House bank completely dead

[ExSail]

Hello all,
Here is a question, I just came back from being out of town for 12 days. Xantrex 3000 watt inverter/charger was working great and had house batteries on float when I left. Xantrex is 2.5 years old, and both 4D batteries are from 2021. Water in batteries was good but I did not check the SG. When I got on the boat I find shore power is good but the Xantrex is completely shut down. Checked the voltage of the batteries and they were both at 0.0. Absolutely toast. Nothing was left on to drain the batteries and even if there was, it was attached to shore power. I attached a battery charger to the port house battery and within seconds the Xantrex came back on line and began to charge. I reduced the charging amount to about 70% from 100%. In about 10 minutes I smell some off gassing and look at the batteries, the port battery is off gassing from one vent cap and as I put my hand on it it was very warm. The starboard battery was cold. I shut off the stand alone charger thinking that the Xantrex would keep charging. 30 minutes or so later I walk back to check and the entire Xantrex is shut down again. I repeat the process only this time I hook the stand alone charger to the starboard battery. Same thing occurs again and the port battery got warm again. Xantrex working and writhing a few minutes it shut off again.
I recently had the Gen set overhauled and the tech ran it for about an hour. If he didn’t shut off the inverter at the panel and had it on at the same time the generator was running could that have caused such a huge overcharge that it cooked the batteries? We have not had any power outages or interruptions of shore power.


So, the questions are:
1) what May have caused the batteries to completely discharge?
2) I don’t run the boat very much at all ( like months between outings) and it sits with the charger/ inverter in the float mode, did this cause the premature death of the batteries ?
3) should I shut off the inverter charger after the batteries go to float mode in the future?
4) as stated we don’t discharge the batteries often at all and live in SW FL. Is three years about what to expect from these batteries if they are not worked hard ?

Thanks for the help

 

[Bmarler]

Unfortunately, it sounds like you have a bad cell, or maybe more. Plates sluff off materials as they age and it builds up on the floor of the battery. Then the cell shorts out and pulls power from the rest of the bank, drawing it down to nothing.
You can try isolating the offending battery from the system and get some life from the remainder, but I’d recommend changing out the entire bank.

 

[Bmarler]

I realized I left out a couple of your questions. Unfortunately, there’s no perfect answer.
Lead acid batteries self discharge if left alone, so if gone for months at a time, some sort of maintainer is required. Maybe not the big charger you have, but a smaller maintainer that can keep up with parasitic draw and self discharge. Typically, your charger should be ok though, if the settings are right.
Life span is usually longer than three years, but sometimes you get a bum battery. It happens.
It makes you mad when you do things right and they fail anyway.
Buy good quality batteries, maybe change to 6volt heavy duty ones, treat them well. That’s all you can do unless you decide to upgrade to lfp.

 

[mvweebles]

Agree with @Bmarler. Try charging one battery and then the other to see if the Xantrex reproduces the fault on one. If you're up to investing in a load tester, would give you good information.

You asked if your generator work might have caused an overcharge condition due to having too many charge sources to batteries. Doubtful. Batteries are frequently setup with multiple concurrent charge sources (solar, AC, alternator).

You don't mention what type of boat you have, but if you end up needing new batteries (likely), you may want to check to see if your Xantrex supports Lithium charging. A single 280-ah battery is around $450 and will give you much more net power than the two 4Ds you currently have. You would need a decent DC-DC charger ($300-ish) from your start battery to the lithium bank and some cabling, but that's it and you won't have to worry about watering again. Lithium should last 10+ years.

Peter

 

[Greg QS]

Agreed
You probably lost a cell in the battery. This will discharge the cells since they keep trying to charge the bad cell. As you saw this creates heat. The charger has a heat sensor and will shutdown as to not burn up the batteries. It is doing its job correctly.
2021 to 2024 you did good on the batteries. Lead acids don't last that long. I have trouble getting 3 years out of mine. Total discharge on a LA battery finishes them off. You may limp along for a little bit, but its just time for new bats.
Remember you wat to replace batteries in banks. Don't replace the one with the bad cell only. The old battery has reduced capacity due to its age. If you install a 1 new one you will make it work Harder and kill it faster. Its what you are experiencing now. The bad battery pulls down the good one.

 

[tiltrider1]

In agreement with above comments. Disconnect the port battery and see if you can bring the starboard battery back to life. If you can then we will know the issue is battery related and not an issue thigh the charger.

As much as I dislike Xantrex, I still suspect a dead cell. However, we can’t rule out the charger just yet.

 

[Nick F]

Another possibility is similar what happened to me one time. The following could be what happened to you:
The shore power went off and the inverter took over the AC loads, discharging the battery. The battery went to fully discharged and this happened to damage one cell. When the shore power came back on the inverter/charger (for whatever reason) would not initiate charging into the dead battery.

After this happened to me I installed a manual transfer switch that puts all the AC loads directly to shore power (bypassing the inverter). When on shore power I set this switch to "bypass". If I am not on the boat, I don't want the house battery to supply AC loads in case of shore power failure - I prefer to lose the food in the freezer over losing the house battery.

 

[ExSail]

Thank you all for the comments. Yes the heat sensor also got hot and I’m sure shut the system down. No choice here. Have to replace both batteries. The one I have ate from interstate battery. Any suggestion on a better 4D. I know that DEKA makes most of the batteries for interstate but am open to suggestions for different brands. I am going to stick with the LA batteries and don’t want to go through the hassle of going to LI batteries. Thanks in advance.

 

[Nick F]

If these are for your "house" battery, get 6 volt golf cart type deep cycle batteries.

 

[SteveK]

Time to switch to LIfePO4

 

[dhays]

Thank you all for the comments. Yes the heat sensor also got hot and I’m sure shut the system down. No choice here. Have to replace both batteries. The one I have ate from interstate battery. Any suggestion on a better 4D. I know that DEKA makes most of the batteries for interstate but am open to suggestions for different brands. I am going to stick with the LA batteries and don’t want to go through the hassle of going to LI batteries. Thanks in advance.

I certainly understand wanting the simplicity of just swapping out for a couple 4Ds. If there is any way you could go with wet cell batteries, that is what I would do. AGMs are just not cost effective (and I just ordered three) but the wet cells still aren't too bad. So if they are in a location where you can access them to water them, that is what I would do.

Switching to 6v wet cells would be a good option as well if you don't mind doing the cabling and the footprint would work.

 

[tpbrady]

I hate to add complexity, but consider that the Xantrex may be the source of the original failure. The Xantrex when first connected to shore power has a delay until it switches shore power through to the AC panel. It also will not start charging until this switch occurs. If this switch fails charging stops and if the inverter is on, the batteries could be drained. When the Xantrex shuts off, with the inverter off, do you still have AC at your panel?

As a post script, when I get the boat set up for winter, I have to remember to put the Victron Multiplus into the charger only mode, so if shore power fails, I don’t kill the batteries.

 

[SteveK]

don't all inverter chargers have a low bat cutoff. My Xantrex and Magnum both do. Set by voltage they stop inverting so the battery is not fully drained. IIRC default was 10v both could be set up to 12v
My LFP battery BMS also has a cutoff based on voltage.

 

[Nick F]

As a post script, when I get the boat set up for winter, I have to remember to put the Victron Multiplus into the charger only mode, so if shore power fails, I don’t kill the batteries.

I put my system into "charger only" mode whenever the boat is unattended on shore power, not just in winter layup.

 

[Mac2]

Were you equalizing your batteries? As a side note, I bought two lifeline batteries (agm) last year. I had them parallel. One of the cells "weeped' from the get go. Returned it for a new battery and everything worked fine. I would not have suspected a new battery being bad, but it happens.

 

[READY]

One of the huge benefits of lithium batteries is bringing them down to zero is both nearly impossible (due to the BMS) and will not kill them. All lead acids are likely damaged if below 50%. Now is the time to make the change. Your charger is still a suspect so if you do replace with wet cells you may just kill them quickly.

I have never heard anyone who has moved to LFP batteries say they regret it.

By the way you will never have to lift those 150+ pound batteries again.

 

[Delta Riverat]

Yup. The time to make the switch is when the lead acid clunkers are shot -

 

[OldDan1943]

If these are for your "house" battery, get 6 volt golf cart type deep cycle batteries.

Gotta have the room

 

[NoRain]

All lead acids are likely damaged if below 50%.

Not even remotely true

 

[Bacchus]

Thank you all for the comments. Yes the heat sensor also got hot and I’m sure shut the system down. No choice here. Have to replace both batteries. The one I have ate from interstate battery. Any suggestion on a better 4D. I know that DEKA makes most of the batteries for interstate but am open to suggestions for different brands. I am going to stick with the LA batteries and don’t want to go through the hassle of going to LI batteries. Thanks in advance.

I'm a fan of Duracell AGMs made by East Penn and hard to beat Sams Club pricing. The AGMs are a premium but I feel they are worth not having the maint, out gassing and acid to deal with. My (3) EP 8D AGMs just finished 11th season and (2) house is showing weakness holding charge andvwill need replacing. Engbstart / thruster 8D still going strong.
I will likely replace ea 8D with a pair of GP31 AGMs.
I'm not ready to consider changes to go to Li and likely won't be boating long enough to break even.

 

[READY]

Not even remotely true

@NoRain Well I should not have said ALL Lead Acids but I still think for many lead acid batteries deep discharge is something that can impact life, especially taking them down to 0%. I was trying to make the point that LFP batteries have a huge advantage in preventing toasting your bank in case of operator error (which many of us have done). Not to mention that the number of cycles out of LFP batteries is typically 5-10X that of many Lead Acid. Each battery brand and build will have different guidelines. Expensive industrial batteries are designed for deeper discharge but I suspect the typical battery found in many boats is not nearly as resilient. I found this from Discovery Battery seems to be a good overview:

Discharging batteries is a function of your application. Below is a list of helpful items:

• Shallow Depth of Discharges (DOD) will result in longer battery life. <30% DOD is recommended for general-purpose deep-cycle batteries
• Lead acid Batteries in solar or renewable energy applications should be sized for no more than 50% DOD. 30% DOD sizing is preferable
• 80% DOD is the maximum safe discharge for industrial semi-traction type deep-cycle flooded, AGM and GEL batteries
• Do not continually discharge any lead-acid battery >80%. This will damage (or kill) the battery
• Recommended maximum DOD for flooded batteries is 50% of capacity
• A periodic equalization charge for flooded batteries is a must
• Do not leave batteries deeply discharged for any length of time
• Lead-acid batteries do not develop a memory and need not be fully discharged before recharging
• Batteries should be charged after each period of use
• Batteries that charge up but cannot support a load have most likely reached the end of their useful life.

 

[NoRain]

Yeah, the word ALL is what I was responding to. I’ve got Lead Carbon AGMs (similar to Firefly) that actually spec 2000 cycles at 80% DoD….but 50% is better.

I agree with the rest of your post.

 

[rgano]

When I switched boats in 2015 from a GB42 with a total of seven LA batteries to this Mainship, I ended up with a pair of AGM house/start batteries and a so-so charger. A quickly executed mod had the boat equipped with two additional AGMs as a separate house bank and a fine Pronautic 1250P programmable charger. Did I say I love AGMs? Month after month, year after year sitting with the charger on 24/7/365 those batteries are rock solid always there ready to go. And yes, I routinely had to replace dead or dying LA batteries in my trawler on average every four years over the 29-year ownership of that boat. I understand and share your reluctance for lithiums, and I cannot emphsis enough my encouragement to go AGM as an alternative, especially in your use case.