Trouble with my battery bank

Currently we have a large bank of house batteries consisting of 12 Interstate U2400 golf cart batteries connected in a series / parallel configuration.* Actually, there are two separate banks of 6 each, connected to a common point on the 12v buss.* About five years ago, I replaced all the batteries due to a greatly diminished amp hour capacity.* Two years later, the bank was condemned by an Interstate dealer, and replaced under warranty.* This is despite taking excellent care of the bank, never running them below 50%, equalizing a few times, keeping up on the water, using proper charge parameters* using a high frequency desulfater.* etc.

I now find that the new 2 year old bank is again way down on capacity.* Yesterday, I borrowed an electronic battery tester and discovered that two batteries were bad, but the rest were fine.* One of the bad ones is the one that the positive cable attaches to.* I now seem to remember that the same battery went bad last time.* The second bad one is in the middle of the same string electrically.*

I do have the positive and negative cables connected to opposite ends of the banks, requiring all current to flow through all batteries

Strangely, the other bank is fine, despite being electrically connected same way. *

I remember FF once saying the first battery in a string should be rotated once in a while, but with two banks connected the same way electrically, why would only one go bad twice?* Not to mention its a real pain to move these things at over 70lbs each.*

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Ideas?.....................Arctic Traveller

I remember reading something about having to rotate the first battery in the 6 volt battery system.

I don't recall the who, what, where, or when but it does stick in my mind.

I do recall it was one of the idiocriencracys of the 6 volt battery system

SD**

I can't think of any reason to rotate batteries in a bank. They all share the current draw equally and they all share the charging current equally. Draw it out on paper and you will see what I mean. You don't rotate batteries in a flashlight, do you?

Ron,

I am pretty sure you are not accurate in this regard.

*As I recall the charge boils off the first battery in the bank.

*It is not when using the batteries that there is an issue.

It is when you are charging them that the problems arise.

I have personally talked to battery manufacturere about this and they say.

They don't know.

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SD


-- Edited by skipperdude on Monday 28th of March 2011 04:03:59 PM

Every time I have added water to my four GC cells, they've all been low by about the same amount.

Gonzo,

Test them with a battery hydrometer and see if they hold the same charge.

*I will bet the first battery is less than all the others.

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SD

I have a pdf file showing different ways to connect a bank to eliminate/reduce the effect you are seeing.

You can e mail me at

jleonard@usa.norgren.com* and I can reply with that information.

AT, A lot depends on how your cables connect to the individual batteries when charging, be it your battery charger or alternators. The charge feed should connect to cables all the same length and size and feed each battery in the bank the same. In other words, if the charge is being put in to the first battery in the bank and the third battery in the bank is down the line, they will not all be charged the same. Does that make sense? The larger the bank and the further away the battery, or pair in the case of 6 volts, are away from the charging connection, the more they will charge differently. Not saying that is your problem but a possibility. Unfortunately there are many potential issues that may be the culprit that only on the boat troubleshooting will find. We have had two banks of 3 pairs of 6 volt Interstates, we average seven years per pair and have used this set up while doing extensive cruising for almost 20 years without issues. Chuck

Jeff, that is very mysterious.* Is the desulfanator the Nano?* Are all of the cables between batteries well constructed and free of surface corrosion? When charging, is the voltage from positive of the lead battery to ground the same as the one furthest away?* Is the voltage for the shore charger set correctly for the batteries?* Why do fools fall in love?

Capn Chuck wrote:
AT, A lot depends on how your cables connect to the individual batteries when charging, be it your battery charger or alternators. The charge feed should connect to cables all the same length and size and feed each battery in the bank the same.

I'm unsure how I could do this, as each cable is a custom length dictated by battery and terminal placement.* Both banks are connected at a common bus, which is where the inverter / charger is also connected.* How would I seperate this out?

In other words, if the charge is being put in to the first battery in the bank and the third battery in the bank is down the line, they will not all be charged the same. Does that make sense?

It might.* I guess the entire 120 amps from the charger would go through the first battery, on to the next, perhaps with a little voltage / current drop at each battery.* Still, the acceptance rate of charge should be similar for all the batteries, so I'd think it wouldn't stress the first one, but I'm not sure

*

The larger the bank and the further away the battery, or pair in the case of 6 volts, are away from the charging connection, the more they will charge differently. Not saying that is your problem but a possibility. Unfortunately there are many potential issues that may be the culprit that only on the boat troubleshooting will find. We have had two banks of 3 pairs of 6 volt Interstates, we average seven years per pair and have used this set up while doing extensive cruising for almost 20 years without issues. Chuck

How are your banks wired?..............Arctic Traveller

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Delfin wrote:
Jeff, that is very mysterious.* Is the desulfanator the Nano?*

Yup, installed when the last set of batteries were installed.* The manufacturer told me it would work on multiple batteries, but the more there were, the longer it would take to work.* Since they were new, he thought it should work just fine.

Are all of the cables between batteries well constructed and free of surface corrosion?

All cable are like new, with zero corrosion.

When charging, is the voltage from positive of the lead battery to ground the same as the one furthest away?*

I've not checked that, but it's a very good idea.


Is the voltage for the shore charger set correctly for the batteries?

According to two engineers at Interstate my charge parameters are correct.

* Why do fools fall in love?

Often time's alcohol is involved......................

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You might want to check voltage between + and - for each of the three, two battery two battery sets. I would do this with a hign quality, high accuracy Digital meter, Do this while they are under significant load. It sounds to me that you may have a bad connection between set 2 and 3 on either the hot or ground side or possibly in the wire between batteries of a set. If you measure the voltage without a load, you may not see a voltage difference between sets. I have a hunch that some where there is corrosion, a bad crimp or bad connection between the lug and the post. Under load, maybe the bad connection heats and opens somewhat. The difference in voltage might be small. I would suggest something like a Fluke 87 meter or equivalent.

For no reason of evidence I am suspicious of the Nanopulser.* I have them as well, but the only reason a battery fails early outside of a manufacturing defect or bad maintenance and operation, which seems unlikely or already ruled out, is over-charging or chronic under-charging.* Under-charging would affect all batteries. Over-charging should affect all batteries as well, especially given the clean cables.* That leaves the possibility that this is all just a sad cry for attention, or some other anomaly.* The Nano by the process of elimination seems to be what is left.*

Perhaps check voltage under all conditions, alternator charging, shore power charging, resting with and without the Nanopulser, each battery positive to ground under all conditions.* There must be a voltage differential developing somehow that is draining the front battery into the others, slowly killing it.

That, or you made it all up.

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http://www.smartgauge.co.uk/batt_con.html

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Look up this site and read it.** There are poor and good ways to connect your batteries and the connections can affect how your batteries charge/discharge and their life.

Compare to your setup.

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Cap'n Chuck* said basically the same thing.* I missed his post, eyes glazing, but at the site above they run through an example to show you how the charge and discharge can be different for each battery depending on how the connections are made.


-- Edited by C lectric on Tuesday 29th of March 2011 12:08:53 AM

I try to keep my life simple.* If I had a 12-volt system, I'd use 12-volt batteries.

The file I have is actually from the smartgauge site that C lectric posted. Didn't recognize it as such when I posted.

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Delfin wrote:
.* The Nano by the process of elimination seems to be what is left.*

Trouble is, the first failure happened without the Nano

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Perhaps check voltage under all conditions, alternator charging, shore power charging, resting with and without the Nanopulser, each battery positive to ground under all conditions.* There must be a voltage differential developing somehow that is draining the front battery into the others, slowly killing it.

Agreed, I'll do this as soon as I get back to the boat, and again after I get the new batts installed.*

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That, or you made it all up.

I only wish I had made it all up, think of the money I could save, not to mention the wear and tear on my back......................Thanks

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C lectric wrote:Look up this site and read it.** There are poor and good ways to connect your batteries and the connections can affect how your batteries charge/discharge and their life.

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*Thanks to you and to jlenord for sending me that info. I did read it, and my configuration closely matches number 2 configuration, which while a small compromise, is as close to ideal as I can get without starting completely over again.It also confirms that my charger is connected in the correct place

The small difference in current draw between batteries using that method should not cause such an early failure.* I hope I find a real difference in current or voltage between batteries when I check them under load.* Thanks again for the ideas..............Arctic Traveller

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It may be worth your while to use a DC reading clip on ammeter to actually read how much a difference between individual batteries the current draw is. If you don't have one try borrow it or the owner and meter.
Take a look at the lugs themselves and where the wire enters the lug barrel. Corrosion can enter inside the barrel and not be seen. You should be able to detect too much resistance with a good DMM depending on where you place the leads by showing up as a voltage drop with a good load. It wouldn't take a lot of resistance in the lugs or battery connections to cause trouble.


I periodically use my ammeter on the conductors looking for any current flow when the boat is shut down which would indicate one battery becoming a load to the others. Or If current is flowing a DMM should be able to show a Vdrop if current is flowing.

Good luck
Clark

"I can't think of any reason to rotate batteries in a bank."

Home Power Magazine is free online and has been a leader in the field for decades.

They have a search function and you can read why the batt set should be rotated at times.

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"If I had a 12-volt system, I'd use 12-volt batteries."

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The reason 6v golf carts is the best choice is the volume lost to spacers creating each cell.

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With only 3 cell spaces there is more actual LEAD (what does the work) in a 6V than a similar sized 12V

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Folks with big DC needs ,and deep pockets usually prefer 2V batts , strung to whatever voltage is required.


-- Edited by FF on Wednesday 30th of March 2011 04:25:20 AM

There was a comment about how to parallel a group of 6 volt batteries.

Battery banks, depending on the number of indivdual batteries included in the bank, should be wired in such a way as to draw current across the bank.

For example, the positive and negative cables connected to three batteries wired together in parallel, should be attached at opposite ends of the bank, to ensure all batteries are cycled evenly.

If the cables are attached to a single battery at the electrical end of the bank, that battery often bears the brunt of the discharge and is likely to become depleted before its brethren, making for an undesirable imballance within the bank.

You need to make up a few sets of short jumpers to wire neg to neg to neg and the same for the positive side.

SD*


-- Edited by skipperdude on Friday 22nd of April 2011 11:25:50 AM

Old Stone wrote:
Can't remember which previous (pretty recent) post discusses this, but all agreed with you and several of the comments had very good illustrations of the various battery hookups.

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*My thought was about the first battery in line crapping out before the others.

this was just another something I read in Wooden Boat Magazine quantifying my earlyer comments.

SD

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