another bloomin battery question..

[Biffer]

...I have read a lot of the threads on this, thank you for compiling them smiley pete, and I think I know the answer but just wanted it confirmed. My leisure bank is shagged but I don't need it tip-top for a while as I'm not planning on cruising and am a liveaboard with permanent shore power. I do need to use my 12v systems on the boat though.Thing is,I can't afford a new bank but I can afford a 5 stage charger. However some threads point to the fact that it is dangerous to keep knackered batteries permanently connected - I'm just not sure if this applies if you are using them daily, or only if you are leaving the boat unused for a while. I do have a very ancient 240-12v blue box, rated at 200w. Would I be better off a)using this off the mains to power up my 12v stuff in the meantime, b)going with knackered batts + permanent charger or c) using my flexible friend to buy a new bank. I'm thinking c) but I would like to use a or b if they are not overly dangerous/ cost ineffective.

 

As I said I've gleened a lot from the many threads so in-depth explanations not necessary!

 

Ta.

Edited May 20, 2014 by Biffer

[Robbo]

If your on shore power you don't need a large bank of batteries if you have a multi stage charger as the charger will provide the power. In fact you could just use the starter battery as your house battery! It's only when you come away from shore power is when that bank counts.

 

With using your 200w 240w to 12v power adapter, it may be underpowered for stuff like pumps and fridges.

 

I would do a load test on your batteries, find the good ones and use a multi charger if your going to be on shore power for a good time. Get one that's rated for the bank ah's you want eventually.

Edited May 21, 2014 by Robbo

[Clifford]

Some (many) marine chargers (my old Sterling 1230 for one) say they don't need a battery conected at all. In "powerpack mode" they just work as a 230v to 12v power supply.

[Tony Brooks]

Before I pronounced I would want to be sure I knew exactly what the ancient blue box is. If its a 12V battery charger then the voltage is likely to be very variable from possibly less than 12V when under a heavy load to well over 15 volts when under a light or no load. This will do any electronic stuff you may have potential harm.

 

The danger with keeping faulty batteries ion change is that they may dry out and then when two plates eventually short out the hydrogen (from the electrolysing of the water in the acid) explodes.

 

If they are knackered simply by loss of capacity (sulphation) then as long as you are in attendance keeping them on charge is probably safe enough. If single cells are bubbling well, brass/copper in the vicinity is tarnishing, or you an smell rotten eggs then you have faulty cells and would not be best advised to keep them on charge.

 

I would go for either buying the charger and using the start battery for the time being or just buying one battery and the charger. Once you have the charger you should be able keep the new and any subsequent batteries in a far better state of charge and thus prolong their life. Gradually buying the bank over a few months will not cause any problems. Neither will identifying individual faulty batteries and just changing those. However doing this does one you to having one of the old batteries go faulty which in term damages the new ones BUT if the charger is connected then is a bit less likely because one will smell or explode before that happens.

[smileypete]

If spending £££ on new batts and or charger is being considered, I'd first recommend getting a multimeter/DC clamp ammeter, £25 online or £40 from the likes of Maplins:

 

http://www.ebay.co.u...efLoc=1&_sop=15

http://www.maplin.co...ultimeter-n41nc

 

That will find out whether the blue box puts out a regulated charge voltage or not, and so whether it's suitable for longer term use. It'll also make it easy to find out how much charge current the batts are taking at any time.

 

If the charge current to each batt doesn't tail off to a low level - up to around 2% of the capacity in Ah for 'open' batts, but *much* less for sealed batts - then I wouldn't leave them on charge for long periods or unattended.

 

There's some good info on maintenance and safe handling precautions at The Battery FAQ:

 

http://www.batteryfaq.org/

 

cheers, Pete.

~smpt~

Edited May 21, 2014 by smileypete

[Biffer]

Fantastic stuff, love this forum. I would never have thought about using the starter battery in the interim. It just happens to be brand new so I've gone with that as the safest option in the meantime.

 

Pete - I have a multimeter already so will put it to use on the blue box, which it seems (Tony) is a 240-12v / 200w transformer. I have used it for powering a 12v bilge pump from the mains but not sure it could cope with a whole boat's worth.

 

I also had an electroquest charger delivered today and it never reverted to 1or 2AH on the display with the old domestic bank but instead remained constantly on 14.2ish volts. So I guess Pete from what you say they are unsafe to charge for long. With the starter it dropped to show 1.2ah after a while.

 

Thanks everyone, and Tony thanks again for your offer of help when we were stuck at Fobney lock the other week!

 

Cheers

Dave

 

[Tony Brooks]

No probs. That box looks like a power supply off a bit of equipment, possibly computer related. If so I expect the 12V output is fairly stable but don't think it will be more than about 5 Amps.

[Iain_S]

If the blue box is the one posted in post 6, it looks like a battery charger for a caravan.

 

A similar one in ours put out 13.8V off load, obviously designed to trickle charge a battery and be connected permanantly when the caravan has 240V available. I can't remember the output on ours, but when it was killed by a shorted cell in the battery, replacements varied between 5A and 10A claimed output.

 

OK for a caravan with very low 12V load, and lots of time to charge between outings, but I can't see it coping with the (probably) much higher load on a boat. (more than one light, bigger water pump, etc)

 

Iain

[Clifford]

If you are permanently on shore power, I can't see why you need more than one battery (for both domestic and starter). It would never discharge?

 

Happy for permanently-wired liveaboards to tell me I am talking bollards.

[Biffer]

Thanks Iain.

 

Clifford - I think you're right but whilst we're not going cruising soon we will be later in the year.