house battery not starting the engine

[shadowdancer]

I have a house battery and a starting battery . the house battery is silent when I try starting the engine I have a battery switch and when its on house only nothing happens when I go to start the engine. the start battery works fine.

do I have to connect the house battery to the starter ?

[Pete7]

Before we answer, some extra questions,

How many batteries in the house bank?

What sort of battery switches do you have?

Have you put a volt meter across the house battery?

Is there any fluid inside it, if it has battery caps you can remove?

How old is it?

When did it last work?

[john61ct]

So many points of failure are possible.

Get a DMM learn to use it.

[smac999]

you have a 1-2-all swtich? and it starts on one but not the other??

or what do you have?

first guess is no common ground between banks. and engine ground goes to engine bank. but could be a lot of things.

[svHyLyte]

Your starting battery is isolated from the house bank which may have been done to avoid the possibility of it being depleted and unable to start your engine by an excessive discharge of the house/start batteries if joined. We have a similar arrangement. However, I also had a momentary switch on the engine panel installed that connects to a solenoid switch that will connect the house bank to the starting circuit. In that manner, if the starting battery is too low to get our engine started, we can use the house bank to do so. We have rarely had to do so but on the few occasions when we needed it, it came in very handy.

FWIW...

[laika]

It may also just be your house bank is on its way out and can't generate the load required to start the engine. You'd likely still hear the click of the starter solenoid but the engine wouldn't turn.

Originally Posted by svHyLyte

Your starting battery is isolated from the house bank which may have been done to avoid the possibility of it being depleted and unable to start your engine by an excessive discharge of the house/start batteries if joined. We have a similar arrangement. However, I also had a momentary switch on the engine panel installed that connects to a solenoid switch that will connect the house bank to the starting circuit. In that manner, if the starting battery is too low to get our engine started, we can use the house bank to do so. We have rarely had to do so but on the few occasions when we needed it, it came in very handy.

FWIW...

Why not use the house bank to start the engine every time and leave the start batt 100% SoC? Our start bank pushes the engine over a lot faster, but would be a hassle and waste a lot of juice trying to get it back to float again after each start.

[SteveSails]

I'll add some more questions for the OP.

Did the house battery start the engine in the past?

Does stuff on the house battery like cabin lights work?

IF the above two are both yes has anyone worked on the electrical system since? What was touched?

If the cabin lights are on leave them on and hit the starter. What happens to the lights? If they go out the batteries are dead, if the same then a wiring or connection problem.

Hope that helps.

[shadowdancer]

it turns out that the (pos) connection to the battery was not tight enough, it was tight but after cranking on it it seems to work. batteries are new, new wire only one battery on house (full) and two on starter with one them for the winch ( both full) solar panel connected to house. will be adding more batteries to house

thanks for all the input just had to track down the problem

rock

[captlloyd]

Originally Posted by shadowdancer

it turns out that the (pos) connection to the battery was not tight enough, it was tight but after cranking on it it seems to work. batteries are new, new wire only one battery on house (full) and two on starter with one them for the winch ( both full) solar panel connected to house. will be adding more batteries to house

thanks for all the input just had to track down the problem

rock

Ah, perfect time for the old medical adage, “ if you hear the sound of hoof beats, don’t look for Zebras”. Perfect.

[guyrj33]

Originally Posted by laika

Why not use the house bank to start the engine every time and leave the start batt 100% SoC? Our start bank pushes the engine over a lot faster, but would be a hassle and waste a lot of juice trying to get it back to float again after each start.

It usually only takes a fraction of an amp hour to start your engine. Leaving your starting battery very near 100% SOC.

[john61ct]

With a robust enough House setup,

dedicated-per engine/genny Starter batts really become Redundant, pretty much the definition of "dead lead" being carted around.

NBD on a big expensive all-the-mod-cons boat, but where weight, frugality and minimalism are valued,

that weight and expense are IMO better spent on a Reserve bank sized to service not just cranking but all Essentials to survival and navigation in the event the main House fails.

Of course monitoring / testing / maintenance protocols constantly fighting the dark forces of chaos, decline and entropy should mean Reserve is never needed, but then

those cruising long-term in primitive places should still value the positive meaning of Redundancy.

[laika]

Originally Posted by guyrj33

It usually only takes a fraction of an amp hour to start your engine. Leaving your starting battery very near 100% SOC.

Thanks, a reasonable explanation. Didn't realize just how little juice the starter took in the scheme of things. Even a Yanmar 3gm start pulling say 400 amps for a second breaks down to 0.1Ah.

That said, somewhat as John describes, i still don't quite see the upside of pulling juice from the start bank if it can be done from the house just as well. Maybe a bit more wear and tear on the starter from not getting quite the same CCAs?

Academic perhaps..

[mitiempo]

Originally Posted by laika

Thanks, a reasonable explanation. Didn't realize just how little juice the starter took in the scheme of things. Even a Yanmar 3gm start pulling say 400 amps for a second breaks down to 0.1Ah.

That said, somewhat as John describes, i still don't quite see the upside of pulling juice from the start bank if it can be done from the house just as well. Maybe a bit more wear and tear on the starter from not getting quite the same CCAs?

Academic perhaps..

Even though the house bank uses deep cycle batteries as long as there are multiple batteries it will provide more cranking amps than a single start battery in most cases.

I would still want a dedicated start (emergency) battery for redundancy.

[chasfgr]

Originally Posted by mitiempo

Even though the house bank uses deep cycle batteries as long as there are multiple batteries it will provide more cranking amps than a single start battery in most cases.

I would still want a dedicated start (emergency) battery for redundancy.

Why?
Have you never started your engine by hand?
For a 3YM it is pretty simple - but I always use my 3 batteries 2 at a time and, in 27 years with that set-up, never been caught out.
In a small boat (<34') there is insufficient room for total redundancy back up for all systems - fuel, water, propulsion, steering.

You need to be perceptive.

[john61ct]

Realistically, even if you can hand-crank **your** engine, many skippers rely on electricity for nav and other essential loads.

My point is a Reserve bank to cover the Main house bank failing can substitute for dedicated Starters as well, even if it takes weeks to get back to civilization.

Of course if your Starters are the same deep cycle batts comprising your House, it devolves into semantic differences, same result.

Big boats can have it all, small ones are better served by multiple-use design choices, IMO.