Managing 12 Volts H Barre

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Managing 12 Volts H Barre

Postby Dee Bee » Sun Nov 27, 2005 11:21 pm

Have any of you read Managing 12 Volts: How to Upgrade, Operate, and Troubleshoot 12 Volt Electrical Systems (Paperback) by Harold Barre

It is a great book. The information in this book is a basic but thorough education in the total management of a 12V system in a car, boat or RV. It is a comprehensive reference that contains clear tables, diagrams and illustrations, showing you how to use and maintain a 12V system.

I found it in the public library. But it is a must buy if you really want to know the fundamentals. The more you read it the better you will understand all aspects of a 12 V system. This book will teach you how batteries, alternators, chargers, switches, sensor, actuators, solenoids, and electrical circuits actually work. With the information in this book you can make intelligent decisions when selecting or operating a system.

It helped me when I built the electrical system for my Zephyr Teardrop.
http://www.nfdc.net/home/cbdb/Teardrop%20Electric.htm

The other information I found most helpful was from 12 Volt Side of Life and Battery Information
http://www.ccis.com/home/mnemeth/12volt/12volt.htm

And from the Poop Sheet on Batteries by Phred Tinseth
http://www.phrannie.org/battery.html

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Postby GeorgeTelford » Mon Nov 28, 2005 4:17 am

Hi Dee Bee

If you read both of the information links that are posted and made notes from each, you will see that they contradict each other, if you added a third column for your book you will find more contradictions, then you will need a fourth column for when they contradict themselves. Amazingly the first Infomation site posted "the battery side of life" even manages to contradict itself in a big and obvious way.....

The next thing is that they are both wrong although they do contain some accurate infomation, the only problem is, is that the amateur (and many Pro's) will not spot the error's.

I got to 50+ error's before I gave up/lost track.

Image

The Grey batteries on the left, because the positive and negative are connected to the same battery (top left in diagram) then this will discharge and charge at a different rate to the bottom battery, the correct way to wire multiple batteries in a 12 Volt bank would be to take Positive from top battery and negative from the bottom battery, then the discharge and charging will be much closer across each individual battery.


The first (site) does a pretty good job of describing why a good 3-4 stage charger should be used, but doesnt mention that if you leave the (standard alternator charging in place) then we will lose charge when driving around, ie our super dooper charger gets the batteries up to 100% and then we drive round with the house batteries in line with vehicle battery, so our 100% house battery starts passing power to the starter to try and find a common level, net result after a few hours both batteries are about 70% max of full.

DB this is about the information on the sites and not a dig at you for posting the links.
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Thanks

Postby Dee Bee » Mon Nov 28, 2005 8:02 am

GeorgeTelford wrote:Hi Dee Bee

If you read both of the information links that are posted and made notes from each, you will see that they contradict each other, if you added a third column for your book you will find more contradictions, then you will need a fourth column for when they contradict themselves. Amazingly the first Infomation site posted "the battery side of life" even manages to contradict itself in a big and obvious way.....

The next thing is that they are both wrong although they do contain some accurate infomation, the only problem is, is that the amateur (and many Pro's) will not spot the error's.

I got to 50+ error's before I gave up/lost track.

Image

The Grey batteries on the left, because the positive and negative are connected to the same battery (top left in diagram) then this will discharge and charge at a different rate to the bottom battery, the correct way to wire multiple batteries in a 12 Volt bank would be to take Positive from top battery and negative from the bottom battery, then the discharge and charging will be much closer across each individual battery.


The first (site) does a pretty good job of describing why a good 3-4 stage charger should be used, but doesnt mention that if you leave the (standard alternator charging in place) then we will lose charge when driving around, ie our super dooper charger gets the batteries up to 100% and then we drive round with the house batteries in line with vehicle battery, so our 100% house battery starts passing power to the starter to try and find a common level, net result after a few hours both batteries are about 70% max of full.

DB this is about the information on the sites and not a dig at you for posting the links.


Thanks George!

I am not trained in electrical systems by trade or profession. I have "taught myself" by reading and so I have assumed the authors info was accurate. I know that some forum members have certification in NEC. I appreciate thier guidance and feed back. The exchange in helpful info is what I like about this forum.

I see what you mean about the wiring connection in your comment about the diagram. I'll make the changes to my system. Thanks again!

Can you recommend sources of accurate information for builders like me?


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Postby GeorgeTelford » Mon Nov 28, 2005 8:49 am

Hi Deebee

Your system looks great, the only 3 things I would have done differently,

1. Gel batteries expensive and no (useful) advantage over lead acid and a few disadvantages, a) Expensive b) Require slower charging.

2. wiring of batteries as mentioned above.

3. would have included a proper charger/power supply, convertors do not really charge batteries well, I tested UK versions and they take weeks to get a battery up to the early 90's % of charged. under normal use they only get the battery to around 70-80% charged. if you dont use the last 50% and you only start at 70% that gives you about 20 Ah from a 100 Ah battery.

But as with all things it depends on your usage, if you stay mainly on hook up sites you will never run out, for wild camping really depends on your usage of lights and fan. The led Light would run forever, but with judicious use of the fan and normal lights you could enjoy many days camping in the boonies.

If you build another Led light three leds in a series with a single resistor would be optimal (depending on their rating) Leds become more conductive as they warm up having three in parrallel can lead to inconsistancies and premature failure (will still last a long while)
Even a designer of robotic devices that I worked with years back made the same error.

the other thing is that adding leds in series lowers the need for resistors and therefore you get more light for same power (Resisters obviously burn up power as heat to lower the voltage, led will provide light instead oif wasteful heat)
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Postby Dee Bee » Mon Nov 28, 2005 12:04 pm

GeorgeTelford wrote:Hi Deebee

Your system looks great, the only 3 things I would have done differently,

1. Gel batteries expensive and no (useful) advantage over lead acid and a few disadvantages, a) Expensive b) Require slower charging.

2. wiring of batteries as mentioned above.

3. would have included a proper charger/power supply, convertors do not really charge batteries well, I tested UK versions and they take weeks to get a battery up to the early 90's % of charged. under normal use they only get the battery to around 70-80% charged. if you dont use the last 50% and you only start at 70% that gives you about 20 Ah from a 100 Ah battery.

But as with all things it depends on your usage, if you stay mainly on hook up sites you will never run out, for wild camping really depends on your usage of lights and fan. The led Light would run forever, but with judicious use of the fan and normal lights you could enjoy many days camping in the boonies.

If you build another Led light three leds in a series with a single resistor would be optimal (depending on their rating) Leds become more conductive as they warm up having three in parrallel can lead to inconsistancies and premature failure (will still last a long while)
Even a designer of robotic devices that I worked with years back made the same error.

the other thing is that adding leds in series lowers the need for resistors and therefore you get more light for same power (Resisters obviously burn up power as heat to lower the voltage, led will provide light instead oif wasteful heat)


Thanks again George for the feed back...

1) I used Gel batteries because they were given to me. Yes they are expensive.

2) I will make tyhe wire changes as discussed

3) I have a proper charger for the batteries. It is a Battery Tender and pictured here. Image
It is specifically designed to charge Gels. I am told Gels require a different bulk / float charge than acid ones. So I bought the Battery Tender for this purpose.
http://batterytender.com/selection_guide.php?osCsid=5a74872747ffeb9248c0ec0330b6681e

I agree with you about LED lights...resistors work but the trade of is energy wasted as heat. Doesn't make sense as a conservation move.

I would do it differently if I made another one.

Great feed back

Dee Bee
Last edited by Dee Bee on Mon Nov 28, 2005 9:57 pm, edited 1 time in total.
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Postby GeorgeTelford » Mon Nov 28, 2005 4:29 pm

Hi Deebee

I was thrown a bit by seeing the battery convertor and also seeing it in the photographs and diagrams.


How do you use the convertor? I am guessing by the switch layout that you switch out the batteries and use the convertor to power the tear? and then I assume use the Batterytender Plus to charge the batteries?

Gels have to be charged at a lower voltage than straight lead Acid and take longer to charge because of it.

I have a 10 X 110 ah battery bank for a total of 1100 AH battery bank, in theory I could use a 220 A charger, but my reasoning was that as long as I could recharge 50% of total in under 1 day it would be good enough and therefore I got a Sterling 30 Amp 4 Stage Charger, this can put 550 AH back into the bank in under 1 day, so then a week plus in the boonies with mains power via invertor could be recharged in 1 day in a campsite, being a Sterling unit its good as a power supply too..
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Converter

Postby Dee Bee » Mon Nov 28, 2005 7:54 pm

GeorgeTelford wrote:Hi Deebee

I was thrown a bit by seeing the battery convertor and also seeing it in the photographs and diagrams.


How do you use the convertor? I am guessing by the switch layout that you switch out the batteries and use the convertor to power the tear? and then I assume use the Batterytender Plus to charge the batteries?


I use the homemade converter to power my 12v DC light system. I didn't want to have 12v and then a duplicate 110 AC lighting system. My homemade switching panel controls the source of 12 v DC Either batteries or converter. I can monitor the voltage and select from either source fropm inside the TD cabin. The batery tender only plugs into shore power.


Thanks for the interest


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Postby Dee Bee » Fri Dec 02, 2005 11:21 pm

GeorgeTelford wrote:Hi Dee Bee

If you read both of the information links that are posted and made notes from each, you will see that they contradict each other, if you added a third column for your book you will find more contradictions, then you will need a fourth column for when they contradict themselves. Amazingly the first Infomation site posted "the battery side of life" even manages to contradict itself in a big and obvious way.....

The next thing is that they are both wrong although they do contain some accurate infomation, the only problem is, is that the amateur (and many Pro's) will not spot the error's.

I got to 50+ error's before I gave up/lost track.

Image

The Grey batteries on the left, because the positive and negative are connected to the same battery (top left in diagram) then this will discharge and charge at a different rate to the bottom battery, the correct way to wire multiple batteries in a 12 Volt bank would be to take Positive from top battery and negative from the bottom battery, then the discharge and charging will be much closer across each individual battery.


The first (site) does a pretty good job of describing why a good 3-4 stage charger should be used, but doesnt mention that if you leave the (standard alternator charging in place) then we will lose charge when driving around, ie our super dooper charger gets the batteries up to 100% and then we drive round with the house batteries in line with vehicle battery, so our 100% house battery starts passing power to the starter to try and find a common level, net result after a few hours both batteries are about 70% max of full.

DB this is about the information on the sites and not a dig at you for posting the links.


George Would this be better?

Image
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Postby GeorgeTelford » Sat Dec 03, 2005 4:26 am

Hi Deebee

Yes thats the way, both batteries will charge and discharge much more evenly now.
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