Engine start batteries not lasting

[Wainui]

I have the starting battery linked to the house with a Blue Seas ACR.
Internally regulated Alt charging at 14.2 volts to house bank.
The start batteries never last more than 2 years.
Last sealed start battery even out gassed and got very hot.
Is this an incorrect way to connect?
Regards

[Emmalina]

Start battery should be the first to charge then the relay should engage on the house bank when the start bat is full !

[smac999]

If the start battery is getting hot at 14.2v it has internal faults and was a bad battery.

Nothing wrong with what you are doing.

[S/V Illusion]

Before jumping to conclusions, measure the charge voltage at the batteries to ensure they are all being properly fed in the proper sequence through the relay. Doing so will tell you if the charger is working as it should as well. Absent those readings, we are all just guessing.

[wingssail]

Originally Posted by Wainui

I have the starting battery linked to the house with a Blue Seas ACR.
Internally regulated Alt charging at 14.2 volts to house bank.
The start batteries never last more than 2 years.
Last sealed start battery even out gassed and got very hot.
Is this an incorrect way to connect?
Regards

Mark, the starting battery may be overcharging if it is receiving charge voltage (and amps) during the period when you are charging the house batteries. You should measure the voltage at the starting battery posts during the bulk and absorb charge cycles. It should not exceed 14.2 once the battery is fully charged.

Our starting batteries usually last 5 years or more. We do not have an ACR or other automatic charging for the starting battery, we just charge it periodically by switching to it. Otherwise it just sits there unused and untouched. (We do not generally use it for starting, usually we just start on the house battery. The starting battery is just for reserve.)

The regulator is set for Flooded Lead Acid and it charges either the house or the starting battery depending on where the switch is set.

I prefer to control the charging myself rather than let an automatic switch do it.

[Stewie12]

I never connected my starter battery to the charger. Why ? Because it has its own alternator and that is as much as it needs. In fact, when I think about it I never changed it.

[Mike Banks]

When the engine has been switched off and cooled down--put your hand on the alternator. If it is warm you just found your problem. The field energiser contact is not releasing when you release the starting switch.

[Stu Jackson]

Originally Posted by Emmalina

Start battery should be the first to charge then the relay should engage on the house bank when the start bat is full !

This is a recurring and often discussed difference of opinion.

One POV is that start battery banks use little of their energy. After a night on the hook, the house bank always needs priority in charging.

Others believe their start bank should take priority.

The reality is that no charging source "knows when a bank is full." VSR merely charge both banks simultaneously, and the battery acceptance determines current flow.



It also seems to be a regional or nationalist difference, i.e., UK residents vs. USA, for example.

Been discussed here and elsewhere for decades.

Your boat, your choice.

[Wotname]

Originally Posted by Mike Banks

When the engine has been switched off and cooled down--put your hand on the alternator. If it is warm you just found your problem. The field energiser contact is not releasing when you release the starting switch.

??????

I have never seen a "field energiser contact" associated with the starting switch and even if such a thing exists, how would it cause the problem reported by the OP i.e. "Last sealed start battery even out gassed and got very hot".

[hlev00]

Are the start and house bank batteries the same chemistry?

What chemistry are your charging sources configured for?

Get a DMM and measure the voltage during charging of the starter.

For a cruising boat with a substantially larger house bank than starter, always charge the house bank first. Rod Collins has a great video that covers this. This one might be it.

https://www.youtube.com/watch?v=E5yrpKgeXvk

harry

[rslifkin]

Originally Posted by Stu Jackson

This is a recurring and often discussed difference of opinion.

One POV is that start battery banks use little of their energy. After a night on the hook, the house bank always needs priority in charging.

Others believe their start bank should take priority.

I go with start priority for 2 reasons: my engines need power to run, so giving house priority could lead to the engines running on battery only for a bit and drawing down the start batteries. And I consider starting power to be safety-critical, so I'd rather get that topped off first.



Realistically, on engine start, if I watch each engine's volt meter, I see the following: voltage comes up over the course of 5 seconds or so, then you see a downward flick in the meter as the ACR engages to charge the house bank. Because the start batteries are already pretty much full at engine start, there's generally no delay in starting to charge the house bank.

[Nicholson58]

We have two X 400 AH @ 24 volts house banks. Either will start the engine. The engine alternator is externally regulated Balmar. There are two key operated relays to engage BAT 1, BAT 2 or both. There is a Bogart battery monitor on each bank. The battery engaged by key is the one being handled by the Balmar. The solar farm, 660 watts, can be switched to charge either #1 or #2 bank. When under sail, the solar is on the working battery to power navigation and autopilot. If motoring, the alternator charges the working battery while the solar handles the other battery. If the ‘spare’ battery is full then solar is switched to the working battery. This may cause the Balmar to stop driving the alternator if the solar can keep up with fridge freezer autopilot electronics. Sailing at night we have available 800 AH, 24 volts.

[hlev00]

rslifkin - Take a look at the video. At about 4:30, with the system charging start battery first it starts relay cycling. Maybe you have a different type of charging mechanism than the ACR or some other difference.


Harry

[rslifkin]

Originally Posted by hlev00

rslifkin - Take a look at the video. At about 4:30, with the system charging start battery first it starts relay cycling. Maybe you have a different type of charging mechanism than the ACR or some other difference.


Harry

I did have a concern about that happening if the house bank is too low and pulls the voltage down too low. In that case, with the ACRs I'm using, you'd end up in a cycle of something like 20 seconds on, 5 seconds off, repeat. In practice, I haven't seen it happen, but I've also never started the engines with the house bank below an estimated 60-ish percent SOC. If I started having an issue like that more than occasionally, I'd likely switch to an isolator of some form (either diode or FET) and re-locate the alternator voltage sense wires.

[hlev00]

Originally Posted by Mike Banks

When the engine has been switched off and cooled down--put your hand on the alternator. If it is warm you just found your problem. The field energiser contact is not releasing when you release the starting switch.

Excellent thought. I had this problem with our Balmar alternator. There was also a magnetic field long after the the key had been switched off as well as a few amps of constant draw (resulting in the heat symptom.) Ironically the backup internal regulator failed in such a way as to result in this very symptom. At least that was the information provided by Balmar after I returned it to them for investigation.