Amperage to expect from Alternator

[smileypete]

Please don't think it's many many hours to get a full charge, the charts in this PDF should give some idea:

http://usbattery.com/wp-content/uploads/2014/05/usb-charging-recommendations.pdf

So for a healthy batt at 50% and a decent size charge source (output is more than 10% of bank capacity) and of course correct temperature compensated charge voltage, you should be looking at 5-6 hours to a full charge.

Occasionally the 'expert wibbling' on here can be somewhat misleading, even if not intended that way.

Edited March 3, 2017 by smileypete

[WotEver]

You'll do best to ignore any charts or recommendations from 'experts' as to how long to charge for. Simply charge until the tail current at absorption voltage is around 3% or less of the battery capacity in Ah, so for your 330Ah batteries that'll be less than 9A. Better still is as I've already suggested, when the charge current has stopped decreasing. 

It takes however long it takes, but expect something in the region of 6+ hours to go from 50% to 99.9% 

[Tony Brooks]

I am gong to back WotEver up. His method allows the battery to tell you when it is fully charged and the tail current will alter over the life of the battery.

Anyone who gives set in stone figures concerning batteries and believes them implicitly is being led up the garden path.  Batteries work by chemical reactions and we know such reactions are affected by temperature. Their characteristics also alter to a degree as they age, how they have been looked after, and their design/materials.

There are some general figures we use to get a "handle on things" but all we end up with is a fairly good estimate. We sometimes talk as if the figures are fixed but that is to try to avoid confusing questioners with too much information that demands things they do not know causing overload and confusion.

[dmr]

Every year this forum talks of fatter and fatter cables, last year it was 70, now its 95mm, just how many amps are people using and how long are these wires?

When I got our boat it was mostly done in 25mm, some was not too good so I redid them in 35mm, and even a bit of 50 as a ground strap to the engine.

The BSS man looked at these 35mm cables and said how nice it was to see a boat done in really thick cables.

If there are electrical problems replacing thick cables with even thicker cables is not usually the answer.

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

[Robbo]

42 minutes ago, dmr said:

Every year this forum talks of fatter and fatter cables, last year it was 70, now its 95mm, just how many amps are people using and how long are these wires?

When I got our boat it was mostly done in 25mm, some was not too good so I redid them in 35mm, and even a bit of 50 as a ground strap to the engine.

The BSS man looked at these 35mm cables and said how nice it was to see a boat done in really thick cables.

If there are electrical problems replacing thick cables with even thicker cables is not usually the answer.

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

It's a 170amp alternator and I presume a 3000watt combi, these pull in the amps so 35mm2 isn't particular thick.

But your right it's the whole circuit that needs to be looked at if you have electrical problems, no good have thick cables if your battery switch is one of those cheapo ones that seem to be popular or the connections are bad.

Edited March 4, 2017 by Robbo

[MtB]

18 minutes ago, Robbo said:

It's a 170amp alternator and I presume a 3000watt combi, these pull in the amps so 35mm isn't particular thick.

 

Both of which seem unnecessarily large for a boat. 

[Robbo]

4 minutes ago, Mike the Boilerman said:

 

Both of which seem unnecessarily large for a boat. 

That depends what you have on the boat. A 3kw inverter is a nice size for most large applicances like washing machines and microwaves.  A large alternator is useful to power these or if you have the battery capacity to take the amps.

[dmr]

2 minutes ago, Mike the Boilerman said:

 

Both of which seem unnecessarily large for a boat. 

Did you ever meet "Newbold" on the K&A? (now sadly given up due to increased enforcement). Only ever started engine when it was time to move the boat, no fridge, no television, minimal lights, lived very happily on their boat for many years.

My new inverter is 1000w but I intend never to use more than half of those, and even then only a couple of times each year (but then we have got a TravelPower) 

[ditchcrawler]

Some time back I bought a second hand, unused 100 a 24 volt alternator that looked just like a standard car type alternator, The other week the front end bearing went for a walk so I took it to our local repair establishment, the chap gave it a quick dose of looking at and said no problem, he then noticed the 24 volt 100 amp stamping on the side of the end plate and his words were "That's a bit optimistic I would say" I have never seen more than 50A come out of it.

[Detling]

The other thing the OP needs to remember is if correctly wired the Ammeter only shows amps into the battery, this may not be the same as amps out of the alternator. If he was using anything else for instance TV, computer, lights microwave fridge etc all the current would be coming from the alternator so needs adding to the battery current to find the alternator current. A largish load could pull the alternator volts down even with full batteries, my alternator causes the engine to grunt as the toaster(for instance) is switched on and the volts do drop.  I had a prestolite? alternator but it was 130A in theory I found that I could never get near that due to internal resistance to the case/chassis. The best I measured was about 80 amps at 1500rpm. I had a proper marine alternator fitted with +ve and -ve cables it is only rated at 90 amp but I have measured 90 amps at tickover 600rpm. The volt drop I was getting with the old one, which was over 1 volt, is now less than 0.2 volts, same positive cable and obviously a new -ve cable, so all alternators are not born equal.

[nicknorman]

2 hours ago, dmr said:

Did you ever meet "Newbold" on the K&A? (now sadly given up due to increased enforcement). Only ever started engine when it was time to move the boat, no fridge, no television, minimal lights, lived very happily on their boat for many years.

My new inverter is 1000w but I intend never to use more than half of those, and even then only a couple of times each year (but then we have got a TravelPower) 

I knew someone who lived in a cave, ate dust and whipped themselves with nettles daily. They didn't have an engine to start and lived happily in the cave for many years until they died of malnutrition.

We have 2500w inverter which is just about enough to run the kettle, washing machine, tumble drier, toaster, Nespresso (but only one at a time, of course). However it doesn't like to start the Dyson which obviously has a huge startup transient demand. For that we either have to run the Travelpower or cringe whilst the inverter cuts in and out several times as the Dyson's motor spins up.

[nicknorman]

1 hour ago, Detling said:

I had a prestolite? alternator but it was 130A in theory I found that I could never get near that due to internal resistance to the case/chassis. The best I measured was about 80 amps at 1500rpm. I had a proper marine alternator fitted with +ve and -ve cables it is only rated at 90 amp but I have measured 90 amps at tickover 600rpm. The volt drop I was getting with the old one, which was over 1 volt, is now less than 0.2 volts, same positive cable and obviously a new -ve cable, so all alternators are not born equal.

This is true, but the OP's alternator is likely to be an Iskra and they can certainly put out the full 175A. I've seen ours up at 180A briefly.

[dmr]

2 minutes ago, nicknorman said:

I knew someone who lived in a cave, ate dust and whipped themselves with nettles daily. They didn't have an engine to start and lived happily in the cave for many years until they died of malnutrition.

We have 2500w inverter which is just about enough to run the kettle, washing machine, tumble drier, toaster, Nespresso (but only one at a time, of course). However it doesn't like to start the Dyson which obviously has a huge startup transient demand. For that we either have to run the Travelpower or cringe whilst the inverter cuts in and out several times as the Dyson's motor spins up.

and I used to live in a cardboard box   Is the big startup current related to the "digital" motor that Dyson uses? I assume this is the mains model. I find the little hand held battery Dyson is just right for boat housework.

[system 4-50]

19 minutes ago, dmr said:

I knew someone who lived in a cave, ate dust and whipped themselves with nettles daily.

That's nothing. I knew someone who lived in a cave, ate dust and whipped themselves with nettles daily - and drank only neat battery acid. Only 6V of course.

[Richard10002]

23 minutes ago, nicknorman said:

I knew someone who lived in a cave, ate dust and whipped themselves with nettles daily. They didn't have an engine to start and lived happily in the cave for many years until they died of malnutrition.

We have 2500w inverter which is just about enough to run the kettle, washing machine, tumble drier, toaster, Nespresso (but only one at a time, of course). However it doesn't like to start the Dyson which obviously has a huge startup transient demand. For that we either have to run the Travelpower or cringe whilst the inverter cuts in and out several times as the Dyson's motor spins up.

I've been thinking of a way to say what you've just said - I don't need to now

i liked the bit about enforcement getting the better of good old Newbold  Not in the sense that someone has given up on their home of many years, more that if you take the p1ss repeatedly, something eventually comes along and bites your bum.

My Sterling 2500W 80A inverter charger powers our Dyson Vacuum with no sign of difficulty. It's about 3 or 4 years old, so may need less power than yours if it's an older model?

[cereal tiller]

14 minutes ago, system 4-50 said:

That's nothing. I knew someone who lived in a cave, ate dust and whipped themselves with nettles daily - and drank only neat battery acid. Only 6V of course.

That person can't be Tim Schmelly,he uses Sealed Batteries,so no Access to the Acid

[dmr]

18 minutes ago, Richard10002 said:

 

i liked the bit about enforcement getting the better of good old Newbold  Not in the sense that someone has given up on their home of many years, more that if you take the p1ss repeatedly, something eventually comes along and bites your bum.

 

Rather sad really, someone spending their entire life out in the sticks, moving a reasonable but not huge distance, and with a home mooring that they rarely used to make it "legal". Then all the London and Western K&A congestion causes an increase in enforcement and good boaters get warnings, which may or may not be justified, and just feel that its not as relaxed as it used to be and decide to leave, quite a few similar boaters have also gone. A sort of London collateral damage.

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

[nicknorman]

56 minutes ago, dmr said:

 Is the big startup current related to the "digital" motor that Dyson uses? I assume this is the mains model. I find the little hand held battery Dyson is just right for boat housework.

 

31 minutes ago, Richard10002 said:

My Sterling 2500W 80A inverter charger powers our Dyson Vacuum with no sign of difficulty. It's about 3 or 4 years old, so may need less power than yours if it's an older model?

Mains model. Not sure exactly what the motor technology is. It's about 6 years old, just a small cylinder one so I was surprised when our 2500w Mastervolt with surge to I think 4000w, struggled to start it.

[Richard10002]

1 hour ago, dmr said:

Rather sad really, someone spending their entire life out in the sticks, moving a reasonable but not huge distance, and with a home mooring that they rarely used to make it "legal". Then all the London and Western K&A congestion causes an increase in enforcement and good boaters get warnings, which may or may not be justified, and just feel that its not as relaxed as it used to be and decide to leave, quite a few similar boaters have also gone. A sort of London collateral damage.

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

Whoops! so he was playing by the rules, but CRT thought he wasn't, and he got fed up of being wrongly accused. Nil Carborundum Desperandum?

I've received letters twice accusing me of being on CRT waters without a licence. I emailed back both times suggesting that I would have to be Dr. Who with his Tardis to be where they say I was, (on the Llangollen Canal I Think). I havent left the Bridgewater since October 2011, other than for a couple of days the other side of Leigh, early last year.

[MtB]

1 hour ago, Richard10002 said:

Whoops! so he was playing by the rules, but CRT thought he wasn't, and he got fed up of being wrongly accused. Nil Carborundum Desperandum?

I've received letters twice accusing me of being on CRT waters without a licence. I emailed back both times suggesting that I would have to be Dr. Who with his Tardis to be where they say I was, (on the Llangollen Canal I Think). I havent left the Bridgewater since October 2011, other than for a couple of days the other side of Leigh, early last year.

 

Seems possible then that someone has cloned your boat licence number plate. 

Either that or the Llangollen data gathering bod suffers from phat phingers syndrome.

[ditchcrawler]

7 minutes ago, Mike the Boilerman said:

 

Seems possible then that someone has cloned your boat licence number plate. 

 

That wouldn't surprise me at all and to Richard 100002, but why have a CRT licence if you don't leave the Bridgewater and if you haven't got one how did they know how to contact you?

[Richard10002]

1 hour ago, ditchcrawler said:

That wouldn't surprise me at all and to Richard 100002, but why have a CRT licence if you don't leave the Bridgewater and if you haven't got one how did they know how to contact you?

I dont have a CRT licence, but the boat had a CRT licence and number when I bought it at the other end of the Trent and Mersey with a month left on the existing licence. I filled in a form to tell CRT that I wouldnt be needing another licence, and why.

I'm guessing that someone is reporting a boat with either the same number as mine had, or maybe misreading a number on a boat without a licence.

[ditchcrawler]

10 hours ago, Richard10002 said:

I dont have a CRT licence, but the boat had a CRT licence and number when I bought it at the other end of the Trent and Mersey with a month left on the existing licence. I filled in a form to tell CRT that I wouldnt be needing another licence, and why.

I'm guessing that someone is reporting a boat with either the same number as mine had, or maybe misreading a number on a boat without a licence.

I see, I was wondering how they got your contact details or if Peel gave them to them.

[jono2.0]

ok, so it looks like I've solved my low voltage issue.

I tested with the engine running the rear of the alternator.  It is a model that only has a positive connection. I put the positive lead to this and the negative lead to the steel welded beam the engine sits on. It has a drilled 10mm bolt screwed through it.  Still low voltage at 13.78volts.   MMM, something not right here.  I checked all connections and bolts on battery and alternator, all nice and tight.  With it being a brand new boat with none of the electrics done apart from a starter battery I wondered if the engine itself hadn't been grounded to the hull.

I found the negative on the engine where the starter battery was terminated and boom (Not literally - haha) 14.2v.  So my conclusion was that the return cable via the shunt from the leisure batteries was terminated to the hull ok but nothing was connecting the engine to the hull.  I temporarily connected the leisure negative to the engine rather than the hull and it's reading a healthier 14.2v and 53.10A. This is with the engine at tick over at 800 rpm.  If I increase the revs it doesn't make much difference with 14.21v at 1300 rpm.

I hope this is ok.  Should I, once cables are made up etc move the negative connection via shunt back to hull grounding, and add another cable from engine neg to the hull grounding? 

Edit: Thanks Alan de Enfield for telling me about my too fast revs!

Edited March 6, 2017 by jono2.0

[Alan de Enfield]

3 minutes ago, jono2.0 said:

This is with the engine at tick over at 8000 rpm.  If I increase the revs it doesn make much difference with 14.21v at 13000 rpm.

Glad you are 'sorted'

But - just as a matter of accuracy - You appear to have added an extra '0' to your RPM