Power Drawn By An Older Inverter

[nicknorman]

 

That is 330Ah to replenish, but it is typically reckoned that inefficiencies in the process mean you may need (say) 1.5 times that, so 330Ah x 1.5 = (as near as damn it 500Ah)

 

This is an often quoted but wildly pessimistic figure. If the batteries are in reasonably good condition, the charge efficiency will be in the 90s %, meaning that you have to put back no more than 11% more than you took out, unless the batteries are getting pretty knackered. If you look at the last bit of charging, say from 95% to 100%, this region is less efficient due to electrolyte bubbling, and maybe for this small region 150% is correct, but of course its 150% of a pretty small amount of charge.

[nicknorman]

As long as your alternator is charging then it will be OK to charge the phone, the load is minute.

 

As for taking three days to charge the batteries then that is about right, although you have a 90 amp alternator, you will never get 90amps out of it, maybe 45 amps.

 

The alternator will not be spinning fast enough to get more, this is the same on every boat, and also the batteries will have an influence at the later stage of charging.

This is not correct either. The alternator may not be spinning fast enough on a badly designed installation, but on a modern engine it will be. Our 175A alternator produces full output at just above idle and well below normal canal speeds.

 

Of course once the bulk phase ends, the current will gradually reduce, not because of the alternator but because the batteries cannot absorb charge fast enough.

Edited July 21, 2013 by nicknorman

[bottle]

This is not correct either. The alternator may not be spinning fast enough on a badly designed installation, but on a modern engine it will be. Our 175A alternator produces full output at just above idle and well below normal canal speeds.

 

Of course once the bulk phase ends, the current will gradually reduce, not because of the alternator but because the batteries cannot absorb charge fast enough.

 

but you have a modern well designed system, not all boats do.

 

Perhaps i should have stated, it is the same for nearly all boats except those with modern well designed systems like Telemachus.

[nicknorman]

Well to be fair, not just Telemachus but any other Beta43 equipped boat, probably any kubota Beta and probably any other jap based engine built in the last 10 years or so. So that's quite a few really!

Edited July 21, 2013 by nicknorman

[cheshire~rose]

We have a Kubota. The alternaror set up was checked to ensure that full charge is enabled at tick over.

I think I cross posted wirh Alan Fincher earlier so to answer him the batteries were replaced May 2012 but the problem had developed by October.

I spoke to Allan Jones ( Keeping up) today on the phone. He has a knack of explaining things in terms I can understand. I have become a bit less fixated by what he refers to as my bat flattery problem. Gearbox concerns, sratches to the new paintwork, a TV aerial remodelled by a low bridge and having 3 hire boats pull out right in front of us ten minutes before a flught of locks then assume I would close their gate for them as they left before turning it for us.

Never mind eh? It is beer o'clock!

[Keeping Up]

Like I said, bat flattery will get you nowhere!

[cheshire~rose]

Just looking from a slightly different angle.

The place we bought the batteries from said they would return them to the manufacturer for testing if we wanted. ( despite telling us they were fine) but we would need to buy another set to use. If the old ones proved faulty they would then credit us for the new ones. A path we did not want to take as we would prefer to replace with a different brand if they are faulty.

If we bought a new set elsewhere then either test the old ones ourselves (ha ha!) Or get someone who knows what they are doing to test them. We should still be within our right to get a refund if they prove faulty shouldn't we?

Just wondering if we should just buy new ones!

[nicknorman]

To determine if its the batteries you need to fully charge, then discharge in a controlled manner. To determine if they are fully charged you need to be able to monitor the charge current, it should be down to perhaps 2% of the bank size or less, to be fully charged. In the absence of any other means, a DC clamp meter from ebay will do this for about £30. Since a charging issue is a possibility, I would do this first.

 

Then, you can do a rough controlled discharge by switching on some moderate power consumers, but not the one in doubt (fridge). For example tunnel light and some other incandescent lights that you know the power rating of. The wait to see what happens, keeping an eye on the voltage. You can then calculate a ballpark figure for the battery capacity as it is now.

 

If you have no means of monitoring voltage and current, I would hesitate to buy new batteries because chances are they have died due to some ill treatment, and until you identify what that is, the new batteries are likely to go the same way.

Edited July 22, 2013 by nicknorman

[nb Innisfree]

To test new batts I would keep them on charge for two or three days then leave disconnected for 24 hrs, check voltage is 12.65 or more, Assuming they are rated at 20hr discharge rate, (most likely) calculate 20% of ah capacity and load batts with something equal to that result. Leave for 10 hrs, (half 20hr rate) disconnect load and leave for further 24 hrs, voltage should be approx 12.2.

 

If you can spare a few days that is.

Edited July 22, 2013 by nb Innisfree

[cheshire~rose]

I just thought I would add an update to this thread.

 

On our way back from our holiday we passed the supplier again and dropped in to discuss the situation.

 

They tested the fridge for us and confirmed it was not drawing more current when operating than it should have been (although I appreciate that it could still be running more often if the thermostat is dodgy) They once again offered to send the batteries off to be tested.

 

We really felt we had nothing to lose at this point but were not prepared to buy more batteries from them so we took the boat back to the mooring, removed the batteries and delivered them by car.

 

We had decided the likelihood of us getting anywhere with the manufacturer was extremely unlikely as we expected they would simply say the batteries had been misused. The best case we could hope for is if one of the batteries was faulty and dragged the others down then perhaps (clutching at staws) the manufacturer would replace that one. What we wanted to know was if we got new batteries how could we be certain whatever had caused the batteries to fail would not simply destroy the new set in the same way.

 

I had yet another chat about the situation with Allan (Keeping-Up) on the telephone. I had some random suggestions about what might have caused it and he was able to quickly remove any doubts I had about the randomness of these ideas as they would not have caused the problems we were having.

 

He then went back to the beginning and we talked through everything that had been done. His suggestion is that when we had the faulty main isolator switch and were plugged into the mains on the mooring the switch was also losing power between the battery charger and the batteries so the battery charger "thought" the batteries were almost full so was only sending a small current to them to top the last bit up but some of that current was being lost in the vltage drop at the isolatior switch and so the batteries never quite got that last little bit they needed to make them full - hence over time that would have caused them to sulphate.

 

We were informed at the weekend that the supplier has 3 brand new batteries at their place awaiting collection - the manufacturer has replaced all three under guarantee!

 

Result! - an extremely unexpected one and the more I think around it the more I cannot believe it has happened but it has. A bit of me wants to fire questions at the supplier about what the problem was but I think we will just go and collect the batteries and run away with them before they change their mind. Everyone has told us that it is almost impossible to get any joy with warranty on batteries as they just have far too many get out clauses on them most people know little enough about how they work that they can wrap people up in technial jargon until they go away accepting they did something wrong. Well perhaps there are still some reliable manufacturers out there who are prepared to stick by their guarantee. This unexpected turn of events has certainly helped us see the supplier/manufacturer in a new light.

[GUMPY]

And the manufacturer was?

[bizzard]

Never-Ready ?

[cheshire~rose]

I do not know who the manufacturer was, the batteries are branded with the name of the supplier