charging 2 batteries

[derekh]

I have been looking at the port engine and the way the charging is connected to main and aux batts. when either master switch is on, both cabin and engine power is available. when both master switches are on both batteries are basically in parallel. I was considering a Sterling 30 amp - 3 output switch mode charger which I know will sort out my shore power charging. I feel that aux and main batts should be totally seperate, being charged via a split charge relay. Is this correct ?

 

[Talbot]

some of the sterling/adverc/etc range are set up so that you can charge two seperate banks at the same time. You need to make sure you know what size the two banks are, to get the right charger, and there should be similar types of battery i.e. wet cell/gell etc as some of these need different charge regimes.

 

[halcyon]

From what you say there would appear to have a number of options, I assume two engines and two battery banks.
You can start both engines from one bank and supply services from the other, one alternator charges service battery, the other alternator charges engine battery, once engine bank up to min level, the alternator is linked to service battery as well, effectivly doubling charge capacity, if one alternator fails the system allows the working alternator to cherge both banks, or link both banks for starting if engine bank low. Or you can have one engine charge port engine battery, and the starboard alernator charge engine and service battery bank, again you can cover alternator failure and link starting. Or you could go as far as two engine batteriey banks and a service battery bank.
Drop us a PM if you want some information on relay units.

Brian

 

[qetoo]

I have had good experience with the "Heart Echo Charge". The Alternator connects directly to the house (domestic) battery and the start battery charges from the house-battery through the Heart Echo Charge. When on shore power, the house-battery is charged from the shore power battery charger, which also keeps the start battery charged through the Heart Echo Charge. I have posted a diagram at:

http://carlten.tripod.com/Electrical_system/electrical.html

 

[William_H]

With two engines and two alternators the simplest arrangement is to isolate each system competely . You need a way to connect one battery to the other for emergency jump start. You can use either battery as a house battery (changeover switch)( or connect via a VSR a house batteryand load) Your shore power charger if it is designed for 2 batteries should be able to keep both charged even if one has the house load on it.
The problem of connecting batteries together when charging from 2 alternators is that one alternator will take all the load while the other takes none. this remains the problem with a Voltage Sensing Relay. On twin engined aircraft they have a balancing regulator. ie one regulator for 2 alternators and one battery. these balancing regulators can be bought but it is simpler to keep the two batteries and alternators isolated when engines are running.
it really gets complicated and you either need to understand what is happening yourself or get abn expert if you can find one. good luck olewill
PS when you say Aux and main batery should be separate this means paralelled by a VSR or diodes for charging while for discharging when engines not running they are separate so that you can not inadvertantly flatten the engine battery.