Tekkie-Lekkie question

[byron]

Most boats have several batteries linked together. 1+1+1 etc.
If one was to attach a charger to battery number one would the charge spill over to the other batteries as and when battery number one is charged up? Or will you just end up with one battery charged higher than the others. I know that one should just pick up the main feed but I was just curious.

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[longjohnsilver]

No answer

Glad to see that I'm not the only one who can't sleep!!!

 

[byron]

Re: No answer

I had wet the bed so I squirmed free of the restraining straps and came on here. This jacket is itchy and my nose is sore from typing.

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[hlb]

Re: Answer!!

No!!


But then again it depends on the idiot who designed the curcuit.

But the good news is that you only need to carry one jump lead on a boat.

Which is usefull at our house cos things have a habit of going missing.

Is this a full enough explanation Byron!!

Haydn

 

[byron]

Re: Answer!!

Thanks Haydn, just wondered, that's all. Hopefully my 9.5KVA gennie will be better than a jump lead anyway

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[boatone]

If I understand the question you are referring to a bank of batteries (2,3,4..) connected in parallel to provide a total amp hours of the sum of the individual batteries amp hours but at the same base voltage - eg 3 x 100amp batteries at 12volts in parallel giving a total 300amp x 12 volts. In this case a charger connected to the bank would charge all three simultaneously buit it would take a lot longer than just charging one battery for the same amp/ hour increase in charge. If the batteries were all of same type and newly installed together and always used in the bank configuration they should maintain roughly equal levels and enjoy equal recharge ("they'll all go together when they go"!!). Where two batteries have different charge levels (an old one and a new one...) and are connected together for some reason the battery at the lowest charge level will 'drag' the other one down to achieve a common level between the two. If charging is taking place via an alternator the lowest level battery will take the charge until it reaches the same level as the higher. In effect, the connected batteries behave like one BIG battery and will only cause problems if they are not of equal status (similar to a duff cell?).
This problem most commonly arises if starter battery and domestic batteries are connected together via (say) a 1/both/2 switch for charging from a single alternator. The alternator charge will go to the battery which needs it most and at such a level that the other battery is unlikely to be called on for support. Some circuits include blocking diodes to ensure that current cannot flow back to a lower source but I hate 'em cos the diodes themselves can take 3/4 volt or so of the charge that is much better utilised hitting the battery.
Dont know if this makes sense but its how I organised my charging circuits and the improvement in battery charge rates and levels was quite dramatic when I got rid of the blocking diode and got 14 volts or so hitting the batteries from the alternator.
Adverc were very helpful with info - http://www.adverc.co.uk
There is also a very good US site on 12v circuits at http://www.amplepower.com/

boatone@boatsonthethames.co.uk

 

[hlb]

Re: But!!

The jump lead is allot cheaper, takes up much less room, dosnt break down and is bloody effective.

You might fill two batteries on the domestic side as they are conected together.

The batteries are all conected together on the neutral side and the two domestic batteries are conected on the positive.

The third battery is for starting the engines only.
Course you could reconect them different and swank about a 36 volt boat. But I dont know were you get the bulbs!!

Course you may have a completly different system in which case answers not the same??

Haydn

 

[ToMo]

Re: No answer

Thats the last time I wish you sweet dreams then !

 

[boomer]

You're right about splitting diodes. By the time wiring loses were added, I was nearly a full volt down! Clearly a disaster from a charging point of view.
On the other hand you need something between the starting and domestic circuits. If you are using a 'proper' domestic battery and a 'proper' starting battery the chemical composition and discharge characteristics are completely different. And you need to ensure that if The Crew watches Eastenders as well as Corrie you will still be able to start up in the morning. The answer IMHO is a relay, triggered by the output from the altenator ( ie circuits split when the engine is not running) in place of the splitting diode. These are dirt cheap and such a system has worked very successfully for me for more than 10 years. It is also in use on a number of emergency service vehicles. Happy to supply diagram for this very simple circuit if anybody is interested.