Refractometer

[ralphclaydon]

Having been losing the Charge on my Trojan T105's i have purchased a refractometer.

I have been in touch with Trojan in USA.

They wanted the Specific Gravity of my batteries after being disconnected for 2 hours.

 

I have results of around 1.300 which i am told is impossible!

Can anyone tell me which scale on refractometer you zero up on?

I zeroed on the lowest reading on the antifreeze scale, is this correct?

[nicknorman]

On my refractometer (cheapo, from eBay) there is a line going across the bottom labelled "waterline" which you set the device to, using distilled water. The corresponding specific gravity is of course 1.0, though on mine the battery scale only goes down to 1.1. The lowest reading on the antifreeze scale is probably 0C which would correspond to water. Surely the instructions that came with it must give a clue?

 

Trojans start out at 1.277, however you also have to remember that temperature has an effect so new batteries that are fully charged and very cold, will be above 1.277. 0.004 per 5 degrees below 27degrees so if the batteries are around zero, the new SG will be 1.3, so your measurement is probably correct. It sounds like it will be easier if you apply the temperature compensation before you report the figures to them (they are clearly a bit dim!).

[ralphclaydon]

Hi Nick

This is their reply!

 

 

Dear Ralph,

These values can not be possible. The specific gravity can not be higher than 1,277.

Check page 17.

Have you add any liquid to the batteries?

Can you let the batteries disconnected 24 hours? And check the values again?

Regards,

[nicknorman]

Hi Nick

This is their reply!

 

 

Dear Ralph,[/size]

 

These values can not be possible. The specific gravity can not be higher than 1,277.

 

Check page 17.

 

Have you add any liquid to the batteries?

 

Can you let the batteries disconnected 24 hours? And check the values again?

 

Regards,

Well i did say they were a bit dim. What they should have said is "the specific gravity at 27deg C cannot be higher than 1.277, please adjust your reading for temperature.".

 

Roughly what was the battery temperature when you took the readings?

 

Anyway, perhaps the more relevant point is that at 1.300 (presumably at low temperature) the batteries are in good condition and probably the issue lies elsewhere - ie in the boat's circuits or even in your expectation. If you give us some more info about what the actual problem is, we might be able to help you.

 

Judging by the level of competence so far displayed by Trojan, it seems unlikely that they are going to be of much help!

Edited February 16, 2015 by nicknorman

[ralphclaydon]

Nick

The temperature is 10 degrees now! so i would have said about 8 degrees when i measured them.

This is ongoing as in my posting a couple of weeks ago when i put some lights on and the Smart gauge went down to 11.9Volts in a matter of half an hour!!

 

Where you advise a Desulphation charge of 15.5v, my battery charger will only do 14.8v!!

I am still struggling to solve the problem!

[Boredrider]

I don't think you need to equalise with those readings, Trojan suggest you should equalise if the readings differ by .03 across the cells in any single battery.

 

You could switch the lights on like you did before, wait until the Smart Gauge says 50% and then check with the refractometer again. That will tell you if the Smart Guage is reading accurately. While you have the lights on, you should check the discharge rate in Amps, using a clamp ammeter. It could be that you have some other (possibly faulty) piece of kit that is discharging the batteries at a much higher rate than the few lights that you have spoken about.

[dmr]

Is the water (acid) level correct?

I reckon that the SG goes up as the water goes down.

 

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

[nicknorman]

Nick

The temperature is 10 degrees now! so i would have said about 8 degrees when i measured them.

This is ongoing as in my posting a couple of weeks ago when i put some lights on and the Smart gauge went down to 11.9Volts in a matter of half an hour!!

 

Where you advise a Desulphation charge of 15.5v, my battery charger will only do 14.8v!!

I am still struggling to solve the problem!

Well if it was 8 degrees ambient in the morning, the battery internal temperature will be lagging behind a bit so if we can make it 7 degrees that is 20 degrees below the reference temperature of 27 degrees, ie 4 x 5 degrees, you need to subtract 4 x 0.004 from the readings, therefore 1.300 becomes 1.284 which is pretty close to the fully charged 1.277, especially as the batteries might in fact be colder especially if they are sitting on the swim.

 

Sorry, I have some guests coming soon and have to tidy the boat, but I'll review your previous posts later (maybe tomorrow morning) to see if we can come up with a plan. In the mean time I'm sure the other guys will help with ideas.

 

In the mean time, can you confirm all the cells are pretty much at the same SG? What does the lowest cell read (before any adjustment for temperature).

Edited February 16, 2015 by nicknorman

[ralphclaydon]

Hi Nick

Thanks for your help.

The readings for my batteries were-

Battery No 1

1.305 1.295 1.305

Battery No 2

1.295 1.285 1.295

Battery No 3

1.300 1.295 1.300

Battery No 4

1.300 1.290 1.295

 

Seems strange that the middle cell in each battery is the lowest!!!

[Chewbacka]

Maybe the middle cell is the coldest?

[nicknorman]

Hi Nick

Thanks for your help.

The readings for my batteries were-

Battery No 1

1.305 1.295 1.305

Battery No 2

1.295 1.285 1.295

Battery No 3

1.300 1.295 1.300

Battery No 4

1.300 1.290 1.295

 

Seems strange that the middle cell in each battery is the lowest!!!

That seems pretty healthy to me. There is some minor difference, but it's not much.

 

Can you tell us again exactly what the problem is?

[ralphclaydon]

Nick,

This is what started things off a few days ago i wrote the on forum.

"I installed 4 of these last March, these last weeks according to my Smart gauge have dropped from 100% to 72 %, i only use a couple of LED light and a water pump. Today i put 4 x 10w bulbs on for about 30 minutes and the charge went from 83% to 72%.

I have checked to make sure nothing is switched on or working which i don,t know about.

I am on shore power so not using inverter etc"

I still have this problem, I have left the battery charger off last night, just to see what happens!

The Smart gauge voltage (Which i have double checked with a volt meter across batteries and seems pretty accurate) was the same as last night.12.70 to 12.80.

after turning on 2 x LED lights and using water pump to fill kettle went down to 12.60 in about 20 minutes!

i will now turn 4 x 20w G4 bulbs on and see what happens in Half an hour.

Thanks

[ralphclaydon]

Have just checked voltage, it has gone down to 12.40. after half an hour,Which is not as bad as last time!!!!!!!

[nicknorman]

Hi Ralph.

 

When specifying a voltage it's important to also specify the conditions, eg when you say "12.4v" above, is that with the lights still on? Or just after turning off? Or some time after turning off? And how and where is the 12.4 being measured? If you aren't specific, it's really easy for us to make an incorrect assumption.

 

Anyway, having looked at the previous thread it does sound like a gradual deterioration which tends to point to the batteries.

 

I suppose the only other possibility is a wiring issue with gradually increasing resistance somewhere. Can you confirm the Smartgauge + and - is connected directly to the battery terminals, and not via any other wires shared with something else?

 

Back to the batteries, I think we concluded that you had never had to add water to the batteries in a year, which suggested undercharging. Even though the specific gravities seem fine, I still think it would be worth doing an equalisation charge. Well I suppose that's partly because I can't think of anything else to suggest!

 

If your charger can't do that, you will have to get something that can and getting an adjustable bench power supply of at least 5A and 15.5v capability is an easy way to do that, although not particularly cheap (£80 - £100) but since the batteries are likely to require an equalisation every 6 months or so it is a long term investment.

 

So to do an equalisation firstly full charge the batteries. You probably need about 10A to equalise 450 AH so with a 5A one you would need to split the batteries into 2 x 225 AH strings and disconnect one string to be equalised. Then just connect the power supply and adjust the voltage up gradually whilst keeping an eye on the current, so as to end up at 15.5v (warm batteries) up to perhaps 15.8v (cold batteries). Leave it like that for perhaps 3 hours after the current has stabilised. Then recheck the specific gravities (out of interest) and check water levels.

 

Repeat for the other 225AH string.

 

If that makes no difference, and all the wiring is fine, then we are a bit stumped and there must be something going on with the batteries.

[ralphclaydon]

Hi Nick

 

I took the 12.40 reading from smart gauge, this is connected directly to the batteries.

You say about a bench power supply etc! and Equalisation.

This goes right over my head!!!

Is it possible to buy a battery charger that will do these things for me?

i would be more at ease with that!

If so could you recommend one?

 

Thanks for your time.

 

The lights were still on when taking voltage.

Edited February 17, 2015 by ralphclaydon

[nicknorman]

Equalisation is just a fancy word for additional charging at a higher than normal voltage after the batteries are fully charged. My own charger (part of the mastervolt Combi) does have an equalise mode but it's rubbish. I therefore equalise simply by manually increasing the charging voltage -I'm lucky because I can do that with my Combi.

 

So I'm afraid I don't have any experience / can't offer advice on a good charger with a good equalise mode, but hopefully someone else can...

[Phil.]

Like Nick I have a mastervolt combi. However I have been told that ctek chargers are very good at recovering and maintaining batteries.

For your size of bank I think the below link is the one you would need.

http://www.mailspeedmarine.com/c-tek-battery-charger-m200-15amp.html

No connection to company or supplier just linked for illustration purposes.

[Rich]

Is it possible to buy a battery charger that will do these things for me?

i would be more at ease with that!

If so could you recommend one?

 

Trojan recently recommended a CTEK MX25 battery charger when I enquired about its suitability. They said "CTEK charges are really good" and "It has option to bulk up to 15,8V This charger is going to work perfectly with our batteries."

 

If you are going to consider one it pays to shop around online as prices vary considerably.

[Keeping Up]

Today I measured my batteries for the first time with my new refractometer, the type from eBay as recommended here. Admittedly they're Varta not Trojan, but it was interesting to see that after a couple of equalisation charges followed by 3 months on float their SG showed at about 1310 (at a temperature that was only just above zero).

[nicknorman]

I have been told that ctek chargers are very good at recovering and maintaining batteries.

For your size of bank I think the below link is the one you would need.

http://www.mailspeedmarine.com/c-tek-battery-charger-m200-15amp.html

No connection to company or supplier just linked for illustration purposes.

 

 

Trojan recently recommended a CTEK MX25 battery charger when I enquired about its suitability. They said "CTEK charges are really good" and "It has option to bulk up to 15,8V This charger is going to work perfectly with our batteries."

 

If you are going to consider one it pays to shop around online as prices vary considerably.

 

I have no experience of either of these chargers, however the spec shows that the M200 does an equalise at 15.8v max 3A for only 30 minutes. The MXS25 only does the equalise at 1.5A according to one bit of the spec, 3A according to another bit, but also limited to 30 mins.

 

My opinion is that 3A is not really enough for 450AH, and 1.5A is definitely not. 30 mins is not really long enough to do much. But I guess it COULD work but you would have to ensure everything was off in the boat so as not to lose any of the precious 3A, and sit around waiting to retrigger it every 30 mins. I would suggest that at least, split the bank into 2 x 225AH and equalise one half in isolation whilst the other half is powering the boat / connected to the normal charger.

 

But both these chargers are a LOT more expensive than a bench power supply, and will be far more irritating, ineffective and time consuming when used to do an equalisation. I would suggest its not worth it unless you want to replace your existing charger.

Today I measured my batteries for the first time with my new refractometer, the type from eBay as recommended here. Admittedly they're Varta not Trojan, but it was interesting to see that after a couple of equalisation charges followed by 3 months on float their SG showed at about 1310 (at a temperature that was only just above zero).

 

That's good, innit?

[Rich]

But both these chargers are a LOT more expensive than a bench power supply,

What's one of them. To us uninitiated, like me, a bench power supply would be a 230v socket but I don't think you mean that, at least I hope not.

[Keeping Up]

I just looked at the manual for my ctek MSX 5.0 which is only powerful enough to do one battery at a time. It says the "recondition" setting which is a pulsed 15.8v supply, lasts for between 30 minutes and 8 hours depending on the condition of the battery.

[nicknorman]

I just looked at the manual for my ctek MSX 5.0 which is only powerful enough to do one battery at a time. It says the "recondition" setting which is a pulsed 15.8v supply, lasts for between 30 minutes and 8 hours depending on the condition of the battery.

As I said, no direct experience of them but my understanding, from reading the specs of the mentioned chargers, is that it normally lasts 30mins, unless the batteries are badly damaged in which case it lasts 8 hrs.

[nicknorman]

What's one of them. To us uninitiated, like me, a bench power supply would be a 230v socket but I don't think you mean that, at least I hope not.

A bench power supply is a power supply designed to sit on a bench! It is to provide the bench's user (eg electronics technician) with a regulated (normally adjustable) dc voltage, normally with adjustable current limit. Typically they have meters for voltage and current.

 

Here is an example from Maplins: http://www.maplin.co.uk/p/100w-slim-bench-power-supply-n93cx

 

Edited to add some folk seem to have had some grief when charging batteries using the above power supply. It is fine u til you turn off the power supply with the battery still connected - this seems to damage it.

 

I would therefore recommend this one, which I have, which doesn't suffer from that problem, even though it is a tenner more and slightly more complicated.

 

http://www.maplin.co.uk/p/80w-switched-mode-dc-multi-voltage-slim-bench-power-supply-n27gg

Edited February 17, 2015 by nicknorman

[lexicon]

A bench power supply is a power supply designed to sit on a bench! It is to provide the bench's user (eg electronics technician) with a regulated (normally adjustable) dc voltage, normally with adjustable current limit. Typically they have meters for voltage and current.

 

Here is an example from Maplins: http://www.maplin.co.uk/p/100w-slim-bench-power-supply-n93cx

 

Edited to add some folk seem to have had some grief when charging batteries using the above power supply. It is fine u til you turn off the power supply with the battery still connected - this seems to damage it.

 

I would therefore recommend this one, which I have, which doesn't suffer from that problem, even though it is a tenner more and slightly more complicated.

 

http://www.maplin.co.uk/p/80w-switched-mode-dc-multi-voltage-slim-bench-power-supply-n27gg

Hi nick

Would a power supply like that be ok to run from an inverter Genny ?