Which Charger?

[WotEver]

Rog, The key words that you used were "apparently simple". Charger size depends on many factors not the least of which is your own personal balance between battery life and charging expense.

 

Cheers

Tony

[Alan de Enfield]

Just to explain, I am utterly incompetent with electrickery (one of my very many failings) however I always read posts like this out of interest and hoping to learn.

 

Can I ask, if this electrickery business is all scientific and governed by physics etc

why can the 'experts' never seem to agree on the answer of any apparently simple question like "what charger" or "what battery manager" etc.

 

Or is actually just a matter of personal taste/choice ?

 

Rog

 

For any ONE set of circumstances there is only one 'correct' answer, the problem is that unless all of the parameters are detailed, then the potential 'variables' mean that there are a potential 'number' of answers.

 

If the OP said :

 

I have a 1600w continuous generator

I will spend £500 on a Sterling 60 amp battery charger with a PF of 0.99

My batteries are 330Ah Flooded Lead Acid

I want to get my batteries to less than a 1% tail charging current

I am prepared to run the generator at 1 litre per hour for 12 hours per day

I am prepared, if necessary, to renew my batteries every 6 months

 

etc etc etc

 

Will it work ?

 

Then a unanimous answer (should) be forthcoming.

 

However -

 

We do not know if the batteries are AGM, Gel, Flooded Lead acid, or even Ni-Cad or NiFe etc

We do not know how long the OP is prepared to run the generator

We do not know how much the OP is prepared to spend on a battery charger

 

etc etc.

 

So as each individual makes an assumption on the variables a different 'answer' will be forthcoming.

Edited January 23, 2016 by Alan de Enfield

[Graham.m]

 

I have 6 Trojan T105's wired in 3 pairs for 12V giving a capacity of 675AH Max.

 

 

 

Alan

 

the batteries are Trojan T105s which is a flood capable of accepting a 15V+ charge voltage

[bottle]

The horses mouth:

 

http://www.trojanbattery.com/pdf/datasheets/T105_Trojan_Data_Sheets.pdf

Read carefully especially the Charging instructions and Temperature compensation

[Arthur Brown]

Part of the reason why electrical questions take so long and attract so many choices of answer is that the questioner usually only offers a small part of the situation in the first post then responders ask for the rest of the question or reply in general terms to the question as asked.

[Graham.m]

The horses mouth:

 

http://www.trojanbattery.com/pdf/datasheets/T105_Trojan_Data_Sheets.pdf

Read carefully especially the Charging instructions and Temperature compensation

 

Who is this aimed at

 

Add

0.005 volt per cell for every 1°C below 25°C

0.0028 volt per cell for every 1°F below 77°F

Edited January 23, 2016 by Graham.m

[bottle]

Whosoever wishes to take advice from the manufacturer.

[Graham.m]

Whosoever wishes to take advice from the manufacturer.

 

Well at 15C the charge voltage recommended is 14.8V + (0.005 x 6 x 10) = 15.1V

 

At 5C that would be 14.8V + (0.005 x 6 x20) = 15.4V

[bottle]

I am not disputing your 15v charge voltage @ 15° c but, as is your habit, missed out the vital bit temperature compensation in the original post.

[Graham.m]

I am not disputing your 15v charge voltage @ 15° c but, as is your habit, missed out the vital bit temperature compensation in the original post.

 

Try the same figure at 18C and I think you will find it is 15.01

[Graham.m]

I am not disputing your 15v charge voltage @ 15° c but, as is your habit, missed out the vital bit temperature compensation in the original post.

 

 

 

The battery in this sort of weather the battery likes to be charged at about 15 volts

 

 

 

Think that was specified by 'in this sort of weather' that would give you a temperature today of something in the order of 8 to 10C

[MtB]

Hiya,

 

Reading recent articles on battery charging - fascinating - got me thinking it might be a good idea to invest in a separate mains battery charger to supplement my alternator charging by giving my batteries a proper staged charge every now & then. I want to run the charger from a Honda Eu20i genny.

 

Obviously, my question is what should I be looking for in a charger?

 

I have 6 Trojan T105's wired in 3 pairs for 12V giving a capacity of 675AH Max.

 

Cheers.

 

 

Bare in mind that as far as I can see, a "proper staged charge" takes many, many hours. Think in tens of hours with the genny running.

 

Be pleased to find this is wrong though.

[WotEver]

If you don't allow the charger to drop into float then it could certainly take up to 10 hours or more I guess, depending on the state of the batteries. The size of charger would be irrelevant (within reason) for the bulk of that time.

[Loafer]

 

 

Bare in mind that as far as I can see, a "proper staged charge" takes many, many hours. Think in tens of hours with the genny running.

 

Be pleased to find this is wrong though.

 

You wouldn't need tens of hours if you did it every day, or every other day even.

 

We need a 7 hour charge every two days, to replace around 90Ah used, down to a tail current of less than 1% (2.5A last time. 450Ah total bank)

If you don't allow the charger to drop into float then it could certainly take up to 10 hours or more I guess, depending on the state of the batteries. The size of charger would be irrelevant (within reason) for the bulk of that time.

 

Did you mean to say that, Wot? I'd have thought that if you DO let it go to float, it could take 10 hrs.

Maybe the simple rule applies here that a battery only takes roughly the number of Ahs it is discharged in Amps.

 

 

 

Are you sure? It's the other way round.

[MtB]

 

You wouldn't need tens of hours if you did it every day, or every other day even.

 

We need a 7 hour charge every two days, to replace around 90Ah used, down to a tail current of less than 1% (2.5A last time. 450Ah total bank)

lurve

Did you mean to say that, Wot? I'd have thought that if you DO let it go to float, it could take 10 hrs.

 

 

Jeez. SEVEN hours of genny on alternate days? I bet your neigbours lurve you!

 

Anyway the poster I was replying to was proposing once in a while, rather than 3 times a week...

[WotEver]

Yup, I meant what I said...

 

As opposed to 30 hours in float

 

Note that I also added the caveat "depending on the state of your batteries".

 

Tony

Anyway the poster I was replying to was proposing once in a while, rather than 3 times a week...

Hence my very rough guesstimate of 10 hours.

[Loafer]

 

 

Jeez. SEVEN hours of genny on alternate days? I bet your neigbours lurve you!

 

Anyway the poster I was replying to was proposing once in a while, rather than 3 times a week...

 

Whoa Mike! I don't HAVE any neighbours as a rule. And you don't HAVE to recharge down to 0.5% of capacity.

 

I just LIKE to, when properly able, without annoying anyone. The final hour or two is with the genny barely ticking over in ECO mode - and I can't hear it inside my own boat, let alone anyone else's!

[Alan de Enfield]

 

 

Jeez. SEVEN hours of genny on alternate days? I bet your neigbours lurve you!

 

Anyway the poster I was replying to was proposing once in a while, rather than 3 times a week...

 

Pretty expensive as well - if the genny is using 1 litre per hour ( my Kipor is 3 hours on 3.7 litres at 1600 Kw Watts) that's over £1 per hour

 

£7 per day or over £100 per month (seems excessive, - get a mooring and pay for a hook-up, or go cruising and use your alternator)

 

Edit as 1600 Kw is quite a lot !!!!!

Edited January 23, 2016 by Alan de Enfield

[Loafer]

 

Pretty expensive as well - if the genny is using 1 litre per hour ( my Kipor is 3 hours on 3.7 litres at 1600 Kw Watts) that's over £1 per hour

 

£7 per day or over £100 per month (seems excessive, - get a mooring and pay for a hook-up, or go cruising and use your alternator)

 

Edit as 1600 Kw is quite a lot !!!!!

 

It isn't expensive. The little Honda 1kW runs forever on a tank with a small load. I'd say I buy a 4 litre can of petrol once a fortnight, at MOST.

 

8 litres of petrol per month? I think that's quite good, especially when it's running so that the laundry gets done.

 

ETA Wait - most of the charge comes from our prior engine run, when most of the grunt is provided.

Edited January 23, 2016 by Loafer

[Graham.m]

It has always puzzled me why people insist on using suitcase generators as illustrated above they are expensive to run, vulnerable to theft. While a in board diesel generator is expensive initially they are easier to use and a lot cheaper to run, typically using something of the order of 0.35 litre per kWh generated. Thus to run something like the Sterling Pro 60A for say 10 hours is about 3.5 litres @ £0.63 say £2.21 or 22p an hour.

 

If the above costs are right then the outlay could be covered in about 5/6 years plus having had the convenience of a 3 or 4 kWh generator.

[Loafer]

It has always puzzled me why people insist on using suitcase generators as illustrated above they are expensive to run, vulnerable to theft. While a in board diesel generator is expensive initially they are easier to use and a lot cheaper to run, typically using something of the order of 0.35 litre per kWh generated. Thus to run something like the Sterling Pro 60A for say 10 hours is about 3.5 litres @ £0.63 say £2.21 or 22p an hour.

 

If the above costs are right then the outlay could be covered in about 5/6 years plus having had the convenience of a 3 or 4 kWh generator.

 

I had a fully plumbed-in HFL 4kW cocooned genny in my previous boat (yacht). It cost me £7000 including installation.

 

My Honda suitcase cost me £250, 2 years ago. That leaves about £6750 available for petrol. About 6750 litres.

 

I'll need another £250 suitcase genny before I can use all that petrol. Or even a third one. Who cares!

[bottle]

 

Alan

 

the batteries are Trojan T105s which is a flood capable of accepting a 15V+ charge voltage

 

 

Graham

 

this is the post that I was referring to, yes they are capable of taking 15+v but you missed out the temperature compensation, weather bit.

[dogless]

Much clearer now

Rog

[Graham.m]

 

 

Graham

 

this is the post that I was referring to, yes they are capable of taking 15+v but you missed out the temperature compensation, weather bit.

 

Too pedantic the info is covered earlier and if anyone really wants to check the full battery details are there.

[bottle]

Yes pedantic, but if giving advice it is always better to make sure there is no chance of misinterpretation and writing that a battery will take 15.1v without necessary information is slapdash and not what I would expect from someone with qualification and experience, as you have inferred you have .