Most efficient method to limit voltage to a motor controller. 1

[Skogsgurra]

A switcher can work. Do not try zeners or linear regulators, they will get very hot (around 150 W to burn). The best way is to use three six volt batteries or one 12 V and one 6 V.

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[LionelHutz]

I am still interested in outcome of the series-parallel debate

What debate? Your description of a series connection as being series/parallel is wrong.

Your drawing is also all wrong. The top picture is a series connection. The bottom arrangement is a complete mess. It basically shows the 2 right batteries connected in parallel to provide 6V output. The left 2 are also connected in parallel but the negative terminals are not connected to the "outside world" and those batteries won't be used for anything.

http://lmgtfy.com/?q=series+parallel

 

[ccjersey]

I have seen 4 batteries connected in a so called "series-parallel" arrangement.

This consisted of 2 pairs of 6 volt batteries, each pair connected in series for 12 volts and then the two series groups connected in parallel to supply 12 volts to the load (starter).

This was in 1970's heavy trucks. On some the 4 batteries were all in one battery box, on the others, there was one pair on each side of the truck.

 

[Skogsgurra]

The battery experts are obviously in structural and agriculture - and their expertise stems from 1970

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[ScottyUK]

Gunnar, that must be a typo. You mean 1097.


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If we learn from our mistakes I'm getting a great education!

 

[172heavy]

http://www.accessconnect.com/images/batteries_series_parallel.jpg

Apparently my terminology was not accurate, the link above is a diagram from google as one of you helpful EEs suggested. This is what I was taught in school to be a series parallel circuit.

I don't mind being wrong but I don't like to be ridiculed for asking a question. I didn't realize that electrical engineers were above a simple discussion.

I am quite sure none of you would be so bold. I would love to sit face to face and have this same discussion with any one if you.

To those of you who are more interested in helping than getting offended because someone questioned your written word, I appreciate your help.

 

[Skogsgurra]

What about just accepting that you have things to learn? It is your stubborn "Still, I am right" attitude that irritates more than your lack of knowledge.

What you show is a parallel-series arrangement - no doubt. But it is not possible to "parallel-series" connect two batteries as you suggested.

Just leave it there and buy controllers that work with the supply voltage you have got.

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[MikeHalloran]

That is indeed a series parallel circuit, but it is not equivalent to the series circuit (comprising two, not four, batteries) that you erroneously characterized as series parallel.

To sort of answer that question, from where the discussion went off the rails, yes you can connect a 12V battery and a 6V battery in series to get 18 volts. It works better if the cells are all similar, i.e. same A-H rating and same chemistry, so it would be better to connect 3 identical 6V batteries in series to get an 18V battery. If you do that, you will need an 18V charger.



Mike Halloran
Pembroke Pines, FL, USA

 

[waross]

Yes that is a series parallel arrangement. Now google series parallel starting circuits.
When engine people are talking about a series parallel system, they are referring to the switching arrangement via a "Series-Parallel Switch" that provides 24 Volts for starting. Two issues that confuse each other.
1/ Connecting two 6 Volt batteries in series for the equivalent of a 12 Volt battery.
2/ Connecting two 12 Volt batteries in series to provide 24 Volts for starting.
At a time when money was tighter and batteries often failed because one cell had gone open prematurely, it was cheaper to change out a 6 Volt battery than a 12 Volt battery. Also large 6 Volt batteries were readily available in most areas. Large 12 Volt batteries were not nearly as common when this system was originally supplied.
Yes, I know, 8D batteries were probably available but these would be expensive and heavy overkill, especially when the battery had to be replaced because of one failed cell.
Back in the 40's when these systems came into use, 12 Volt batteries were found to be inadequate for the dependable starting of large diesel engines. Given the rougher roads, light bulb technology was not adequate to supply filaments that were dependable at 24 Volts. (At a given wattage a 12 volt filament is much heavier and stronger than a 24 Volt filament.)
To address these issues the series parallel switch was developed to provide 24 Volt starting and the use of 12 Volt lamps and accessories.
At this time, (1940's most North American cars used 6 Volt batteries and 6 volt battaries were available almost anywhere. Hence the use of 2 6 Volt batteries in place of one 12 Volt battery.
Last week I was asked to check an old 4x6Volt system to see if the batteries were connected properly. Yes Gunnar, the truck is in agricultural service. grin

Bill
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"Why not the best?"
Jimmy Carter

 

[172heavy]

I purchased to correct controllers as suggested by someone early on.

I do realize that I have a lot to learn which is awesome because learning is my favorite part about the engineering profession. I learn something on every project that I take on.

The reason I posted the drawing is that I wanted to make sure I was aligning my understanding of the terminology with a proper drawing.

Skagsurra or what ever you name is, the comment about all of the battery experts being in the structural or ag disciplines is what pissed me off, just because someone asks a question or try's to point out their point of view doesn't mean that they consider themselves experts. I pointed these examples out not as arguments or to challenge your knowledge but in hopes that you or someone would maybe explain the error that I was making to me. Some of the members here did exactly that such a waross and a few if the other members.

Anyway my problem has been solved so again I say thank you.

 

[Skogsgurra]

Hmm.. My handle can easily be copied and pasted in case you have a problem with it.

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[LionelHutz]

As an engineer, you should have the capability of performing a simple task such as Google search so you understand the terminology, instead of posting back multiple times about what you were taught or what you think you understood.

 

[waross]

Series parallel terminology. Simple but:
Series parallel may be passive or active (for want of better terms). Four 6 Volt batteries connected for 12 Volts would be a passive series parallel application. This is the application that electrical circuit people may be most familiar with.
In automotive applications a switch (a series parallel switch) that connects 12 Volt batteries in either series or parallel would be an active series parallel application. This is the series parallel application that automotive people may be most familiar with.
Although not as common now as in years past, some truck manufacturers used four 6 Volt batteries in a passive series parallel connection for 12 Volt service and reconnected them all in series with an active series parallel switch for 24 Volt starting.

Bill
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"Why not the best?"
Jimmy Carter