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04-01-2020, 01:40 PM
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#1
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New Member
Join Date: Mar 2020
Location: Iowa
Posts: 9
Year: 2002
Chassis: 3800
Engine: T444E
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6v vs 12v Batteries
What are the pluses/minuses for 6v compared to 12v batteries?
2 6v batteries (200 AH ea) ran in series VS
2 12v batteries (200 AH ea) ran in parallel
Both 12 volt 400 AH systems.
Thanks!
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04-01-2020, 02:05 PM
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#2
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Bus Crazy
Join Date: May 2016
Location: Grayson County, VA
Posts: 1,428
Year: 1996
Coachwork: Amtran
Chassis: International
Engine: DT466
Rated Cap: 65
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Quote:
Originally Posted by Cladano
What are the pluses/minuses for 6v compared to 12v batteries?
2 6v batteries (200 AH ea) ran in series VS
2 12v batteries (200 AH ea) ran in parallel
Both 12 volt 400 AH systems.
Thanks!
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I think I remember reading that the 6v golf cart batteries have beefier plates and are supposed to be more robust, more charge cycles and whatnot. That's why I went with them. There's some pretty sharp folks on here that would know more about it, hopefully they'll chime in.
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04-01-2020, 02:30 PM
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#3
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Bus Geek
Join Date: Apr 2012
Location: So Cal
Posts: 3,226
Year: 1935
Coachwork: Superior
Chassis: Chevy
Engine: 317 ci/tid / Isuzu
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I'd go with 6 volt deep cycle. If you choose 12 volt be sure it is a deep cycle battery. Standard car batteries are designed to be slightly discharged in a short burst and then rapidly recharged. The deep cycle batteries are designed to be discharged slowly and re charged slowly. A standard car battery won't have a very long life treated like a deep cycle.
Jack
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04-01-2020, 03:09 PM
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#4
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Bus Nut
Join Date: Jul 2016
Location: Western Oregon
Posts: 876
Year: 1995
Coachwork: Blue-Bird
Chassis: TC RE 3408
Engine: 5.9 Cummins 12V Mechanical/Allison MT643
Rated Cap: Blue-Bird says 72 pass.
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I am not the expert you are waiting for, but I think the last sentence of the OP is incorrect.
Wouldn't the 2 6V batteries wired in series add up to 200 Ah instead of 400 Ah?
I think you would have to use 4 6V batteries to get 400 Ah. If I am correct, two pairs should be wired in series and then the pairs would be connected in parallel. But like I say, I am not an expert.
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04-01-2020, 04:07 PM
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#5
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Bus Crazy
Join Date: May 2017
Location: Athens, TN
Posts: 1,574
Year: 1999
Coachwork: Amtran
Chassis: International RE
Engine: International T444e
Rated Cap: 76
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Quote:
Originally Posted by Cladano
2 6v batteries (200 AH ea) ran in series VS
2 12v batteries (200 AH ea) ran in parallel
Both 12 volt 400 AH systems.
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No, the 2x6v in series bank is 200Ah, the 2x 12v in parallel bank would be 400Ah. Aside from that, I'm not sure the merits of each. I would guess that the series bank needs to be balanced as well.
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04-01-2020, 04:35 PM
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#6
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Bus Geek
Join Date: Nov 2016
Posts: 2,775
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Yes a bank composed of good 6V GCs is much more robust than 12V units, and not more expensive.
These are the best value by far, in the world:
Duracell (actually Deka/East Penn) FLA deep cycle golf cart batteries, 2x6V, around $200 per 200+AH @12V pair from BatteriesPlus or Sam's Club. NAPA relabels it here: https://www.napaonline.com/en/p/NBP8144 Deka self-labeled also sold at Lowes.
No balancing required other then paralleled units should first be at the same SoC roughly before connecting.
Afterwards, do a few equalizing cycles first, and then keep the C-rate low for the first dozen cycles to break them in.
Can last 6-8yrs cycled daily, still 80% SoH, if cared for properly.
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04-01-2020, 05:40 PM
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#7
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New Member
Join Date: Mar 2020
Location: Iowa
Posts: 9
Year: 2002
Chassis: 3800
Engine: T444E
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Sounds like you guys are saying that if you have 2 6V batteries in a series (as to get a 12V system) you don't add the combined AH's of those batteries??
So 2 200AH batteries wouldn't combine and give you 400AH? You would only get 200AH?
I've heard a lot of good things about the GC2 batteries but it would be a tough sell (if wanting a 12v system) if I have to have 4 200AH 6V batteries to get the same AH as 2 200AH 12V batteries?
Sorry this stuff is hard to get into my thick head lol
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04-01-2020, 05:50 PM
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#8
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Bus Crazy
Join Date: Feb 2015
Location: Cincinnati, Ohio
Posts: 1,001
Year: 2000
Coachwork: Blue Bird
Chassis: International
Engine: TE 444
Rated Cap: 12
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amps are related to volts, so a 6 volt 200 AH battery is 1200 watt hours and a 12 volt 200AH battery is 2400 watt hours, it would be easier to explain to the average person if batteries were rated in watt hours because you could then just add up the watt hour numbers to get your capacity then you could divide by volts of your system to get amp hours if you wanted that
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04-01-2020, 06:03 PM
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#9
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Bus Geek
Join Date: Nov 2016
Posts: 2,775
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Quote:
Originally Posted by Cladano
Sounds like you guys are saying that if you have 2 6V batteries in a series (as to get a 12V system) you don't add the combined AH's of those batteries??
So 2 200AH batteries wouldn't combine and give you 400AH? You would only get 200AH?
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Series connected doubles voltage, Ah stays tge same.
Paralleling doubles Ah, V stays the same.
Need two pair 2P2S to double both.
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04-01-2020, 06:13 PM
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#10
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Bus Nut
Join Date: Jul 2016
Location: Western Oregon
Posts: 876
Year: 1995
Coachwork: Blue-Bird
Chassis: TC RE 3408
Engine: 5.9 Cummins 12V Mechanical/Allison MT643
Rated Cap: Blue-Bird says 72 pass.
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And that is why 6 volt batteries are often or usually used in multiples of 4, right?
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04-01-2020, 06:25 PM
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#11
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Bus Geek
Join Date: Nov 2016
Posts: 2,775
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If you want 400+Ah @12V, or 200Ah @24V, yes.
Otherwise, it depends.
Once you get past 700Ah better to go to higher capacity cells @2, 3 or 4V though, too much paralleling is not optimal.
Many banks you need a forklift or crane to move the cells around
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04-01-2020, 07:24 PM
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#12
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Bus Nut
Join Date: Jul 2019
Location: Suburbs of Winterset, OH
Posts: 802
Year: 2005
Coachwork: Thomas
Chassis: FS65
Engine: Mercedes 6.4L
Rated Cap: just the 2 of us
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About 17 years ago, I had a JET Electric car...basically it was a 1980 Plymouth Horizon TC-3 that was professionally converted to run on electric (battery) power. It had 20, 6 volt deep cycle batteries. I'm sure the engineers used 6 volt for good reason. If it was durability or increased range, I don't know. I do remember that the car was down right scary at hwy speeds...it was fine around town though.
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04-01-2020, 07:56 PM
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#13
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Skoolie
Join Date: Oct 2016
Location: Motor City
Posts: 146
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Quote:
Originally Posted by Cladano
I've heard a lot of good things about the GC2 batteries but it would be a tough sell (if wanting a 12v system) if I have to have 4 200AH 6V batteries to get the same AH as 2 200AH 12V batteries?
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What 12 volt 200 AH battery are you looking at? That would be a very big battery, and not cheap, right?
It's REALLY hard to beat the $/AH of Sams/Costco golf cart batteries.
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04-01-2020, 08:21 PM
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#14
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Bus Nut
Join Date: Jul 2016
Location: Western Oregon
Posts: 876
Year: 1995
Coachwork: Blue-Bird
Chassis: TC RE 3408
Engine: 5.9 Cummins 12V Mechanical/Allison MT643
Rated Cap: Blue-Bird says 72 pass.
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I am looking at these: https://www.batteriesplus.com/productdetails/SLIGC115
Just two, for lights, fans, and water pump. They will be charged from the alternator when the engine is running. No solar, that will come later, and involve another bank of batteries.
These Duracell branded batteries come in more powerful sizes, but those are too big to fit in my OEM battery box with the starting batteries. These 230 Ah will fit nicely. I'm not concerned about the extra weight because I can see that there were 2 very large batteries in there at one time. Much larger than the batteries that came with the bus.
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04-01-2020, 08:26 PM
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#15
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Bus Geek
Join Date: Nov 2016
Posts: 2,775
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Quote:
Originally Posted by ennonne
It's REALLY hard to beat the $/AH of Sams/Costco golf cart batteries.
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The Costco ones are not nearly as good as the Deka/Duracell.
Made by JCI/Johnson, meh. Avoid
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04-01-2020, 08:28 PM
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#16
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Bus Geek
Join Date: Nov 2016
Posts: 2,775
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Quote:
Originally Posted by gs1949
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That's them.
Don't buy the AGM version
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04-01-2020, 09:05 PM
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#17
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Bus Crazy
Join Date: May 2017
Location: Athens, TN
Posts: 1,574
Year: 1999
Coachwork: Amtran
Chassis: International RE
Engine: International T444e
Rated Cap: 76
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Quote:
Originally Posted by Cladano
Sorry this stuff is hard to get into my thick head lol
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I think it makes the most sense to track battery capacity in watt hours (energy).
Watts = Volts * Amps. Watts represent power.
Watt Hours = Watts * Hours. Wh represents energy.
This helps you understand how much energy your batteries can hold regardless of configuration/voltage. Having 100Wh of energy means you can sustain a 1W power draw for 100 hours, or 10W power draw for 10 hours, or 100W power draw for 1 hour, and so on.
Lets say you have two 6V, 100Ah batteries.
If you wire the two 6V batteries in series, you get:
12V * 100Ah = 1200Wh.
If you wire the two 6V batteries in parallel, you get:
6V * 200Ah = 1200Wh.
Its the same capacity in either case, as you have the same number of batteries.
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04-01-2020, 09:49 PM
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#18
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Bus Nut
Join Date: Jul 2016
Location: Western Oregon
Posts: 876
Year: 1995
Coachwork: Blue-Bird
Chassis: TC RE 3408
Engine: 5.9 Cummins 12V Mechanical/Allison MT643
Rated Cap: Blue-Bird says 72 pass.
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Quote:
Originally Posted by john61ct
That's them.
Don't buy the AGM version
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I definitely won't. How could I get my hydrometer in there without drilling a few holes?
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04-01-2020, 10:02 PM
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#19
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Bus Geek
Join Date: May 2016
Location: Eastern WA
Posts: 6,401
Year: 2002
Coachwork: Bluebird
Chassis: All American RE (A3RE)
Engine: Cummins ISC (8.3)
Rated Cap: 72
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Quote:
Originally Posted by gs1949
I am not the expert you are waiting for, but I think the last sentence of the OP is incorrect.
Wouldn't the 2 6V batteries wired in series add up to 200 Ah instead of 400 Ah?
I think you would have to use 4 6V batteries to get 400 Ah. If I am correct, two pairs should be wired in series and then the pairs would be connected in parallel. But like I say, I am not an expert.
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Well you get to be the expert today.
You are correct and the first person to catch it.
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04-02-2020, 05:49 AM
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#20
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Bus Geek
Join Date: Nov 2016
Posts: 2,775
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Wh are good for when comparing systems that operate at different voltages.
But when actually measuring energy capacity, utilization, consumption or deterioration over time etc
stick to the Ah settings on your instruments.
Otherwise too much variation by current rate.
Basically Ah is canonical, Wh is derived.
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