A bad egg in my bank.

[Mrhigherbeing]

It seems I have a dead or dying battery in one of my 3 leisure batteries.

They are all of varying ages and two seem to be fine but are being killed off by the rotten one..

 

How best to identify which one is bad?

I have an idea which it is as its little green 'charge' window is black and the others are green. But how to be sure?

 

SO should I replace all of them or just the bad egg?

 

Bearing in mind I am a student and my student loan does not cover some new fantastic wounder battery that might be out there.

 

Cheers all.

 

IAN

[Gary Peacock]

Ian

You could try and borrow a battery tester or sweet talk your local garage into testing them for you.

In an ideal world it would be better to start with 3 new batteries.

This doesn't always mean spending megabucks on the latest all singing and dancing carbon gel says they will last for ever batteries.

But don't mix batteries of different ratings in a bank and if possible stick to one manufacturer.

 

Cheers

 

Gary

[John Orentas]

Ian.

 

Replied yesterday on a simillar topic.

 

"I noticed a reply from Bernie on this topic which seems to come up time and again.

 

If you suddenly find that your 3 service batteries are flat it does not mean that you have 3 dud batteries. Beacause they are connected together in parallel, one dud battery will discharge the others, you must charge them up then separate them electrically, after a day or two one of the units will be much more discharged than the others, thats your dud. If you can borrow one of those big testers with a massive resistance built in to it, that will give an indication much more quickly."

 

I bought a 110 A/h liesure battery a few weeks ago £40. I find the large caravan/ motorhome dealers much better value that other places. I get 6 or 7 years out of cheap batteries. Or you can pay 4 times as much and get one that lasts twice as long.

 

John Squeers.

[DHutch]

So do guess just wire your batterys up in parallel?

 

- becuase i have always wondererd how i should use them

 

- we have four 12v batterys making 2 24v batterys (we run a 24v boat)

 

- does anyone know, should i always use all of them, or should i just use one battery at a time, and switch between them when on gets low (they are wired so i can eather have battery1, battery2, Both, or Off)

 

- also, should i wire my mains charger to charge the battery or batterys im using (like the althernator) - or should i wire it to charge them both, sparatly?

 

 

daniel

[maffi mushkila]

It seems I have a dead or dying battery in one of my 3 leisure batteries.

They are all of varying ages and two seem to be fine but are being killed off by the rotten one..

 

How best to identify which one is bad?

I have an idea which it is as its little green 'charge' window is black and the others are green.  But how to be sure?

SO should I replace all of them or just the bad egg?

 

You have identified the bad one that is why the indicator is there.

 

You could after charging disconnect all three batteries and do a voltage check. 12/14v depending how long you charge them. If the black spot is 2v less than the others then it has probably lost a cell.

 

So change the black one.

 

Of course it could be that the charge indicator is not working, in which case write to the manufacturer and complain about their quality control.

[maffi mushkila]

also, should i wire my mains charger to charge the battery or batterys im using (like the althernator) - or should i wire it to charge them both, sparatly?

I suppose that depends on your charger. Does it have the balls to charge all four batteries at the same time?

[ChrisPy]

Ian.

 

Replied yesterday on a simillar topic.

 

"I noticed a reply from Bernie on this topic which seems to come up time and again.

 

If you suddenly find that your 3 service batteries are flat it does not mean that you have 3 dud batteries. Beacause they are connected together in parallel, one dud battery will discharge the others, you must charge them up then separate them electrically, after a day or two one of the units will be much more discharged than the others, thats your dud. If you can borrow one of those big testers with a massive resistance built in to it, that will give an indication much more quickly."

 

I bought a 110 A/h liesure battery a few weeks ago £40.  I find the large caravan/ motorhome dealers much better value that other places.  I get 6 or 7 years out of cheap batteries.  Or you can pay 4 times as much and get one that lasts twice as long.

 

John Squeers.

<{POST_SNAPBACK}>

I was planning to buy 2 x 220AH carbon fibre Elecsol batteries for about £400, but as my early years will not be as a permanent live-aboard, I may opt for 4 x 110AH ordinary leisure batteries temporarily, to see how I get on with them.

I really don't want to leave the shorepower connected when I'm away for 2 months at a stretch.

Will they retain any charge when I am away?

Will they be damaged by discharging themselves below the magic 50%?

Any ideas?

[John Orentas]

Daniel.

 

There is no reason that you can't have 4 batteries in circuit together, but:

 

They must be all in good condition, simillar size and ideally the same manufacturer. Also they must be housed and clamped down in suitable trays or boxes with lids.

 

You must do this correctly with clamp terminals and cables that are more than adequate for the loads it will take. You must have a mulimeter to check what you have done.

 

Connect 2 of the batteries in series, (+ to -). Do the same with the other 2.

 

You now have effectively 2 x 24 volt batteries. Check the voltage and polarities with your meter.

 

You are now in a position if you wish connect those 2 'batteries' together.

 

Connect them together, this time in parallel. Note the links you are about to use are also the output connections.

 

Link + 24v to + 24v. and Link - 24v to - 24v

 

You must do this neatly and with the correct components. Double check everything as you go along. It is very easy to make mistakes.

 

John Squeers

[DHutch]

yeah, well all the batterys are the same, and there wired with arc welding earth cable (8mm copper straned) - there wired into two 24 batterys, and as i sayed, there both wired to a (vetus) battery switch that allows my to switch to use eather both, one, or the other (or neather) baterys

 

- what i was asking is how i should use this switch, i normal use should i have it on "both" or should i alternate between each "battery"

 

- as fot the chargers, it is a sterling charger with three out puts, one output goes to the bow battery, and they i was going to wire the other two outputs directly, one to each battery - but it ended up with one output wired to the boat side of the main battery switch.

 

 

thanks, daniel

[John Orentas]

Daniel.

 

Do you have any equivalent circuits to the starter motor, is electrical power required to start up (or is it just a match).

 

If you don't need starting power you could use the switch,

 

Pos 1. - 1st 2 batteries

Pos 2. - 2nd 2 batteries

Pos 3. - Everything off

 

If you have a permanently installed charger I would use a swtich to isolate the input AND output of the charger and interlocked with the 'Charge' output of the alternator to prevent the two charge systems comming together.

 

How do other people do that !

 

John Squeers

[John Orentas]

Chris.

 

The batteries will retain a charge for 2 months if they are in good condition but depending how easily your engine starts. Just in case you might be advised to take one battery home so that you can bring back a fully charged one for the first engine start. I have left my boat for 5 weeks a few times, I have never noticed any particular flattening of the batts.

 

Where did the "magic 50%" figure come from, it is a good thing to keep the batts fully charged but that is not the same as saying you are doing any great damage if you don't.

 

£400 pounds is an awfull lot to pay for 440 A/hs of batteries when you can get perfectly adequate ones for less than half of that price.

 

 

John Squeers

Edited November 30, 2004 by John Orentas

[maffi mushkila]

IIRC a 12 volt battery has 6 cell which when fully charged should produce 2.2 volts. If the cells fall below 1.8 volts you have a problem.

[John Orentas]

Maffi.

 

Not so simple this, I have trouble getting my head around it.

 

I know from experience that one dud battery in a bank of 3 will flatten all of them, I have had the problem a few times.

 

What has happened to that dud battery, obviously one of it's 6 cells has jacked it in. If it went open circuit, given that they are in series nothing would happen apart from you only have two batteries instead of 3.

 

Therefore that one cell must have shorted out leaving a nominal 10 volt battery in parallel with 2 x 12 volt ones. Why should that flatten everything over a short period ?

 

John Squeers

[rustyduck]

John O - the remaining batteries are now at a higher voltage and so will effectively try to charge the dud. However as the dud is now only a 10v battery, it will eat up as much power as the others can supply, converting most of it to heat, and dragging the good ones down.

 

The single cells in the battery slowly create Christmas tree like structure on the surface of the plates during charging. The trees, called dendrites, eventually get to the point that they connect and produce a hot spot short circuit. Intelligent chargers try to reduce the formation of these by changes in voltage and/or current.

[John Orentas]

Rusty.

 

All that sounds good to me, but when the 10 volt one is totally discharged doesn't it go open circuit. ?

 

John Squeers

[rustyduck]

No, the short circuit will still remain. The heat produced through this high resistance short will boil off the electrolyte, but the connection is still there.

 

And yes, once the single cell has been isolated from the rest of them then it will go open circuit and you are back to having a bank of 2 batteries.

 

 

Edited after actually reading what I'd written ( for once ).

Edited December 1, 2004 by rustyduck

[dor]

Rusty: I hope you don't start a trend; if people actually start reading their posts before sending them, these boards won't be nearly so entertaining

[John Orentas]

Yes, dangerous precedent that, let's hope it doesn't catch on.

 

John Squeers

[rustyduck]

Another dangerous precedent is re-reading the original question.

 

So MrHB, I would suggest one of three courses:

 

1) Chuck it out, put in a similar sized one (preferably of the same make) and wait until the other two finally pack in. You would then be best off replacing them all in one go when finances allow. Cheap initially, a bit dearer in the long term.

 

2) Change the lot and get the full life expectancy from them all. Dearer now, but will last longer before you have to do it again.

 

3) Chuck it out and live with the reduced capacity until you can afford a new set.

 

Otherwise you'll be changing batteries frequently and damaging the new ones almost the second you connect them up.

Edited December 1, 2004 by rustyduck

[Paul Evans]

But I just have to preview every post before I post it - otherwise I end up with all sorts of strange typos. Perhaps that's where I'm going wrong...........

[DHutch]

Daniel.

 

Do you have any equivalent circuits to the starter motor, is electrical power required to start up (or is it just a match).

 

John Squeers

 

Yep, bit o paper, few sticks, couple o fire lighters and a match!!

 

- lol