Strange battery charging problem

[Johny London]

I'm sure everyone remembers my poor charging regime and the lengthy thread that ensued.

 

I'm still using my set of somewhat reduced capacity 4x110ah batteries - a couple hours engine running in the morning, a couple in the evening, and then switch off the 240v (including fridge) at night. This gives me enough laptop time in the evening, led lights and various pumps etc.

 

So, for now carrying on quite happily - but I have noticed a new phenomenon creeping in lately.

 

Today for example: I ran the engine for an hour or so when I got up (with 240v back on as normal). I then cruised for 3 1/2 hrs. A couple hours later, and my batteries are already back down to 12.3v so I have fired up the engine again.

 

What I am saying is this - it would appear that the leisure batteries are not getting much (or any?) charge when I'm cruising. I can't think what this could be but I'm sure someone will enlighten me - be gentle!

 

Just to re iterate - I know the batteries have reduced capacity, but a couple hours charging off the engine normally sees them up to say 12.8v which lasts all day or all evening. Even on longer cruises, they don't seem to get as much charge as when the engine is just running in neutral.

 

I have two alternators, 50a for engine, 175 for leisure.

Edited December 9, 2016 by Johny London

[Top cat]

Do you have an ammeter in the charging circuit ? If not get one it's essential to know what's going in and out. A permanently installed one with a shunt is best failing that a clamp on DC hand held will help in the short term.

 

Without knowing the ins and outs it's difficult to advise.

 

Top Cat

Edited December 9, 2016 by Top cat

[Iain_S]

Do you know what voltage you're getting when running the engine?

[Arthur Brown]

Lots of hard numbers are needed! When you have collected them you will understand a lot more about your electrical system yourself.

 

1/ go really psyco and record the current consumption from the batteries say every 15 minutes, Record also what the charge current is say every 15 minutes also.

2/ record the battery voltage rested (first thing in the morning no load overnight) and at the same time as you read the currents.

 

Determine the charge voltage and if you ever can the charge current and tail current when fully charged.

[WotEver]

As TC and Ian state, without some readings of current and voltage (preferably both but right now either one would be useful) we really have no idea.

 

I'm referring to when cruising.

[Chewbacka]

You may have a dead battery that is pulling the rest down.

Try disconnecting the batteries from each other and measure each individual battery's voltage

[Bod]

What RPM do you normally charge at, whilst moored up?

Did you cruise at a lower RPM?

Maybe the alternator wasn't running fast enough, during cruising.

 

Bod

[by'eck]

Suspect battery capacity has dropped to a tiny fraction of original. If this is the case, it doesn't matter how long you charge them and how powerful the alternators are, the bank simply won't be capable of storing much charge. They will therefore reach the minimal fully re-charged capacity in short order, but by the same token they will discharge to a low level quickly when asked to maintain anything but the lightest load after charging ceases.

Edited December 9, 2016 by by'eck

[BruceinSanity]

Suspect battery capacity has dropped to a tiny fraction of original. If this is the case, it doesn't matter how long you charge them and how powerful the alternators are, the bank simply won't be capable of storing much charge. They will therefore reach the minimal fully re-charged capacity in short order, but by the same token they will discharge to a low level quickly when asked to maintain anything but the lightest load after charging ceases.

And in my experience, once batteries are below 50% of original capacity, weird stuff starts happening with charging.

[Tony Brooks]

12.8 volts? "a couple hours charging off the engine normally sees them up to say 12.8v" also need clarifying. If that is with the engine still running then it is nowhere near fully charged. With the engine still running and revving the voltage should be around 14 to 14.5 dependant on the alternator.

 

If its just after you stopped running then they are still not fully charged and the voltage will drop quickly as soon a s a load is applied. The 12.8 volts at that time is surface charge and not the real state of charge.

 

Apart from the readings others have asked for how many alternators do you have (I am not going to look for and read the other thread)? If its one the maybe your charge splitter had gone faulty unless you only have one battery bank.

 

Voltage readings while or just after charging can not really give an accurate indication of state of charge. You need an ammeter for that (or a Smartguage but that's a little less accurate than an ammeter).

 

 

[MtB]

Given the OP mentions running his engine for two hours, twice a day, A total of four hours a day (his neighbours must love that!), yet never seems to get above 12.8v, it sounds as though the batteries are in a perpetual state of deep discharge and probably totally goosed (technical term) too.

 

If the two hour morning charge is being dissipated so quickly that another two hour charge is necessary in the evening, battery capacity must be microscopic. My electrical needs are similar and with decent batteries I'm finding a six hour charge once a week is about right.

[mross]

You may have a dead battery that is pulling the rest down.

Try disconnecting the batteries from each other and measure each individual battery's voltage

No need to disconnect all of them! Just open battery isolator or take the negative lead off. There can be no current flowing through any cell then.

 

Oooops. that will only apply to batteries in series.

Edited December 10, 2016 by mross

[WotEver]

No need to disconnect all of them! Just open battery isolator or take the negative lead off. There can be no current flowing through any cell then.

They'll still all be in parallel.

[mross]

You are correct, of course. I'll strikethrough my post so that your's still makes sense. I had been thinking about my last ship's transitional batteries which were 120 or so NiFe cells in series. You had to careful working on those!

[b0atman]

You are correct, of course. I'll strikethrough my post so that your's still makes sense. I had been thinking about my last ship's transitional batteries which were 120 or so NiFe cells in series. You had to careful working on those!

now Nife or Nicad they would sort all our problems out.

[Johny London]

Thanks for the replies. I fully accept that the batteries are only holding a small capacity now, but they seem to be workable for now, and I have so much else that urgently needs my time and money that I am working around them for the time being.

 

To answer a few questions:

 

Twin alternators 50/175 amp.

 

No ammeter but a smart gauge is sitting in its box waiting for me to fit it. In the meantime I have an lcd voltmeter permanently hooked up.

 

When running the engine - and when the fridge is not active, charge voltage climbs up to 14.4-14.5v after the two hours.

 

Ignoring initial float charge, batteries sit at about 12.8v (best case) after charge period.

 

I try not to let the batteries get below 12.2v but sometimes if I fall asleep on the settee they can get down to 12v. I switch 240v off then go to bed and in the morning batts are usually back up to about 12.15 if that has happened.

 

I charge the batteries at engine idle speed ie 900 rpm. I typically cruise at 1400 rpm or so.

 

I have not checked the (charge) voltage while actually cruising.

 

Mike - six hours once a week? I was massively told off in my other thread for charging "an hour or two morning and/or evening" (not my exact words but near enough if I remember correctly) which equates to a heck of a lot more than six hours a week. I'm sure if I said I want to run all my boat electrics for 6 hours a week charging, I would never hear the end of it.

 

To reiterate - I know the batteries are goosed. I wonder if I am wasting diesel charging them (compared to a healthy set - though you can't get more out than you put in anyway).

The purpose of this post was that I appear to get hardly any recharge from cruising, compared to idling. I would have thought the other way around. It makes me think of a mechanical fault though of course I have checked the belt tensions.

 

As an aside - I wonder why the low voltage warning on the inverter never went off while I was in the process of goosing the batteries in the first place - it was all I had to warn me at the time.

[dmr]

There is a rule in electronic fault diagnosis:..... if you find a fault fix it, don't waste time trying to understand or discount it, and then look for more faults.

You have a fault, your batteries are dead, don't waste time and diesel trying to understand the characterises of your broken batteries.

 

.............Dave

[WotEver]

I suspect as others have suggested that your comment that "they seem to be workable for now" simply isn't true. They appear to have now passed the stage where they're barely holding any charge and got to the stage where they're not holding any worthwhile charge at all.

 

The fact that you see charging voltage rising to 14.5V suggests that there's nothing wrong with the charging. Your batteries have simply finally died.

Edited December 10, 2016 by WotEver

[Arthur Brown]

Remember that the Smartgauge when installed (start now!) will only show state of charge. It does it well but does NOT measure battery capacity so it could show 100% but the batteries could be 5AH or 5000AH

 

The only direct way of determining capacity is to count the amps in and count them out again. BUT batteries are neither amp or power perfect more amps and more power needs to go IN than can come out.

 

Sitting there monitoring your present batteries will NOT help their imminent demise, BUT WILL give you an understanding of the charge current available from your system at various RPM -you don't say what charge or cruise RPM you use. Learn all you can about batteries otherwise you risk killing the next set in short order.

 

The shortest battery life recorded on this forum was three weeks, the longest IIRC was 10 years. The difference between long and short lifes of batteries is largely the charging regime that they live under.

[mross]

-you don't say what charge or cruise RPM you use. Learn all you can about batteries otherwise you risk killing the next set in short order.

Yes he did! "charge the batteries at engine idle speed ie 900 rpm. I typically cruise at 1400 rpm or so."

[Johny London]

Yes, maybe just the batteries last gasp then. I just have so much stuff needs my time and money right now.

 

Regarding the smartgauge, I'm assuming it works out % of charge just by being told the battery type then reckoning from the voltage it's at? I could do that with a voltmeter and a chart for a fraction of the cost - anyway it is sitting in its box so will hopefully fish it out very soon.

 

Regarding new batteries - would I be better off getting a couple of inexpensive ones for now, vs my existing lot of 4 gooses? Assuming I work out the correct regime.

 

I have also read about reviving batteries that are sulphated, ether with a special charger or diy style being careful with a psu and voltmeter. One article I found related to dead car batteries and had very positive results - of course I'm not saying you can keep batteries alive forever but as these are only months old I wonder if they would respond well. Of course, I don't have access to any mains - if I did I would have tried with the Victron charger/inverter.

[dmr]

 

Regarding the smartgauge, I'm assuming it works out % of charge just by being told the battery type then reckoning from the voltage it's at? I could do that with a voltmeter and a chart for a fraction of the cost - anyway it is sitting in its box so will hopefully fish it out very soon.

 

 

You are not the first person to say this, and almost certainly not the last.

 

All you have to do is turn EVERYTHING off, wait about 10 minutes (some would say a couple of hours) then measure the battery voltage and use the standard chart giving "state of charge vs OFF load voltage". Then remember to turn everything back on, re-progam the radio and anything that has lost its memory settings. And do always remember to turn the fridge back on. Take care doing this at night when the lights are turned off. I used to do this stuff but I find the Smartgage a bit more convenient.

 

..............Dave

[Top cat]

As you have already spent the money you might as well install your Smartguage it isn't difficult but follow the instructions to the letter. Then fit an ammeter and ask the experts on here how to interpret it. The Smartguage will tell you when you need to start charging the ammeter will tell you when you can stop charging.

 

That way you have some hope of your next set of batteries lasting get more than a few months.

 

Top Cat

[ditchcrawler]

 

 

 

 

Regarding new batteries - would I be better off getting a couple of inexpensive ones for now, vs my existing lot of 4 gooses? Assuming I work out the correct regime.

 

I have also read about reviving batteries that are sulphated, ether with a special charger or diy style being careful with a psu and voltmeter. One article I found related to dead car batteries and had very positive results - of course I'm not saying you can keep batteries alive forever but as these are only months old I wonder if they would respond well. Of course, I don't have access to any mains - if I did I would have tried with the Victron charger/inverter.

Are you saying replace the duff 4 with 2 good ones, if so they would probably serve you better than what you have now. As for mending the old ones I wouldn't bother trying.

[Arthur Brown]

!/ You have a smartgauge, You've paid for it, go fit it NOW. Used correctly it can only help you keep the batteries in good order, then fit new batteries and keep them well.