Brand new leisure batteries going flat

[Robbo]

Yes. In the same test he was unable to break a Rolls battery. He repeatedly took it down to 0V and it just refused to die.

 

I suspect that Trojan would perform similarly to the Rolls.

 

Which Rolls? The 5000 or the 4000, the 4000 is similar to the Trojans, but the 5000 are much better still with about double the number of cycles to the same DoD.

T105s are only about twenty quid more these days, although you have to buy in pairs to get 12V.

 

You may also need a bigger bank as they don't like to give the amps like a leisure battery does.

[WotEver]

Which Rolls? The 5000 or the 4000, the 4000 is similar to the Trojans, but the 5000 are much better still with about double the number of cycles to the same DoD.

I don't believe he said. If he did I don't remember.

[WotEver]

I can't find that post right now but I have found this one:

 

I've been running tests recently involving just this. ie discharging batteries down to zilch in order to deliberately ruin them to check a battery monitor which also calculates the state of health.

 

Brand new ("leisure" - not real deep cycle but not a complete cheapo. ie not an engine start battery with handles on it) battery, cycled a few times to get it up to working capacity, tested out at 85Ahrs (the label said 90Ahrs, the man in the shop reckoned them to be at least 100Ahr - obviously talking crap).

 

5 discharges down to zero % SoC followed by immediate, good, charges, reduced it to a 60Ahr battery.

 

The same thing done to an engine start battery actually broke it after the fourth discharge. It hardly worked at all after that.

 

Back to the leisure battery. Another week with daily cycles down to zero % and it was down to 40Ahrs. It has been cycled daily since then but only down to around 65% and remains about the same. This started about 1 month ago.

 

On monday I start doing exactly the same tests with two proper (very expensive) deep cycle batteries. I shall post the results. Will be a few weeks. I suspect it will take somewhat longer.

 

But remember, people who treat batteries this way are usually the same people that leave them flat for days and/or don't charge them up properly either which, obviously, compounds the problem.

[Justme]

While we're talking about voltages it's worth pointing out that 11.x volts is effectively completely flat. Considering that you should try to keep the voltage above 12.2V as an absolute minimum then not only have these batteries been undercharged they've also been hammered.

 

Except under heavy load.

[WotEver]

 

Except under heavy load.

Hence the usefulness of SG vs a Voltmeter.

[Alan de Enfield]

Hence the usefulness of SG vs a Voltmeter.

 

Is that

SG = Specific Gravity, or

SG = Smart Gauge.

 

As we have both methods to give the answers to the questions I think that maybe we should use the full names to differentiate between the methods

[WotEver]

 

Is that

SG = Specific Gravity, or

SG = Smart Gauge.

 

As we have both methods to give the answers to the questions I think that maybe we should use the full names to differentiate between the methods

In this particular context, either

[Richard10002]

 

You may also need a bigger bank as they don't like to give the amps like a leisure battery does.

I've got 4 Trojan T105s, and they have no trouble powering a Dyson Hoover, Nespresso Coffee maker, via a 2500W inverter. I think I specified the inverter at 2500W on the basis that I wanted to run a Hoover.

 

I think I see 80A to 100A on the monitor at times.

 

Cant imagine wanting much more than that?

[Robbo]

I've got 4 Trojan T105s, and they have no trouble powering a Dyson Hoover, Nespresso Coffee maker, via a 2500W inverter. I think I specified the inverter at 2500W on the basis that I wanted to run a Hoover.

I think I see 80A to 100A on the monitor at times.

Cant imagine wanting much more than that?

2500watt is around 230amp at 12v, the 4 trojans will struggle providing this and the voltage will drop and the inverter may cut out especially when at a high DoD.

[nicknorman]

2500watt is around 230amp at 12v, the 4 trojans will struggle providing this and the voltage will drop and the inverter may cut out especially when at a high DoD.

It depends on the temperature but even in winter we can use the 2kw electric kettle in the morning without the inverter complaining too much (450AH 12v T105s). However once they get down to near 50% it does start to struggle a bit. Better in summer when they're warm.

 

Ideally I'd like another pair of T105s but no room with the present layout.

Edited August 30, 2016 by nicknorman

[Robbo]

It depends on the temperature but even in winter we can use the 2kw electric kettle in the morning without the inverter complaining too much (450AH 12v T105s). However once they get down to near 50% it does start to struggle a bit. Better in summer when they're warm.

 

Ideally I'd like another pair of T105s but no room with the present layout.

Diesel heaters tend to voltage sensitive, if one keeps cutting out this is a thing to look out for.

[MtB]

But they're twice the capacity so that evens out

 

Tayna are selling them at £108 right now.

 

 

Not if you have a 24v battery bank.

 

I can buy a new 24v bank of el cheapos for £160, but a new 24v bank of Trojans costs £432.

But I take your point. Perhaps I'll fix an extra boiler tomorrow and get the Trojans

[Sea Dog]

Not if you have a 24v battery bank.

 

I can buy a new 24v bank of el cheapos for £160, but a new 24v bank of Trojans costs £432.But I take your point. Perhaps I'll fix an extra boiler tomorrow and get the Trojans

Which will cost another 432 to replace when you goose them this winter when your solar stops producing and you're back to struggling with your charging regime again. They'll be more robust, of course, but will they be robust enough to survive your previously reported difficulties? It a tough choice!

[WotEver]

Not if you have a 24v battery bank.

 

I can buy a new 24v bank of el cheapos for £160, but a new 24v bank of Trojans costs £432.

But they're still twice the power, so that'd be £320 for el cheapo's...

[Terryb]

 

 

Sorry to keep on about this but no, your fridge uses 2 Amps while it is running, for however long. Not 2 amps per hour.

 

An amp is a unit of current and therefore independent of time. Please try to grasp this concept or you will remain mired in confusion about battery charging.

So then explain the where Jonny went wrong then. Because he said " I think it usesabout 2 amps per hour" As I am quite sure Jonny is capable of realising that half of one hour equals half of the 2amps Doh !!

I dont know if you are aware sometimes MtB just how condescending your comments are.

[Alan de Enfield]

Trying to make this as understandable as possible :

 

An amp is a specific measurement, it is an 'instantaneous' reading and the piece of equipment will always use 'one amp' be it for 1 second, 1 hour, or 1 day, however, when you relate it to time (ie how many amps are used over that time) it becomes 'Ah', so a fridge may use "48Ah over 24 hours"

 

The official definition of Ampere (amp) is :

An ampere is a unit of measure of the rate of electron flow or current in an electrical conductor. One ampere of current represents one coulomb of electrical charge (6.24 x 10¹⁸ charge carriers) moving past a specific point in one second.

 

So if you say 'amps per hour' you are actually saying "1 coulomb per second per hour" which is obviously nonsense.

 

 

Think about a 100w light bulb , you don't say 'it is a 100 watts per hour light bulb', it is just a '100 watt bulb'

The alternator on your engine is called a '75 amp alternator' - Not a '75 amp per hour alternator'

 

Use of the correct units may appear to be pedantic, or condescending, but are important when discussing 'things' so everyone is 'singing from the same hymn sheet'

Edited September 2, 2016 by Alan de Enfield

[Tony Brooks]

So then explain the where Jonny went wrong then. Because he said " I think it usesabout 2 amps per hour" As I am quite sure Jonny is capable of realising that half of one hour equals half of the 2amps Doh !!

I dont know if you are aware sometimes MtB just how condescending your comments are.

 

Sorry Terry but I think it is you who does not grasp the basic principles, along with the majority of questioners on here from my observations.

 

2 amps per hour is a nonsense. We can GUESS that the OP meant 2 Amp hours but that is not what he said. but even then unless he tells us how long this "consumption" of 2 Ah goes on for we are no further forward. If it was for half an hour he would have drawn one amp hour from his battery, if 24 hours then 48 Ah.

 

Now if he had a brand new, full capacity and fully charged 110 Ah battery the fridge alone would have depleted all but 14Ah of the sensible usable capacity so by morning the battery woudl have been discharged to a point that damage was likely to ensue. Errrr - did that not seem to be the problem?

 

Amps = an instantaneous measurement related to how many electrons are flowing.

 

Amp hours = a non SI unit (as far as I know) used to make it easy for most people to know how much electricity a battery holds or has been taken out of it.

 

Amps per hour = nonsense and expects the reader to guess what is meant.

 

Actually you and the OP are lucky Gibbo is not still here. If he was he may well have made far worse comments than MIke's about you both.

[Terryb]

So Sorry, Tony, (and Mike) It's too much for my tiny little brain this morning. I'll get my coat.

[Murflynn]

the amps per hour topic is worthy of promotion to the level of cassettes vs. pump-outs and bow thrusters.

 

.................. not to mention continuous cruisers ................ oh, I just did

 

 

 

 

 

 

 

 

 

 

 

 

we were taught at school to equate electric current to water flow in a pipe.

 

current (amps) = flow (litres/second)

voltage = pressure

 

thus demonstrating that amps per hour would be a rate of increase (acceleration) of the amount of electricity being transmitted - which is of course a load of b*ll*x unless you are an electrical engineer doing some serious research project in an academic environment.

 

remember:

amps/hr = amps per hour

Ah = amp.hours = amps times hours

 

unfortunately the confusion is fed by technical illiterates in the sales and advertising business (commonly referred to as eejits) attempting to summarise manufacturers' data sheets by claiming that fridges have amps/hr consumption.

in my experience at least 50% of the data presented in, for example ebay listings, is misrepresented in this way, and a similar level of technical illiteracy has been established as the norm in TV channels like Discovery, Quest and the like.

Edited September 2, 2016 by Murflynn

[Alan de Enfield]

Maybe another analogy (lets see if it works)

 

Your boat engine is running at 1000rpm

You run the boat engine for one hour, it is still doing 1000rpm

You run the boat engine for ten hours it is still doing 1000rpm

 

You do not say that the engine is doing 1000 revolutions per minute per hour.

[Tony Brooks]

So Sorry, Tony, (and Mike) It's too much for my tiny little brain this morning. I'll get my coat.

 

Please do not worry over much about this, as Murflyn says such confusion is promoted by people who should know better so its hardly surprising it keeps cropping up. However when it does it needs putting right as soon as possible and anything that seems to support it also debunked. Mike may be blunt at times but as far as the Op was concerned he was correct, the OP will never sort out his problems until he grasps the basics. I hope that the replies to you were more constructive and helped a number of member understand the issue.

[Keeping Up]

Shoreline Fridges used to have the terminology wrong in all their literature and on their web site, and frequently talked about "amps per hour". They have now realised their mistake and their literature all refers to "amp-hours per hour", as a way of describing the average current taken over a period of time during which the motor will spend some time running (and taking an unspecified number of amps) and some time not running (and taking zero amps).

[Richard10002]

It strikes me that the fundamental unit we are counting is the coulomb, and an Amp is merely a number of coulombs per second. Thus, when someone says the equivalent of x Amps per hour, they are actually saying x coulombs per second per hour, which they would know that they dont mean.

 

It's strange that people are comfortable with kilowatt hours as unit of power, probably because we see it on our electricity bills, so it's in common usage.

 

I wonder if trying to think of an Amp as so many Coulombs of energy per second might help people to not add "per hour"?

[Alan de Enfield]

Shoreline Fridges used to have the terminology wrong in all their literature and on their web site, and frequently talked about "amps per hour". They have now realised their mistake and their literature all refers to "amp-hours per hour", as a way of describing the average current taken over a period of time during which the motor will spend some time running (and taking an unspecified number of amps) and some time not running (and taking zero amps).

 

My new Waeco fridge manual gives an "average power consumption 40w"

 

Item number CR-0080E

Capacity: 78 litres

Freezer compartment: 8 litres

Average power consumption: 40 W

Weight: 23 kg

 

 

Now 40w at 12,5 volts = 3.2 amps.

The fridge actually runs approximately 20 minutes per hour (1/3 of an hour)

Or - to put it another way 1.1Ah over 1 hour, or 26.4Ah over 24 hours.

 

 

 

 

It strikes me that the fundamental unit we are counting is the coulomb, and an Amp is merely a number of coulombs per second. Thus, when someone says the equivalent of x Amps per hour, they are actually saying x coulombs per second per hour, which they would know that they dont mean.

 

 

 

See post #66

[Machpoint005]

we were taught at school to equate electric current to water flow in a pipe.

 

current (amps) = flow (litres/second)

voltage = pressure

 

thus demonstrating that amps per hour would be a rate of increase (acceleration) of the amount of electricity being transmitted - which is of course a load of b*ll*x unless you are an electrical engineer doing some serious research project in an academic environment.

 

Beat me to it!

Spot the Engineer.

It strikes me that the fundamental unit we are counting is the coulomb, and an Amp is merely a number of coulombs per second. Thus, when someone says the equivalent of x Amps per hour, they are actually saying x coulombs per second per hour, which they would know that they dont mean.

 

It's strange that people are comfortable with kilowatt hours as unit of power, probably because we see it on our electricity bills, so it's in common usage.

 

I wonder if trying to think of an Amp as so many Coulombs of energy per second might help people to not add "per hour"?

 

Pedantry no.2. A Kilowatt Hour isn't a unit of power, it's a unit of energy.

Edited September 2, 2016 by Machpoint005