Wednesday, January 1, 2014

Re: [Electric Boats] Batteries in parallel [1 Attachment]

Hi Richard,

The house system is separated by diodes which is good.

Where is the Contactor?

Be sure to leave the motor switches off while the boat is unattended and make sure that you have the same voltage on both banks when you turn both motor switches on.   If one is higher, then switch the higher battery on first,  turn on the motor and increase the throttle until both batteries are at the same voltage and then turn the second switch on.  If one of the chargers fail then you would have dissimilar voltages on the batteries and when you switched the second battery on you could get arcing inside the battery switch which would start to cause increased resistance.   If arcing does occur, then repetitively switch on and off to get a better contact.   

I would like to see a voltmeter on both 48 volt batteries, always visible.  

Periodically check each individual battery voltage after the charger has been off for at least 4 hours to make sure the batteries are still in balance.   Lifeline batteries are very good at staying in balance for a long period of time.   Your setup looks like you are charging at the 12 volt level which means you get a balancing charge each time you turn the chargers on.  

Sooner or later one of the batteries will fail but it will likely be in 7 or 8 years. 

Which system do you have?   Can you send me a complete diagram with the AC system of the boat included?   

Is the converter an isolated power supply which you have chosen to hook to a common grounding point?  

Is the common grounding point hooked to seawater potential?   

Is the AC system also hooked to seawater potential?   

Do you have an isolation transformer or a galvanic isolator?   

Is the boat used in fresh water or in salt water or in brackish water? 

We can help you with Lithium when the time comes.    

Thanks,

James



James

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