Found this info concerning connecting batteries, thought would run it around for all out EE gents to give it a rating,
Don't be bashful, let her rip.
Thanks
SmartGauge Electronics - Interconnecting multiple batteries to form one... (http://www.smartgauge.co.uk/batt_con.html)
IMO, #2 is close enough and easily done.
I agree on the easy method, however I have added the 4th Gel 8D to my get up in the LP Gas compartment (LP tank removed), wired it directly to the inverter/charger along with the existing original setup. It works great, but some times I think too much ?
Actually, was wondering what would be the best from a theory point of view.
We changed to layout #2 for both house and start banks.
B&C,
That reminds me of my engine setup, used pair of 2/00 for the pos. and same for the neg, connected to the outer terminals, now starting with or without the boost is identical.
I use number three. All cables equal lenght. The closer you can get to this the better the life and power will be.
Yearly rotation of the batteries in the bank will help equalize the batteries lives.
I use #3 but have the wires #4 all going to a common copper bus bar ie neutrals to n bar and positives to p bar all pretty much the same length.
johnH
Dave,
Looks to be a good article with excellent illustrations. I do have a problem with the smug statement in the last paragraph. "There really is no excuse whatsoever (apart from, perhaps, incompetence or laziness) for using the first example given at the top of this page. " Not everyone is an electrical specialist but most readers seek to gain knowledge from those with expertise. If one is seeking to teach, It's best not to belittle the reader.
Pierce
Think it was meant to get attention
WORKED TOO!
That was an amazingly useful article. Many thanks, especially given the fact that we're about to install a hideously expensive battery that's made out of 4 cells wired together from Balqon. Hopefully the the cells will be wired in at least #2, but if not I may well be able to fix it within the case of the unit itself and I'll probably shoot for #3 or 4. Amazingly timely gem of information. :-)
It's all over engineering unless continuously drawing high loads all the time (which I doubt many people are doing on their battery banks on their RV). If you have sufficient big cable connecting batteries, the run is so short that it really won't make a PRACTICAL difference.
In the real world, dirty connections are likely to be much more resistance than attaching a bunch of wires. And adding all that many more wires adds more connections to get dirty.
I have to agree with Krush. So few owners will pull terminals and clean them on a regular basis. All you have to do is to go back and feel the terminals after even a winter start of a few seconds. The terminals will be warm to hot, all because there is resistance between the battery terminal and the connector. This is real world, not a fantasy world of someone with an big ego that can type.
Pierce
I like the idea of running the batteries to bus bars, Where is a good place to buy these?
I agree, but disagree :o
I'm not an engineer or mechanical-guru by any means. What I have is common sense;
I agree on a std installation, 2-3 (wet cell, agm, gel) batteries-over kill.
I disagree that the flow charge-discharge is not affected in a standard setup. It gets complicated with 4 batteries like some have done especially if you have a expensive lithium ion setup. For these I would think the best is the way to go. ^.^d
Im lucky, PO has a bar #2 this was don years ago, like 95, 96, so it means something and he was an engineer!
Photo's Please
sorry this is not a better picture I was waiting in the snow in my house slippers got 8 inches last night not my best idea.
the rod goes through where you would normally connect a cable.
OH'BOY!! I'm screwed? Everytime I look at different battery wiring configurations I get more confused!!
I have one large 8D 12V for the coach, one 12V starting battery for the engine/chassis, one solar panel up on the roof that hooks up to something in the battery compartment under the steps, one salesman's switch, and one boost switch on the dash. This is the way it came to us except for changing the engine/chassis battery from a 8D. Currently the pos to pos and neg to neg is the way the batteries are connected.
We have "lost" the 8D coach battery twice in five years! I read somewhere that not to leave the boost switch on when hooked up to shorepower or it would fry the house battery. True? Currently I was moving the engine battery over to the house battery side and putting in a new engine battery. Gets expensive!!
norm, same exact setup that I had with the 88 you're fine. That Coach is only designed for 2 sets of batteries.
My wet cell batteries lasted 2-4 years untill I changed that old charger.. then house lasted until I sold it.
The solar should be connected to engine, directly only. But if you store it inside that dosent work. Its ok to tieboth together for a trickle charge but dont leave the boost on unless starting.
My advice and experience is free, you determine if its worth anything
John, sorry to say in my mind your battery cable/connections look like they need a good going over/replacement as they sure look bad to me(but I have been wrong before)
Lon & Cheryl-- I made my own bars out of 2"x3/8th copper bars and drilled/tapped for mounting battery cables to. Made my own insulators out of fibreglass resin (moulded ) to mount them on . Here is a picture so you get the idea.
JohnH
Bill, link did not work for me
JohnH
PowerBar - Blue Sea Systems (http://www.bluesea.com/products/category/BusBars/PowerBar)
Any of these should work depending on your application.
JohnH, really? :o LOL
Hey in 7 days we have had 16-18" of snow.. God willing, my last winter like this.
I promise.. I will get them cleaned up.. ;D
Soap & water along with a battery brush, pickling spray (the red stuff) and
rotating after load testing each battery yearly is akin to money in the bank. pc
Lets try this one.Welcome to Mark's Fulltime RV Resource (http://marxrv.com)
Must be lots of fun skiing all over the place!!!!
We have a neice who could not get to work driving her BMW there in Sudbury (west Boston) so she sold it and got a new R Rover Evoque!! Must be bad I guess. We have too much sun down here so I wonder if a trade off could be made??
JohnH
After reading the article, I decided to check my battery wiring. The 2 engine batteries are connected using method 2. The house battery wiring is a puzzle? The neg terminals are on the left side of the batteries and the positive on the right side. There are jumpers from neg to neg and pos to pos. There is only one neg cable from somewhere in the motorhome and it is connected to the left battery. There are 4 positive cables (2 large and 2 small) and 1 large and 1 small are connected to each battery. The large pos cable to the left battery is connected to the large fuse above the battery compartment. So what method is this #1 or #2?
Jerry, you show two 8A8D's in parallel.
Yes, all three methods have the batteries in parallel and mine are in parallel, but what is the method of connection?
Well, I didn't get much response from the forum on this, but I think I have it figured out. Appears to be a combination of method 1 and 2; if that is possible. Moving the large and small positive cables from the left to the right battery and leaving the jumpers in place would make it method 2. May need to buy longer bolts for the right positive battery connector. No doubt it would be a lot neater with all the positive cables on a bus bar, but that means installing a bus bar and a cable to the battery. Anyone else have this arrangement? I may have shifted the connections when I replaced the batteries 7 years ago. I know from the posts that some of you have installed a bus bar.
I have the problem solved. I had a piece of heavy wall 3/4 " copper tubing that I converted into a mini bus bar on the battery post connector. It was rigid copper so I heated it with a torch to soften, then squeeze it flat in a vise; then drill some holes for the bolts. With all the positive cables on the bar, it is definitely method # 2.
Jerry,
Is your battery tray on rollers, or do you have to overcome gravity and friction to pull it out?
Thanks,
Trent
It's like extra heavy duty drawer slides with ball bearings and it has a lot of grease on the slides. I'm guessing about 20 lbs of force to pull it out. One bolt has to be removed to pull it out. After the last post I decided it would be better to have the heavy cables in the middle of the bar. Both of these 7 yr old MK 8A8D batteries do not have much capacity left and need replacing. I plan to buy 8G8D as the gel battery can take a deeper discharge and more recharge cycles than the AGM.
A follow up on this thread. Right after my last post discovered that one of the batteries had a bad cell or at least I think that was the problem. With batteries disconnected and isolated one dropped to 11.7 volts and the other stayed at 12.5. Used just the good battery on our trip; no dry camping, so it could handle our needs. Searched the internet for MK 8G8D and Marine Battery.com had the best price, placed an order, and they showed up about 10 days later on a 54' R & L semi trailer. Packed on a pallet with shrink wrap. Trailer had a lift gate. Driver called and I met him at the intersection as I knew he could not make it down the street and turn around without a lot of trouble. He said he would roll them down the street with his pallet jack and leave it at the drive, but I convinced him that it would be much quicker and easier for the both of us to put them in the back of my car. He even took the pallet. Link to Marine Battery website said free shipping, but I did pay shipping. $1253 with shipping. Marine Battery is really an Apex Super Store website. I charged them and after sitting overnight both show 13 volts. My brother-in-law helped me swap them out. Sold the old ones for $21.35.
Now that they are installed, I realize that these batteries do not have a hold down like all car batteries do. My chassis batteries on the coach have that. Does your coach have a hold down on the house batteries or is it like mine?
Its called Series Parallel connection.
The series connection increase Voltage and the Parallel connection increases Amperage. Therefore a Series Parallel connection increases both Volts and Amps.
In a Series connection you connect a Negative to Positive and a Parallel connection you connect Negative to Negative and Positive to Positive. Leaving one Negative and one Positive terminal to connect to your equipment.
Just type "Series Parallel Battery Connection" in your search engine and it should produce link with diagrams.
PS, Don't forget to grease the terminals with a non graphite grease..
Jerry,
My house batteries do not have a hold down either.
Trent
In the real world, minimize the number of connections/cables (unless it's an extra ground cable) and don't worry about rotating the batteries. There are already enough problems from corrosion and associated high resistance so don't make more by making the installation more complicated than necessary. In probably over 90 percent of the time, good intentions for cleaning terminals, etc. go out the window once the installation has been made, only to surface months or years later when a problem occurs. Using high quality terminals components along with careful installation are the key to the least amount of problems.
Pierce
I agree with what you said, but I was just trying to kept it simple and not have to buy new cables, install bus bars, etc. I suppose we should not have any roll over accidents or these 155 lb batteries will be flying around near the fuel tank.
Jerry,
Was making a general statement. Example would be using military type terminals with the two sets of fasteners compared to the stock set. They only cost a couple of bucks more but provide a more secure connection. As I remember, Ken installed them with photos on his U300. When you have the set of cables with the terminals already installed, some good stainless hardware is a step up from the mild steel they come with. Cuts down on the corrosion and won't end up eaten away.
I melted a set of terminals starting without a block heater at high altitude with the temps in the teens. Changed over to heavy duty fasteners as well as making the cable contact area as flat and clean as possible so the max amps can flow through with the least possible resistance. Many batteries come to a bad early end because of poor cable ends/fastener condition.
Pierce