Battery charger

[Evo]

A year or so ago - or whenever it was - I bought a Chinese 1500W Pure sine wave Inverter. Its been brilliant.

 

For charging our bank of 4 110's we have a 100amp alternator on the engine and a solar panel to keep them charged up when not in use. No 240v charger at all.

 

However,I also have a 240/110v 4.5Kva on-board genny. Trouble is the Genny does not charge the batteries and I would like it to. I realise an Inverter/charger Combi such as a Victron/Sterling would probably have been the best way to go initially but i didn't.

 

 

So now I'm looking at keeping my unobtrusive super slimline inverter and adding a seperate, as thin, battey charger next to it.

 

What amperage charger do I need..?? it seems they go up massively as their amperage increases. In fact I think 30-40 amps is as high as I want to go else they get silly expensive and big.

 

Anyone recommend a good un....do I need 40amps..?? I need a thinnish one as opposed to a huge Victron square type.

[Guest]

A year or so ago - or whenever it was - I bought a Chinese 1500W Pure sine wave Inverter. Its been brilliant.

 

For charging our bank of 4 110's we have a 100amp alternator on the engine and a solar panel to keep them charged up when not in use. No 240v charger at all.

 

However,I also have a 240/110v 4.5Kva on-board genny. Trouble is the Genny does not charge the batteries and I would like it to. I realise an Inverter/charger Combi such as a Victron/Sterling would probably have been the best way to go initially but i didn't.

 

 

So now I'm looking at keeping my unobtrusive super slimline inverter and adding a seperate, as thin, battey charger next to it.

 

What amperage charger do I need..?? it seems they go up massively as their amperage increases. In fact I think 30-40 amps is as high as I want to go else they get silly expensive and big.

 

Anyone recommend a good un....do I need 40amps..?? I need a thinnish one as opposed to a huge Victron square type.

At the risk of insults,I have run a Sterling 40A Universal charger off my genny (and occasionally mains) for 7 years. No probs. whatsoever. This has charged 4x110Ah batteries. Can't fault it. It is compact and quiet. I wouldn't go below 40Amps.

Edited November 14, 2011 by Guest

[Chris Pink]

this looks worth a punt;

http://www.caravantechnology.com/Caravan-and-Leisure-40A-Battery-Charger-P3.aspx

[bottle]

Hi Evo

 

Gibbo's take on charger size: http://www.smartgauge.co.uk/chargesize.html

[Guest]

Hi Evo

 

Gibbo's take on charger size: http://www.smartgauge.co.uk/chargesize.html

Fair points I think. My charger is way too small at 40 Amps, but I can't run much bigger off the genny.

[blackrose]

Fair points I think. My charger is way too small at 40 Amps, but I can't run much bigger off the genny.

 

Your charger output is about 9% of your battery a/h capacity which is ok - you'd get them charged a bit quicker if you had a bigger charger - but it would only speed things up until the charge got to 40amps. Below that it would charge at the same rate. You must have a 1kw generator if it can only power a 40 amp charger?

 

The OP can buy a bigger charger because he has a big generator, although I wouldn't go above about 90amp output (20%) for a 440 a/h battery bank.

Edited November 14, 2011 by blackrose

[sebrof]

Fair points I think. My charger is way too small at 40 Amps, but I can't run much bigger off the genny.

 

I have 2 Victron 50s. On shore power, with discharged batteries, I turn on both. Using the Honda, I turn on one.

 

Two 50s are cheaper than one 100, believe it or not.

[blackrose]

I have 2 Victron 50s. On shore power, with discharged batteries, I turn on both. Using the Honda, I turn on one.

 

Two 50s are cheaper than one 100, believe it or not.

 

I have a similar setup with 2 Sterlings - 1 x 40amp and 1 x 30amp. On long-term shore power I just use the 30amp and with the generator I use both for faster charging.

Edited November 14, 2011 by blackrose

[Guest]

Your charger output is about 9% of your battery a/h capacity which is ok - you'd get them charged a bit quicker if you had a bigger charger - but it would only speed things up until the charge got to 40amps. Below that it would charge at the same rate. You must have a 1kw generator if it can only power a 40 amp charger?

 

The OP can buy a bigger charger because he has a big generator, although I wouldn't go above about 90amp output (20%) for a 440 a/h battery bank.

Yes 1kW, it can just manage the charger though has cut out on occasions if the batteries are quite low. Sometimes have to run the engine for a few mins. to give the genny a chance (although I don't like to run the engine out of gear.)

Edited November 14, 2011 by Guest

[matty40s]

Yes 1kW, it can just manage the charger though has cut out on occasions if the batteries are quite low. Sometimes have to run the engine for a few mins. to give the genny a chance (although I don't like to run the engine out of gear.)

 

I have a haart inverter and a 2.6 genny. The genny will not charge the battery bank through the inverter(acording to Gibbo) so he suggested I get a 40 -50 amp charger to do the job.

[blackrose]

I have a haart inverter and a 2.6 genny. The genny will not charge the battery bank through the inverter(acording to Gibbo) so he suggested I get a 40 -50 amp charger to do the job.

 

An inverter cannot charge batteries unless it is a combi (combined inverter & charger).

[Bob18]

Is it that the OP has a 4.5kw generator but no charger to go with it?

This being the so the solution is to find a good multi-stage charger that will run off his generator. It needs to have enough output so the first (high current) stage isn't too long, and enough control to do a proper full charge in a sensible period of time.

 

Given that size of generator it should be possible to find a multi-stage charger that will work.

 

BUT

We don't know how far these batteries are being allowed to discharge between recharge sessions, all we do know is the OP is worried that one particular make of charger may not fit the space available.

What is drawing current from that battery?

Why have a 4.5kw generator and not use that to supply a "fair proportion" of the 230v requirement?

 

And lots more questions will follow...

 

Another thing - don't expect to be able to charge your batteries with a charger running off an inverter attached to the same batteries...

[Bob18]

How "slim line" is your inverter?

The Victron Pheonix 12/50 is only 108mm thick, and the Mastervolt Mass 12/50 130mm thick.

Both these are "multi-stage".

[blackrose]

Another thing - don't expect to be able to charge your batteries with a charger running off an inverter attached to the same batteries...

 

Whoever manages to do that will have solved the world"s energy problems and become very rich!

 

What's the reason for it being slimline? Is it going in a cupboard or something (sorry I can't be bothered to go back to the original post). If so, don't forget about ventilation.

Edited November 14, 2011 by blackrose

[Duchess Omnium]

 

Another thing - don't expect to be able to charge your batteries with a charger running off an inverter attached to the same batteries...

 

Every time I think I am beginning to understand boat electrics I get more puzzled. Please could you explain? I think what he said was his invereter doesn't charge in any case, but if it were a combi, could he not plug iin his generator and charge the batteries (I'm asking because that is what I want to do if I can get the right generator and my head round the subject).

[matty40s]

An inverter cannot charge batteries unless it is a combi (combined inverter & charger).

 

The Haart is a combi unit, but will not charge at lower ampage levels. Apperently it starts, then stops, starts, then stops, starts, then.....Gibbo helped design the unit, so I guess he knows what he was on about!!

[blackrose]

Every time I think I am beginning to understand boat electrics I get more puzzled. Please could you explain?

 

I think he just meant that you can't run a separate mains charger from an inverter and expect it to charge the batteries that the inverter is using to run the charger. It's a physical impossibility because of losses in the system. In effect it would be a perpetual energy circuit!

 

.... but if it were a combi, could he not plug iin his generator and charge the batteries (I'm asking because that is what I want to do if I can get the right generator and my head round the subject).

 

Yes, you can do that.

 

The Haart is a combi unit, but will not charge at lower ampage levels. Apperently it starts, then stops, starts, then stops, starts, then.....Gibbo helped design the unit....

 

Sounds about right!

 

(If Gibbo is lurking nothing will bring him back if that comment doesn't. )

Edited November 14, 2011 by blackrose

[Evo]

How "slim line" is your inverter?

The Victron Pheonix 12/50 is only 108mm thick, and the Mastervolt Mass 12/50 130mm thick.

Both these are "multi-stage".

 

Its half that at tops 50mm. If I was going to spend that much I'd buy one of these Victron but thats the point really, I allready have an inverter, I was trying to get away from spending a bloody fortune. I was after reccomendations for cheap high amp battery charger

 

I could run my genny all weekend on a gallon of diesel, I dont care how long it takes, I'm on a fairly isolated mooring with no neighbours as such. I dont liveaboard so rapid charging is not necessary. I dont really need multi-stage fancy charging either, thats for when you are on a shoreline hookup. If I lived aboard I'd bite the bullet and be up the shop for that victron.

 

If its going to cost me £300+ for just a battery charger I'll leave it a year or so and save up for the all-in-one Slim victron anyway.

 

I allready have a changeover switch for the genny/inverter so everything is there just to plug in a charger. I think its a bit of a waste thats all, I was running the genny most of last weekend sanding down wood and paint, it could of been charging my batteries aswell. I guess anything is better than nothing but I'll have a search around for a 40amp charger and see what else I can come up with.

Edited November 15, 2011 by Evo

[Evo]

Well I've had a look around and £300 is cheap..!!!! they go up from that..!!!

 

I'm not paying that for a battery charger, its taking the piss. Is just me or what, I still think £300 is alot of money...??

 

 

I'd have alot more fun rigging up a belt drive for one of my spare 12v alternators to piggy back on the genny. I could have 70amp+ charging then for next to sod all.

 

I cant believe a box with a rectifier, transformer, and a few diodes, costs £300 plus.

[bottle]

Fun maybe but unless you can spin the alternator at 3,000 rpm (more like 6,000) and the alternator is rated at about 120amp, you will not.

[bizzard]

A year or so ago - or whenever it was - I bought a Chinese 1500W Pure sine wave Inverter. Its been brilliant.

 

For charging our bank of 4 110's we have a 100amp alternator on the engine and a solar panel to keep them charged up when not in use. No 240v charger at all.

 

However,I also have a 240/110v 4.5Kva on-board genny. Trouble is the Genny does not charge the batteries and I would like it to. I realise an Inverter/charger Combi such as a Victron/Sterling would probably have been the best way to go initially but i didn't.

 

 

So now I'm looking at keeping my unobtrusive super slimline inverter and adding a seperate, as thin, battey charger next to it.

 

What amperage charger do I need..?? it seems they go up massively as their amperage increases. In fact I think 30-40 amps is as high as I want to go else they get silly expensive and big.

 

Anyone recommend a good un....do I need 40amps..?? I need a thinnish one as opposed to a huge Victron square type.

 

For lowish usage,i work it out like mine, 12amp per 110volt battery at £50 ago,so about 48-50amp=£200.And your batteries should last about 6 years. bizzard

[Evo]

Fun maybe but unless you can spin the alternator at 3,000 rpm (more like 6,000) and the alternator is rated at about 120amp, you will not.

 

 

No problem at all. Its a single cylinder electric start diesel Yanmar with a directdrive 240v 4.5Kva alternator hanging off one end. Quite easy to take off the huge pull starter on the other end and fit a pulley in its place - any size you like. Fab up some brackets to hold the alternator and job done. Would cost me sod all except the price of a fan belt.

[Bob18]

I can believe that a "box with a rectifier, transformer, and a few diodes" will cost £300 plus. Especially if you want a low profile transformer - they are "stupid" prices for the power needed and always have been.

 

The trouble is the cost of copper has gone through the roof in the last few years, so the cost of transformers has followed These days of course many of the compact chargers aren't simple "transformer plus diodes", but have a lot more in the box to make them work in an intelligent manner.

 

A make to look out for is Ctek, they do a range of very compact maintenance chargers, but they "ain't cheap" for a unit that will maintain your 400Ah battery costing about £160-230. (A bit better than the Victrons of this world, but not much...)

 

I do like your idea of sorting out a way of hanging a spare alternator on the end of your generator. Just be aware of what speed the engine runs at and make sure the alternator is geared correctly otherwise you will not get anything like its rated output.

[Chris Pink]

Well I've had a look around and £300 is cheap..!!!! they go up from that..!!!

 

I'm not paying that for a battery charger, its taking the piss. Is just me or what, I still think £300 is alot of money...??

 

 

I'd have alot more fun rigging up a belt drive for one of my spare 12v alternators to piggy back on the genny. I could have 70amp+ charging then for next to sod all.

 

I cant believe a box with a rectifier, transformer, and a few diodes, costs £300 plus.

 

Putting aside your basic lack of understanding about how a modern battery charger works, see my post #3

[Evo]

Yes, I saw that Pinky, thanks, its the cheapest to date, I'll ignore the attempted insult.

 

 

Still reckon I prefer removing the redundant pull starter and fitting one of my spare alternators. I was thinking £100 tops for a simple battery charger to put some decent amps into 4 leisure batteries whilst the genny was running for a couple of hours or so.

Edited November 15, 2011 by Evo