( fire, acid explosions, loss of property)
If in doubt, swallow your pride and seek local experienced/qualified help from someone you trust.
( internet advice can be very helpful , but is not always 100% correct and carries no responsibility ! )
Click to expand...

I couldn't agree more. This man, 'does' know his limitations. I will take all that is offered to me, and ultimately, do exactly as you have suggested. I'm no fool. I spent twenty years working with all sorts of explosives, of just about every size and shape. But the education process has to go through, what it has to go through, BEFORE practical application.

Thanks for the concern, and advice.
 
Ok, the processes IS working.

I've experimented on paper, and not got hurt.

Is this better ?

I still understand this connection method will achieve what I want/need.

A battery bank with 48 volts output, and 80 ampere hours.



By all means, if this is still not correct, let me know.
 
Ed, no !
Each of those 12 v , 20 ah batteries has 12x20 = 240 Wh capacity ..( theoretically at low discharge rates)
So in total, 4 of them will comprise 4x240 = 960 Wh capacity
No matter how you connect them ,..series parallel or melted together,.. they can never give more than 960 Wh.
You cannot beat the laws of energy conservation. ,,or create more energy just by changing connections !
So you see that 48v x 80Ah = 3,840 Wh is impossible with those 4 batteries.
Connected in series as 48 volts , they will still have 20 Ah. (4s, 1p)
Connected in parrallel as 12 v , they will have 80 Ah. ..(1s, 4p)
2 in series as 24v , then paralleled with 2 more at 24v, will have 40 Ah (2s, 2P)
If you want 48v and 80 ah, either you will need 16 of those batteries ( 4s, 4 p in connection ),
..or use 4 x 80 Ah batteries in series (4s, 1p)
 
No you can't magically connect 4 batteries series-parallel and get 4 times the voltage AND 4 times the Ah.

4 batteries in series= 4x the voltage but the Ah stays the same as a single battery
4 batteries in parallel= 4x the Ah but the voltage stays the same as a single battery
2 batteries in series connected parallel to 2 batteries in series= 2x the voltage and 2x the Ah of a single battery

So if you take 4 batteries that are 12V and 20Ah you can get:
48V pack with 20Ah
12V pack with 80Ah
24V pack with 40Ah

edit: I typed too slow and Hillhater beat me... :wink:
 
Dear Mr Hillhater and Mr SlowCo

You guys are special, to take the time to try and get this subject through to me.
I so appreciate it. I believe all that you are telling me.

My motors and other parts are scheduled to arrive this coming Thursday.

Based on what you gentlemen, are telling me, I might have a dilemma, on my hands.That being said, I may have selected a motor system that will require too much battery to make it practicable.

I have a question:
Not sure even how to ask.
I will do my best to write it so you understand, my misunderstanding :confused:

You have given me, that it's possible to increase volts and ah at the same time.

So if you take 4 batteries that are 12V and 20Ah you can get:
48V pack with 20Ah ...Understood
12V pack with 80Ah ...Understood

24V pack with 40Ah... Understood BUT!

Q- Why did the AH increase (double) for the 24V pack example, but not for the 48V Pack?

In the video demonstration, time line 3:13 - 3:31 ish, they double the voltage to 24v and doubled the ah to 230 ah. (2 x 12v = 24v pack and 2 x 115ah = 230ah pack)

My thinking here,which may be flawed guy's, bear with me.

In the beginning of the video, time line 0:30 - 1:18.
They created a 48 volt bank by connecting three of the pos/neg terminals. They state they now have a bank of 48v 115 ah. (This understood at this point)

Note here, that the batteries in the video, have now been turned.

First

Using the logic of how they created the 48V bank, lets look at time line 3:13 - 3:31.
If they were to connect the two 24V banks, (middle two batteries) together, as they did in the 0:30 - 1:18 segment, then that should create a 48V bank....right, Please !

Second

If the above suggestion, of connecting the two center batteries, to make a 48V bank, is correct, (per the example in the beginning of the video), then at this point you were to connect the remaining posts (POS to POS) and (NEG to NEG), as they do at TL 3:37+, then why isn't the AH increased (doubled as the 24V 40 AH example) was?

I don't see what I'm missing here

Again, thank you both, so much for your time and effort
Ed
 
Watch again..
They create 2 x 24v, 115Ah pairs, by joining the pairs of batteries in SERIES..2x (2s,1p)
If they were to then join those two pairs together in SERIES , they would have a 48v, 115Ah (4s, 1p) pack again exactly as they had at the start.
once they have a 48v (4s,1p) pack, ANY connection between a +ve and a +ve terminal , or a -ve and -ve, will short out one or more batteries . ! :shock:
Note... you can test/prove this with a couple of old car batteries and some THIN wire to try “touch” connections...and watch the sparks !! :wink:
 
Hillhater said:
Watch again..
They create 2 x 24v, 115Ah pairs, by joining the pairs of batteries in SERIES..2x (2s,1p)
If they were to then join those two pairs together in SERIES , they would have a 48v, 115Ah (4s, 1p) pack again exactly as they had at the start.
Click to expand...
Understood
once they have a 48v (4s,1p) pack, ANY connection between a +ve and a +ve terminal , or a -ve and -ve, will short out one or more batteries . ! :shock:
Click to expand...
OK, sorry to be a PITA, but as stated earlier, this is kinda important. and I want to learn.
So with that thought then, why does that not happen, between terminals, on the 2 x 12V to 2 x 24V pack?

I promise to let this rest, for maybe a later time.

Not sure this is wise....unless 'you' have experience and want to demonstrate.. :lol:
Note... you can test/prove this with a couple of old car batteries and some THIN wire to try “touch” connections...and watch the sparks !!
Click to expand...
Click to expand...
 
once they have a 48v (4s,1p) pack, ANY connection between a +ve and a +ve terminal , or a -ve and -ve, will short out one or more batteries . ! :shock:
OK, sorry to be a PITA, but as stated earlier, this is kinda important. and I want to learn.
So with that thought then, why does that not happen, between terminals, on the 2 x 12V to 2 x 24V pack?
Click to expand...
Im not sure i understand ....” between terminals, on the 2 x 12V to 2 x 24V pack?”...
But basicly, you cannot have 2 or more batteries connected in series AND parallel , at the same time.
Keep it simple to start to understand..
One battery.....
You know you cannot connect the =ve and +ve, or it shorts 12v
2 batteries 12v in series, is the same as one 24 v battery..so you cannot connect the spare +ve and -ve terminals or it will short the 24v unit
2 batteries 12v, in parallel is the same as one 12 v battery of twice the capacity..so you still cannot connect the +ve and =ve terminals or you will short 12 volts
Whatch that video a few times and you will eventually get it. :thumb:
 
you can't hook up series and parallel at the same time with the same set of batteries; this shorts them out and probably starts a fire.


if you ever make a drawing of a pack that shows the plus and the minus of the same battery connected to the same point, you've drawn a pack that is shorted out and has zero volts across that connection, and lots of heat and probably fire, if you build it that way. ;)


to use "series-parallel", you must have as many sets of batteries (or cells) as you want to multiply the ah by.

so let's say you need 48v at 80ah, and you're using 12v 20ah batteries.

to get 48v, you need 4 batteries. that' gets you 48v 20ah.

to get 80ah, at 48v, you need four times the amount of batteries used above.

so you would need 16 batteries in total: four sets of 4 seriesed 12v 20ah batteries, wired in parallel. (there is more than one way to do this wiring, but it still takes 16 of them to do this).

you could wire them so that only the main + and - of each set of 4 seriesed batteries is wired to the main + and - of each other set. that's probably teh msot common way of doing it with 12v lead batteries.

but the msot common way of doing it with individual cells (like the leaf cells inside the modules) is to not connect them as series sets of four first, but rather to connect them as a parallel set of four, where all the + and all the - of the four batteries are connected. then you make three more of these, and then connect the + of the first to the - of the next, and so on, utnil you have four parallel sets of four in series. (it actualy doesn't matter if the series or parallel connections are made first, just that all of them are independent, and not shorting across any batteries).

both of those methods get you a 48v 80ah battery pack.

(edited example to match your initial example voltage and capacity)
 
to do what you *intended* to do in your first image, here is a version that shows what is actually required. it takes 16 batteries, four sets of four.

12-V-TO-48-20-AH-TO-80-AH.png

the actual series connections would probably be done differently for current carrying ability, but the above does effectively give you a 48v 80ah pack built of 12v 20ah batteries.
 
Obviously I can't be putting 16 batteries in this project. I mean I could, but where would I sit?

Somebody said...get bigger batteries. So I went looking.

Here's what I found. Maybe this will satisfy the OHM's law thing.

A picture is worth a 1000 words, right..so here it is.
This diagram is laid out just like in the video, except the values are changed from ( 12V to 24V ) and ( 20ah to 35ah ).

 
my brain is having troulbe tracing the connections, so i redrew it. if yours is teh same as mine, then yes, it will work. if it's not teh same as mine (which is a more conventional way of showing this, and is clearer), then try redrawing yours like mine but with your connections and we'll see if it should work.
2-x-24-V-x-35-ah.png

basically, if you want double the ah, you have ot have double the number of batteries.

think of it this way. wh is the real measure of capacity, not ah, because wh is v x ah.

if you want a 48v 80ah battery, that is 48 x 80 = 3840wh, which with 12v 20ah (240wh) batteries takes 16 of them to do. if you only use four 48v 20ah batteries to do it, no matter how you hook them up, there's still only 48 x 20, or 960wh in them.


anyway, bigger batteries take more space than smaller ones, so you end up using the same (or more) space for the same wh.

for instance, a 35ah 12v battery takes about twice the space of a 20ah 12v battery.

a 24v battery takes about twice the space of a 12v battery.

so a 24v 35ah battery takes about four times the space of a 12v 20ah battery.

meaning, if you use four 24v 35ah batteries, you still end up taking the space (and weight) of about 16 12v 20ah batteries. there's just less wiring between them. ;)

either way, you'll probably really only get about half the capacity out of them that they're rated for, at the currents you'll be using them at. one of the problems with lead.


something else to think about with the lead is that a 12v 35ah battery probably weighs around 30+lbs, at a guess. so a 24v 35ah would be around 60lbs. four of those is 240lbs.

i've seen specs for as little as 22lbs for such a battery, but...in my limited experience the lighter a lead battery is for a given voltage and ah, the less current it can provide without sagging more in voltage, and the less capacity you actually get out of it for that current draw, and the less number of charge/discharge cycles (and calendar time) it lasts before it begins to fail. those may not all be true at the same time for all lead batteries.


that's the problem(s) with lead...it's huge and it's heavy, for what you get out of it. (short life, high weight and volume, low capacity). :(

they're still used in a lot of powerchairs and forklifts simply because the lead *is* heavy and is useful as ballast to keep from tipping over. but there are other solutions in use for those, too.
 
Thanks for the work up amberwolf.

I will have to look at it in the morning. It's just after mid=night, and these old eyes need to shut.

Until later

Thanks and good night sir.
 
I spent about an hour at my local Battery Mart today.

I won't go into detail, just yet.

First, I would like your feedback on the following diagram.

 
i don't follow your wiring, but there is still absolutely zero way you can ever get 80ah *and* 48v from only four 12v 20ah batteries. (pardon the theatrical emphatic line spacing...but this is important)

ever.

if you want 48v from 12v batteries, you need four of those in series. if you only have four 12v 20ah batteires, you can *only* get 48v 20ah.

that's it, (by wiring them in series).

*or*

you can have 12v 80ah (by wiring them in parallel).

but you *cannot* have both 80ah and 48v at the same time from only four 12v 20ah batteries.

if you wire four 12v 20ah batteires in parallel and series at the same time, you short them out and possibly cause a fire, but you still don't get 48v 80ah.



to get 48v and 80ah from 12v 20ah batteries, you

*must*

use sixteen of them, as i showed in that diagram previously, and described in text.

it'd be nice if it worked a different way, but it is impossible to get 48v 80ah from any less than sixteen 12v 20ah batteries.


again, use the wh instead of ah, and it will be clearer.


if you want 48v 80ah, that is 48 x 80 = 3840wh

a single 12v 20ah battery is 12 x 20 = 240 wh.

3840 / 240 = 16 batteries of that size.
 
Just_Ed said:
First, I would like your feedback on the following diagram.

Click to expand...
Ed, Connecting like that will result in sparks and smoke !..
why dont you just get yourself four of those 4 ah , 12v sla batteries ($10 each) or even just 4 little 9 volt PP9 transistor radio/ smoke alarm batteries, a cheap multimeter, and a few small jump leads.
Then you can experiment and replicate some if these connection systems and learn for yourself how this works .
 
His diagram won't go up in smoke but it will be 24v at 40Ahr (2series, 2parallel). To get 48v at 80Ahr with those batteries, it would take 16 of them (4 series, 4 parallel). 16 of those would be pretty heavy. And with lead-acid you need about twice the Ahr compared to lithium to get the same range.
 
Good Morning Everyone.

I worked on this subject, late into the night, yet again. Because of the importance of this matter,
I MUST learn ...'WHY'..., in some cases it works, and in other cases, it won't.

Everyone has been very, very, accommodating, and I am learning (and retaining), much about this subject.
But I do not want to wear out my welcome.

For me, and me alone, I must learn the WHY.

Going forward, I must understand WHY, this works in some instances, and not in other instances.
I have thought about experimenting, but truly, I just need the appropriate explanation, that is alluding the question.

The question has been asked to numerous knowledgeable individuals here, as well as, on AtomicZombie, and at Battery Mart. I have learned, (thanks to everyone's input), HOW the series, and parallel circuits work. I've read and watched how these circuits work, and are completed. Some of the information, from different sources, has been contradicting, which has added to my not being able to say,....I GOT IT !

What I haven't learned, is 'why' the example works to a point, then just stops.

In presenting the diagrams, (which is a communication element), without added verbal explanation,
is exacerbating the misunderstanding, or lack of comprehension.

Physical size matters in this, because of the vehicle design. Another reason for wanting to pursue this subject.

So, as I stated earlier, I do not want to wear out my welcome. I am putting this subject to rest for now.
I have a couple of, other irons in the fire, regarding how to obtain power, for my project.

If anyone wishes to contribute more, I am here to listen, but it must be voluntary.
I thank you for your help, to this point. I am truly grateful.

Regards
Ed
 
the best way to figure it out is using the wh example.

if you want to make a larger battery, you must have enough actual batteries to total that size, in wh (watt-hours).

take one single battery you wish to use. multiply it's volts by it's amp-hours (ah). that's it's wh.

take the voltage of the whole pack you want to have, and multiply it by the ah you want to have. that's the total wh you need.

divide the total wh by the single battery wh, and that is the minimum number of batteries you *must* use to make the pack from.

if you cannot fit that many batteries in the space you have available, or carry that much weight, you must either use a different battery technology that is smaller and/or weighs less, or you must use a lower wh battery pack that does not need as many batteries and thus does not take as much space / weight.

you would have to start with the volume available to put them in, and/or the weight limit for them, and divide that by the same property of the single battery you wish to use, to determine how many you can fit. then you can multiply the wh of that single battery by the number you can fit, and that will be the max wh you can fit in there, with the chosen battery type.
 
perhaps it's clearer if stated this way:

series adds voltages.

parallel adds amps (and amp-hours ah).

but you *cannot* add both *at the same time* for *the same set of batteries*

*ever*.

so you can "stack" batteries to add their voltage.

then you can parallel multiple separate stacks.

but you cannot parallel the batteries already in a stack, or you are shorting them out, and get nothing (other than potential fire).

you cannot series the batteries already paralleled, or you are shorting them out, and get nothing (other than potential fire).


to make it clearer to yourself and others, you should stop drawing your sets in a single line with any kind of "spaghetti" lines connecting anything.

first draw the batteries themselves that you will add in parallel, in a line across left to right, as i did in my drawing showing sixteen batteries. then connect all the positives together. then connect all the negatives together.

then draw the next set(s) of batteries you wish to put in series with those. they *cannot* be the same batteries. then draw the series connections between one row of parallel batteries and the next, from the positive of the bottom one to the negative of the next row up.

if you cannot put the batteries in a grid as i showed, using only straight vertical or horizontal wire lines connecting the terminals, without crossing any other wire lines, then you cannot connect them that way, because you would be shorting them out.

that is how series-parallel (or parallel-series) works.

you can never ever connect the *same* batteries in series *and* parallel at the same time.
 
Just_Ed said:
What I haven't learned, is 'why' the example works to a point, then just stops.
Click to expand...
that's the thing. it doesn't.

series-parallel or parallel-series works perfectly as long as you only connect things in series that you want more voltage from, and then connect multiple sets of those in parallel to get more ah.

or connect things in parallel that you want more ah from, and the connect multiple sets of those in series to get more voltage.


what you seem to be trying to do is do both at the same time, and that is not an example of series-parallel or parallel-series at all, which is why it *seems* to stop the example...but it doesn't, because it isn't the same thing.

i do understand you want to get as much as possible out of what you can fit in the space available, but there is a physical limit to what can be done with specific starting pieces.



so if you start with 12v 20ah batteries, it's going to take sixteen of them to make 48v 80ah. that's it, no way around it. if you want four times the voltage, you need four times the batteries. if you want four times the ah, you need four times the batteries. if you want both at the same time, you need four times four, so sixteen times the batteries.

if you start with 24v 35ah batteries, it's going to take four of them to make a 48v 70ah battery. if you want twice the voltage, you need twice the number of batteries. if you want twice the capacity, you need twice the number of batteries. if you want both at the same time, you need two times two, so four times the batteries.

note that the actual batteries in the second example will be almost four times the size of the batteries in the first example, so the actual volume (and weight) of the total pack will still be almost the same, but the second pack has less total capacity (70ah vs 80ah). there is less wiring, however, so it is simpler to build with less potential points of failure.


if you start with 12v 35ah batteires, it's going to take eight of htem to make a 48v 70ah battery. if you want four times the voltage, you need four times the batteries. if you want twice the capacity, you need twice the number of batteries. if you want both at the same time, you need four times two, so eight times the batteries.
 
My drawings replicate the same exact battery orientation, that is demonstrated in the video. Look at the video, TL 3:40,

https://www.youtube.com/watch?v=9n0oo2hHZv8

The 'only' difference, 'I see', is my drawing has completed the circuit between #2 and #3 battery, thus completing the series, for 48 volts.
The same series connections as in the video, TL 0 :57. The only difference, 'I see' is the orientation of the batteries.

The why part for me...Its all well and good to say my set up will be like the Fourth of July, but with out knowing and understanding, what specific, action (in my drawing) will a cause this short, it doesn't come into focus.

Also, I have just finished an email to https://www.techdirectclub.com/ regarding the use of one of the Nissan Leaf battery packs.

In particular. this one.
https://www.techdirectclub.com/solar-rv-powerwall-nissan-48-volt-battery-g1-lithium-ion-3-5-kwh-66-amh-w-option-and-1-bms-lot-of-7/

We'll see what they have to say.
 
Just_Ed » Jan 29 2020 11:21am

Good Morning Everyone.

I worked on this subject, late into the night, yet again. Because of the importance of this matter,
I MUST learn ...'WHY'..., in some cases it works, and in other cases, it won't.
Click to expand...

I remember in the beginning (before dirt) struggled with the amp issue.

I think but not sure, the series issue is the amps do not increase just the volts. It may seem that you are not getting more watts but you are. Trust the math , think of watts when you are adding batteries together.
Examples:

12V 20ah is 12 * 20 = 240 watts
one battery = 240 watts, two batteries = 480 watts and so on.

2 batteries, parallel: parallel states add the amps. 12V 20 ah is 12*40 = 480 watts. You are good with this because the amps doubled as well as the watts.
2 batteries, series: series states add the volts. 12V 20 ah is 24V 20 ah = 480 watts. Here you may wonder what happen to my amps, they are still there 20 amps per 12 volts.

If you try to double the amps with the volts then 24 volts * 40 amps = 960 watts you can not get 960 from 480, trying will get you fire not watts. If it could be done then the people here would be doing.

Focus on the watts not just amps. think of amps*volts=watts

When you wire batteries together group them in series or parallel first then combine them. Same with the diagrams of battery connections make it look simple. I had to look at your pics for a while to figure out if they would even work. some would and some would not but it was not easy.

I tried to stay out of it but thought another angle would be helpful. Once you get it it will be simple.
12-V-TO-48-20-AH-TO-80-AH-REDO-2.png
I can redo for parallel but it stated 48V but you can not get 80 amps unless you stick to 12V.

in series you only have one connection to each battery post.
With that said you can build another series with four more batteries then parallel connect the two series together. For that find a battery pack build thread.
 
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