Engine battery issues. Solar and acr the cause?

[Cutwater28GG]

Been anchored for two days (1 night). End of second day my house batteries are showing 90% capacity on the balmar
Smartguage. The solar has done well topping up the batteries

I decided to start the engine to add some battery juice for the fridge over night. Engine failed to crank
Short crank and nothing. Clearly not enough volts.

Something has dragged down the engine battery over the two days

Managed to start by crossing over the house batteries onto the engine battery

The battery is only two years old and pretty well babied for that time. I don’t think the battery is toast

I either have a really bad parasitic draw on the engine battery ( alas I didn’t note the engine batt volts before I managed to start) or.

I have a suspicion I have an issue with the acr design on the cutwater with solar
My solar panel is shaded by the radar. So as the boat swings solar charge swings from 7 amps to .5 amps depending on the shadow . This can happen every 2 minutes or so.

With the timer in the acr before it isolates could it Get the engine battery into a state when it is dragged down to match the house battery?

Even still at 90% charge on the house it’s seems to me that the engine batt should still start at that same volts.


Ideas?

 

[knotflying]

You don't mention what year or engine. Did you inadvertently leave the key in the on position? Was your battery switch off?

 

[BB marine]

You have to many possibilities and not enough information to speculate cause. First what was battery condition at the time of start up? With house system active and a draw I would suspect ACR would/should have made a disconnect from engine battery. A quick check is green light is on ? Indicating batteries linked.
An ACR senses when the voltage of either of the batteries rises to a level indicating that a charge source is active (13.0V for 2 minutes). The ACR′s contacts then connect and the ACR applies the charge to both batteries. If the voltage on both of the batteries subsequently drops to 12.75V for 30 seconds, the ACR will disconnect, isolating the batteries.

If you are seeing voltages at below 12.75 Volts at house or engine battery and the green light is on issue with ACR. Typically 12.70V is considered 100% charge. 90% is 12.5V. If your house battery was at 90% green light should be off and ACR open unless your engine battery is still at or above 12.75 which I doubt it would be if the engine is not running and it is linked to the house battery through the ACR. ACR should be open.

A 2 year old battery may only be capable of holding a 90 percent charge. With that condition the only time the ACRs should be liked is when the engine is running and voltage increase to engine battery comes from charging system 13V or higher.

My first test would be multi VOA meter test of each battery bank at rest no charging system activated but after a full charge was applied to each bank.Test voltage, check ACR to see if open or closed. Compare voltages house, thruster,engine if all voltages are at or above 12.76 green light on if any are below 12.75 and green light is on there may be an issue with ACR. Remember 12.70 is typically considered 100% charge.

Check to see if any thing is drawing from you engine battery. Load test your engine battery. In most troubleshooting of a battery system the first culprit to proof is the battery. Once you know for sure the battery is in good working condition follow through with next steps. We all have been burned with the "its a new battery it can't be that"

Battery connections removed and cleaned and tightened while doing your checks. Good engine ground checks. Starting at the basics and working to the more complicated issues saves a lot of time in troubleshooting.

Good luck

 

[NorthernFocus]

Current always flows downhill. No matter how the ACRs are opening/closing you can never pull one battery lower than another if it has no load on it. Sounds like you had something drawing on the start battery. The key switch is a good place to start. Not sure how the Volvo panel works but on many systems the hour meter counts when the switch is on whether engine is running or not. May be a clue there.

 

[snydzy]

I had similar problem. Not sure if this was the cause or not..... My 25sc had both SunSaver Duo charge leads connected to the Engine/House ACR. I believe the charge current from the solar was not allowing the engine battery to disconnect from the house because of the direct voltage being applied to the ACR terminals, thus dragging the engine battery down with the house. Eventually the ACR failed. I did move the solar charge leads off the ACR and reconnected them directly to both banks.... combined the thruster battery with a switch to the house bank and eliminated the second (bad) ACR. Haven’t had a problem since. Are your solar charge leads feeding the ACR?

 

[jkhiser]

When I posted recently on similar starting topic http://www.tugnuts.com/viewtopic.php?f=18&t=12965, a few folks pointed out the single dual purpose battery might be borderline for starting the D4. May be ok while new, but with some age no joy.

Early last season, with new batteries, I had no problem. Later in the season, after running a few hours, shut down without shore power, I could never get a restart without parallel. At this point, I have changed all batteries, completely checked wiring from battery to starter, both power and ground, and verified which items were powered from the start battery, and added manual switch to control ACR mode. I still need to get a clamp on and check for any unusual draw while shut down.

Had a good restart yesterday after one hour stop for lunch, but the season is still new.

 

[NorthernFocus]

When I posted recently on similar starting topic ...a few folks pointed out the single dual purpose battery might be borderline for starting the D4. May be ok while new, but with some age no joy...

This is a good thing to point out. If using a single battery for starting it is advisable that it be a true starting battery. Many make the mistake of installing a dual purpose with just barely adequate CCA/MCA but plenty of AH capacity thinking that it will provide multiple cranks if necessary. But the reality is that after a crank or two it won't provide enough cranking amps to turn adequate RPM for start. Whereas a true starting battery though having less reserve capacity actually has more useful amps for starting.

Or you can add another battery in parallel. 😀

 

[chrispangaro]

May not be directly related but.... I have a R25 classic, 2008 which I have installed a 100w solar panel on, regulated through a simple PWM regulator and feeding into the house bank. After a few long runs under power I thought the capacity on the anchor was less than it should be. Batteries are two year old AGM. ACRs working as intended. After a bit of research I suspected that when running under power on a sunny day the engine alternator regulator was “seeing” a high voltage at the battery banks (all connected by the ACRs) which was caused by current flow from the solar even though the batteries were less than fully charged. Night runs and short power via charger led to higher charging voltages. I read somewhere this could be a phenomenon, leading to the alternator not doing much charging when the solar was active.

Solution I am trying is a simple auto relay on the positive feed wire from solar to solar regulator. It is opened or switched by current from the engine (electric) coolant pump. Thus when engine is on solar is disconnected and when engine is off solar can charge. So far seems to be making a difference. My monitoring of this also shows that the alternator feeds the house bank with the engine start battery needing to be connected byACR to be charged. Not sure why this is the case or if it’s been changed by a previous owner.

Tricky business this electrickery

Good luck

Chris

 

[Cutwater28GG]

thanks all

its a 2012 cutwater 28 with the Volvo D4.
Key was removed. Engine and Thruster (and cross over) breakers were off during the entire time until I went to restart.

All batteries are universal AGM UB121100 (110Ah) spec: https://a89b8e4143ca50438f09-7c1706.../003/510/original/ubD5751-spec.pdf?1440174712

its not clear what the CCA are for this battery. perhaps its not a good option for the engine. (it was the factory installed model on my boat that I replaced with the same)

looking back at my records the battery was installed Jan 2016. so 3.5 years or at least 4 years from manufacture. it could therefore be approaching the threshold of failure which I dont notice if its normally charged by shore power and not left to sit for 2 days - with perhaps a parasitic drain

I ran the engine for 1 hour after I managed to start with the cross over at 9pm. house batteries were brought up to 98% capacity. Engine battery looked to be at the same volts as house when I turned off the engine. boat started in the morning with just the engine battery.

it does strike me that this battery fails to start the engine as soon as it comes slightly off full charge. therefore being at its limit of cranking capability. i.e. underspeced for the task at hand. an alternative with higher CCA may be a good idea.

my next steps are

1. get a clamp meter on the battery cables and see what the parasitic draw is on the batteries at rest. (with the solar off)
2. investigate the ACR LED status and see if its triggering per Brians comments
3. load test the engine battery and see where its at.
4. double check if I have a single charging circuit or one for each bank from the shorepower charger. there has to be some damage to the engine battery if I charge the house batteries through the engine battery if there is a single bank charger in play. as its probably cooking the engine battery until the house is charged.

Chris I do think you are on to something that the ACR's can get confused (be design) by the Solar voltage coming in over the top of the engine alternator or shore power charging circuit, or solar alone.

 

[jkhiser]

This is one of the reasons I added a manual switch to control ACR mode.

http://www.tugnuts.com/viewtopic.php?f=18&t=13254