I know a bunch of you have made the switch to golf cart batteries for the $ and weight savings plus the increase in Amp Hrs. I'm in the process of doing the same and really appreciate all the fine articles and advice on the subject I've found here. But in researching with my favorite Tech boat author, Nigel Calder, ("Boatowner's Mechanical and Electrical Manual" McGraw-Hill, third edition) I find a recommendation as to wiring the series-parallel set up with cross wiring that I don't think I saw and anyone else's notes or articles. I'm just wondering if anyone else has wired their 6v GC's this way. I've attached a scan of the page from the book. The page is 22 from chapter One. He says, "In a series/parallel setup, it is an excellent practice to cross-connect the positives and negatives on the 6-volt batteries, or 2-volt cells, as shown in Figure 1-21. This minimizes differences in the way the batteries work and perform." Not that I would ever doubt Mr. Calder but I'd seen no reference to anyone else doing this. All comments welcome. Thanks
Sam
Capt. Sam Murphy
1994 Catalina 36, Hull 1327
Shoal draft, two cabin model.
Panama City, Florida
When I first did this I didn't have much experience wiring up batteries, so I had enough trouble figuring out how to wire two of the golf cart batteries together to form a single 12v battery (conceptually), then the other two to form a second single 12v battery...and then add the parallel wires on the right terminals to double the amps correctly.
When I mentally try to add in his inner cross-connections to my setup, I still can't conceptualize how that forms two 12v batteries anymore. He's surely right since he's like....God.... but I was just too chicken to try it. :-)
If I had it to do over again, I would though, coz I'm better with the vom than I used to be. Thanks for bringing this to my attention.
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
Sam,
This is how I wired my batteries 12 years ago. Makes for a 12Volt and 415 amp battery bank. Made my crossover wires red on one end and black on the other as a reminder. Interesting I did this on my boat to increase the weight on the port side because there was a slight list to starboard. Believe I got the diagram from Trojan batteries.
BTW I purchased my last set of batteries 6 years ago from Napa. Still going!
Gary Bain
S/V "Gone With The Wind"
Catalina 36', Hull #: 1056, Year: 1990, Engine: M-35
Standard Rig
Moored: Boothbay Harbor, Maine
Home: Auburn, Maine
Sam,
I reference opposite end connections all the time, as do actual battery manufacturers, whether folks listen or pay attention is another thing. (wink) As for the cross connections, in speaking with battery manufacturers, they don't seem to feel that it makes as much of a differnce as wiring positive and negative off opposite ends as shown below, so long as you start out with balanced batteries. I have done cross connections on several boats, with bigger series/parallel banks but in the end the owner is always confused. iF they have to touch the wiring and it can make for a potentially dangerous situation as most don't fully comprehend what is going on. With the cross connect you first make two parallel 6V banks and then make each paralell bank series. Parallel batteries are in better balance, but it creates a wiring nightmare for most boat owner. For ultimate safety, I rarely usie this wiring combo and instead prefer a good commission parallel top balance charge..
What is a Deep Cycle Battery
People move to 6V batteries not just for the Ah capacity and cost but also because they are actually a deep cycle battery not just a DINO (deep-cycle in name only)...
Incorrect:
Correct:
-Maine Sail
https://www.marinehowto.com/
Thanks Guys, those replies are just what I was looking for. Yes, Ben getting around that wiring diagram mentally is exactly my problem and I'm afraid as Maine Sail mentions, that It might confuse me or a subsequent owner later. And Gary, that is good to hear about the longevity of your 6v GC's. And I was about to spend about $1,300 on replacing my Lifeline AGM's!! This is why I LOVE this organization. The knowledge I've gained and money saved has been HUGE.
And lastly, thank you Maine Sail for that additional diagram. I had read that I should connect opposite Neg, and Post. ends of the paralleled batteries to the system, but didn't have it in my installation plan.
You're held in every bit as much esteem and Mr. Calder.
Sam
Capt. Sam Murphy
1994 Catalina 36, Hull 1327
Shoal draft, two cabin model.
Panama City, Florida
Interesting. MaineSail, I have mine wired exactly as per your correct diagram. (Actually, I think I got that diagram off your website back when I installed?)
But, your diagram is different from Calder's. Notice that his cross-connection forms an inner "box" of 4 wires, not 2. It is that inner box which confuses me. I can easily see how your diagram works to form 2 12v batteries set in parallel (with + and - lead-outs at opposite ends). But I can't see the same with Calder's inner box setup, and he doesn't explain the "why" of it at all in his book (i.e. why it works technically).
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
Actually, "MainSail" did address the extra two cables when he stated 'two 6v batteries in parallel (one bank), then wired together with two others (another bank) in series...
I just got around to removing my 4D batteries and replacing with Trojan T-105's... had to stretch the original f/glass boxes by 1/2", used west system epoxy - also had to cut one of the boxes lengthwise and removed 1/2" to make it narrow enough to fit in the space. Also replaced the original 2x4 supports with starboard, Here are before and after pictures:
---- Howard & Linda Matwick ----
--- S/V "Silhouette" - Nanaimo, BC ----
--- 1999 C36 MkII #1776 M35BC ---
Hi Howlin,
I have the same C36 as yours. I viewed the images that you have included. Did you have to remove the bolt and the back plate that holds the chair for the chart table? Were you able to reinstall the chair and the bolts?
I also could not see the container that you extended after the batteries were installed. Do you have more images?
Thanks for your help.
Sail La Vie 1999 Catalina 36 MKII, M35B-17031, Coyote Point, San Mateo, CA
About Sail La Vie
Haro: I did remove the chair, because I am not putting it back in, but plan to make a storage cabinet in that area instead. If I would have kept the chair I would have had to shorten the bolts to ensure the new box fit... Here's a 2nd with view from the top...
---- Howard & Linda Matwick ----
--- S/V "Silhouette" - Nanaimo, BC ----
--- 1999 C36 MkII #1776 M35BC ---
Howlin - thanks that is more clear. I had forgotten that there are two trays there. It appears that you can, one day, reinstall the chair if you wanted to. Bolts would have to be inserted from the battery side out.
Sail La Vie 1999 Catalina 36 MKII, M35B-17031, Coyote Point, San Mateo, CA
About Sail La Vie
[quote=HowLin]Actually, "MainSail" did address the extra two cables when he stated 'two 6v batteries in parallel (one bank), then wired together with two others (another bank) in series0[/quote]
He addressed it and his is correct, but it is still significantly different from Calder's setup (which was my only point).
Take a look at Calder's diagram and count the total number of lugs required. Then take a look at
MaineSail's correct picture and count the number of lugs. MaineSail's requires fewer total lugs. Also Calder's setup forms an inner "box", while MaineSail's does not.
The question then is Calder onto something? Is his setup better for some reason?
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
Yes Ben I understand what you are saying, but you didn't get my point...
Maybe I can explain it better, with a drawing. (PDF attached)
Think 2 - 6V batteries wired in parallel - with 2 more 6V battery banks which are also in parallel...
Now, take these two 6V banks - and wire them together (in series) to create a large 12 V bank.
Done this way, the "inner box" as you put it, would be included... Calder thinks that wiring it this way would create a totally "balanced" path for electron flow, I'm not sure that I think the difference is significant, so I didn't wire my boat to include this "inner box"...
---- Howard & Linda Matwick ----
--- S/V "Silhouette" - Nanaimo, BC ----
--- 1999 C36 MkII #1776 M35BC ---
Ben,
I addressed it in the "words" in my post not the diagram. FWIW the diagram I posted is the exact diagram Lifeline, Trojan, Crown etc. all use and recommend. Why? Because as I mentioned, doing the "box" or complete parallel then series of 6V batteries often confuses people and can lead to dangerous situations where the slight "benefit" can become a potential risk far to easily, thus the battery manufacturers themselves don't even recommend it.
If treating the batteries well, meaning a commissioning charge, equalizations, proper charging voltages and full charges then balance issues using the non-box should not be a problem. If you pair up out of balance batteries, right off the store shelf, don't commission charge them and don't routinely get to full and equalize then yes the parallel batts would probably do better than non-parallel...
Trojan Battery
-Maine Sail
https://www.marinehowto.com/
Thanks, MaineSail. That was the missing piece for me.
Regarding equalization, I have yet to find an equalizer at a reasonable price and my MasterVolt PowerCharger 12/20-3 has no equalization feature that I know of.
ONE of my solar charger models has an equalization feature, but it hard-coded to equalize every 30 days and you can't override it and do it manually. Really frustrating trying to find a simple way to equalize my batteries.
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
Howard, I see your point now. Thanks for the diagram. I'm pretty sure I can set it up correctly for the "box", but I'm still trying to understand the physics of the "boxed" (aka full-parallel) setup, i.e. where the electrons would now flow and why. That's the part that Calder never explained, as I recall.
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
[quote=benethridge]I'm still trying to understand the physics of the "boxed" (aka full-parallel) setup.[/quote]
With series batteries it is possible for the series batteries to not be at the same SOC or what we call out of balance.. Let's assume you wire in series two 6V batteries one at 6.37V and one at 6.25V. This would net a 12.62V battery that looked "fully charged"... However one battery is at 100% SOC and the other is at about 80% SOC. They would pretty much remain at that SOC imbalance, up and down, unless you pushed them to an absorption voltage and held it there long enough for current to stop declining. Most "smart" chargers go to float "prematurely" before the current stops declining at absorption voltage. An equalizing voltage would get them to a better balance and if held there long enough for the 6.25V battery to catch and then up all is good..
Parallel batteries, by the nature of a parallel connection, are at the same voltage and while it takes a long time to reach the same SOC (Ohm's law of voltage vs. current differentials as related to current movement between batteries) they will be charging at the same voltages not one at a high voltage and the other at a lower voltage and will stay in better balance. If left in parallel long enough they simply balance themselves.
If the 6V batteries are first wired in parallel and charged at absorption until they get to a point where current stops declining, then pushed to an EQ voltage for a short time, the batteries are now in balance and ready to be wired in series. This short-cuts the SOC balancing time it takes at resting voltages.
Alternatively you can hold them at absorption, in series, until current stops declining and then go to an EQ voltage. While the balance won't be as perfect it will be good enough.
The above parallel wiring is what I call a commissioning charge and I do this to every series bank that gets installed using a lab grade power supply. Series lead acid can become out of balance just like Lithium batteries except we can't overcharge lithium to get them back in balance. We can simply push lead acid voltages higher and force a balance to happen faster. If however you chronically undercharge or operate in a PSOC state, and never push high enough, the batteries can remain at different SOC's for a while when wired in series.
With a good installation and good charging practices it becomes a minimal to non-issue and this is why battery manufacturers don't advise the "box" wiring....
-Maine Sail
https://www.marinehowto.com/
I understand that...or most of it anyway, but what does the "boxed" setup buy you? Does it mean I can now avoid the need to equalize?
Is the boxed setup what you mean by "parallel batteries, by the nature of a parallel connection"? I already have two golf cart batteries mounted in series, and then another two in series and then those are mounted in parallel (per your diagram). So I'm still confused about that meaning of "parallel" in your latest post vs the boxed (aka "complete parallel" in your earlier post) setup.
Bear in mind that I would install the boxed setup and LEAVE it that way for all charging. I would NOT remove the box after a commissioning charge. That is to say, I may have a good installation but need the "box" because I cannot adhere to "good charging practices" simply because I have no way to equalize at a reasonable price.
So that also becomes a key question that may eliminate the need for the boxed setup: How can I reasonably equalize? Many authors talk about it but I have yet to find the equipment at a reasonable price.
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
I suppose it all depends upon each individuals assessment of "reasonable"... The sheer number of poor quality chargers I see out there tend to cost owners far more over the life of the boat than what a good full featured charger with temp compensation, EQ, etc. or a small 10A lab grade power supply would cost, in order to equalize the batteries.
Any "marine" charger that does not have an equalization feature or external temp compensation, is simply not "smart" nor really suitable for a boat that cycles batteries. Non marine UL chargers are never suitable on boats, but many are out there.. D'oh.....
The Sterling ProCharge Ultra is a decent marine charger, the perfect marine charger has not yet been built, but even a small 10A X 30V adjustable lab grade power supply is all you need for equalizing and these can be had for $90.00 - $120.00.
Personally I only use lab grade power supplies for charging and equalizing in my shop and when working on customers boats.
-Maine Sail
https://www.marinehowto.com/
Thank, MaineSail. Do I really need 10amp and "lab grade" accuracy?
Can I get by with this 3amp, which is less accurate but is only $43?
Dr.Meter® HY1803D Variable Linear Single Output DC Power Supply -- 0-18V @ 0-3A
http://www.amazon.com/gp/product/B00O8DJ8QC?keywords=mastech%20dc%20power%20supply&qid=1452252399&ref_=sr_1_1&sr=8-1
There is also a Mastech in that price range on Amazon. It's like yours (more accurate), but it's also only 3amp.
Is 10amp necessary?
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
If you are doing one battery at a time then 5A supply could work but if you want to do the bank then the 10A will be the right choice. Keep in mind that in the early stage of EQ the current needed to get to 15.5V will very often exceed 5A, even on a single battery, especially if the charger you used to get it "full" is not a high quality charger.
In an ideal world the batteries would be chock full & accepting less than 3A, but even then a 3A supply is usually too tiny for equalizing... It takes current to drive voltage and you need to start somewhere. At the end of EQ you should be well below 3A, but often not at the beginning, especially with sulfated batteries as the sulfate begins to re-convert or shed.
Keep in mind in the image above that is a single group 31 battery at about 3 hours into an EQ and it is now just barely below 3A....
What is your on-board charger..?
Something like this should work...
http://www.ebay.com/itm/DC-Power-Supplies-30V-10A-110V-Precision-Variable-Digital-Adjust-w-Clip-Cable-/271608504736?hash=item3f3d20e1a0:g:-90AAOSwd4tUGApJ
-Maine Sail
https://www.marinehowto.com/
[quote=benethridge]Thanks, MaineSail. That was the missing piece for me.
Regarding equalization, I have yet to find an equalizer at a reasonable price and my MasterVolt PowerCharger 12/20-3 has no equalization feature that I know of.
[/quote]
I now see that you have a single voltage profile, non-adjustable, no equalization charger that is not well suited to charging golf cart batteries. A 14.25V absorption is far too low for GC batts so you will need to be doing EQ more often than a charger that can charge at 14.6V -14.8V in absorption..
For about the price of that charger I offer my customers the Sterling ProCharge Ultra which comes standard with the temp sensor, EQ mode, optional remote control, has 11 charge profile presets plus a fully custom charge program you can dial in just for your batteries. You get all those features plus a 5 year warranty for about $5.00 more than the Mastervolt.
Its frustrating to see a company such as Mastervolt selling such a featureless one-size-fits-all charger for big $$...
My .02 would be to sell that Mastervolt on eBay or Craig's List and buy a charger that can be properly set up for your batteries and that can perform an equalization...
-Maine Sail
https://www.marinehowto.com/
Sounds good and is pretty much what Calder recommends anyway. Where do I sign up?
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
I just thought of something - the reason I got a not-so-great shorepower charger in the first place: I plan to live in anchorages, and off my 400watt solar setup, so any shorepower-based battery charger won't often be usable.
I need to find a solar charger which has equalization capability (plus the other capabilities you mention).
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
Here are a couple that MAY fit the bill, although neither are stated to be marine-quality:
http://www.blueskyenergyinc.com/uploads/pdf/BSE_SB3000i_Data_Sheet.pdf
http://www.outbackpower.com/downloads/documents/flexmax_6080/specsheet.pdf
The former is less expensive but is much more limited on the total volts it will handle from the solar panels, so I don't think it will reasonably handle my four 100 watt solar panels....or not without losing much of the advantage of MPPT.
I have yet to find one that is stated as marine quality.
The reason I'm postiing this, is that from what I read above, this will mitigate (if not eliminate) the need for the "box" setup from the original post.
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
[quote=benethridge]Here are a couple that MAY fit the bill, although neither are stated to be marine-quality:
http://www.blueskyenergyinc.com/uploads/pdf/BSE_SB3000i_Data_Sheet.pdf
http://www.outbackpower.com/downloads/documents/flexmax_6080/specsheet.pdf
The former is less expensive but is much more limited on the total volts it will handle from the solar panels, so I don't think it will reasonably handle my four 100 watt solar panels....or not without losing much of the advantage of MPPT.
I have yet to find one that is stated as marine quality.
The reason I'm postiing this, is that from what I read above, this will mitigate (if not eliminate) the need for the "box" setup from the original post.
[/quote]
I am not a big fan of trying to equalize on solar. It takes far too long to get to 100% SOC, then you rarely have enough hours left in the day, or the consistency in output, to run a solid 15.5V (temp corrected) for the duration needed..
You mention an MPPT not handling your voltage?? On sail boats you will rarely see series beat parallel. I have data-logged this on multiple cruising sailboats and never once logged series beating parallel. Every time I have seen series beat parallel it is almost always on a power boat with zero obstructions....
Outback controllers are great, the blue Sky's are a slower tracking MPPT and you will also want the IPN Pro Remote.
Perhaps the best bang for the buck, in a 30A controller, is the Morningstar TriStar MPPT 30. These are very fast tracking and are loaded with features and control...
That said, for needing to equalize, a small 10A power supply is still the best bang for the buck...
-Maine Sail
https://www.marinehowto.com/
Thanks, MaineSail. I see your point. However my boom is forward and low so it will not shadow the panels, and I have nothing sticking up (like a wind generator or radar) back there. Other than the mast at certain angles, only the backstay will normally shadow the panels, and I've measured that loss. Does not appear significant.....so I'm thinking I can still get an advantage with MPPT?
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263