when will they ever learn?

[WotEver]

No, for exceeding 14 days in one place:)

Is that legal?

[Loafer]

Excellent!

[carlt]

Is that legal?

No. There's a rule against it.

[WotEver]

No. There's a rule against it.

Give 'em an inch...

[FadeToScarlet]

Do Blue Sea have it wrong?

[MtB]

I'd say no they don;t have it wrong. "Amp" is a widely accepted abbreviation for "Ampere", so "Ampage" and "Amperage" would both be right.

 

Although not as right as "current"!

 

£12.65 for a bolt in a plastic bracket? Sheesh!!!!

[WotEver]

It's now so widely used, particularly in the US, that it's become 'correct' through popular usage.

 

It grates for me to see it, it should be "High Current", but I feel like the sole voice shouting in the wind.

 

Tony

[Murflynn]

the sequel is resistance which is universally used, whereas ohmage would not be recognised by anyone.

however, on the other hand, potential (difference) is rarely used and voltage is the norm.

 

English is thankfully a living, growing, changing language.

[John V]

It's now so widely used, particularly in the US, that it's become 'correct' through popular usage.

 

It grates for me to see it, it should be "High Current", but I feel like the sole voice shouting in the wind.

 

Tony

 

If you wish to get on the short list for the "Pedant of the year" award ....you need to try harder

[cuthound]

It's now so widely used, particularly in the US, that it's become 'correct' through popular usage.

It grates for me to see it, it should be "High Current", but I feel like the sole voice shouting in the wind.

Tony

You are not alone Tony.

 

It grates with me too.

[Col_T]

With apologies for bringing the thread to the original topic.

 

Just to check my understanding:-

 

Amp is a measure of current flow over time, typically one hour.

Amps per hour indicates a rate of change in a flowing current.

Current flows from negative to positive.

Amp.hour is a measure of capacity, hence it's use in battery ratings.

 

A question then - if a 110 Amp.hour battery can provide 110 amps, nominal, and the amp rating already includes in the one hour time duration, why are batteries not rated as 110 amps?

[RLWP]

if a 110 Amp.hour battery can provide 110 amps, nominal, and the amp rating already includes in the one hour time duration, why are batteries not rated as 110 amps?

 

Because they deliver 1 amp for 110 hours, or 440 amps for a quarter of an hour, or 1100 amps for 6 minutes (maybe)

 

Richard

[nicknorman]

With apologies for bringing the thread to the original topic.

Just to check my understanding:-

Amp is a measure of current flow over time, typically one hour.

Amps per hour indicates a rate of change in a flowing current.

Current flows from negative to positive.

Amp.hour is a measure of capacity, hence it's use in battery ratings.

A question then - if a 110 Amp.hour battery can provide 110 amps, nominal, and the amp rating already includes in the one hour time duration, why are batteries not rated as 110 amps?

Nearly but not quite. An Amp is a measure of current flow. Instantaneous current flow at a particular moment, so not "over time, typically one hour". If I ask you how fast you are driving, you will tell me the instantaneous speed at that moment, you won't tell me the speed "over time, typically an hour". That would be the answer to a question about your average speed, which is a different thing.

 

Oh and current flows from positive to negative. But current is a bit of an imaginary concept since actually it is negatively charged electrons flowing the other way.

[Paul C]

and the amp rating already includes in the one hour time duration,

 

It doesn't (include one hour time duration)

 

why are batteries not rated as 110 amps?

 

Because its the wrong units.

[HappyDayz]

ABH = Amp hours

 

as often expressed on side of rechargeable batteries.

 

a fully charged battery in good condition and at reasonable ambient temperature, will deliver the rated voltage, example 12 volts for so many hours, example 3 hours before the voltage starts to drop.

 

If used as a standby battery you first measure the 'load' current in amps, devid the rated AH by that result to tell you how long a fully charged battery will operate the chosen equiipment for.

 

It us a test i have used for many years when servicing security control equipment.

 

Alan

[dmr]

Amps per Hour realistically does not exist, many people use it by mistake when they mean Amp-hours (amps times hours...a measure of capacity).

All this forum talk of rate of change of current is really just the forum pedants trying to point out that "amps per hour" is wrong, looks like the forum has inadvertently created a misleading unit.

 

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

[MtB]

With apologies for bringing the thread to the original topic.

 

Just to check my understanding:-

 

Amp is a measure of current flow over time, typically one hour.

Amps per hour indicates a rate of change in a flowing current.

Current flows from negative to positive.

Amp.hour is a measure of capacity, hence it's use in battery ratings.

 

A question then - if a 110 Amp.hour battery can provide 110 amps, nominal, and the amp rating already includes in the one hour time duration, why are batteries not rated as 110 amps?

 

 

A first class example of someone trying to learn and being confused by posters here who persist in stating current in "Amps per hour", and claiming 'everyone knows what is meant' when corrected.

 

Dear OP, there are two or three posters on here who do this deliberately, thinking it's funny. Watch out for them, you'll figure out who pretty quickly.

[Loafer]

With apologies for bringing the thread to the original topic.

 

Just to check my understanding:-

 

Amp is a measure of current flow over time, typically one hour.

Amps per hour indicates a rate of change in a flowing current.

Current flows from negative to positive.

Amp.hour is a measure of capacity, hence it's use in battery ratings.

 

A question then - if a 110 Amp.hour battery can provide 110 amps, nominal, and the amp rating already includes in the one hour time duration, why are batteries not rated as 110 amps?

 

A 110 Ah battery can provide MUCH more than 110 Amps. If you drop a spanner across its terminals, it could even provide 1000 Amps until it blows up in your face a few seconds later. Your spanner will be a dribble of molten steel!

[dmr]

 

It doesn't (include one hour time duration)

 

 

Because its the wrong units.

 

Batteries are rated both in their capacity (in amp hours) and how much current they can deliver for a short time (CCA cold cranking amps) measured in amps.

 

For starter batteries CCA is more important, for leisure batteries the capacity (Amp Hour) is more important.

Sometimes capacity is rated in "Reserve capacity" which is how long the battery can deliver a certain current for. This is getting less popular (fortunately) but is still used a bit by battery shops.

 

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

[WotEver]

 

 

A first class example of someone trying to learn and being confused by posters here who persist in stating current in "Amps per hour", and claiming 'everyone knows what is meant' when corrected.

 

Dear OP, there are two or three posters on here who do this deliberately, thinking it's funny. Watch out for them, you'll figure out who pretty quickly.

 

Hear hear. Col reads the "it really doesn't matter, stop being a pedant" posts and draws conclusions which demonstrate very clearly that it DOES MATTER.

 

Tony

To summarise...

 

Amp is a measure of current flow over time, typically one hour.

 

No. It is a measure of instantaneous current flow.

 

Amps per hour indicates a rate of change in a flowing current.

 

Yes it does, but nobody uses it - it is actually an accelerating current draw and is meaningless in boaty applications.

 

Current flows from negative to positive.

 

Nope, that's electron flow. Current flows from Positive to Negative.

 

Amp.hour is a measure of capacity, hence it's use in battery ratings.

 

Yes

[cuthound]

Depending on the discharge rate, a lead acid battery rated at 100AH will deliver more or less than that capacity, depending on the date of discharge and for how long.

 

Mr Peukert sussed this out years ago. See here.

 

https://en.m.wikipedia.org/wiki/Peukert%27s_law

 

Batteries are typically rated at C10 (10 hour rate) or C20 (20 hour rate. Discharge them at a lower rate, for example C50, and you will get more than the rated capacity, or at a higher rate, say C5 and you won't get the badged capacity.

 

Confirming what Loafer said about how much current a battery can de!over instantaneously, I once saw a galvanised bucket full of water disappear when the cleaner accidentally dropped it across the bus bars of a 15,050 AH battery. Apart from a black mark on the ceiling and some splashes of molten metal, nothing was left!

 

Edited to add clarity.

Edited February 19, 2016 by cuthound

[Col_T]

Thanks all for the answers, and for furthering my education - at least I'm getting an idea of how much I don't know!

 

A supplementary question related to current flow and electron flow, and the fact they flow in different directions. Wiring diagrams - should these be read positive to negative (direction of current flow) or negative to positive (direction of electron flow)? Thinking about it further, I guess the more relevant question is "is a wiring diagram only meant to show which components are in a particular circuit" because if so, knowing which direction stuff flows in is irrelevant?

[John V]

Providing there are no diodes in the circuit

[WotEver]

A wiring diagram generally shows simply what is where.

 

Direction of current flow (+ve to -ve) is all you need to concern yourself with. Electron flow is only of relevance to physicists.

 

Tony

 

The direction of current flow is why we now have -ve earth cars and boats.

[Chewbacka]

With apologies for bringing the thread to the original topic.

 

Just to check my understanding:-

 

Amp is a measure of current flow over time, typically one hour.

Amps per hour indicates a rate of change in a flowing current.

Current flows from negative to positive.

Amp.hour is a measure of capacity, hence it's use in battery ratings.

 

A question then - if a 110 Amp.hour battery can provide 110 amps, nominal, and the amp rating already includes in the one hour time duration, why are batteries not rated as 110 amps?

Batteries have a few important parameters, these being

1) Voltage

 

2) Capacity which is quoted in Ah (in your example 110Ah - however because of the way batteries work you only get this capacity at a defined constant discharge rate.

 

3) Cold Cranking Amps (CCA) the max amount of current the battery can supply for a high load demand - typically the starter motor - and not for very long.

 

4) Sometimes the spec sheet for a leisure battery will also tell you how many charge/discharge cycles the battery is good for, and it is maybe a lot less than you expect. This can be 'improved' by never discharging below about 50% and fully recharging as soon as possible.

 

Google is your friend if you want to know more...............