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House Battery Issue


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Is a 'last thermometer' an auto correct / typo, or some kind of really technical thermometer?

There is a digital thermometer probe taped onto one of the batteries, but its job is temp compensation from the solar controller. I am interested in differential temps across the cells. I have an IR thermometer on board, that would be suitable wouldn't it? if I point it down the hole onto the fluid (of course, the IR thermometer is onboard, and the batteries are at home in the shed now... arghhh)

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For what its worth we occasionally have a similar thing happen in our off the grid set up of 15 years . typically we run two sets of 4 6v lead acid 220ah batteries  in series (24v system) with the two sets paralleled. last summer 3 of the batteries (in one bank) started needing frequent top ups but the system seemed normal in everything else.early one morning before the sun came up i noticed amongst all the 6.2s and 6.3s i had a 5.8v on one battery (less than two years old) - changed it with a new one and all is well again... By any chance Fish have you compared the resting voltage of them? I know you have a couple of guru's onto it but i thought i'd put in 5c worth anyway...

So have checked he resting voltage after about 18 hrs rest.

The good one is 6.55, the one that is miss behaving is 6.54v, nothing in it really. No obvious problem there. We are still taking them back to the supplier for a warranty check, so we'll see what comes of that. Anyone know what / how the supplier would check them? I'm assuming they'd do a full equalisation charge, then a load test (24 hrs?) and monitor all of the vitals through that process. The retailer has a tool for checking the CCA, but that is clearly not appropriate for house batteries.

 

I'm guessing if its not a battery fault, then its an over charging issue with the internally regulated alternator. Our start battery is AGM, and also has its own (much smaller) solar trickle charger. What happens to an AGM if you over charge it? not being FLA, I can't see if its boiling water off etc.

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Ok, it's very unlikely that its a battery problem then, but to be sure a voltage drop under load test is required. CCA test is a waste of time on a house bank, it must be load tested. Load testing is putting a constant load on the battery, (usually for 20 hours), and seeing how long it takes to get to 10.5v (5.25 for six volt batts). I have a rig that does this for 12v batts, but not 6v.

 

An example would be a 100 amp hour batt, at the 20hr rate. So this battery should drop to 10.5v after 20 hours with a 5a load. if it reaches 10.5v in 10 hours, then its actual capacity is 50 amp hours. Most batteries need a few cycles before reaching their rated capacity.

 

A SG of each cell would be interesting. Maybe one has been topped up with contaminated water??

 

Make certain your supplier can properly load test - ask them what the actual capacity was when they measured it.

 

We'll see what happens once tested.

 

Then I'd still be looking at voltage drop between the charge source and both the batts. If you don't know how to do a proper voltage drop test, then get someone who does to do it, and watch. Its not hard, is quick, but it MUST be done under load.

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My initial guess would be the linking cable between the 2 batteries.  If that is broken/underspec/undone/too long I think that could produce the symptoms you see?  It is the battery on the charging side that is heating?

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My initial guess would be the linking cable between the 2 batteries.  If that is broken/underspec/undone/too long I think that could produce the symptoms you see?  It is the battery on the charging side that is heating?

Hmm,

yes it is.

The linking cable was brand new at the same time as the batteries. But it was from Super Cheap Auto. Its maybe 40mm too long (surely that wouldn't make a difference?) and has a U in it. Goes onto threaded studs on both sides, surely I couldn't screw up putting a nut on a threaded stud?

 

Edit - photo of set up

 

20190815_165640.jpg

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Fish.   If you have a digital Multimeter?   Disconnect the batteries from all wiring and let them rest for a while to settle their voltages.  Then measure the resistance across the - & + of each battery.   If one has a largely higher internal resistance to the other [being the same brand and age] I would say there would be an internal fault and the higher resistance is causing the heating of a few cells. 

Please ignore if this has already been suggested.

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Nope not the linking cable. In series, any voltage issue would be seen across both batteries.

Also, 2.54 and 2.55V could be a red hearing. You need a really good multi meter to get you an honest result. How do you know if the 2.54 is not actually 2.549. And I would expect you to be seeing differences in readings of 0.01 of a volt anyway. Many Multimeters would have internal errors of 0.01 of a volt. You would need to be using a top end device of a couple hundred bucks to get better accuracy.
You need to get a sparky to place a sophisticated battery analyzer on the thing and get a proper readout you can compare across both batteries.

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So the supplier has come back after the warranty check.

They state that "the batteries have been grossly overcharged, cooked, was not far from exploding".

 

Clearly this isn't a warranty issue. Needless to say, my tits are in a tangle at having to pay for new batteries when I haven't even used my current new batteries....

 

And randomly, we have been told our alternator is too small for the system... which would be the opposite of overcharging the batteries I would have thought.

 

To recap, we have 180 watts of solar via an MPPT controller on the house batteries, which are (were...) 220 Amp /hr R232's (2 x 6 volts).

We have a new engine, with a 70 amp internally regulated alternator. Note, we have only done 22 engine hours in the last 10 months, longest run was probably 2 hrs under engine... how can that lead to over charging?

 

The other possible issue was poor connection / high resistance in the cable between the 2 batteries, leading to the first one cooking. We are going to try to investigate that further.

 

The current plan is to convert the alternator to externally regulated. We have an existing Balmar smart charger, with temp relay for the alternator. Concerningly, 2 auto lectricians have said the alt is too light / small frame for external reg. Issue is heat dissipation. We understand we can 'detune' the alt to work fine, for example setting a max output to 60 A instead of 70 A, and have the alternator temp feedback as well.

 

The other alternative is to not use the solar for charging. Might be acceptable short term while we get everything set up, tested and sorted.

 

Either that, or I'll get some paraffin lamps, biff everything electrical off the boat and just be done with it...

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hmm. Is there any deformation of the batt cases? if it was seriously overcharged, then there would have been a lot of heat, and its likely visible. Or is this an excuse not to cover them under warranty.

 

The possibility I'd see as most likely is that the solar kept the batts full. Then the engine running with say 14.4v will cause overcharging.

So, what is of critical importance is the charging voltages. What is the max (Bulk) charge voltage. How does the solar reg step back to float? is the float voltage correct? Does the solar go back to bulk every day, as its been off overnight? If so, for how long - it it time based or voltage, or current? Its possible that the solar controller could do this if the batt goes up to bulk voltage for hours every day.

The internal reg is no good. None of them are. Set single voltages (say 14.4) is too high for full batts.

 

This type of issue is why I strongly recommend a batt computer that has history data  available. This info protects both the supplier and the user, as there can be no arguments about how the batts were treated.

 

If you dont fix the issue, this will happen again :-(

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I had a long running complex and baffling similar issue that took months and loooots of $$$s to suss involving replacing every component in the system. Ultimately the rogue component turned out to be nearly new alternator that had accumulated belt dust through the cooling vents resulting in shorting within the case - and spurious charging including voltage spikes (16+) which fried my batteries. Luckily all my electronics were new enough they had auto shut-off to avoid damage.

 

We found this out by sending alternator away to a test specialist where problem was diagnosed and fixed - via dismantling and cleaning.

 

My brand new setup, the belt is distributing dust at an alarming rate. I thought there might be an alignment issue. Had the Commissioning Volvo mechanic look at it and he seemed unperturbed. But it's making a hell of a mess.

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My brand new setup, the belt is distributing dust at an alarming rate. I thought there might be an alignment issue. Had the Commissioning Volvo mechanic look at it and he seemed unperturbed. But it's making a hell of a mess.

Check the alignment yourself. Put a straight edge on the alt pulley and see if it aligns with the crank pulley. Should be within a mm or so. Is the belt a serpentine or V, or twin V? If its a twin V, does the tension on each belt seem about the same?

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Yes I did indeed have a small but significant alignment issue (about 3mm I think we found). Previous marine muppet engineers had failed to resolve this despite being paid lots of $$$. Thankfully IT came to the rescue and seems to have improved things dramatically in short-order. I’m taking Aleana out tomorrow morning for a couple of days and will try to use the engine as much as possible to test the newly aligned setup for dust.

 

I’ve never noticed belt dust buildup on any of my previous boats last 30 yrs so I’m convinced it can and should be minimal to zero for a correctly installed system. Otherwise you have a problem that needs resolving - even if your ‘friendly’ local marine electrical engineers assure you otherwise - in which case they are wrong.

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Hm lateral, that is not my understanding. Most internal regs are single voltage set, often at 14.4v. They are voltage regulators, and run at that all the time. The current the alt outputs will vary according to batt charge state, temp etc, but these are single stage voltage regulators.

Most cars don’t run 10+ hours per day, and wet cell batts can normally handle up to about 14.4v. They will use quite a bit of water though if in constant use. Most car batts are almost never fully charged. An hour or 5 at 14.4 does them no harm.

However, if a batt is full, extended periods at 14.4 can and does kill them. This may be what the solar, in conjunction with the engine/ alt, has done. This is why the manufacturers specify a float charge at around 13.6 (normally).

Again, a caveat. Read your batts product data sheet, and use the correct voltages for your specific batteries!

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The solar controller set points are as follows:

Equalisation charge 14.6 v

Boost Charge 14.6 v

Float charge 13.4 v

Boost recon. charge 13.00 v

Low volt reconnect 12.6 v

I took these from the battery manual, I'm going to re-check these later today.

The equalisation charge was set to run once a month.

 

We had these batteries for a period with the old engine, which had the smart charger on it. I believe the bulk charge was set to 14.6 v on that, that system would drop the volts when the batteries were charged.

 

The new engine has the internal reg alt, its always at 14.4 v, we have a volt meter on the engine panel in the cockpit, it doesn't moved. We verified this with a volt meter at the batteries and at the main switches (closest we could get to the alt safely with the engine running).

 

I regularly record battery volts when I get on the boat, recorded in the log book (OCD I know, I also read my insurance policies on a Saturday night...) The house batteries are typicality between 13.2 to 13.5 on the terminals, depending on how much sun is on the panels. Occasionally I've recorded a 14.6 v on them from the solar. They have been recorded at 12.94 v, with a comment that it was cloudy.

 

The longest single run time on the new engine I can find in my records is in the order of 1.7 hrs. I can't imagine we'd would have run the engine more than 2 hrs continuously. Additionally, we have a voltage sensitive relay, so the start battery is charged first. When this comes up to charged, the relay opens so that the alt starts charging the house batts - so the house batts aren't getting the full herbs for the full engine run time.

 

The short story is that I can't see how we could have damaged the batteries so quickly and severely. The advice that we need to solve this issue before getting new batts is salient, as I'll get my tits even more in a tangle if I fry a third set of batteries...

 

I've got some other questions and comments but I'll get my thoughts ordered before posting them all.

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Fish, what mulitmeter are you using to measure batt voltage at the terminals? Do you see any difference there to what you instrument panel meter says? I'll say this. Modern batteries rarely die, they are murdered! But it is possible that the issue id not what the supplier says it is. At this point you cannot prove your charge history. This is why I recomend that a battery computer with logging;

65ac0dda32f3c158ce053d9a4379cb493e9fb48f

 

Then you can print out the history and have evidence. Cost is around $550 with the bluetooth connector.

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We use a hand held multimeter with a digital display, probably in the order of $30 to purchase.

The solar controller displays batt and panel voltage. It is a an Epever Tracer A series. The batt voltage on the solar controller always reads slightly higher than what we manually read at the batt terminals.

 

The engine volt meter display in the cockpit is analogue. Bit hard to tell the difference between 14.0 and 14.5 volts.

 

Note that the solar controller has temp compensation with a probe strapped to the batts, so I can't see how that would generate any heat (with a temp adjusted control).

 

The batt in question had dry cells on 2 occasions. Not a lot, we took action immediately it happened a 2nd time. We check the fluid regularly, and had topped them up previously before the plates were showing. I like to think we are technically literate, we do take care of our batteries (allegedly). Its not like we've left them on a mains power charger for a week or something.

 

There was no visible signs of issues on the battery casings, i.e. not melting or burn marks. We actually only dropped off the 1 batt, we still have the other. There is very slight bulging at the ends, the sides are perfectly straight. The plates themselves look a bit wavy, but I don't recall what they looked like new, and I don't have the knowledge to say if they look any good or not. We haven't got the first batt back. Apparently they've taken the top off to check the cells, so its un-serviceable. I will follow up with the retailer on details. I'm keen for photos myself.

 

We checked the resting voltage of both batts before we dropped them off, they were 6.54 / 6.55 v. If one had shorted plates (supplier says 2 plates shorted) would the resting voltage have been the same?

 

As a thought, if there was a high resistance connection between the two batts, the solar doesn't put out high amperage. Is my understanding correct that a high resistance connection wont have much of an impact at low amps, but will at higher amps? The solar  I think can do 10 amps max, but I've only seen it at 5 once or twice, and is typically around 1 or 2 amps. The engine alt is rated to 70 amps, so while not a big alt in terms of some set ups, this could be impacted by a high resistance connection?

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Hi IT, 

what is the ball park cost for a logging system? I want to understand cost, verse a new set of batteries...

 

Also, how do you tell if you are overcharging an AGM battery?

Our start is an old AGM, it hasn't given us any trouble. It is on the same engine alternator, and has its own solar panel, an old 25 watt with a PWM controller. Should be enough to counteract the charge loss when sitting over time, and maybe trickle charge it up a bit.

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