Equalising

[MtB]

At a quick glance at the specs this one appears to http://www.asap-supplies.com/30-amp-battery-charger-for-24-volt-batteries-61112313

 

 

£565.28???!!! That's even more than my Sterling thing was!!

 

Amusing to see the page suggests buying a pure sine wave inverter to go with it haha!

[nicknorman]

Well yes, which is why I asked!

 

Can anyone suggest a charger that can be set to 32V?Or are these impossible charge voltages specified by manufacturers to stave off guarantee claims?

But if you set Custom to 30.2v, what voltage do you actually get with a cold temperature probe? Is 30.2 the absolute maximum output voltage, or is it the nominal voltage at 25C in which case at 5C you could expect another volt or so.

 

Anyway I have to say it is a bit odd that Trojan and Yuasa (and probably other manufacturers) specify this high finishing voltage and yet no chargers seem to be available that actually do that.

Edited January 7, 2017 by nicknorman

[MtB]

But if you set Custom to 30.2v, what voltage do you actually get with a cold temperature probe? Is 30.2 the absolute maximum output voltage, or is it the nominal voltage at 25C in which case at 5C you could expect another volt or so.

 

 

Dunno, I've not tried.

 

It always seems to absorption charge at 30.0v whatever the temp, even though I have the temp probe installed.....

[Richard10002]

The equalising setting on my Sterling Inverter Charger charges at 15.5V, (presumably 31V on the 24V version). In the absence of an alternative, I'd use this and see how it goes. It runs for 4 hours, unlike the normal charging modes which limit themselves to an hour much of the time, so need resetting every 50 mins or so.

[dmr]

A friend (and occasional poster here) has just pointed out that as I am 60 in a couple of weeks that I should now take care of my personal batteries. He recommends sleeping in longer for a better recharge and afternoon naps to equalise.

 

He's not very technical so did not specify the equalisation voltage, can anyone help?.

 

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

[ditchcrawler]

A friend (and occasional poster here) has just pointed out that as I am 60 in a couple of weeks that I should now take care of my personal batteries. He recommends sleeping in longer for a better recharge and afternoon naps to equalise.

 

He's not very technical so did not specify the equalisation voltage, can anyone help?.

 

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

Maybe that is where I am going wrong Dave. I don't nap

[beerbeerbeerbeerbeer]

A friend (and occasional poster here) has just pointed out that as I am 60 in a couple of weeks that I should now take care of my personal batteries. He recommends sleeping in longer for a better recharge and afternoon naps to equalise.

 

He's not very technical so did not specify the equalisation voltage, can anyone help?.

 

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

Before rest, Anything above 4.8%, 5.2% is ideal.

 

But not too much...you'll end up with 'eggy smell'.

Edited January 7, 2017 by Goliath

[WotEver]

A friend (and occasional poster here) has just pointed out that as I am 60 in a couple of weeks that I should now take care of my personal batteries. He recommends sleeping in longer for a better recharge and afternoon naps to equalise.

 

He's not very technical so did not specify the equalisation voltage, can anyone help?.

 

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

It's not the voltage but the time taken for such equalisations that's important. I find somewhere between 20 minutes to an hour is generally sufficient.

[MtB]

Some more perplexing data:

 

Charged the batteries last night with the genny. I started at 5pm and ran for three hours up to 8pm, during which time the SG reported the SoC rose from 54% to 100%.

 

This morning, with the SG showing 97% I proceeded to cruise for about three hours. At the end of the three hours cruising the SG was once again showing 100%, the charging voltage was 28.27V (according the the BMV-702 which seems accurate), and the tail current as I stopped the engine was 1.90A.

 

Then I 'finished off' with a further 45 minutes of silent charging usuing the current pump set to 30.3V, during which time the charge current fell from 6A approx (I forgot to write it down) to 3.1A when I had to disconnect as I had to catch a train.

 

On return to the boat this evening (no load on the batteries in the interim) The SG was still reporting 100% so out of curiosity I checked the specific gravity of a couple of cells. I picked the cells having the highest and lowest readings last time.

 

The highest cell last time was 1.267 at probably about 15C. Today at a prism temp of 20C this cell was 1.224.

 

The lowest cell last time was 1.254 at approx 15C. Today it was 1.208 at 20C.

 

A bit of googling suggests this means this battery is only about 75% SoC. A massive variance from the SmartGauge reading of 100%

 

I'm beginning to conclude the SG is less than useless in determining higher SoC values. Its not just a little inaccurate as the board has tended to say, it is wildly inaccurate.

[system 4-50]

 

...

Curiously I notice the SG 'likes' the value 74%. It will tumble to 74% after charging and sometimes display it for a full 24 hours before the display begins descending further.

I haven't read the whole thread through again but wondered if this is significant since the default for a newly connected SG is 75%. Could your SG be getting disconnected/switched out at some point? Or perhaps it is defective and getting reset internally?

Probably irrelevant or covered elsewhere if so please ignore.

[mross]

Mike, have you considered a bench power supply? I have a £40 unit but it's only suitable for 12V systems. I plan to use it to equalise my Trojans. You could set a voltage AND limit the current at the same time. Obviously, it would supplement your normal battery charger.

[mross]

Here's one on eBay that is adjustable 0-40V and 0-6A

 

http://www.ebay.co.uk/itm/Voltcraft-VLP-2403pro-Triple-Output-Variable-Bench-DC-Power-Supply-Linear-/401255862267?hash=item5d6cb68ffb:g:XXYAAOSw5cNYbXTS

 

I searched for "power supply" bench dc

Edited January 8, 2017 by mross

[Gareth E]

I have a question. I have a 20a Sterling Pro Ultra, I use a genny, battery is a 12v Trojan. I didn't fit the temperature probe, laziness, it would have meant drilling another hole in the bulkhead.

 

My batteries are sat at around 6 or 7 degrees. The charger is set at 14.8v. If I had fitted the temperature probe, would the charger then charge at (around) 1 volt more? I ask because the highest setting on the custom program is 15.1. If so, does this mean that fitting the probe is more or less essential, if I want to maintain the health of the battery? Also, I'm concerned that if I did charge a what effectively is around 15.8v it might blow my tv up, or a pump, or something else. Also, if the temperature sensor is fitted will the voltage shown on the face of the charger stay at 14.8, or would it show the higher, temperature compensated voltage?

[mross]

Does your TV have a nameplate on the back? Normally it would state the permitted input voltage range. It will take more than 12v because all car/caravan/boat systems will experience more than 12V when charging.

 

When the temperature compensation is active the display will show the actual voltage but you can check with a multimeter or battery monitor.

Edited January 8, 2017 by mross

[cuthound]

Without the temperature probe, you risk sulphation your batteries and hence expensive early replacement.

 

Why not buy a regulator for youth TV like this one?

 

https://www.amazon.co.uk/cigarette-equipments-Hunterfield-distributed-reserved/dp/B008A6GCXK/ref=pd_lpo_107_bs_tr_t_2?_encoding=UTF8&psc=1&refRID=S3FSPG7HF5NQ8809GQ3M

[MtB]

Without the temperature probe, you risk sulphation your batteries and hence expensive early replacement.

 

Why not buy a regulator for youth TV like this one?

 

https://www.amazon.co.uk/cigarette-equipments-Hunterfield-distributed-reserved/dp/B008A6GCXK/ref=pd_lpo_107_bs_tr_t_2?_encoding=UTF8&psc=1&refRID=S3FSPG7HF5NQ8809GQ3M

 

 

Personal experience suggests WITH a temperature probe, one risks sulphation and expensive early replacement.

 

I've done everything right (superficially at least), i.e. fitted a Sterling Pro Charge Ultra (with temperature probe!), set it to the correct battery type according to the manual, fitted a SG and a brand new set of batteries. I've charged to 100% once a week, never let them fall below 50% yet three months later my battery capacity is down to 60% of new.

 

The thing is, received wisdom on this board is incomplete. People say the SG is not necessarily accurate when displaying 100% and I imagined this meant the batteries were at perhaps 95% and a further hour of charging would finish them off. HOWEVER, on testing the specific gravity of my electrolyte after not only hours and hours of cruising with the batteries at 100% according to the SG, and then a couple of hours of 'overcharging' (desulphating) the SG readings show the batteries nothing like fully charged.

 

My next experiment will be to wait until the batts need charging again, charge them to 100% of the SmartGauge then stop charging and take another set of specific gravity readings of the electrolyte. I'm suspecting they will show a SoC of about 75%.

 

In fact on reflection I should take a set of readings before starting charging too, to assess the accuracy of the SmartGauge when reading 50%.

 

All interesting stuff and I'm posting it so other people - new boaters especially - can see the variance between superficial received battery charging wisdom and my personal experience of the same!

Edited January 8, 2017 by Mike the Boilerman

[cuthound]

Personal experience suggests WITH a temperature probe, one risks sulphation and expensive early replacement!

 

I've done everything right (superficially at least), i.e. set my Sterling Pro Charge Ultra to the correct battery type and fitted a SG and a brand new set of batteries, and charged to 100% once a week, never let them fall below 50% yet three months later my battery capacity is down to 60% of new.

I thought your problem was that your Stirling charger cannot raise the voltage high enough?

 

My 12 volt Victron Combi raises the charge voltage to 16 volts when the temperature falls below zero.

[nicknorman]

A bit of googling suggests this means this battery is only about 75% SoC. A massive variance from the SmartGauge reading of 100%

 

I'm beginning to conclude the SG is less than useless in determining higher SoC values. Its not just a little inaccurate as the board has tended to say, it is wildly inaccurate.

 

I think you misunderstand what the SG is telling you. Remember, it tells you the SoC of your batteries relative to their capacity as it stands now, not their new capacity. This of course is a major strength of the SG over the likes of a BMV. You did charge your batteries to near 100% SoC as evidenced by the tail current. However the batteries are significant sulphated, ie some of the acid is locked away as sulphate and that is why the specific gravity is quite low even when the batteries are ostensibly fully charged. As far as the SG is concerned, you just have batteries that have a much lower capacity than when new and it is correctly reporting the SoC relative to the current capacity.

 

I would say that overall, you have answered the question you asked earlier about whether leaving the batteries to discharge for a week and then charging them once a week might create sulphation. It seems it does!

Here's one on eBay that is adjustable 0-40V and 0-6A

 

http://www.ebay.co.uk/itm/Voltcraft-VLP-2403pro-Triple-Output-Variable-Bench-DC-Power-Supply-Linear-/401255862267?hash=item5d6cb68ffb:g:XXYAAOSw5cNYbXTS

 

I searched for "power supply" bench dc

I think this would be a good way to provide the "finishing voltage", the only slight problem is that most bench supplies only go up to 30v - presumably some safety issue? So although you have found that one that fits the bill, they are fairly rare and expensive.

Personal experience suggests WITH a temperature probe, one risks sulphation and expensive early replacement.

 

I've done everything right (superficially at least), i.e. fitted a Sterling Pro Charge Ultra (with temperature probe!), set it to the correct battery type according to the manual, fitted a SG and a brand new set of batteries. I've charged to 100% once a week, never let them fall below 50% yet three months later my battery capacity is down to 60% of new.

But as I said a moment ago, you have left them in a discharged state for a week, repeatedly. So whilst you have done things mostly "right", I think in that specific area you may well have created the problem.

Edited January 8, 2017 by nicknorman

[mross]

It was £150 which is less than most chargers. I also found one for under £30 but it would need an enclosure.

 

http://www.ebay.co.uk/itm/DPS5015-0-50V-15A-Programmable-Step-down-DC-Digital-Regulated-Power-Supply/252653778188?_trksid=p2050601.c100574.m4253&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D37140%26meid%3Daba78c43b3d14254944323a645514333%26pid%3D100574%26rk%3D1%26rkt%3D4%26sd%3D252653778188

 

This is programmable, so less risk of selecting the wrong voltage. And with the current limiting, you could guard against excessive gassing. I suppose you could also raise the voltage slowly from float to equalising while keeping an eye on current.

[MtB]

I think you misunderstand what the SG is telling you. Remember, it tells you the SoC of your batteries relative to their capacity as it stands now, not their new capacity. This of course is a major strength of the SG over the likes of a BMV. You did charge your batteries to near 100% SoC as evidenced by the tail current. However the batteries are significant sulphated, ie some of the acid is locked away as sulphate and that is why the specific gravity is quite low even when the batteries are ostensibly fully charged. As far as the SG is concerned, you just have batteries that have a much lower capacity than when new and it is correctly reporting the SoC relative to the current capacity.

 

 

 

Thanks Nick. Yes I was misunderstanding. I will recalibrate my understandings.

 

 

 

I would say that overall, you have answered the question you asked earlier about whether leaving the batteries to discharge for a week and then charging them once a week might create sulphation. It seems it does!

 

But as I said a moment ago, you have left them in a discharged state for a week, repeatedly. So whilst you have done things mostly "right", I think in that specific area you may well have created the problem.

 

 

But these are two different things to my mind. "Leaving batteries discharged for a week" seems different from "discharging continuously from 100% to 50% over a week long period".

 

My empirical evidence suggests as far as the battery is concerned though, it is just as likely to sulphate up whilst actually in use and above 50% SoC, as when left unused at less than 100%SoC.

[MtB]

Mike, have you considered a bench power supply? I have a £40 unit but it's only suitable for 12V systems. I plan to use it to equalise my Trojans. You could set a voltage AND limit the current at the same time. Obviously, it would supplement your normal battery charger.

 

 

Thanks for the suggestion, no I hadn't!

 

I'm not entirely sure though as the elapsed time necessary to fully charge my batteries seems to run into the tens of hours per week. This is simply impractical and I'm now wondering if I should change my policy to buying a new set each spring (which will be looked after by the solar), then just allowing them to get trashed over the three winter months when I have the least time available for charging and they need the most time spent charging.

 

However, there is new information to add to the mix. I'm getting a Whispergen to play with! So that will change EVERYTHING...

[mross]

You could run a bench supply from the inverter when cruising, possibly.

[MtB]

You could run a bench supply from the inverter when cruising, possibly.

 

 

Yes, good point. I can independently isolate the domestic bank and connect an inverter to the alternator charging the starter battery.

 

Possibly less mucking about than fitting an Adverc...

[Richard10002]

I would say that overall, you have answered the question you asked earlier about whether leaving the batteries to discharge for a week and then charging them once a week might create sulphation. It seems it does!

 

But as I said a moment ago, you have left them in a discharged state for a week, repeatedly. So whilst you have done things mostly "right", I think in that specific area you may well have created the problem.

 

 

I think Mike describes a situation where he charges his batteries to 100%, (or near enough), on a Sunday, (perhaps over Saturday and Sunday). He then uses them without further charging over the course of the week, then he charges them again the next weekend, and so on.

 

He therefore doesn't leave them discharged to 50% for a week but, they are a bit more discharged each day until they are at 50% on say, Saturday. There is no charging over the course of the week.

 

Assuming this is a battery killing regime, we could do with identifying how many days the batteries can be discharged without charge, or how far they can be discharged before some charging should take place.

 

In fact, is it a function of time with no charging, rather than depth of discharge? I think I recall that you discharged your Trojans to 30% SoC regularly, on the basis that this encouraged them to reach max capacity.

 

If Mike had a bigger bank, such that his weeks useage only took them to 80% DoD, would they survive for many years, or would they still suffer because they havent experienced any charging for 6/7 days.

 

Could it be that, no matter how deep we discharge our batteries, they ought to have a few hours of charging every day, or every other day, or whatever, ("whatever" being less than 7 days).

 

In fact, perhaps it could be said that a battery on permanent shore power charge, and therefore constantly as close to fully charged as possible, and being charged constantly, (mostly at float), is experiencing the ideal regime.

 

Perhaps a boater who cruises for 5 or 6 hours every day, with only occasional periods where they dont cruise every day, creates close to the ideal regime for battery longevity. i.e. batteries experience some charging every day, and are charged to 100%, (as good as), every day.

 

Of those boaters who have batteries which last them for many years, I wonder what is the commonality, (deliberate or otherwise), between their charging regimes?

[mross]

But what will the domestic alternator be doing? We have to consider all possible risks. need some advice from NN and others.