New Boats Charging System

[AnchorageGuy]

The new boat has a charging system set up that I am not too sure of. It has a single Iota 45 charger connected to a Hellroaring battery isolator which is connect to two banks of two golf carts and a third start battery. The alternator is also connected to the isolator and charges all three batteries. Is there anything inherently wrong with this set up. I know there are more optimal set ups and will address those later but for now is this OK?

[camaraderie]

You're fine Chuck. You'll see a little voltage drop but you can keep 'em charged that way. The Iota (with the 3 stage option right?) would be better off direct to your house bank and then an echo charger to your start battery would be more optimal but it can wait a bit.

[AnchorageGuy]

Thanks, Cam, I plan on doing just that later

[Rick]

Get rid of the diode isolator. They are nothing but trouble and prevent the alternator and Iota from properly charging the batteries unless both sources have direct battery sensing. Use battery combiners to do the isolator function or else merely use your manual method of combining with switches.

Keep in mind that those batteries need to get to 14.4V @ 70 deg F in order to recover lost capacity with deep discharge cycling. Diode isolators will prevent that unless the sources have direct battery voltage sensing. Begrudge the diode isolator losses and lack of reliability. Even with direct battery voltage sensing should a diode fail you could damage the alternator if its regulator is an external 3-step one (as it should be).

[AnchorageGuy]

Originally Posted by Rick

Get rid of the diode isolator. They are nothing but trouble and prevent the alternator and Iota from properly charging the batteries unless both sources have direct battery sensing. Use battery combiners to do the isolator function or else merely use your manual method of combining with switches.

Keep in mind that those batteries need to get to 14.4V @ 70 deg F in order to recover lost capacity with deep discharge cycling. Diode isolators will prevent that unless the sources have direct battery voltage sensing. Begrudge the diode isolator losses and lack of reliability. Even with direct battery voltage sensing should a diode fail you could damage the alternator if its regulator is an external 3-step one (as it should be).

Rick, This particular isolator is only suppose to have a 0.05 to 0.08 voltage loss. At this point it is what I have and plan to upgrade and improve including adding another Iota 45 and run both chargers with a echo charger for the starting bank. BTW, what battery combiners would you recommend for two banks plus starting battery? But just wanted to be sure I am OK for right now. We just bought the boat and have lots of upgrades and improvements to do. Thanks.

[David M]

Battery combiners are not perfect nor close to it. Pick your poison.

[GordMay]

Chuck:
Which particular isolator "is only supposed to have a 0.05 to 0.08 voltage loss"?

At rated currents, a silicon diode has a forward voltage drop of about 1.0 VDC, and a Schottky diode drops about 0.6 VDC.

[AnchorageGuy]

Originally Posted by GordMay

Chuck:
Which particular isolator "is only supposed to have a 0.05 to 0.08 voltage loss"?

At rated currents, a silicon diode has a forward voltage drop of about 1.0 VDC, and a Schottky diode drops about 0.6 VDC.

Gord, They are this type

Hellroaring Battery Isolator/Combiner BIC-75300

[GordMay]

Hellroaring specifies their voltage drop at 5 amps.
Is that a realistic charge rate?

[AnchorageGuy]

Gord, Have not talked with them yet to get confirmation of info but would not think the voltage drop would increase as charging voltage increases. The unit apparently will let you charge up to 120 amps.

[Lance]

Hello Rick , I am setting up a house bank from 8x 3.2 volt 200 ahr lithium iron phoshate batteries ,= principal 24 volt with DC to DC converter for the 12 volt supply .
In respect to these diodes I will have to have a battery monitoring system which runs in connection to modules across each set of terminals , this cuts the system in the event of a voltage drop in any one cell .
Could this be the same as these diodes you mentioned any info or experience you may have would be appreciated .
These Batteries are from the electric automotive industry i am using them on my Cat as a weight saving exercise . ie 8 x 200ahr bank = ~ 56kg .
They are expensive but effectively dry cell batteries ,
I intend to charge from solar Balmar 70 amp alternator plus wind etc .
regards Lance

[bill good]

Lance,
Why 24v to 12v? would that not involve more losses?