Starter battery not connected to charger

[teddythetwig]

I recently went to start my engine, and was greeted with a dead starter battery. The boat is relatively new to me, and I haven't dove into the wiring yet, so I was surprised to find that the starter battery was not connected to the charger, only to the alternator.

My house bank consists of two deep cycle batteries, and each is connected to a different post on the battery charger(they are also wired to I & II on the battery isolator switch)

If the starter battery isn't connected to the charger, I can only assume that the house battery bank isn't connected to the alternator either.

Is it normal to use a 1,2,both isolator switch to separate your house bank?
Is it normal to not wire the starter battery to the battery charger?

[Mirage35]

Not at all normal in my experience or knowledge. Sounds like someone misunderstood the purpose of the battery selector.

“House bank” describes it - this is one or more batteries connected to act as a single “bank”, typically number 2 on the selector.

And both banks should be charged by charger and alternator (some nuances there that others may get into, but speaking in general).

[smac999]

since you have 3 battery banks. you would need a 3 bank charger in order to connect to all 3. which it sounds like it isn't.

the charger not connected to the engine battery has nothing to do with the alt. it may have a diode spliter / battery isolator on it. (or may have nothing)

personaly I would join the 2 house batterers together. run the charger to the house battery and the engine battery. and buy a blue sea add a battery kit and replace your current swtich and add the ACR. then both banks are isolated, and both will charge from the engine. and both will charge from the charger.

[Unity]

Two house banks and one engine bank is very common. The trick here is understanding how the charging circuit works - which sounds like is a shore charger and the alternator.

It is unusual to have the circuit being just alternator to engine bank, and shore charger to the house banks. Often there is a device that lets the alternator charge all three banks - either an isolator (diodes that allow charge current to flow to all banks without the banks draining into each other) or a combiner (a relay/switch that connects the banks when a charge current is detected).

If it's an isolator, it usually has four red wires (one from alternator, three to battery banks). If its a combiner, then you may find it as a device that is connected between your engine battery and one or both of your house banks (it will have two or three power lines and one ground).

If you find a combiner, then that would explain your configuration (alternator chargers engine start, which in turn triggers the combiner to charge the house banks), though you would want to then understand why it didn't keep your engine battery charged. If you find an isolator, then the alternator will charge the batteries but the shore power will never charge the engine start.

You should also check for another battery switch that lets you bridge the engine start battery over to the house battery. This is an emergency switch that will let you start the engine even when the engine battery is dead. Make sure to always leave that disconnected except when you can't start the engine.

Now - having said all that - if your engine battery is not being drained by the house (such as the emergency switch being in the combined position while you used the house bank), and if your alternator is going to the engine battery, then there is no reason that battery should be dead. So you may need to look at if your alternator is working (blown diodes are common), or perhaps you need to replace the engine battery.

Good luck tracking this down...

[john61ct]

You need to get a DMM, ideally an ammeter and maybe a helper / teacher to map out what you have now in a detailed diagram.

Then through research and discussion you will come up with a detailed diagram of where you want to get to.

[hzcruiser]

Originally Posted by teddythetwig

[...] I was surprised to find that the starter battery was not connected to the charger, only to the alternator.

My house bank consists of two deep cycle batteries, and each is connected to a different post on the battery charger(they are also wired to I & II on the battery isolator switch)

Is it normal to use a 1,2,both isolator switch to separate your house bank?
Is it normal to not wire the starter battery to the battery charger?

Some might say it's not normal because they haven't seen it before, others will say that it's an outdated concept. I'm saying that it is similar to how my boat was wired up initially and it worked just fine:
The first 1-2-both switch was used to connect the starter batt and/or the house bank to the starter motor. I could start the engine on "both" and the alternator would charge both banks. When I turn off the engine I also turn off the power to the starter motor, it's part of the procedure.
Later down the track, the PO added a second set of house batts which required a second 1-2-both switch.

Some people would find that unacceptable as well yet I don't think this would be against all the possible yachting regulations out there. Your boat, (mostly) your call.

[RaymondR]

Or put a two way voltage sensitive relay between the house and cranking batteries.

[roland stockham]

Unless you leave the boat for extended periods you start battery should always be charged. There is a potential problem with connecting it to the same charging system as the deep cycle batteries. In order to recharge a deep cycle FLA battery you need 14.4-14.8v but applying the same voltage to your start battery will overcharge it. Provided it is an open cell this is not a big issue but it will reck any sealed battery. This may be why it was not connected to the charger

[john61ct]

Primary charge sources to House.

Echo Charger to Starter(s)

FLA starters, just keep the water up.