START Bank Cooked

[MJH]

My electrical system is in two banks 100% Gel batteries, House and Start. The HOUSE bank is two 8D batteries that were replaced this spring (2019); old bank lasted 15 years. The Start bank is a group 27 (2010) plus a U-1 (2011) to meet the engine cold cranking amp requirements. I have not removed the START bank yet from the boat.

Alternator is a Balmar 110A (2010).
Regulator is a Balmar MC-614-H (2010).
Blue Seas Systems #7650 Battery Switch and Automatic Charging Relay (2009).
Xantrex LinkPRO Battery Monitor (2013)
Kyocera solar panels 4x140W = 560W connected to HOUSE

Regulator, Solar Panels, Battery Monitor all have temperature sensors. Alternator temperature sensor was inoperative.

Returning from Alaska I had an early departure from Prince Rupert (no dock power used) solo in the fog (wife flew home on dental emergency) with all electronics running. One hour later I smelled something coming from the cabin, looked inside and saw optional red alert light on Battery Monitor. Checked battery monitor and it indicated START battery was overcharging at 18V. Lifted cover over start batteries and disconnected negative terminals. Returned home using HOUSE bank only.

I want to determine what happened before buying new START batteries.
Don't understand how a 12V system, that has operated well for so many years, now cook the START bank at 18V.

What caused this after so many years of good service?

Did the new HOUSE bank have anything to do with it?

Was the START bank just old?

~ ~ _/) ~ ~ MJH

[Shenandoah52]

Originally Posted by MJH

What caused this after so many years of good service?

Did the new HOUSE bank have anything to do with it?

Was the START bank just old?

~ ~ _/) ~ ~ MJH

I had a situation on my boat where 24 volts would sporadically spike thru the 12 volt system and blow up the ignition coil on my motor. I finally got it fixed when I replaced a corroded main harness connector that somehow would allow at least one of the circuits onboard to create an "in series" situation between my two 12v batteries.

Also, very often 12v accessories are connected directly to the positive terminal on a battery so that even when all the battery banks are turned off your automatic bilge pump, as an example, would still be able to function. In other words, they are not routed through some kind of controller box but they are instead wired direct.

So..."Did the new HOUSE bank have anything to do with it?"
Are there any wires attached to the positive post(s) on that house bank such as what I just described? Because of the "new" nature of your house battery bank perhaps a good inspection of all wires leading from the house battery bank would be a good fast way to start your investigation. Also look at all the wires coming from your start battery bank.

For the purposes of what I am talking about you would want to determine the function of any wires other than the heavy cables that are attached to the positive posts on any of your batteries. The purpose would be to see if an "in series" situation could occur to create the over-voltage.

[Pete7]

Originally Posted by MJH

What caused this after so many years of good service?


Was the START bank just old?

~ ~ _/) ~ ~ MJH

That start battery isn't just old it should be in a museum You probably have a single cell shorting out inside one of the start batteries, or the build up of plate material in the bottom of the battery has shorted it out.

Pop some new batteries in and go from there. See if you can find a single AGM rather than two for the engine start to keep it simple.

Pete

[Stu Jackson]

Originally Posted by Pete7

That start battery isn't just old it should be in a museum You probably have a single cell shorting out inside one of the start batteries, or the build up of plate material in the bottom of the battery has shorted it out.

Pop some new batteries in and go from there. See if you can find a single AGM rather than two for the engine start to keep it simple.

Pete

Most likely the reason.

[MJH]

Thanks to all who replied. I'll recheck my wiring.

~ ~ _/) ~ ~ MJH

[Kelkara]

Originally Posted by Pete7

You probably have a single cell shorting out inside one of the start batteries, or the build up of plate material in the bottom of the battery has shorted it out.

Can someone explain this to me. I can see why this will fry the start battery ... but why will it generate 18V from the alternator? ... if the regulator is functioning shouldn't it just cook the battery at 14.4V?




I don't know how the OP has his charging systems wired, and he hasn't specified that the alternator is still charging the house bank correctly. Could it be that the alternator is wired to the start battery and the regulator has failed allowing the alternator to produce 18V? If so the ACR will cut out over 16V protecting the house bank. If the solar is wired to the house, then he could have got home on solar alone without noticing that his alternator was toast.

[MJH]

Originally Posted by Kelkara

Can someone explain this to me. I can see why this will fry the start battery ... but why will it generate 18V from the alternator? ... if the regulator is functioning shouldn't it just cook the battery at 14.4V?

I don't know how the OP has his charging systems wired, and he hasn't specified that the alternator is still charging the house bank correctly. Could it be that the alternator is wired to the start battery and the regulator has failed allowing the alternator to produce 18V? If so the ACR will cut out over 16V protecting the house bank. If the solar is wired to the house, then he could have got home on solar alone without noticing that his alternator was toast.

Thank you for your questions...they are mine as well.

Yes, the alternator is wired to the Start batteries and the solar panels are wired to the House batteries. The LinkPRO Battery Monitor will only reflect when the solar panels are charging the House batteries but not the alternator charging the Start batteries.

I can't say for certain if the alternator or the regulator are operating correctly. I would think the regulator should have not allowed the Start batteries so much voltage. However, when I last read the Balmar regulator readings they were all normal.

~ ~ _/) ~ ~ MJH

[Pete7]

Originally Posted by Kelkara

Can someone explain this to me. I can see why this will fry the start battery ... but why will it generate 18V from the alternator? ... if the regulator is functioning shouldn't it just cook the battery at 14.4V?

I don't know how the OP has his charging systems wired, and he hasn't specified that the alternator is still charging the house bank correctly. Could it be that the alternator is wired to the start battery and the regulator has failed allowing the alternator to produce 18V? If so the ACR will cut out over 16V protecting the house bank. If the solar is wired to the house, then he could have got home on solar alone without noticing that his alternator was toast.

Well, bit of guess work, but I recon the start battery or batteries, failed first. The alternator and controller thinks a battery now with 5 cells (10v) needs charging so ramps up the voltage. Battery now gets really hot and the alternator is still trying to charge it. Surprised the smell wasn't evident. Alternator or the controller may have been damaged.

So remove existing start batteries and check voltage separately, this may give a clue. Replace with new battery and test charging voltage.

Pete

[MJH]

Originally Posted by Pete7

Well, bit of guess work, but I recon the start battery or batteries, failed first. The alternator and controller thinks a battery now with 5 cells (10v) needs charging so ramps up the voltage. Battery now gets really hot and the alternator is still trying to charge it. Surprised the smell wasn't evident. Alternator or the controller may have been damaged.

So remove existing start batteries and check voltage separately, this may give a clue. Replace with new battery and test charging voltage.

Pete

Per my original post, the smell is what got my attention one hour after leaving the dock.

~ ~ _/) ~ ~ MJH

[rom]

I don't know how the balmar VR works but some (most?) simple VR will stop regulating if disconnected from pos or neg (depinding on VR type), and will just let the alt work full power full time, and voltage will rise until something fries.