Bad battery or bad charger?

[john61ct]

No, if the Absorb setpoint is exceeded, regulator has failed.

Bulk just means **lower** V, that point has not yet been reached

[caleuche]

Originally Posted by john61ct

Says who, just the people who installed it?

No, says me, Juan. And Marqus too.

[caleuche]

Originally Posted by MJH

I don't like the idea of the starting battery being charged "from the house battery"...the start battery "should always be charged first" or in conjunction with house battery charging (the idea being you will always be able to start your engine). The Blue Sea Systems Automatic Charging Relay does that for my boat.

~ ~ _/) ~ ~ MJH

If you are under the impression that the starter batteries are charged only when the house batteries are full, that's not how it goes.

[caleuche]

Originally Posted by Zil

Was the high voltage only on one starter battery? What was the other start battery doing? Are both charged from the DC/DC ?

Yes, only on starboard. Port side is charged by an identical, independent charger, and it shows 12.8-12.9V.

[caleuche]

Originally Posted by Marqus

Given the OP's info so far, to me it's a bit early to condemn the Mastervolt charger.

If the battery was in some way deficient, could the charger not have (by design) pushed up to 16v in BULK mode?

That's what I initially thought (after all, mastervolt called the device 'Magic') but the charger output specs says up to 15V. I do have a healthy charger and healthy battery on the port side to play with, but since I have a knack for making things worse, before getting too creative I'm going to wait a couple of days for a response from mastervolt on how to diagnose this issue and what tests to run.

[Zil]

I would temporarily swap batteries or chargers and observe what happens.

[hellosailor]

"If the battery was in some way deficient, could the charger not have (by design) pushed up to 16v in BULK mode?"
Absolutely not, because 16 volts will boil out ANY battery. And, it will exceed the operating voltage range of every piece of electrical and electronic equipment on the boat, putting out a serious risk of blowing every instrument, radio, and light bulb.
Nothing should ever go above 14.4 volts without express human permission to do so, i.e. during a properly secured equalization cycle.

[john61ct]

Well except for the banks and scenarios where the owner has determined that 14.8 or even 15V are perfectly OK.

and some banks want to stay below 14.2V, there is no one general number that applies to all models of lead batts.

[Marqus]

Originally Posted by hellosailor

.... exceed the operating voltage range of every piece of electrical and electronic equipment on the boat

Good point.
And as John points out, during Bulk charging the voltage level is always below Absorption voltage level.

Certainly seems a bad sign that Caleuche's mastervolt charger was putting out 16v.

Slightly off-topic: what happens with those solar smart charges that automatically throw in an equalization cycle every now and then - won't the typically high equalization voltage hurt boat electronics ?

[john61ct]

Yes, the bank mfg spec'd voltage may be too high for sensitive electronics.

Equalization should be done manually, isolated single unit at a time, and following the mfg specific protocol. Often requires a separate power supply running off shore power.

If the automatic "feature" can't be disabled, get a different charger.

[caleuche]

An update to close this topic: the charger was outputting 15.8V when not connected to anything, when connected to a good and fully charged battery, and when connected to the suspect battery. Mastervolt sent me a new device, and things are back to normal now. The battery seems to have survived. So, to answer my own question: bad charger.

Thanks all.

Juan

[MJH]

Originally Posted by caleuche

If you are under the impression that the starter batteries are charged only when the house batteries are full, that's not how it goes.

NO, that's not what I'm saying. With my Blue Sea Systems Automatic Charging Relay batteries are combined for charging until the starting battery is full and separated (thus full ready for starting), then the charging continues for the house battery until it is full. While the house battery will normally always require more charging it is more important to be always able to start the engine (think of engine problems requiring multiple starting attempts or simply bad house batteries not letting the start batteries get charged if configured for priority over the start batteries.

Start batteries have priority over house batteries. The ultimate test is which would you rather have working start or house?

~ ~ _/) ~ ~ MJH

[Stu Jackson]

Originally Posted by MJH

>>>>>>>>>>>>>>>>>>>>>>

Start batteries have priority over house batteries. The ultimate test is which would you rather have working start or house?

~ ~ _/) ~ ~ MJH

Charging relays usually combine when charging voltage is present. They have NO way of knowing what state of charge any bank may be.


Ultimate test is I'd rather have the house bank get the main charge, there's not much to fill up on a start bank, maybe two amp hours at most. For most adequately sized start banks, you'd get 24 start tries before hitting 50% SoC.



This is a philosophical issue, and prioritizing the start bank seems to be a "thing" in the UK from my time over on ybw. Maybe all their fun&games with Lucas starters (non-starters?!?) made them feel that way.


I have a house bank and a reserve bank. I use the house for everything, check and use the reserve/start bank to start on a regular basis.


Your boat, your choice.

[john61ct]

Originally Posted by MJH

With my Blue Sea Systems Automatic Charging Relay batteries are combined for charging until the starting battery is full and separated (thus full ready for starting), then the charging continues for the house battery until it is full.

No. Any ACR / VSR simply combines and separates based on the presence of an active charge source, simple voltage level setpoints.

There is no way for any such device to "know" when any battery is full.

[john61ct]

Starter batt care is trivial, they are cheap and robust.

All focus on detailed issues should be on getting House recharged as full and frequently as possible.