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Charging of domestic batteries


rowland al

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37 minutes ago, Gareth E said:

I'm butting in a little here: I have a single Trojan 12v, 105ah, with low usage of around 25ah a day. I have a decent solar array and a wind turbine. Currently I run the genny for an hour each evening. At these times the battery volatge is around 12.5 to 12.6, with no loads on. Every third evening I run the genny for around 3 hours, this results in a tail current of around 1.5 amps.

Is my charging regime a good one or might I be better scrapping the daily charges, just run the genny when down to 12.2 for however long it takes to fully charge?

What you haven’t mentioned is the charging voltage. If your charger/solar voltage is say 14.4v, whilst this might be OK in the summer it is likely to be too low for the winter if the batteries are in the cold. Optimum charging voltage increases significantly with reducing temperature and with Trojan recommending a finishing voltage of 14.8v even for warm batteries (though as I said, you can get away with less) the recommended voltage for batteries at say 5degC is a lot more and 14.4 or so is too far away. This might result in sulphation slowly building up, despite your otherwise seemingly reasonable charging regime.

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46 minutes ago, Tony Brooks said:

Sound fine to me. It seems Trojans do not like sitting partially discharged as MtBM found out so the daily charge is important.

And if that is the case, you might just as well spend your money on el cheapos and recharge those every day, without having to f*rt around with equalisation every week or fortnight. Ok, so you might have to replace them more frequently, but meantime you've saved a load of hassle and diesel.

It occurs to me that the real advantage of Trojans and their ilk is the ability to cope with heavy discharge currents, as must be needed to handle the stall current of a golf cart motor with two fat Yanks and their fully loaded golf club bags on board, so once more it all comes back to how you plan to use the juice in your boat.

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5 minutes ago, Dr Bob said:

They are the numbers I use. Reproduced in many places across the web. Can't remember seeing a set of numbers showing 12v = 25% SoC. Similar to Tojans data.

Yes. One source, copied many, many times. Is the degree to which it is copied and thus it’s ubiquitousness on the web a good indication of its validity? The thing is, there are other tables out there with different values. Which is right? Which is right for your particular batteries? Do batteries with a lot of calcium in the plates have the same SoC to voltage relationship as those with lots of antimony? So many questions!

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6 minutes ago, BruceinSanity said:

And if that is the case, you might just as well spend your money on el cheapos and recharge those every day, without having to f*rt around with equalisation every week or fortnight. Ok, so you might have to replace them more frequently, but meantime you've saved a load of hassle and diesel.

It occurs to me that the real advantage of Trojans and their ilk is the ability to cope with heavy discharge currents, as must be needed to handle the stall current of a golf cart motor with two fat Yanks and their fully loaded golf club bags on board, so once more it all comes back to how you plan to use the juice in your boat.

No, the opposite is true. A leisure battery is pretty much a starter batter whose primary design criteria is to provide very high currents with a cold battery for a short period of time. Large area of thin plates. Trojans etc are designed to have thicker plates thus more tolerant of deep cycling. They are not as good at providing high discharge current.

i know this not only from the theory but also from practice. When we swapped our 4x110AH leisure batteries for 450AH Trojans, their ability to run the electric kettle (200A) was noticeable worse - ie the terminal voltage was noticeably lower under the same circumstances of high load. Meaning of course that even more current had to be drawn to provide the 2kw of power, more AH used due to power loss at high current. I now tend to avoid using the kettle if the batteries are below 75% or so because the inverter gets close to its cutout voltage.

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7 minutes ago, nicknorman said:

No, the opposite is true. A leisure battery is pretty much a starter batter whose primary design criteria is to provide very high currents with a cold battery for a short period of time. Large area of thin plates. Trojans etc are designed to have thicker plates thus more tolerant of deep cycling. They are not as good at providing high discharge current.

i know this not only from the theory but also from practice. When we swapped our 4x110AH leisure batteries for 450AH Trojans, their ability to run the electric kettle (200A) was noticeable worse - ie the terminal voltage was noticeably lower under the same circumstances of high load. Meaning of course that even more current had to be drawn to provide the 2kw of power, more AH used due to power loss at high current. I now tend to avoid using the kettle if the batteries are below 75% or so because the inverter gets close to its cutout voltage.

How are they at handling high charging currents? I am definitely thinking that the high output from my alternator (175A) is contributing to the short life I am getting from cheaper batteries.

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34 minutes ago, Keeping Up said:

How are they at handling high charging currents? I am definitely thinking that the high output from my alternator (175A) is contributing to the short life I am getting from cheaper batteries.

If possible, how checking the SGs after a full charge?

Edited by smileypete
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14 hours ago, Mike the Boilerman said:

In addition, there must still be some Smartgauge-adulation/hero worship threads that would benefit from having my balanced and reasoned views adding ;)

But how many sets of scales do you have and are they in calibration? :P

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1 hour ago, nicknorman said:

Yes. One source, copied many, many times. Is the degree to which it is copied and thus it’s ubiquitousness on the web a good indication of its validity? The thing is, there are other tables out there with different values. Which is right? Which is right for your particular batteries? Do batteries with a lot of calcium in the plates have the same SoC to voltage relationship as those with lots of antimony? So many questions!

If the battery manufacturer provides a specific SoC/Voltage table for their batteries (many premium brands such as Trojan, Yuasa, US Batteries, Lifeline do), then obviously it is better to use that, rather than a generic one, particularly if they show temperature compensated charge voltsges as well.

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1 hour ago, Keeping Up said:

How are they at handling high charging currents? I am definitely thinking that the high output from my alternator (175A) is contributing to the short life I am getting from cheaper batteries.

Obviously 175A for 450AH is a lot more than the 10-13% recommended by Trojan. I'm sure it doesn't help the life when the intial current is 160A or more. But this doesn't last long and fairy soon, the current is down below 100A. Still a lot though, I suppose.

Anyway so far fine after 4 years but of course that is 4 years leisure use - hard leisure use though (Kettles, toaster, Nespresso etc), and we are out on the boat a lot, 13 weeks this year I think. The Mastershunt counts cycles as full cycle (ie down to 0%SoC) equivalents. I think it is on about 90 at the moment, So that is perhaps 360 cycles down to 75% SoC. The gravities still get back up to where they should be (1.277) and the capacity seems to be as-new so far. Well better than brand new, they were quite sluggish for the first several cycles and in fact hit their prime after about 6 months. Which is as per the manufaturer's data - 100 cycles or so to hit maximum capacity. Which of course is about half way through life for leisure batteries!

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1 hour ago, smileypete said:

If possible, how checking the SGs after a full charge?

The ones I am using now are sealed (not my choice). I must say I'll be glad to get back to using unsealed ones when I next change them, but these are less than 6 months old so I hope it won't be all that soon. I'm trying to decide whether or not to fit 12v Trojans next time.

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57 minutes ago, Keeping Up said:

The ones I am using now are sealed (not my choice). I must say I'll be glad to get back to using unsealed ones when I next change them, but these are less than 6 months old so I hope it won't be all that soon. I'm trying to decide whether or not to fit 12v Trojans next time.

Could do, if you can monitor and maintain them, and provide the correct charge voltage, and EQ voltage as and when needed. That does need a level of long term interest that's not for everyone I guess.

In your case*, for moderate use even decent truck batts might pan out OK, something like Numax 656 from Tayna look good value, though they are rather tall and so will need good charging.

(* I know Keeping up has been through many types of batts, and might not mind being a battery guinea pig on this one. :)  )

Edited by smileypete
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1 hour ago, nicknorman said:

they were quite sluggish for the first several cycles and in fact hit their prime after about 6 months. Which is as per the manufaturer's data - 100 cycles or so to hit maximum capacity. Which of course is about half way through life for leisure batteries!

I thought this was worth repeating :)

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18 minutes ago, Dr Bob said:

...as I said in post 52

I suspect that all lead acids are pretty similar. I have heard that a few manufacturers use a weaker acid, especially if the battery is destined for hot climates, maybe this changes things a little bit.

Dave

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I was thinking about buying a cheap ish 12v 'starter' battery and running it in parallel with the 2 x 6v 'domestic' Trojans as an experiment. I'd be interested to see whether I get the benefits of both types, or disadvantages. It will certainly be around half the price! Will it last as long? Hmm.

What could possibly go wrong? 

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On 07/11/2017 at 08:01, Tony Brooks said:

 

You got told the ammeter was probably in the wrong place within the first few posts so you got the probable answer. The fact you seemingly did not like or understand it does not mean you did not get or see it.

This is a repeat of the Perkins 4-108 cold start topic and the fridge volt drop topic. The OP has done some degree of self diagnosis and is looking for confirmation rather than the truth.

To pick up on your 2 points Tony.

I said I needed to reverse engineer the circuit to assess whether the ammeter is in the wrong place. So a good suggestion.

As regards your second point, I can confirm that I'd like to get to the bottom of the truth. You are wrong that I was looking for confirmation and can't see why you think this!?

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10 minutes ago, rowland al said:

To pick up on your 2 points Tony.

I said I needed to reverse engineer the circuit to assess whether the ammeter is in the wrong place. So a good suggestion.

As regards your second point, I can confirm that I'd like to get to the bottom of the truth. You are wrong that I was looking for confirmation and can't see why you think this!?

 

Now a quote from you from the first page of  answers. I highlight the relevant bit

"Again, I do appreciate everyone's replies here. 

So, two basic questions I can't get my head around. 

1) Why does the ampmeter show 20a charging a minute or so after starting from the starter battery, but only shows 1 to 2 amps charging when the domestic batteries are only 50%. Ampmeter in wrong place then? I should point out we are talking old fashioned analog ampmeter here, not digital. 

It makes no sense to me. The starter battery must be near 100% all of the time so would need less charge. Surely a higher charge current would be shown for the more depleted domestic batteries. 

2) Would it be better for me to charge my domestics using my 240v generator (run via belt off engine) and a battery charger than just my alternator? If so, I suppose that means a battery charger run off 240v is  more efficient than just using my 70a alternator? "

 

Not if the ammeter is not measuring it would not and you were told that was likely in, I think, the first reply. I submit that the phrase in red looks as if it is trying to justify your thoughts, not act on advice given.

Personally I do not see that tracing the ammeter wiring is "reverse engineering", It is likely all it will take is a quick look behind the instrument panel to show you that the ammeter is one of the "boy racer" types with thick cables running to it. Brian (I think) told you that sort is far from accurate and I told you they are likely to mess up the charging (volt drop on very long charging cables that are usually supplied undersized for the run plus a moving iron current "indicator"). At that point there is no need to reverse engineer anything, you just need  an accurate ammeter correctly fitted and connected.

You have been asked for a photo of the meter, has it appeared yet?

56 minutes ago, rowland al said:

I was thinking about buying a cheap ish 12v 'starter' battery and running it in parallel with the 2 x 6v 'domestic' Trojans as an experiment. I'd be interested to see whether I get the benefits of both types, or disadvantages. It will certainly be around half the price! Will it last as long? Hmm.

What could possibly go wrong? 

The above seems to me to show that you are still not accepting what you are seeing is an ammeter connection problem and not a battery one.

Although I said I would not help any more I fear the most likely outcome of doing want you suggest is that as long as you keep both battery types very well charged to avoid sulphation for most of the time the much lower cyclic life of the starter battery will cause it to internally short long before the Trojans.  That is fine as long as you notice it and act very quickly, if you do not its is likely to more deeply discharge the Trojans leading to more sulphation and a reduction in cyclic life. I would urge you not to try it. Just get the ammeter sorted and then do your best to keep the Trojans fully charged by observing the tail current.

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1 hour ago, rowland al said:

I was thinking about buying a cheap ish 12v 'starter' battery and running it in parallel with the 2 x 6v 'domestic' Trojans as an experiment. I'd be interested to see whether I get the benefits of both types, or disadvantages. It will certainly be around half the price! Will it last as long? Hmm.

What could possibly go wrong? 

You're joshing me. :)

I reckon 95% of narrowboaters are best off with decent brand leisure batts, but if the Trojans are working out fine for you that's good.

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21 minutes ago, Tony Brooks said:

 

Now a quote from you from the first page of  answers. I highlight the relevant bit

"Again, I do appreciate everyone's replies here. 

So, two basic questions I can't get my head around. 

1) Why does the ampmeter show 20a charging a minute or so after starting from the starter battery, but only shows 1 to 2 amps charging when the domestic batteries are only 50%. Ampmeter in wrong place then? I should point out we are talking old fashioned analog ampmeter here, not digital. 

It makes no sense to me. The starter battery must be near 100% all of the time so would need less charge. Surely a higher charge current would be shown for the more depleted domestic batteries. 

2) Would it be better for me to charge my domestics using my 240v generator (run via belt off engine) and a battery charger than just my alternator? If so, I suppose that means a battery charger run off 240v is  more efficient than just using my 70a alternator? "

 

Not if the ammeter is not measuring it would not and you were told that was likely in, I think, the first reply. I submit that the phrase in red looks as if it is trying to justify your thoughts, not act on advice given.

Personally I do not see that tracing the ammeter wiring is "reverse engineering", It is likely all it will take is a quick look behind the instrument panel to show you that the ammeter is one of the "boy racer" types with thick cables running to it. Brian (I think) told you that sort is far from accurate and I told you they are likely to mess up the charging (volt drop on very long charging cables that are usually supplied undersized for the run plus a moving iron current "indicator"). At that point there is no need to reverse engineer anything, you just need  an accurate ammeter correctly fitted and connected.

You have been asked for a photo of the meter, has it appeared yet?

The above seems to me to show that you are still not accepting what you are seeing is an ammeter connection problem and not a battery one.

Although I said I would not help any more I fear the most likely outcome of doing want you suggest is that as long as you keep both battery types very well charged to avoid sulphation for most of the time the much lower cyclic life of the starter battery will cause it to internally short long before the Trojans.  That is fine as long as you notice it and act very quickly, if you do not its is likely to more deeply discharge the Trojans leading to more sulphation and a reduction in cyclic life. I would urge you not to try it. Just get the ammeter sorted and then do your best to keep the Trojans fully charged by observing the tail current.

Thanks for that Tony. 

Unfortunately the wiring is a bit of a rats nest and is not under an easy to remove panel (old classic engine!). TBH, I'm a bit nervous about disrupting anything but I shall endeavour to get a photo soon when I get the chance,

The bit you quoted in red is an assumption and a question (I was simply trying to understand, not assert).

I still don't understand (yes may be due to ammeter location - work in progress I guess). Interestingly I tried starting the engine with a jump lead connecting the positive of the domestic battery to the positive of the starter battery, I observed exactly the same result in that the ammeter showed 20a or so charging after starting the engine for a few minutes then it crept back to 1-2amps. Domestics were about 12.2v at the time, starter 12.8v. Where do you think the ammeter might be located to see this effect? 

Hopefully I can give some more feedback Friday/Sat. 

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13 minutes ago, smileypete said:

You're joshing me. :)

I reckon 95% of narrowboaters are best off with decent brand leisure batts, but if the Trojans are working out fine for you that's good.

I'll be honest and say I am very suspicious when it comes to leisure batteries, That link further up on the thread from the caravan club tests just added to it. Also a bit weird they wouldn't name the brands which were iffy. Maybe law suits beckoned. 

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1 hour ago, rowland al said:

Thanks for that Tony. 

Unfortunately the wiring is a bit of a rats nest and is not under an easy to remove panel (old classic engine!). TBH, I'm a bit nervous about disrupting anything but I shall endeavour to get a photo soon when I get the chance,

The bit you quoted in red is an assumption and a question (I was simply trying to understand, not assert).

I still don't understand (yes may be due to ammeter location - work in progress I guess). Interestingly I tried starting the engine with a jump lead connecting the positive of the domestic battery to the positive of the starter battery, I observed exactly the same result in that the ammeter showed 20a or so charging after starting the engine for a few minutes then it crept back to 1-2amps. Domestics were about 12.2v at the time, starter 12.8v. Where do you think the ammeter might be located to see this effect? 

Hopefully I can give some more feedback Friday/Sat. 

Your current ammeter is obviously not measuring the current going into the domestic bank. You are nervous about disrupting stuff, so you current ammeter is not going to be much use. If you want to understand your boat electrics, you need a proper ammeter with a shunt installed on the negative of the domestic bank. The cheapest is the NASA one - and not difficult to fit. Order one now and fit it on the weekend so you then know what power is going in or out of your domestic bank.

Edited by Dr Bob
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2 minutes ago, Dr Bob said:

The cheapest is the NASA one

Oh no it isn’t! (Well, it is coming up to Panto season). There’s one for a fiver being discussed on another thread. Oh, plus three quid for a shunt. 

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