Battery bank leakage

[Nightwatch]

Hope someone can answer this query.

I have a 4 battery leisure bank on my narrowboat. I have been told that two are defective and the other two are getting that way. I have purchased 2 new 110amp hr batteries and intend to install within the next couple of days when I am next at the boat. I have a question. As I am only replacing two batteries will the two remaining suspect batteries "suck" power from the two new ones therefore reducing power time. Also whilst I'm on the subject, should i disconnect the two suspect batteries and live with the 2x110amp hr ones until I save up for two more or leave then connected. I have a 4000w inverter, this will of course use power if used, I only run chargers for phones/cameras and the occasional telly will two new batteries supply? I may seem a little thick, but I'm not really.

[magnetman]

Hope someone can answer this query.

I have a 4 battery leisure bank on my narrowboat. I have been told that two are defective and the other two are getting that way. I have purchased 2 new 110amp hr batteries and intend to install within the next couple of days when I am next at the boat. I have a question. As I am only replacing two batteries will the two remaining suspect batteries "suck" power from the two new ones therefore reducing power time. Also whilst I'm on the subject, should i disconnect the two suspect batteries and live with the 2x110amp hr ones until I save up for two more or leave then connected. I have a 4000w inverter, this will of course use power if used, I only run chargers for phones/cameras and the occasional telly will two new batteries supply? I may seem a little thick, but I'm not really.

Hello. I'm under the impression that it is generally a bad idea to mix old and new batteries although I don't believe that the old ones will actually damage the new ones they may well pull down the overall effectiveness of the bank. The person who knows most about this subject on this forum is called 'Gibbo'. He has done extensive testing of batteries and will be able to give you an accurate answer.

 

4000w inverter sounds a bit big? for phones and laptops etc 300w is more than adequate.

[Nightwatch]

Hello. I'm under the impression that it is generally a bad idea to mix old and new batteries although I don't believe that the old ones will actually damage the new ones they may well pull down the overall effectiveness of the bank. The person who knows most about this subject on this forum is called 'Gibbo'. He has done extensive testing of batteries and will be able to give you an accurate answer.

 

4000w inverter sounds a bit big? for phones and laptops etc 300w is more than adequate.

Inverter on boat when purchased. Many thanks for your comments.

[Keeping Up]

If any of the old batteries have a shorted cell, then it can't be mixed with new ones and is only fit for scrap. If all the old ones are merely tired and generally kn*ckered then you can happily parallel them with the new ones.

Edited August 2, 2008 by Keeping Up

[Nightwatch]

If any of the old batteries have a shorted cell, then it can't be mixed with new ones and is only fit for scrap. If all the old ones are merely tired and generally kn*ckered then you can happily parallel them with the new ones.

Now I'm really being thick. How do I tell if any of the cells have shorted? Does this mean they are touching when veiwed with cap removed?

[Keeping Up]

Now I'm really being thick. How do I tell if any of the cells have shorted? Does this mean they are touching when veiwed with cap removed?

No, unfortunately you can't tell by looking at them. You can only tell by using a voltmeter (the battery has become a 10v battery instead of a 12 volt battery, so that even if you charge it up fully it still has between 10 and 11 volts instead of between 12 and 13) or by using a hydrometer (5 cells can be charged up to show in the green sector of the float but one can't and remains in the red sector)

[Nightwatch]

No, unfortunately you can't tell by looking at them. You can only tell by using a voltmeter (the battery has become a 10v battery instead of a 12 volt battery, so that even if you charge it up fully it still has between 10 and 11 volts instead of between 12 and 13) or by using a hydrometer (5 cells can be charged up to show in the green sector of the float but one can't and remains in the red sector)

Once again thanks. I will buy a hydrometer, the chap who tested them had one, actually at Tooleys Boatyard in Banbury. Name droping! I had no money at the time so had to get away asap to avoid sales presure. not that there was any. Managed to buy the batteries on ebay for £131 including £20.00 postage. better deals can be had for 4 batteries but once again funds dictated. I was told that of the four batteries two are 110 ah and the other two were alot larger possibly 185 ah.

In fact the boat when I bought it had electrical problems. Over time two of the "shunts" have been by-passed and the sterling "traffic Light" box disconnected. I not too bad at nuts and bolts but electrics confuse me. I need a friendly electrician to sort I think.

[Keeping Up]

You aren't the only person asking the same question. See here. At least the answers are consistent too, for once!