Recommendation for 12v TRUE Deep Cycle (not hybrid) Batteries?

[Mastiffman]

Picked up a couple of 6v 208ah Deep Cycle Golf Cart Batteries today for my first FE Project.

Do people use the 6v Deep Cycle batteries becasue they are Cheaper or because they are guaranteed to be True Deep Cycle. As opposed to some 12v Deep Cycles being called Deep Cycle Battereis when they are in fact Hybrids?

 Wouldn't it be better to go with a 12v 200ah+ Battery to save space and enable an easier upgrade to 24v or 48v in the future?

 Your thoughts on this?

[birdhouse]

Ah for Ah, i don't think 12v batts would save you much space.  in order for a battery to be true deep cycle, and have decent Ah ratings, it is going to be big and heavy. 

two 6v min for 12v system
four 6v min for a 24v system
eight 6v min for a 48v system. 

some folks even make up 48v systems out of 2v deep cycle batteries.  (yes 24 of them)

adam

[jvnn]

I'm looking toward a 48V system in the future and I'm good with using eight 6V batteries..

But I have read somewhere in here that a big bank of small batteries can have problems keeping them equalized.
How much of an issue is this?

[ChrisOlson]

Wouldn't it be better to go with a 12v 200ah+ Battery to save space and enable an easier upgrade to 24v or 48v in the future?

12 volt batteries don't save any space.  Our battery bank is 24 Rolls T12-250's (24 volt system with 12 volt batteries).  They are rated at 200 ah @ 20 hrs.  They are twice the size and weight of a 200 ah 6 volt - full of electrolyte they weigh 140-150 lbs.

The main advantage with 12 volt vs 6 volt (or 2 volt) is the number of series connections you have to make with cables.  Our 24 volt bank only has one series connection in it.  Batteries in series can tend to get out of whack if they're not perfectly matched.  And if you have one battery fail prematurely in a series string, usually every battery in the string gets wrecked and has to be replaced just because of one bad one.

Most people use series strings of lower voltage batteries because the batteries are cheaper per kw (typically) than 12 volt.  12 volt batteries are more complicated internally, and more expensive to manufacture.

However, my belief is that the money folks save by using 2 or 6 volt batteries in series ends up being a moot point when they have a battery failure before the bank is due for replacement and end up having to replace an entire string or bank because of it.

Batteries in parallel don't care if they're evenly matched for ah capacity as long as they're all the same voltage.  You can mix old with new, and different ah capacities in parallel strings with no adverse effects on the batteries.  A weak battery in a parallel string simply doesn't pull its share of the load.

So there's various ways to go about building a battery bank.  It depends on what you want, how much maintenance and monitoring you want to do, and how much money you want to spend.

Personally, when we bought our new bank 15 months ago we went with the big 12's.  They were quite expensive (almost $10,000) but if I have a battery go bad at 5 years with two years of the 7 year warranty left I can simply replace it without affecting it or the 5 year old batteries still in the bank.  You can't do that with series batteries, no how no way.
--
Chris

[bob g]

one option is to run a string of 6volt batteries for the 48volts, but keep another 6volt in rotation, much like a spare tire is rotated out of the trunk/boot and put on the front of the car, while one of the rears go into the trunk,, er something like that.
while the spare battery is out of the string, it can be properly serviced, equalized well, logged for specific gravity and all that.
then if sometime in the future you have one fail in the string you will have the spare that is effectively the same age as the rest of the string and you get more mileage out of the string as a result.

i plan on doing this with my string for 48volts, and use anderson connectors to make the interconnects so that i can easily switch out any battery within the string and put the spare in rotation.

if i were to be planning on using batteries deeply, and was starting out, i would go with 8 of the 6volt golf cart batteries to cut my teeth on... well maintained they will return reasonable service and even though not last anywhere near as long as a set of rolls/surrette (my preference)
they work out to be a fair value in $/kw/hr delivered.

fwiw

there are issues with parallel strings of batteries too, most especially if you don't monitor your bank properly and keep them watered, keep the specific gravity by equalization  etc.

i have seen older batteries being the weaker sister coming up to what the regulator/controller sees as fully changed long before the others get there. this of course causes the newer batteries to not break down their sulfation and it gets hard, reducing capacity to near that of the weaker sister.

it also seems like if you have one battery go bad, it usually isn't long before another starts to fail, then another...

having said that, series strings can be a holy nightmare if you let them get out of whack, if you aren't monitoring them regularly you will find one getting lower in specific gravity, and thus lower in capacity, and if you  don't have means to correct the one battery in the string ... well it gets to be a problem.

i had a set of agm 6volts get out of whack, it took many hours of careful equalization (yes you can do it to agm's if you follow the manufactures guidelines carefully), followed by deep cycling, followed by more equalization, wash rinse repeat over about 5 days!

i won't let that happen again!

friends don't let friends let their battery strings get out of whack!



bob g

bob g

[Watt]

We've been down this road before.   

Wouldn't it be better to go with a 12v 200ah+ Battery to save space and enable an easier upgrade to 24v or 48v in the future?

12 volt batteries don't save any space.  Our battery bank is 24 Rolls T12-250's (24 volt system with 12 volt batteries).  They are rated at 200 ah @ 20 hrs.  They are twice the size and weight of a 200 ah 6 volt - full of electrolyte they weigh 140-150 lbs.   

 

The main advantage with 12 volt vs 6 volt (or 2 volt) is the number of series connections you have to make with cables.  Our 24 volt bank only has one series connection in it.  Batteries in series can tend to get out of whack if they're not perfectly matched.  And if you have one battery fail prematurely in a series string, usually every battery in the string gets wrecked and has to be replaced just because of one bad one.   Does that mean you are going to have to replace two t12-250's when one or your batteries fail?

Most people use series strings of lower voltage batteries because the batteries are cheaper per kw (typically) than 12 volt.  12 volt batteries are more complicated internally, and more expensive to manufacture.  I'm not quite sure I understand the logic here.  Can you explain a bit more?

However, my belief is that the money folks save by using 2 or 6 volt batteries in series ends up being a moot point when they have a battery failure before the bank is due for replacement and end up having to replace an entire string or bank because of it. Is this true for all batteries including traction batteries in material handling?  I know for sure we don't replace the entire forklift battery when one cell shorts, opens or looses capacity.  We just replace the cell.  One 85-23 cell delivered is around $400.  When we have multiple cells to replace, in multiple batteries, shipping cost and cell costs are down around $300 bucks a piece.

Batteries in parallel don't care if they're evenly matched for ah capacity as long as they're all the same voltage.  You can mix old with new, and different ah capacities in parallel strings with no adverse effects on the batteries.  A weak battery in a parallel string simply doesn't pull its share of the load.  As bob mentioned, this is not always true.  One case is in the shorted battery cell which brings all batteries in parallel down to it's voltage.  That is if the battery doesn't blow its top off.

So there's various ways to go about building a battery bank.  It depends on what you want, how much maintenance and monitoring you want to do, and how much money you want to spend.

Personally, when we bought our new bank 15 months ago we went with the big 12's.  They were quite expensive (almost $10,000) but if I have a battery go bad at 5 years with two years of the 7 year warranty left I can simply replace it without affecting it or the 5 year old batteries still in the bank.  You can't do that with series batteries, no how no way.  You still have batteries in series.  Am I missing something?

At about $10,000 bucks, that would be about $400 a t12-250 battery. If your in series battery failure hypothesis is correct, that would make it a $800 repair ever time one battery fails.  I calculate a total of 57.6kwh of storage with your 24 batteries at 20 hour rate.  GNB 12-85-19 traction batteries have a retail price of around $3400 buying two would be $6800 bucks and have just a tad better 20 hour rate than your setup.  If one cell fails, at less than $300 bucks a piece with shipping, I know for sure only that one cell will be requiring a replacement when considering a forklift battery.  Granted, that one cell replacement will not be done in a few minutes but can be done very easily with power from adjacent cells and a carbon arc rod.

I believe I will stick with my traction batteries and will buy new ones as my old ones play out.  I have one 36v 935ah @6hr ( surely not that rate anymore ) which is over 20 years old and going as strong as it was 5 years ago when I got it abused.  The only problems have been from me when I dropped this battery and broke two cells internally.  Since I only use 24v of the set, I just tapped a different cell which I kept charged and conditioned.  I also have a 1000ah @ 6hr 24v forklift battery going strong that is over 10 years old.  All of these batteries are in series ( along with numerous 6v gc2 and 12v 8d batteries ) to form a 72v nominal array and as bob mentioned, all I've had to do is keep a steady eye on them ( every few months ) to insure they are properly watered and equalized.  Only 1 time have I had to shut the system down to equalize the older 935ah group.  They've all worked fine for me.  Yes, it is true that batteries in series work better if the series batteries are sized the same but, it is not impossible to work with different size batteries in series.
--
Chris

[Mastiffman]

12 volt batteries don't save any space.  Our battery bank is 24 Rolls T12-250's (24 volt system with 12 volt batteries).  They are rated at 200 ah @ 20 hrs.  They are twice the size and weight of a 200 ah 6 volt - full of electrolyte they weigh 140-150 lbs.

The main advantage with 12 volt vs 6 volt (or 2 volt) is the number of series connections you have to make with cables.  Our 24 volt bank only has one series connection in it.  Batteries in series can tend to get out of whack if they're not perfectly matched.  And if you have one battery fail prematurely in a series string, usually every battery in the string gets wrecked and has to be replaced just because of one bad one.

--
Chris
[quote/]

one option is to run a string of 6volt batteries for the 48volts, but keep another 6volt in rotation, much like a spare tire is rotated out of the trunk/boot and put on the front of the car, while one of the rears go into the trunk,, er something like that.
while the spare battery is out of the string, it can be properly serviced, equalized well, logged for specific gravity and all that.
then if sometime in the future you have one fail in the string you will have the spare that is effectively the same age as the rest of the string and you get more mileage out of the string as a result.

i plan on doing this with my string for 48volts, and use anderson connectors to make the interconnects so that i can easily switch out any battery within the string and put the spare in rotation.


i had a set of agm 6volts get out of whack, it took many hours of careful equalization (yes you can do it to agm's if you follow the manufactures guidelines carefully), followed by deep cycling, followed by more equalization, wash rinse repeat over about 5 days!

i won't let that happen again!

friends don't let friends let their battery strings get out of whack!



bob g

bob g

 Okay, thatnks for the grat input guys. It's Really Appreciated.

[ChrisOlson]

Does that mean you are going to have to replace two t12-250's when one or your batteries fail?

No.  I have two big banks @ 12 volts each.  There is one series connection between the two banks to form the 24 volt power at the bus.  So if one battery goes bad I end up with one bank low on voltage and the other high on voltage under load.  I got dual volt meters monitoring the two banks and if they get out of whack I investigate what is causing it.

The OP wondered about "true" deep cycle 12 volt batteries, and the Rolls T12's are "true" deep cycle with a 7 year warranty.  But they cost twice as much per kW capacity as, say, two marine deep cycle/starting batteries @ 125 ah each.  Two six volt golf cart batteries @ 208 ah each are also less money than one of the T12-250's.  But for my inverter setup, where I need 720 amps to get full surge power from two inverters, it would take too many series strings of 6V batteries in parallel to maintain voltage at the bus.  That's why, I assume, Rolls recommended the T12's for us, since at 720 amps draw at the inverters, each battery only has to deliver 60 amps and it easily maintains 25 volts at the bus with the inverters at 18 kW full surge load (which I use quite often when I'm welding and such).

If I would've used twelve 2 volt batteries, then each battery has to deliver 720 amps, which they can do but they can't maintain voltage at the bus because that 720 amps is flowing thru every single series connection in the bank.  So you end up with too many feet of wire carrying 720 amps.

If I used 6 volt batteries then I'd have to have twelve series strings with 4 batteries in each string (48 batteries) to keep the amp load @ 60 amps per battery.  Once again I got too many feet of wire to maintain voltage at the bus at full load.

Surrette battery recommended what we got for our inverters, and it works flawless with a maximum of 180 amps flowing in any single cable in the battery bank with the inverters pulling 360 amps each at full surge power.
--
Chris

[Watt]

Have you changed the way you are wiring your batteries again since this thread? http://www.anotherpower.com/board/index.php/topic,513.0.html That simple diagram, along with what you have explained as a tap between each two batteries, looks to be a large amount of wire being used. 

[ChrisOlson]

Yes.  Not major, but I eliminated the series bars on the bank and am now making the series connection in the bus.  I had some minor issues with the banks getting slightly out of balance during absorb.  It has had the single series connection in the bus now for six weeks with no problems with balance anymore.

As I stated on that thread on Anotherpower, I'll report back in September on what changes I've made and how it has worked.

As far as wire being used, have you ever tried to deliver 18 kW from a bank with 24 batteries, and maintain nominal voltage at the inverter studs with a 24 volt system and no incoming power from RE sources?  Try it once.  You'll find out real quick what can cut the mustard and what can't.  Hint: dual 4/0 cables don't even come close.
--
Chris

[Frank S]

Chris that sounds ore like a job for duel 500MCM than duel 4/0

[ChrisOlson]

Chris that sounds ore like a job for duel 500MCM than duel 4/0

I'm using 8 parallel feeds from the bank to my SquareD bus and dual 4/0 from the bus to the inverters.  It works with minimal drop at full load.

The thing is, the inverters are rated at 25.0 volts, not 24, for full power output.  At 24.0 volts they'll deliver about 92% rated surge load and I can usually run my Lincoln 225 welder with them (intermittent welding) while simultaneously running the rest of the normal loads in the house and shop.  But if we got the AC unit running, besides the normal loads,  then the voltage has to be above 25 or they won't do it.  And that's at the inverter studs under load.

Most people don't worry about it because they never push their inverters that hard.  But we didn't buy those inverters to just look impressive because of theoretical capacity.  We bought 'em to put out power without having to run a generator.
--
Chris

[Mastiffman]

Chris that sounds ore like a job for duel 500MCM than duel 4/0

I'm using 8 parallel feeds from the bank to my SquareD bus and dual 4/0 from the bus to the inverters.  It works with minimal drop at full load.

The thing is, the inverters are rated at 25.0 volts, not 24, for full power output.  At 24.0 volts they'll deliver about 92% rated surge load and I can usually run my Lincoln 225 welder with them (intermittent welding) while simultaneously running the rest of the normal loads in the house and shop.  But if we got the AC unit running, besides the normal loads,  then the voltage has to be above 25 or they won't do it.  And that's at the inverter studs under load.

Most people don't worry about it because they never push their inverters that hard.  But we didn't buy those inverters to just look impressive because of theoretical capacity.  We bought 'em to put out power without having to run a generator.
--
Chris

 Nice Chris. Sounds like a Truely impressive Resource that you have. Do you happen to have a link to some photos of the entire system? I would love to see it.

[Watt]

As far as wire being used, have you ever tried to deliver 18 kW from a bank with 24 batteries, and maintain nominal voltage at the inverter studs with a 24 volt system and no incoming power from RE sources?  Try it once.  You'll find out real quick what can cut the mustard and what can't.  Hint: dual 4/0 cables don't even come close.
--
Chris

Looks like it may be time for you to move up to 48v Chris. 

Yes, that's why we regularly change out these size cables as it's too small - yet the only thing that will fit the buss bars if you hold your mouth just right.


 
4/0 dlo
350+ dlo
Notice the 530+ dlo which gets really hot!  That 4/0 is some tiny stuff.  Easy to work with also. 


" As I stated on that thread on Anotherpower, I'll report back in September on what changes I've made and how it has worked. "

Darn, right now it's not the bees knees hook up.  We'll just have to wait till September.   

[Mastiffman]

As far as wire being used, have you ever tried to deliver 18 kW from a bank with 24 batteries, and maintain nominal voltage at the inverter studs with a 24 volt system and no incoming power from RE sources?  Try it once.  You'll find out real quick what can cut the mustard and what can't.  Hint: dual 4/0 cables don't even come close.
--
Chris

Looks like it may be time for you to move up to 48v Chris. 

Yes, that's why we regularly change out these size cables as it's too small - yet the only thing that will fit the buss bars if you hold your mouth just right.


 
4/0 dlo
350+ dlo
Notice the 530+ dlo which gets really hot!  That 4/0 is some tiny stuff.  Easy to work with also. 


" As I stated on that thread on Anotherpower, I'll report back in September on what changes I've made and how it has worked. "

Darn, right now it's not the bees knees hook up.  We'll just have to wait till September.   

This might be a silly question... But, isn't there some type of end that you could put on them to allow larger wire than that? Lowering the frequency of wire changes?

[Watt]

This might be a silly question... But, isn't there some type of end that you could put on them to allow larger wire than that? Lowering the frequency of wire changes?

Yes there are DLO terminals.  Connecting the motors to the wire is by DLO crimp terminal.  The VFD's are not stud/compression terminals, they are mostly like your standard breaker.

 

Here is a picture of a crimped end.  The bolt is only used to pull the cable, not for connection.



The VFD connection is designed to take the bare wire and be torqued.  The crimp terminals add resistance.  More heat.

Something similar to this.  Will get a true picture if needed next repair. 





These DLO cables are rated for higher temperatures/voltages compared to house-hold cables.  A larger cable could be used yes but, we are still under the limitations of the connections and terminals.  I am not aware of such a listed terminal or means of connecting a solid terminal into this type connection?  DLO cable is very flexible with the disadvantage of being larger than solid or something like a THHN/WN wire.  The connections used are rated for AL/CU but, to stay within the vibration and heat ratings, this type of cable is all that will meet requirements. 

[ChrisOlson]

Looks like it may be time for you to move up to 48v Chris. 

Actually, the 24 volt works fine.  Our solar runs at about 108-140 volts, depending on temperature of the panels, and the wind turbines run up to 145 volts.  The 48 volt inverters don't have any more surge capacity than the ones we got.

The other thing is that each battery has to deliver the same amps regardless of whether the system is 24 or 48 volt.  As an example, if you have four 12 volt batteries with them arranged series/parallel for 24 volt with a 2,400 watt draw - 2,400 / 24 = 100 amps.  Each battery has to deliver 50 amps of the load (50 x 12 volts = 600 watts per battery).  Configure the same bank with all four batteries in series for 48 volt and every battery still has to deliver the same 50 amps to meet the load.  The only difference is that you got 50 amps going to the inverters instead of 100.  The wiring from the bus to the inverters is easy.  Getting the bank wiring balanced is the hard part and series connections don't help with that because every series connection is handling the full load amps.

48 volt systems are over-rated as to efficiency by people who don't understand battery banks.  And 24 volt is a lot safer to work with when servicing the bank.
--
Chris

[Watt]

Looks like it may be time for you to move up to 48v Chris. 

Actually, the 24 volt works fine.  Our solar runs at about 108-140 volts, depending on temperature of the panels, and the wind turbines run up to 145 volts.  The 48 volt inverters don't have any more surge capacity than the ones we got.

The other thing is that each battery has to deliver the same amps regardless of whether the system is 24 or 48 volt.  As an example, if you have four 12 volt batteries with them arranged series/parallel for 24 volt with a 2,400 watt draw - 2,400 / 24 = 100 amps.  Each battery has to deliver 50 amps of the load (50 x 12 volts = 600 watts per battery).  Configure the same bank with all four batteries in series for 48 volt and every battery still has to deliver the same 50 amps to meet the load.  The only difference is that you got 50 amps going to the inverters instead of 100.  The wiring from the bus to the inverters is easy.  Getting the bank wiring balanced is the hard part and series connections don't help with that because every series connection is handling the full load amps.

48 volt systems are over-rated as to efficiency by people who don't understand battery banks.  And 24 volt is a lot safer to work with when servicing the bank.
--
Chris

I see you don't have 48v so it can't be the bees knees but, when you finally have to go 36kw for surge you can use the same wiring you already have.  Throw a wrench in them batteries and see how safe 24v is.  It'll be just as safe as 48v. 

As far as the OP question, I'd go 12v forklift batteries ( true deep cycle ) if you have a way to move them. 

[ChrisOlson]

Throw a wrench in them batteries and see how safe 24v is.  It'll be just as safe as 48v. 

You can throw a wrench across a 2 volt and melt it.  I'm talking about the voltage and one of the hated chores off-grid folks have endure - servicing the battery bank.  Accidental contact with the conductors on 24 volt will give you a nice tingle but you'll survive it.  48 volt will lay you out deader than a stone.
--
Chris

[Watt]

Throw a wrench in them batteries and see how safe 24v is.  It'll be just as safe as 48v. 

You can throw a wrench across a 2 volt and melt it.  I'm talking about the voltage and one of the hated chores off-grid folks have endure - servicing the battery bank.  Accidental contact with the conductors on 24 volt will give you a nice tingle but you'll survive it.  48 volt will lay you out deader than a stone.
--
Chris

Not a very good argument.  Any voltage can drop the right person deader than a stone.  With any configuration, the right safeguards should be in place. 

[jvnn]

I think I am starting to drink Chris'  kool-aid regarding 12V batteries versus two 6V batteries in series.
I am also thinking maybe a 24V system makes more sense for me given I'm looking at a system roughly as follows;
Grid interactive solar system where I plan to limit the batteries to about 80% DOD
Probably an outback VFX 3524
Battery bank ~ 9 to 12kWH nominal
Solar array ~ 1400 to 1800W nominal

So what think the guru's about the following choices for battery?
Are any of these a better internal design for my plan (IE could potentially last longer)?
8 ea Trojan 27TMX 105AH marine/RV
8 ea Trojan 30XHS 130 AH Marine/RV
8 ea Trojan T 1275 12V Golf Car ~roughly 150AH

Or am I making a mistake here by leaving out other options?
Thanks!

[Watt]

I think I am starting to drink Chris'  kool-aid regarding 12V batteries versus two 6V batteries in series.
I am also thinking maybe a 24V system makes more sense for me given I'm looking at a system roughly as follows;
Grid interactive solar system where I plan to limit the batteries to about 80% DOD
Probably an outback VFX 3524
Battery bank ~ 9 to 12kWH nominal
Solar array ~ 1400 to 1800W nominal

So what think the guru's about the following choices for battery?
Are any of these a better internal design for my plan (IE could potentially last longer)?
8 ea Trojan 27TMX 105AH marine/RV
8 ea Trojan 30XHS 130 AH Marine/RV
8 ea Trojan T 1275 12V Golf Car ~roughly 150AH

Or am I making a mistake here by leaving out other options?
Thanks!

You have not listed a " true " deep cycle battery.  I don't think you understand Chris' " Kool-aid". 

Will the batteries you listed work? Yes, for a while. 

[Mary B]

Okay I have someone over on an amateur radio forum listing golf cart batteries as "hybrid" while I class them as true deep cycle. I am talking the 6 volt 220+ amp hour batteries. Which is correct?

[Mastiffman]

You can throw a wrench across a 2 volt and melt it.  I'm talking about the voltage and one of the hated chores off-grid folks have endure - servicing the battery bank.  Accidental contact with the conductors on 24 volt will give you a nice tingle but you'll survive it.  48 volt will lay you out deader than a stone.
--
Chris

Not a very good argument.  Any voltage can drop the right person deader than a stone.  With any configuration, the right safeguards should be in place.

 Okay, this is what I picked up on Friday from the local Supplier for my "lil' ole" 1kw Starter Systems Battery Bank....

 It's 2awg Copper Welding Wire (they din't have any alluminum) and some 1awg #2 Flex, 3/8" Bolt Lugs as well as some Wire Shrink.

 Is the a Rule of Thumb as far as Length OTHER than Making them all the Identical Length between connections?

[bob g]

how are you planning on attaching those ends?

in my opinion they must be swaged on at the very least, and if you plan on soldering them, a good mechanical connection is the first thing to establish... so a swaging tool is needed.

you can get a good hammer type tool from a decent auto parts store for less than 20 bucks, and it will last for thousands of crimps, alternatively you can do as others have here and buy a pair of bolt cutters,and grind the notch in the jaws to get the crimp you want.
harbor freight has those for about 20bucks or less a pair.

or you can go for a high dollar crimping tool, some of which can set you back a couple hundred bucks or more.

fwiw
bob g

[Watt]

Okay I have someone over on an amateur radio forum listing golf cart batteries as "hybrid" while I class them as true deep cycle. I am talking the 6 volt 220+ amp hour batteries. Which is correct?

Hybrid?  Unless it's Very thick plate cell ( deep cycle ) combined with very thin plate cell ( starting ), I don't believe the word hybrid should be used.  Maybe lithium and lead acid?

What are the ratings of the batteries they are listing?

If you are referring to the deep cycle term: IF the battery has a quarter inch thick set of plates, they are deep cycle and they can be cycled many times before they expand and begin to break apart.

[Watt]

You can throw a wrench across a 2 volt and melt it.  I'm talking about the voltage and one of the hated chores off-grid folks have endure - servicing the battery bank.  Accidental contact with the conductors on 24 volt will give you a nice tingle but you'll survive it.  48 volt will lay you out deader than a stone.
--
Chris

Not a very good argument.  Any voltage can drop the right person deader than a stone.  With any configuration, the right safeguards should be in place.

 Okay, this is what I picked up on Friday from the local Supplier for my "lil' ole" 1kw Starter Systems Battery Bank....

 It's 2awg Copper Welding Wire (they din't have any alluminum) and some 1awg #2 Flex, 3/8" Bolt Lugs as well as some Wire Shrink.

 Is the a Rule of Thumb as far as Length OTHER than Making them all the Identical Length between connections?

I think I understand your question.

If you only have batteries in series, your series wires do not have to be the same length. 
 
Rule of Thumb?

Keep the wires as short as possible.
Insure wires are sized correctly.
Number of connections should be kept to a minimum.

[Mastiffman]

how are you planning on attaching those ends?

in my opinion they must be swaged on at the very least, and if you plan on soldering them, a good mechanical connection is the first thing to establish... so a swaging tool is needed.

#1 you can get a good hammer type tool from a decent auto parts store for less than 20 bucks, and it will last for thousands of crimps, alternatively you can do as others have here and buy a pair of bolt cutters,and grind the notch in the jaws to get the crimp you want.
harbor freight has those for about 20bucks or less a pair.



or you can go for a high dollar crimping tool, some of which can set you back a couple hundred bucks or more.

fwiw
bob g

 This is what I was planning on doing. I asked the gentlmen at the retail counter when I got the wire and lugs and he mentioned the Hydrolic Crimper. That's not in my budget. So the hammer Type sounds the most economical. I doin't have a Bench Grinder so the bolt cutters are out of the question as well.

[Mary B]

He is calling these hybrid http://www.usbattery.com/usb_us2200xc.html

Okay I have someone over on an amateur radio forum listing golf cart batteries as "hybrid" while I class them as true deep cycle. I am talking the 6 volt 220+ amp hour batteries. Which is correct?

Hybrid?  Unless it's Very thick plate cell ( deep cycle ) combined with very thin plate cell ( starting ), I don't believe the word hybrid should be used.  Maybe lithium and lead acid?

What are the ratings of the batteries they are listing?

If you are referring to the deep cycle term: IF the battery has a quarter inch thick set of plates, they are deep cycle and they can be cycled many times before they expand and begin to break apart.

[Watt]

He is calling these hybrid http://www.usbattery.com/usb_us2200xc.html

Okay I have someone over on an amateur radio forum listing golf cart batteries as "hybrid" while I class them as true deep cycle. I am talking the 6 volt 220+ amp hour batteries. Which is correct?

Hybrid?  Unless it's Very thick plate cell ( deep cycle ) combined with very thin plate cell ( starting ), I don't believe the word hybrid should be used.  Maybe lithium and lead acid?

What are the ratings of the batteries they are listing?

If you are referring to the deep cycle term: IF the battery has a quarter inch thick set of plates, they are deep cycle and they can be cycled many times before they expand and begin to break apart.

If I had to guess Mary, my guess would be the same old battery with a small percentage plate length increase ( if at all - at the 25a/h rate, that comes out to a 200a/h battery which I'm sure is to 1.75v per cell ).  More capacity but I doubt they have added any extra plate thickness to add durability and more cycles.

[Mary B]

Their own literature says: "Our plates are the thickest in the business" http://www.usbattery.com/usb_images/usb_golf_fly_2a_08.pdf

[Watt]

Their own literature says: "Our plates are the thickest in the business" http://www.usbattery.com/usb_images/usb_golf_fly_2a_08.pdf

That's what that say.

One way to settle it, cut one open!

I guess a .0000000000001" is thicker. 

Don't know what to say but, I have some old 6v US batteries that lasted for ever.  Only thing that killed them was me. 

Thing is, those look like the rest and I just can't see through them.  The capacity doesn't impress me but, maybe the cost per a/h is the difference? 

[bob g]

what sort of pricing can you get on those, i wouldn't be afraid of them
if they are competitive with the trojan equivalent in price.

they look to be a decent entry level deep cycle battery and not one of those wannabe hybrid marine types.

perhaps one could call their engineering dept and find out how thick the plate really are?

i am thinking if they are anywhere around .170" or better then they ought to have a reasonably competitive lifespan.

my bet is a well cared for set of these will probably last as long as a poorly managed set of expensive batteries at a fraction of the cost.

some years ago, using sandia labs test results i did a cost analysis of various deep cycle batteries, everything from the t105 trojan to the 5000 series rolls surrette. my findings came down to if you keep them maintained properly all of the various deep cycle batteries work out to being very close in cost per kw/hr delivered over their lifespan. the difference was so close that i gave me pause and made me reconsider some of the lessor expensive batteries out there.

i did not factor in shipping costs, or added labor in swapping out a cheaper set 2-4 times during the life of a very expensive set, but on a small system and if you are close to a supplier it comes down to careful consideration as to which is a better buy all things considered.

also if you go with a more reasonable priced battery to start with, you can learn the hard lessons without risking as much money. if you do your research you can learn on them and still get very decent life out of them, and when they are done you can then decide whether to go the same route or step up with confidence to an expensive set knowing you have the knowledge needed to get maximum life out of them.

fwiw

bob g