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My Sister has a Springer Water bug with inboard diesel engine with single alternator with one domestic battery and one starter battery connected with a 4 way rotary switch. marked Off 1,2 or both.

Around 3 months ago I fitted a single output 20amp electroquest battery charger connecting the fused output to one of the batteries and negative on opposite same batteries negative terminal and kept the main rotary switch set at both, thinking the charger would charge both batteries.

 

When I fitted it I couldn't tell if it was working as went both red then to green very quickly. There is an old Engel 12 volt fridge and the batteries are both flat now as had fridge on for 2-3months. Battery with charger connected reading 3.7 volts and other battery 10.2 volts.  On setting 1 and 2 got around 7.5 volts each from my multi-meter.

 

can you wire up a single output charger to a bank with a rotary switch? If so how? Also suspect duff switch as get no power to lights in the both position. Originally it worked up until now.

 

The 2 positive cables goes from the rotary switch separately to each battery and the negative is shared and joins each battery negative.

 

Will a charger charge really flat batteries? Tried starting the engine and no start in any rotary switch position.

Like to get this sorted. 12 volt wise we have 5 LED lights and the slimline engel 12 volt fridge.

 

Any ideas what the issue is?

Tomorrow I'll take some pictures of the battery wiring and rotary switch. May even try separating the 10 volt battery and fitting charger direct to confirm if charger actually works.

 

  Many thanks. James.

 

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Sounds like you left something switched on, ( fridge /lights/pump/alarm) or other. The domestic side battery has died, you may just be able to recover the starter battery if it's pretty new but the likelihood of that happening is quite small.

Jump start it with leads from a fully charged battery and let it run for about an hour to get it back to 12.5 v and see how long it lasts. If that's the leisure battery at 3 v bin it, it will never come back past about 7 or 8 v and wont have enough charge to power anything.

Experts may give more detailed advice soon

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Yes, the  problem here is not about how the switch is wired, but more about leaving a fridge on for 3 months! Your domestic battery is dead. Like a Norweigen Blue. It will not see life again! You MUST keep these batteries full all the time....well at least get them back to fully charged every few days. The engine start battery .....likely the one at 10V .....may recover if you can get an equalisation voltage into it.

Once you get two new batteries you can easily check with a multimeter to see what switch positions will charge one or two batteries.

Your lights are not working cause the batteries are dead - not because of a duff switch.

You must learn how to manage your batteries ....ie dont leave a fridge on....or the next set will be dead in a couple of months.

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Turn the fridge off. One cabin battery will go flat in no time, and with the switch on ''both'' you'll end up with engine battery flat as well, unless your running the engine continuousely. Might be worth taking the battery to a garage or car sales site to kick it back into life with a hefty boost-starter machine, to whack a quick 100amps into it.

Edited by bizzard

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We have a 12v fridge and we use it when we are running the engine and for a few hours afterwards. We always turn it off at night unless we are plugged into shore power. A fridge will flatten a couple of batteries in a day or so.

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Thanks everyone.

 

What I don't get is why didn't the mains 20amp battery charger not charge the batteries as needed as connected and on ever since turning on the 12 volt fridge?

I don't want to buy new batteries and wreck them.

Yes domestic battery 3.6v and starter 10 volt. I'll get new ones. My thinking was I could use the capacity of the 2 batteries, 110A each for fridge and the mains charger keep them charged.

 

James.

Edited by canals are us?

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Can't really say without looking. Most manufacturers say to charge batteries once a month through the winter if you take them home and store them but if you leave them on a boat and connected to a charger that might not be good for them if there is a heavy drain like a fridge. Is there water in them? if they are dry then they are finished. Does the charger work? If the power goes off it might need to be turned on to re start it. Really hard to know.

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5 minutes ago, canals are us? said:

Thanks everyone.

 

What I don't get is why didn't the mains 20amp battery charger not charge the batteries as needed as connected and on ever since turning on the 12 volt fridge?

I don't want to buy new batteries and wreck them.

Yes domestic battery 3.6v and starter 10 volt. I'll get new ones. My thinking was I could use the capacity of the 2 batteries, 110A each for fridge and the mains charger keep them charged.

 

James.

I’d guess that the charger is u/s. What were the voltages on the two batteries when the charger was on?  I bought a cheap charger from Halfords a couple of years ago and took it back the same day - it didn’t work. 

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16 minutes ago, canals are us? said:

Thanks everyone.

 

What I don't get is why didn't the mains 20amp battery charger not charge the batteries as needed as connected and on ever since turning on the 12 volt fridge?

I don't want to buy new batteries and wreck them.

Yes domestic battery 3.6v and starter 10 volt. I'll get new ones. My thinking was I could use the capacity of the 2 batteries, 110A each for fridge and the mains charger keep them charged.

 

James.

You said in your first post you didnt know if the charger was working. "both went from red to green". You cant use the red/green to tell if a charger is working. Why didnt you check it with a multimeter when you installed it and made sure you were getting charge into domestic battery. If you didnt do this, then it is possible that the batteries were not charging. I would never install a battery charger and walk away. I would check it on a daily basis until I was sure it was behaving itself and check voltages via a battery monitor or at worst via a multimeter.

 

eta.. a 12V fridge will take circa 5-6A when the compressor is running so that is 30% duty on the charger. Maybe on 40% of the time. I would not leave a charger on like that for 3 months without checking it after zero checks when installed. I would never leave a fridge on for more than a week unattended.

Likely either the charger is duff or the switch position was wrong and now charging to the batteries.

Edited by Dr Bob

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1 minute ago, Dr Bob said:

You said in your first post you didnt know if the charger was working. "both went from red to green".

Could he be referring to the green/red infamous "Magic Eye" incorporated into the battery ?

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1 hour ago, canals are us? said:

Around 3 months ago I fitted a single output 20amp electroquest battery charger connecting the fused output to one of the batteries and negative on opposite same batteries negative terminal 

  Many thanks. James.

 

I don't quite understand how the charger is connected. do you mean you connected it to the + an - terminals of one of the batteries?

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1 hour ago, canals are us? said:

Around 3 months ago I fitted a single output 20amp electroquest battery charger connecting the fused output to one of the batteries and negative on opposite same batteries negative terminal and kept the main rotary switch set at both, thinking the charger would charge both batteries.

You should be able to feed charge to both batteries from the charger by connecting the charger positive to the same battery terminal that the alternator is connected to. Negative to the common negative. Check that the negatives from both batteries are connected together.

Don't rely on crocodile clips, use crimped on ring terminals.  

If the alternator feeds the domestic battery then if this is position 2 on the switch just the domestic battery will be charged on position 2 but both batteries at the both position.  It's possible that the fuse in the charger lead has blown - check with your multimeter. 

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3 minutes ago, ditchcrawler said:

I don't quite understand how the charger is connected. do you mean you connected it to the + an - terminals of one of the batteries?

Yes. The fused output positive connected to the positive of one battery and the negative on the same battery.

3 minutes ago, rusty69 said:

Was the boat occupied whilst fridge was on? 

No, mostly not in use, but fridge on with a few items in it.

Batteries not looked at electrolyte level but the batteries look old. The charger has 2 lit led's one to show mains on ie red. 2nd LED red to show charging and green to show in float.

 

Thanks. James.

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7 minutes ago, canals are us? said:

Yes. The fused output positive connected to the positive of one battery and the negative on the same battery.

No, mostly not in use, but fridge on with a few items in it.

Batteries not looked at electrolyte level but the batteries look old. The charger has 2 lit led's one to show mains on ie red. 2nd LED red to show charging and green to show in float.

 

Thanks. James.

So, the batteries were possibly knackered before you connected the charger? 

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1 minute ago, philjw said:

You should be able to feed charge to both batteries from the charger by connecting the charger positive to the same battery terminal that the alternator is connected to. Negative to the common negative. Check that the negatives from both batteries are connected together.

Don't rely on crocodile clips, use crimped on ring terminals.  

If the alternator feeds the domestic battery then if this is position 2 on the switch just the domestic battery will be charged on position 2 but both batteries at the both position.  It's possible that the fuse in the charger lead has blown - check with your multimeter. 

This is how I wired it. charger output positive to domestic positive and negative to common negative. I can see the black cable going to the domestic negative then link from domestic to starter.

Originally I had a 15 amp fuse in the positive lead to the batteries and yesterday it blew a 15 amp fuse 3 times when fitting. I put a 30amp fuse in and not blown so far sine yesterday. Also the charger has a 25 amp fuse and that is fine. Terminals are ring type and crimped.

 

Many thanks. James.

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1 minute ago, rusty69 said:

So, the batteries were possibly knackered before you connected the charger? 

Good thinking Batman!

Why was the charger purchased? .....because the batteries needed charging better...ie they were knackered?

 

Wish I was clever like you.

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I would switch that charger off straight away and dump those batteries, at 3 and 7 volt they are knackered and may well damage your charger.

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20 minutes ago, Dr Bob said:

Good thinking Batman!

Why was the charger purchased? .....because the batteries needed charging better...ie they were knackered?

 

Wish I was clever like you.

The boat never had any mains on board so wired in a consumer unit and sockets and as my Sister is spending time on board wanted to wire in my old 4 year old battery charger to run lights and fridge.

 

I remember after buying the boat the batteries were at 12.5 volts. can't remember if I measured output with charger on but charger been switched on for 3 months same as fridge. My suspicion is charger US and killed of batteries.

 

Many Thanks. James.

Edited by canals are us?

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3 minutes ago, canals are us? said:

The boat never had any mains on board so wired in a consumer unit and sockets and as my Sister is spending time on board wanted to wire in my old 4 year old battery charger to run lights and fridge.

 

I remember after buying the boat the batteries were at 12.5 volts. cant remember if I measured output with harger on but charger been switched on for 3 months same as fridge.

 

Many Thanks. James.

James, from your comment on the voltage being 12.5V says you are not 'skilled in the art of battery management'. Sorry to be blunt but saying 12.5v is meaningless unless it is clarified by the duty it is seeing. Bottom line is that when you put the charger in, you did not check it was charging by checking voltages with and without the charger. This was then combined with no one checking voltages during the 3 months of operation with the fridge. If that had been done, and the person doing the checking knew what voltages to look for, then you would quickly have discoverd if the charger was working or the batteries were going flat.

Lead acid batteries do need managing if used as a domestic bank on a boat. They are not plug and play.

Get 2 new batteries and monitor voltage to check the charging is working.

Look at the pinned battery primer. I'm sure Rusty will post a link soon !!!! .....and learn it.

When you get your new batteries installed, come back if you are not sure of voltages.

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15 minutes ago, canals are us? said:

The boat never had any mains on board so wired in a consumer unit and sockets and as my Sister is spending time on board wanted to wire in my old 4 year old battery charger to run lights and fridge.

 

I remember after buying the boat the batteries were at 12.5 volts. cant remember if I measured output with harger on but charger been switched on for 3 months same as fridge.

 

Many Thanks. James.

And the the fuse through its hand in and the fridge dragged the guts out of the poor old batteries at a guess 

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Sadly there is no volt meter on the boat or battery monitor and I have been away twice working for 5 and 4 weeks and my Sister wouldn't know how to use a multi meter or even think of looking at her batteries.

 

When I installed it I seem to think the charger function was odd as it went to float too early so suspected batteries full as had ben cruised for 7 days ,54 miles, being delivered and though batteries were nearly full at 12.5 volt and so gone to float. I cant remember fully as busy with other work but sure I measured the batteries float voltage around 13.2v.

I'll get a digital volt display from ebay and wire it in. I find mine useful as well as a NASA BM2 and MT50 solar Meter on my boat.

I'll get my Sister to buy new batteries and I'll fit them and see if I get an increase in volts to indicate the charger is working. The charger has printed the float charge to look for and bulk charge. Certainly when I run her engine I got 14.2 volts at the batteries.

 

James.

Edited by canals are us?

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