Do I need to replace my batteries?

[john61ct]

Some ways similar, but optimizing for standby longevity, like alarms, UPS etc, is a different design for constant use deep cycling.

But if you can carry the weight sometimes the big 2V ones get auctioned off for scrap value, still plenty of life left.

[ramblinrod]

Originally Posted by Mike Banks

It sounds to me as though you need to replace the engine starting battery. Usually these are not "Deep Cycle" and have heavy loads when in use--so they do not last as long.

Many years ago I was involved in telecommunications, and we used flooded cell batteries to power our telephone exchanges in the event of mains failure.

These batteries were routinely discharged by one tenth of their ampere-hour capacity, then re-charged. It is true they were stored in optimum conditions and were not subject to movement--and were similar to the types of cells used in submarine battery rooms of the day. They were made by Chloride as I recall--the same company that made EXIDE. I had a car battery by EXIDE that lasted ten years--but that battery was mounted under the vehicle not in the engine bay, and was topped op by distilled water as required, and charged by a generator and voltage regulator, not an alternator. A DC generator is a longer, deeper and softer charging method...

So--your house batteries may still be OK. It sounds as though you are not over-depleting them before recharging them--and that is what these deep cycle batteries prefer.

The Telephone Exchange batteries for the old Strowger types and Cross-bar types of exchanges were of the deep-cycle type, (there were two banks of them) and they lasted as long as twenty years before we replaced them, but they were hardly ever drained in earnest. Most power outages only lasted a few hours at most.

Different beasts.

A start battery is basically on float it’s entire life. It rarely gets discharged below 98%. They typically last 8-12 years.

A deep cycle bank on a liveaboard, discharged to 50% every day should last around 4. Really good batteries, like Surrette / Rolls should last double.

[Paramotorgreg]

Thanks to everyone for all your useful advice and comments.

Just to explain further,....

The batteries are sealed maintenance-free batteries - there is no way that I can see to test them with a hydrometer; test the water level; or add water.

It is possible that the autohelm may be powered by the engine battery. This was a hypothesis of mine but seemed ridiculous so i dismissed it, but the fact that someone else has found this on their boat means it is a possibility. I will check it.

All the battery terminals are clean and there is no corrosion or discharge.

When charging the voltmeter never shows that the voltage goes above 13.5v. When the batteries have been charged overnight from shore power and the battery charger is showing that it is in float status the voltmeter shows 12.5v on both service and engine start batteries. From your advice it seems that I should start charging when the voltage drops to 12.3/12.2v instead of waiting until the voltage drops to 11.9v, but I think in that case I will probably need to charge 4 times per day!

The engine is a Yanmar 4JH2-HTE, not sure how big that is.

[arsenelupiga]

i have exide gel and in manual says to recharge when OCV 12.5V, which corresponds to 60% SOC.

Too lazy to do 20 hour test or similar hence I follow above exide guideline and do not let OCV below 12.5, except on rare occasions.

suggest to find manual for your batteries else you are just guessing.

[sailorboy1]

Personally I feel the OP's batteries have been constantly undercharged and surely have reduced capacity. If I had a boat for 3 years and had been doing so, plus I didn't even know how old the batteries were, I would be planning to replace them (I replaced a 4 year old set 20 months ago because I could tell them starting to go and I wanted to be able to replace on my schedule).

But if you want to be sure you need to know where they really are. The only way is to first truly fully charge your batteries, then do some load test even if is justrunning a given load and see what happens. You don't really need to do a full test to find if batteries are weak.

[sainted]

Originally Posted by Paramotorgreg

Thanks to everyone for all your useful advice and comments.

Just to explain further,....

The batteries are sealed maintenance-free batteries - there is no way that I can see to test them with a hydrometer; test the water level; or add water.

It is possible that the autohelm may be powered by the engine battery. This was a hypothesis of mine but seemed ridiculous so i dismissed it, but the fact that someone else has found this on their boat means it is a possibility. I will check it.

All the battery terminals are clean and there is no corrosion or discharge.

When charging the voltmeter never shows that the voltage goes above 13.5v. When the batteries have been charged overnight from shore power and the battery charger is showing that it is in float status the voltmeter shows 12.5v on both service and engine start batteries. From your advice it seems that I should start charging when the voltage drops to 12.3/12.2v instead of waiting until the voltage drops to 11.9v, but I think in that case I will probably need to charge 4 times per day!

The engine is a Yanmar 4JH2-HTE, not sure how big that is.

If, even during the acceptance phase of it's charge cycle, your battery charger is not going to 14.4 volts, then it's time for a new battery charger. Maybe. It might be programmable enough to correct the problem, but if it's an older one, probably not. If it's also possible that the volt meter on your panel is very inaccurate. Mine is. I rely on the digital volt meter in my battery monitor, which is highly accurate.

Our the batteries are really being charged at these low voltages, then they are certainly compromised.

Get a decent digital volt meter at your local Loews and double check. It's a necessary tool to have in your kit anyway.

[Caliber40]

Agreed sounds like batteries are not being charged properly.

Once charge is removed and they have settled down, with no load they should be reading 12.8 V.

If you think you have to charge 4 times a day to avoid going below 12.3 something is wrong. Not sure how you charge 4x a day....if batteries are hooked up to shore power they are constantly under charge....same if your under power. If you are sailing with modest loads you should not drop below 12.5 except after several hours. If they are dropping fast batteries are toast which I suspect they are.

Your engine is a 75 HP turbo charged Yanmar! Good engine!

[Black Diamond]

Be careful changing the engine start versus the house bank. Many new boats have the. batteries ganged together for charging and will keep them together until the house bank voltage drops below a certain level (say 12.3 Volts). At that time a switch disconnects the engine battery from the larger bank so you are (theoretically) always can start your engine. Given this the chemistry and charging characteristics of the batteries needs to be similar.



FWIW

[borzoijay]

My questions are several......
1. Am I discharging the batteries too much?

Yes, 50% max, but try not to do that. Not not less than 80% routinely. You can't tell accurately from voltage alone.

2. Am i not charging the batteries enough?

Probably not.

3. Are my batteries at the end of their useful life and do I need to replace them?

Maybe

4. Is there anything I can do to increase their longevity now?

Your batteries are AGM. I never got a straight answer from any manufacturer of AGM batteries other than LifeLine, but Lifeline recommends equalizing their batteries periodically. When doing that, disconnect everything from the batteries except the charger (the charger must be capable of providing an equalizing voltage setting; around 15.2 volts for several hours). I have rejuvenated my LifeLine battery bank several times by equalizing. You might check with the manufacturer for their recommendation. If you do an equalization, keep an eye on the temperature.

5. If they need replacement, what can i do to the new ones to maximize their life?

I recommend never discharging below 80%. I use a Xantrex LinkPro monitor with the battery temperature monitor to ensure that I know the state of battery charge. Yes, they are expensive; around $300, but the peace of mind and kindness to your batteries is worth it

[charly]

I suggest read Nigel Calders book on maintainance, the chapter about batteries. A fantastic source for many things on a boat.



"nigel calder: boatowner's mechanical and electrical manual"


Charles

[GrowleyMonster]

What they said, mostly. I will again stress the need to ensure that the start battery is isolated from the house bank system.



It does sound like undercharging, but you could also have a voltmeter that is reading low. Check independantly with another meter. I would say also that it is high time your batts are equalized, but I don't mess with those sealed batteries and can't really advise. With ordinary FLA batteries, an equalizing charge will often recover a battery subjected to chronic undercharging.


The moral here is, if you replace with lead, don't get sealed batteries. Actually, golf cart batteries make great house batteries, second only to telco cells and very high end batts like Rolls/Surette. A start battery doesn't need to be a deep cycle battery but if it is, it should be plenty big. A proper start battery operates differently than a deep cycle. It is meant to deliver a quick hard jolt for just a few seconds, rather than a steady load for hours. When you replace, consider two start batteries and an A/B/both/off switch. Never switch to OFF while the engine is running and an alternator is charging the batteries or you will likely blow the diodes or the regulator. And BTW, have your alternator checked. Check start relay too.


Your batteries are getting a little long in the tooth but if they had been properly maintained they would likely give you another year or two of service. As it is, be prepared to write them off and get new ones. BOAT = Break Out Another Thousand.

[Unregistered-1]

They're stuffed. Find someone online who has done a well-reviewed comprehensive battery refit and copy them.

[Pinto]

Originally Posted by Paramotorgreg

I have been reading a lot about batteries on this forum and it is clearly a very complex subject - there are some quite different and sometimes contradictory points of view on how to get the best life from them and how long they should last. I am therefore not expecting simple answer, but I would appreciate and be grateful for some expert opinions.....

I have 4 Varta Professional 180Ah 930 180 100 batteries as my service bank. I also have one Varta Promotive 180Ah M16 680 109 100 as my engine starting battery. I don't know exactly how old the batteries are, I inherited them with the boat, but I have owned the boat for 3 years. I charge the batteries using shore power or my generator when the service bank voltage drops to 11.9v (I don't generally monitor the engine start battery voltage, but typically when the service bank drops to 11.9 it is higher at ~12.6v). I have a Mastervolt Mass 12/60 battery charger. When I charge on shore power I charge continuously. When I charge on the generator I charge for approx 1 hour in the morning and 1 hour in the evening or until the service bank voltage shows 13.5v.

Generally the only significant load on the service bank is the fridge and my understanding is that there is no load on the engine start battery other than starting the engine or generator.

On a couple of occasions recently I have started the engine in the morning then sailed all day. Although in the evening the service bank is showing 12.0/11.9v and the engine battery has been turned off all day, when I have tried to start the engine there has not been sufficient power to turn over the engine. Fortunately there has been enough power to start the generator so it has been necessary for me to start the generator and charge the batteries for a few minutes (5?) before I can start the engine.

My questions are several......
1. Am I discharging the batteries too much?
2. Am i not charging the batteries enough?
3. Are my batteries at the end of their useful life and do I need to replace them?
4. Is there anything I can do to increase their longevity now?
5. If they need replacement, what can i do to the new ones to maximise their life?

All advice and information grateful received, and preferably with the minimum of technical language, because as you may have gathered I don't have a huge understanding of this subject.

Hi

"On a couple of occasions recently I have started the engine in the morning then sailed all day. "

Expect trouble --


1. Am I discharging the batteries too much? YES
2. Am i not charging the batteries enough? YES

"12.0/11.9v"

If I were showing readings that low - I would be sweating and beating myself with rose thorns.


Get a little voltage readout that runs all the time, so you see it at every glance - (make sure it agrees with a couple of multimeters etc). Nice little neat digital ones cost little in money and power consumption.

and, keep that voltage UP ---

I do not like under any circumstances to see my readings anywhere near 12.5 --

I like to see 12.7, 12.8 at rest.

Without charging if the fridge is running etc. - it can be ok to run lower -


but, if nothing is running and you are at 11.9 or 12 - you are killing the batteries --- end of story.


Lead acid batteries are only happy in one state --------- FULL.



"3. Are my batteries at the end of their useful life and do I need to replace them?"

I would get them up to charge and keep them there and see how they perform.


"5. If they need replacement, what can i do to the new ones to maximise their life?"


Treat them like if they are down even the slightest - that you are not loving them enough.


A quick and dirty test re. "The batteries are sealed maintenance-free batteries - there is no way that I can see to test them with a hydrometer; test the water level; or add water."

is to pick one up -- if it's light to lift ---------- it's probably a goner

they lose weight near death - often like us

[Jacko]

Originally Posted by sainted

As has been previously noted, there's quite a bit to learn about battery monitoring, performance and longevity.

Some battery monitors track the amps going into and coming out of your batteries and thereby determine their state of charge. Ie, if you have a bank that can store 400 amp hours and the battery monitor measures 200 amp hours coming out, you'd be at 50% state of charge. If you pump 200 amp hours (plus a bit to account for inefficiencies), you're back to a fully charged battery bank.

Other monitors use some proprietary algorithms to determine your battery's state of charge using only the voltage (Sterling makes that one, Balmar sells it on this side of the pond). This monitor also give SOC as a percentage. If you get this type of monitor, you should also have an amp meter so you can tell what your charging sources (alternator, battery charger, solar, etc) are doing.

The numbers that you report in your post suggest that you have been under charging your house bank. Lead acid batteries have a maximum charge voltage of about 14.4 volts (it varies a little depending on type of battery, such as flooded vs gel vs AGM). Once the battery reaches 14.4 volts it's at about 80% SOC. A smart battery charger will start lowering its charge rate whilst maintaining 14.4 v (called the acceptance voltage) until the battery is fully charged, which is indicated by the rate of charge getting down to about 4% of capacity, or 16 amps in our example. Some battery chargers don't actually use the number of amps to determine the end of the absorption phase, but use a timer and guess. Once the batteries are fully charged, the charger should float the batteries at about 13.4 volts to maintain the charge but not over charge the batteries.

The fact that you are only charging your batteries until you get to 13 odd volts indicates that you are under charging them, which will kill 'em sooner rather than later.

Last but not least, the fact that your engine start battery won't crank the engine at the end of the day (unless you are inadvertently discharging it into a house load) strongly suggests that it is toast.

If 'in I were you, I'd replace the batteries, make sure I've got a three-stage battery charger that can be programmed for your house bank capacity and install an amp meter and some kind of SOC monitor (could be combined, of course).

Scott

Thank you Scott for your very simple but clear explanation of how things work. I found it expanded my thoughts after 15 years on this boat and thinking I was well set up and things were right my system is exactly as you explained. Cheers Jacko

[Unregistered-1]

Consider have a separate very small solar panel to float the start battery. If the small solar panel amps is 1/10th of the start battery AmpereHours, then you won't need a regulator on it, and can wire the panel directly to the start battery (small fuse for it right on the battery.)

The only time the start battery should be anywhere near the house battery is in an emergency (engine wont start - need a jump start). This is pretty unlikely however, but good insurance.