House / Starting Batteries

[stevensuf]

i bought the 30 watt on ebay for my cousin, he has no shore power where he is. cheaper going rate their is 2 pounds per watt. 80 watt panels under 150 pounds. i did my rca competent crew then day skipper this year (sail) , just wanted to learn to sail, have the offshore for this year, have no friends with sail boats so the only choice.though it is a bit of an uphill struggle with the old school mob on here.but hey i can speak sail now that foriegn language that deifes you at the start

[Pete7]

If your selling the Sealine then I wouldn't change anything, but if you want to combine the batteries we use a VSR from these folks.

Power Store

So engine running and voltage quickly goes past 13.7 volts the VSR connects the house bank to engine start battery. When the engine stops, the voltage falls to below 12.8 volts (takes a while as surface charge can hold the voltage up for a bit) then the VSR separates so you don't accidently discharge the engine start battery. Our solar is connected into the house bank and we don't worry about the engine start as its an AGM and will withstand the 3 months the engine isn't started.

We much prefer the Moody over the Sealine btw.

Pete

[osirissail]

Originally Posted by stevensuf

Im just wondering how the charging of these is seperated from engine alternator and shore power charger and how the starter battery is isolated form the house ones do they use diodes?

As others have mentioned there are multiple ways of keeping your engine starting battery protected from being drained by house battery stuff. But for charging from the alternator the old and tried and true method is the item shown below. It is device with diodes in it that split the output from the alternator into one leg to the starting battery and the other leg to the house battery.
- - Other devices like voltage sensitive charging relays close when one battery is "full" and then send the output to the other battery and then disconnect the connection if the voltage drops below a set point. There are many different versions of those devices.