Battery chargers

[John C]

Now I have access to mains electricity it seems silly to use the engine to charge the batteries while at the mooring. I would like to buy a battery charger, something simple (and cheap) that would only be used when I'm on the boat. The charger would need to be able to charge 2 x 110AH batteries, any ideas on the size of charger (in amps)? Would something from Halfords or Screwfix do the job?

 

John

[Proper Job]

Leisure mooring or live a board?

 

 

 

..... I'm off to get some pop corn

[Justme]

Whilst connected to the mains how much 12v power will you still use?

How much power will you use when not connected to the mains?

How flat will the bats be when you connect to the mains & how long will you stay connected?

[WotEver]

Any particular reason you only want to charge the batts when you're there instead of keeping them fully charged and thereby extending their life?

 

Tony

 

edit to make sense

Edited December 6, 2010 by WotEver

[classicstove]

You may like to consider buying a slightly more expensive charger which will not only charge batteries until fully charged, then provide a trickle charge to keep them in good condition and extend life and some of those available also now offer desulphatation (if thats how you spell it) which also helps to prolong the life of the batteries

[bottle]

Hi John

 

I dare you to put either, battery, charging, battery charging, or battery chargers into the 'search'.

 

You need a three/four stage charger not a cheapy 'car battery' charger.

 

As for size, some say 10% of battery bank some say bigger.

 

Have a look at Gibbo's site: Link

[nb Innisfree]

I would say 40-50amps.

[Robin2]

I would say 40-50amps.

 

I had a Sterling 30Amp charger on my previous boat (in a marina). Charger was on all the time unless I was away for a few days and met all my needs.

 

When you have mains power you don't need to run an inverter so there won't be heavy 12v loads. As long as charger can supply more than your instantaneous needs it will keep the battery charged.

 

The only reason for a big charger would be if you need to charge the batteries quickly from a low level of charge.

[nb Innisfree]

I had a Sterling 30Amp charger on my previous boat (in a marina). Charger was on all the time unless I was away for a few days and met all my needs.

 

When you have mains power you don't need to run an inverter so there won't be heavy 12v loads. As long as charger can supply more than your instantaneous needs it will keep the battery charged.

 

The only reason for a big charger would be if you need to charge the batteries quickly from a low level of charge.

 

Handy after or between power cuts.

[Robin2]

Handy after or between power cuts.

 

Is this an attempt to justify a big charger?

 

I don't think it holds water because John C already has an engine alternator.

[blackrose]

If he's on shore power he only really needs a 20 amp charger because he can leave it on indefinitely.

 

The only reason to buy a bigger charger is if he has especially large 12v loads or he wants to use the charger from a generator when moored up somewhere else without shore power.

 

The 20amp Sterling here will do the job, although there may be cheaper 3 stage chargers available.

 

http://www.yachtbits.com/sterling_power/sterling_pro_charge_c_battery_chargers.php

[Scotty]

I broke the 10% rule and bought a 10A sterling charger for my 330Ah battery bank.

 

If the batteries are low, I take the boat for a day trip and the alternators replace the bulk of the charge.

By the end of the day the batteries are accepting less than 10A anyway so overnight on the 10A charger is plenty.

[blackrose]

I broke the 10% rule and bought a 10A sterling charger for my 330Ah battery bank.

 

If the batteries are low, I take the boat for a day trip and the alternators replace the bulk of the charge.

By the end of the day the batteries are accepting less than 10A anyway so overnight on the 10A charger is plenty.

 

If you keep the charger switched on while moored up on shore power, would it give you sufficient output for living aboard? (Without taking the boat out or using the alternator).

Edited December 6, 2010 by blackrose

[Scotty]

Possibly i'm quite a low power user, but I don't live on the boat so can't say.

 

I found that the batteries were often sat at around 90% (Smartgauge) and there was no point using a 40 or 50A charger to put in the last 10% of charge.

[WotEver]

If you keep the charger switched on while moored up on shore power, would it give you sufficient output for living aboard? (Without taking the boat out or using the alternator).

You'd still need to do a power audit to answer that.

 

If you have a 20A charger and use less than say 18A on average then yes. If you use over 20A on average then no.

 

Tony

[John C]

Many thanks for the answers. I should have known better than expect a simple answer. But there was one in there, thanks Mr. Bottle.

 

To answer the questions, I am not a live aboard, we visit the boat every other weekend(ish) and holidays. My power consumption is low, a few (LED) lights and occasional TV, radio and waterpump. I will not leave the charger connected permanently because the cable lies along the towpath, I can see this causing problems if I am not there to keep an eye on it.

 

I have a small solar panel that seems to be able to hold the batteries at whatever level of charge I leave them in. With shore power connected while I am at the mooring a battery charger will keep the batteries (fully) charged without the need to run the engine for extend periods.

 

So, I'm off to Machine Mart to see what they've got.

 

Thanks all

[blackrose]

You'd still need to do a power audit to answer that.

 

If you have a 20A charger and use less than say 18A on average then yes. If you use over 20A on average then no.

 

Tony

 

Yes, it was just a general question as I realised we all have different power usage requirements. I guess it also depends on the a/h capacity of the battery bank should one exceed the charger's rated output.

[nb Innisfree]

Is this an attempt to justify a big charger?

 

I don't think it holds water because John C already has an engine alternator.

 

Still handy though.

[Robin2]

Still handy though.

 

There is always a choice between spending money on battery chargers or beer

[boots]

I broke the 10% rule and bought a 10A sterling charger for my 330Ah battery bank.

 

If the batteries are low, I take the boat for a day trip and the alternators replace the bulk of the charge.

By the end of the day the batteries are accepting less than 10A anyway so overnight on the 10A charger is plenty.

 

 

You think that is breaking the rule!!! we have a 675Ah bank and was originally was planning on getting something like a 30A charger, but ended up with a Sterling 5A jobbie!! - (tin hat donned). but....we have a shoreline connection and only use the boat at weekends (when we go cruising, and not every weekend). So, she will sit there for several weeks with no use. I'm guessing that at best it would take about 2~3 weeks to charge the bank up. (which is not a problem for us)

 

So far, every time we have visited, the batteries seem to be fully charged, though I don't expect they are in particularly good condition as they spent most of last Christmas (during the freeze) flat!

 

One day, guess will buy a bigger charger - but this one came up v. cheap and was easy to fit as I was able to mount it in the engine bay (it is a waterproof charger) rather than running heavy cables into the cabin.

 

Wonder if this is a record - smallest charger relative to bank size....

[madcat]

I was told by a chap in Maplins that a 20amp charger was too big for a pair of 110ah leisure batteries..............um...... anyway all Im off to Machine mart to see what they have as I want an automatic charger I can keep on the boat,our old 12a one hums like a hive of bees and besides when we need it at home Im in a bit of bother if Ive left it on the boat!

[nb Innisfree]

Apart from cost I think the biggest charger is best hence my earlier 40-50amps, it will recharge safely in minimum time if there is a short period of available shorepower + it will still do the job of a small charger i.e. absorption. 10% isn't a rule it's just a rough guide, a figure plucked out of the air really a bit like the 50% rule really except that is at least a bottom line for discharge.

[bottle]

I was told by a chap in Maplins that a 20amp charger was too big for a pair of 110ah leisure batteries..............um...... anyway all Im off to Machine mart to see what they have as I want an automatic charger I can keep on the boat,our old 12a one hums like a hive of bees and besides when we need it at home Im in a bit of bother if Ive left it on the boat!

 

No, it is not.

 

By that I assume you mean a three/four stage charger. (all chargers are automatic in a way)

Edited December 10, 2010 by bottle

[madcat]

I wasnt about to believe the man in Maplins but I'm too old to want to bash my head against a brick wall arguing with him.

Our old charger is a simple beast in that it charges to a certain level when it decides the battery is charged and then switches its self to to dishing out a lower voltage.It is not a complicated 4 stage "smart" device just supplies a charge and then switches to float mode.It will not be the most efficient charger on the planet but one just like it but bigger amperage would be just fine.I will be getting another solar panel soonish, the last one cracked and I got my money back.Still have a regulator so wont need to buy one of them.