Battery Issue - Suspect Bad Amp? Er, no. Battery.

[212s]

Edited to add: checked out the Blue Sea website. Their diag chart shows that in order to disconnect both sides of the ACR must be below 12.75V for 30 seconds. So maybe it is operating as designed?

Thanks for the edit...I was scratching my head until you said this. Yes the ACR will disconnect once it senses that charging current is no longer available. My stock switches and ACR does the same thing - after turning off the engines, the ACR light will stay on for about 20+ seconds before it breaks the dual battery connection and goes back to start and house isolation.

Typical fully charged batteries sit around 12.7v idle. Let it sit for a few minutes and it should settle down to that level, leave the charger off then turn on your amp with the volume set to zero and see if the voltage drops significantly, like 0.5v or more. If so, you have a bad amp that is bleeding current. If the voltage drop is subtle, like 0.0-0.1v then that's fine and it could be the ACR is bad.

 

[tdonoughue]

Today's report:

Got the hydrometer and tested the house battery. All cells at the tippy top. So green lights there.

Unplugged the charger and let its capacitors die out. Voltage on the house battery was 13.0V. Turned on the boat and then turned off all of the accessories. Helm read 12.5V; I confirmed that at the battery with the meter. I tested the draw on all wires. The normal house lead (the stock one) was drawing .3A, but that was it. Nothing measurable to the engines. Small draws elsewhere (.1A or less).

Turned on the stereo only (plus amp and pre-amp). Battery went to 12.2V. 3A draw on the battery in total (I had turned it down a little and it was not a big bass song). Hooked up the ACR negative lead and measured its draw--minimal. The voltage continued to hold at 12.2V (which I think for a flooded battery is like 50/60%).

I tested the ACR, per the testing specification from Blue Sea, measuring the voltage from the poles of the ACR to the negative. When I plugged in the charger, it combined the batteries as it should have (based on the measurements). When I unplugged it, as soon as the voltage came down enough, it unhooked as designed. So no problem with the ACR.

The stereo still playing and all the other accessories off, the battery held its own at 12.1V basically all the while I was out there. I replaced the spark plugs, cleaned up and labeled some stuff--kept playing and the voltage held. I did plug in the LED lights I installed (basically driving/fog lights I repurposed--one in the engine bay and one by the batteries). Put the ammeter on one of those--it is drawing 1.5A! That surprised me. So that night it dropped so badly, if I had both lights on, that would be 3A--nearly as much as my amp--for just those stupid lights. May need new lights...

Anyway, I found no problems. I don't know why the battery drops so quickly down to 50%. That bit still worries me. Didn't do that when they load tested it. Open to ideas.

 

[FSH 210 Sport]

Today's report:

Got the hydrometer and tested the house battery. All cells at the tippy top. So green lights there.

Unplugged the charger and let its capacitors die out. Voltage on the house battery was 13.0V. Turned on the boat and then turned off all of the accessories. Helm read 12.5V; I confirmed that at the battery with the meter. I tested the draw on all wires. The normal house lead (the stock one) was drawing .3A, but that was it. Nothing measurable to the engines. Small draws elsewhere (.1A or less).

Turned on the stereo only (plus amp and pre-amp). Battery went to 12.2V. 3A draw on the battery in total (I had turned it down a little and it was not a big bass song). Hooked up the ACR negative lead and measured its draw--minimal. The voltage continued to hold at 12.2V (which I think for a flooded battery is like 50/60%).

I tested the ACR, per the testing specification from Blue Sea, measuring the voltage from the poles of the ACR to the negative. When I plugged in the charger, it combined the batteries as it should have (based on the measurements). When I unplugged it, as soon as the voltage came down enough, it unhooked as designed. So no problem with the ACR.

The stereo still playing and all the other accessories off, the battery held its own at 12.1V basically all the while I was out there. I replaced the spark plugs, cleaned up and labeled some stuff--kept playing and the voltage held. I did plug in the LED lights I installed (basically driving/fog lights I repurposed--one in the engine bay and one by the batteries). Put the ammeter on one of those--it is drawing 1.5A! That surprised me. So that night it dropped so badly, if I had both lights on, that would be 3A--nearly as much as my amp--for just those stupid lights. May need new lights...

Anyway, I found no problems. I don't know why the battery drops so quickly down to 50%. That bit still worries me. Didn't do that when they load tested it. Open to ideas.

What is the temperature?? That can play a pretty big part in a battery‘s output...

You are doing the home work that will eventually lead to a much better understanding of how your boat is working.

 

[Dumbassbass]

Unfortunately I think we may have just gone beyond my pay grade. My gut still says battery capacity but all tests seem fine, we're missing something. Anyone out there on the inter-web know an audio guy that can chime in?

 

[tdonoughue]

What is the temperature??

Oh, it was about 58 or 56 degrees... Should not have affected it that much, I would think. Not like we were freezing or anything.

 

[FSH 210 Sport]

Oh, it was about 58 or 56 degrees... Should not have affected it that much, I would think. Not like we were freezing or anything.

Right on... just had to ask.

 

[mrcleanr6]

Sounds like bad batteries to me.

 

[212s]

Turned on the stereo only (plus amp and pre-amp). Battery went to 12.2V. 3A draw on the battery in total (I had turned it down a little and it was not a big bass song). Hooked up the ACR negative lead and measured its draw--minimal. The voltage continued to hold at 12.2V (which I think for a flooded battery is like 50/60%).

I think you have a drain somewhere other than the amp - the battery shouldn't drop below 12.6v (100%) when idle and fully charged, and then drops to 12.2v (50%) when you turn the stereo on. If you turn everything off again does the voltage rise back to 12.5-12.6v? If it does, you have a parasitic drain somewhere, amp or otherwise. If it doesn't rise, then you have a bad battery or one that has sulfated due to excessive low discharge levels - the load test should have revealed this unless they just tested current instead of voltage. If you have a bad cell in the battery, it will still produce good current flow but low voltage as one of the six cells is not producing full voltage. Each cell should produce 2.1v when fully charged x 6 = 12.6v when idle, but a typical car/boat battery can't be checked per cell. Large batteries like 24v and 48v units used in forklifts and such can be checked per cell as each is wired in series to produce the necessary voltage requirement. One bad cell can be replaced in some of these units, but not with a car/boat battery.

Note that 50% or 12.2v is the minimum any lead-acid battery should ever drop before recharging to maintain good life. A deep cycle can handle down to 12.0v (25%) but you loose life expectancy at those levels by as much as 30-40%.

 

[tdonoughue]

Thanks, folks. Additional thinking/researching last night leads me to the same conclusion.

Batteries can have an 'open cell', which means that the plate separate. It will read normal, but then under a heavy discharge, the battery heats up internally and the plates separate, leading to a sharp voltage loss. When the battery cools, it again acts normal. That seems consistent with what I am seeing. Would explain why when I shut things down it will hold its voltage, but when I turn everything on I see a big drop (that usually doesn't come back).

Additional fact: I just fixed the strap on that battery. The connector clip had cracked off. Didn't think much of it, but I don't know when it broke exactly. So that battery may have bounced around during rough waters. Oh, and one of the things that can cause an open cell? Vibration or sharp shocks to the battery.

I think I need a new battery.

 

[FSH 210 Sport]

I think you have a drain somewhere other than the amp - the battery shouldn't drop below 12.6v (100%) when idle and fully charged, and then drops to 12.2v (50%) when you turn the stereo on. If you turn everything off again does the voltage rise back to 12.5-12.6v? If it does, you have a parasitic drain somewhere, amp or otherwise. If it doesn't rise, then you have a bad battery or one that has sulfated due to excessive low discharge levels - the load test should have revealed this unless they just tested current instead of voltage. If you have a bad cell in the battery, it will still produce good current flow but low voltage as one of the six cells is not producing full voltage. Each cell should produce 2.1v when fully charged x 6 = 12.6v when idle, but a typical car/boat battery can't be checked per cell. Large batteries like 24v and 48v units used in forklifts and such can be checked per cell as each is wired in series to produce the necessary voltage requirement. One bad cell can be replaced in some of these units, but not with a car/boat battery.

Note that 50% or 12.2v is the minimum any lead-acid battery should ever drop before recharging to maintain good life. A deep cycle can handle down to 12.0v (25%) but you loose life expectancy at those levels by as much as 30-40%.

212s,

You are spot on with your post!

TD,

I‘m going to make assumption this battery situation has developed over time since you installed your new batteries in October of 2019 and that this issue did not exist when the batteries were new. As 212s stated, the idle voltage should be 12.6 VDC when fully charged. It does sound like the plates in the battery or batteries have become sulfated. Have you tried using the equalizing function of your MinnKota to help clean the plates?

https://www.minnkotamotors.com/learn/technology/battery-chargers

This also will stir the electrolyte and remove any stratification in the electrolyte.

Here is a link to Trojan batteries’ technical support page. I think they have some great tech support documents and how to vids.

Battery Maintenance | Trojan Battery Company

Trojan Battery Company is the worldwide technology expert for long-lasting deep-cycle batteries. In addition, we have become one of America's most successful independent battery manufacturers.

www.trojanbattery.com

 

[tdonoughue]

It does sound like the plates in the battery or batteries have become sulfated. Have you tried using the equalizing function of your MinnKota to help clean the plates?

Only bought the batteries in 10/2019 and they have always been on the MinnKota from day 1 (other than when out on the lake). And I have run the deep equalization (on both batteries). No change. I would expect some improvement were it from sulfation. I would also not expect that so soon having been on a smart charger their entire lives--that should minimize it...

That is why I suspect the open cell(s).

Edited to add: excellent website--thanks for that!

 

[Dumbassbass]

Please - Let us know the outcome - grey matter request, and what technology you choose for replacement. I took the LiFePO4 option on my trolling motor batteries (isolated from all other things electronic) and will be choosing when the time comes for house battery replacement as they run about twice as long (discharge at full rated capacity up to exhausted 100%) as opposed to lead acid alternative (discharge at full rated capacity to only 50%) and roughly 30% of the weight of lead acid. 4000-5000 charge cycles so total life before replacement is about 5x longer. A bit pricy upfront but i think more donuts for the dollar.

 

[tdonoughue]

Will do, of course! My, those LiFePO4's are pricy! I am seriously considering an AGM set this time around. Really would like the AGM for the house battery, and given the ACR don't want different types for house and start. But trying to not have to explain to the boss that I want to drop $600 on the boat for 2 batteries...

Researching...

 

[FSH 210 Sport]

Only bought the batteries in 10/2019 and they have always been on the MinnKota from day 1 (other than when out on the lake). And I have run the deep equalization (on both batteries). No change. I would expect some improvement were it from sulfation. I would also not expect that so soon having been on a smart charger their entire lives--that should minimize it...

That is why I suspect the open cell(s).

Edited to add: excellent website--thanks for that!

You’re welcome for the link! I’ve been using Trojan deep cycle batteries for a long time and I think they’re the best you can get. Trojan has a great customer tech line you can call, and I learned quite a bit from the guy I talked to. An interesting thing I learned about flooded batteries, at lest the Trojan batteries is that they have a break in period. If memory serves, I think the tech said that Trojan batteries do not achieve full capacity until after 50 cycles. According to the tech this gives their batteries a superior life span. He explained it much better than that..

Dumbassbass makes some great points about lithium batteries! When the time comes to replace my 36V troller bank I may go that route. Having said that, I’d check with Yamaha about about using the lithium batteries on the house bank. Apparently there can be issues when charging off of their outboard engines. When I asked the Trojan battery tech why that was he told me the following. Lithium batteries can discharge and charge at a much faster rate than lead acid batteries which can lead to “alternator“ failures, I E Really high charge rates. The Trojan Trillium batteries have an internal switch that prevents too high of both discharge and charging rates. Give Trojan a call and see what they say, I don’t think I’m doing it justice. Trojan can also tell you whether or not your MinnKota charger will work on their lithium battery, again if memory serves, I think he said the AGM setting is where you’d set the MinnKota.

Im pretty sure I damaged my house battery during my initial outings as I didn’t have a shore powered charger recharging it after a day on the water. I was relying on the boats engines to do that and my run times were very short...and I’m noticing behavior similar to your batteries. Who knows, maybe if you take it back to Costco they will replace it for you?

 

[tdonoughue]

Found Northstar 24 AGM's on clearance at West Marine, so pulled the trigger on those. For $232 a piece, can't really beat that for Northstars, it looks like. And $10 shipping (!).

Couldn't justify the expense of lithiums, but they are something to watch.

If you left it partially discharged for awhile, it sounds like your batteries may have sufication. Does your charger desulfate? Try that before you take it for a return...

 

[FSH 210 Sport]

Found Northstar 24 AGM's on clearance at West Marine, so pulled the trigger on those. For $232 a piece, can't really beat that for Northstars, it looks like. And $10 shipping (!).

Couldn't justify the expense of lithiums, but they are something to watch.

If you left it partially discharged for awhile, it sounds like your batteries may have sufication. Does your charger desulfate? Try that before you take it for a return...

Awesome! Sounds like a pretty good deal!

yeah I’ll run an equalizing charge on them today! I’ll check hydrometer readings first, do the equalizing charge and recheck.

 

[Dumbassbass]

I bought mine from Dakota ( not affiliated nor endorsing over any others but best$ + 11 yr.warranty) it did take a while to get delivered because they mfr based on orders.

 

[mrcleanr6]

what northstars did you get? the regular agm or the pro's. the pro are the tppl type. i just bought a pair of group 27 pros for the new boat to replace the regular wet cell 24's that it came with. of course we are off season here so i havent put them in the boat yet but definitely a quality piece compared to regular batteries. regular batteries from most auto parts stores are just a shot in the dark anymore. they just arent made to the quality that they once were. over the past 8 years, out of all the batteries i have bought i would say 25-30% of them have been faulty. they are junk within 6-12 mos. the others that are good i usually get 5 years out of or so. its a roll of the dice.

 

[tdonoughue]

Here it is: NORTHSTAR BATTERY Elite High Performance Pure Lead 24M AGM Battery with SAE/Threaded Terminals | West Marine

I would be surprised if for that price it was the TPPL type. I think I did see those (at West Marine), but they were significantly more $. I don't have a trolling motor (never will...) or anything like that, and even the stereo is about the max of what I want/need. So I think this one will do just fine.

Agree on the auto parts batteries. Was considering an AutoZone, but only because it was an AGM for $180. But then comparing that against a Northstar for $230... No contest. Even without the TPPL. And of course all of the other good names were same price for much less battery or significantly more for the same. Hopefully these will last me for awhile (I got 2 as planned, so I will upgrade the start battery while I am at it--better for the ACR operation).

 

[mrcleanr6]

Yes the std agm northstar. Not tppl but still a very good battery. You should be happy with those.