Checking batteries during pre-purchase surveys

I’m under contract on a 2007 boat, and about to go to surveys. Of my many concerns is the current state of the batteries (house, starter, genset, and thrusters) and whether they will need to be replaced relatively promptly.

Can I get some feedback, please, on whether it’s possible to assess the current quality and expected future longevity of the batteries during a survey? Is this possible during a day, or does it require a longer discharge/charge/discharge cycle.

Thanks very much in advance.

You can get some indication of battery health. Here is what I would do: If they are flooded lead acid, check electrolyte level on some of them. If low, they have not been maintained well. Then, at beginning of survey, turn off shore power and put some load on the inverter. Say 500-600 watts with a small heater on low resulting in a 50-60 amp draw on the house bank. Check the voltage before you start the load test (should be 12.6V) and every couple of hours. A 400 Ah bank for example should let you draw 200 Ah before voltage drops below 12.2V or so. That would be 3-4 hours. Adjust load and time according to bank size. If voltage drops rapidly and/or inverter shuts down, the batteries need to be replaced.

if this is too much hassle, just assume the batteries have to be replaced and reflect it in your bid.

That is excellent information. I will show up with a small heater as you suggest.

This seller drives a hard bargain, and unfortunately we want this boat. Without some objective indication of a need for a refresh, this Seller is unlikely to budge.

Again, many thanks!

I would look at the date.

Any battery over 5 years old should be replaced as part of your new owner fitting out process.

Well if you really want the boat and it checks out ok otherwise then accept that the batteries are probably going to need replacement and move forward with the deal. Good luck, hope it surveys for you.

gsholz said:

You can get some indication of battery health. Here is what I would do: If they are flooded lead acid, check electrolyte level on some of them. If low, they have not been maintained well. Then, at beginning of survey, turn off shore power and put some load on the inverter. Say 500-600 watts with a small heater on low resulting in a 50-60 amp draw on the house bank. Check the voltage before you start the load test (should be 12.6V) and every couple of hours. A 400 Ah bank for example should let you draw 200 Ah before voltage drops below 12.2V or so. That would be 3-4 hours. Adjust load and time according to bank size. If voltage drops rapidly and/or inverter shuts down, the batteries need to be replaced.

if this is too much hassle, just assume the batteries have to be replaced and reflect it in your bid.

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I’m sorry but in my decades of maintaining flooded lead acid batteries as part of my profession, plus two decades in various boats anchoring out and running off of house batteries, I have found this not to be the case.

You are refering to a “open circuit” battery test.

A flooded lead acid battery under any apreciable load WILL go to 12.0 volts rather quickly and stay there. It will then drop in voltage slowly over the discharge process.

Some boaters here might experience what they think is contrasting results. That is simply because they have huge house banks compared to the average loads put on them by their boats systems. This would naturally result in a slower degradation to 12.0 volts.

Battery testing

Any Battery test to give true evaluation of battery health & expected longevity would Include a few things like the load testing mentioned above but also a couple more things as well. Examples come to mind of these:

1. - I would check the specific Gravity of the electrolyte for each cell.

2. - Check for any date codes on the batteries to see their chronological age

3. - remove the surface charge first before any other testing.

4. - borrow a Midtronics battery conductance tester & use that to evaluate the batteries state of health.
They (Midtronics testers) do a pretty darn good job of showing you where the state of health of the battery is in it's limited life span. Many, like the one I have, give you a print out with a speed-o-meter type graphic showing where the battery is now health wise & lifespan wise.


The battery tester & it's print out -IMHO - will carry more weight in the negotiation on price that any home grown test you work out.

This is what the factory uses to determine battery health.

Good Luck.

Alfa Mike

Great information all and, as happens sometimes here in TF, a little baffling on the divergent ideas.

How about another approach: once I ascertain the actual age of these batteries (assuming that I am able to do so), how old is OBJECTIVELY too old? That is, for run-of-the-mill lead acid batteries, does basic good maintenance practice suggest replacement at any accepted interval?

Thanks again.

Lead Acid batteries and less than 10 throughout the boat?????.... hardly even something to consider for a sale....for the next cruise yes.


Fancy high tech batteries and charging system...I don't know enough to comment but from what little I know it could be a sales issue on a smaller boat.


Starter type lead acid batteries only need a simple load test that most load testers can handle. Borrow one from Advance Auto if you can.

Load test mentioned using inverter only good on the house bank.
If Lead acid a hydrometer check may be your best bet and provide hard data to present.
I figure around 7 yrs as practical batty life assuming reasonable maint.
If at or near that life I would figure you will need to replace within a year or so or immediately if you are planning extensive cruising.
Playing devils advocate - From the sellers perspective I would argue that as long as everything operates properly then there is no need for seller to replace (or allow $) for new battys - I'd argue it's a used boat but everything works.
If you find odd individual cell readings for spec gravity that indicate a bad cell then you have a legit argument.
When I bought my current Mainship I negotiated around a similar situation where batty's were questionable (signs of poor maint/boiling over/ improper charging or bad cells) but everything started & ran. I presented hydrometer readings to seller and broker. We finally agreed on about 40%-50% cost of new battys as an allowance.

Kawini said:

Great information all and, as happens sometimes here in TF, a little baffling on the divergent ideas.

How about another approach: once I ascertain the actual age of these batteries (assuming that I am able to do so), how old is OBJECTIVELY too old? That is, for run-of-the-mill lead acid batteries, does basic good maintenance practice suggest replacement at any accepted interval?

Thanks again.

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If I was buying a boat and any battery was over five years old I would just automatically replace it after I closed on the purchase. Batteries are a maintenance item and every boat needs to have some things done to it to fit it out for your cruising

ksanders said:

If I was buying a boat and any battery was over five years old I would just automatically replace it after I closed on the purchase. Batteries are a maintenance item and every boat needs to have some things done to it to fit it out for your cruising

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Yes. I replace my FLA start batteries after 4 years irrespective of how they check out. After 8 years I throw away the FLA house bank T105s. My two AGM thruster batteries are a puzzle, the 1st two sets are toast after 5 years.

As Kevin says, just a maintenance item which I liken to impellers, heat exchangers and fuel filters. Change them out early works for me with no obsessing over getting the last 5% life.

Thanks again all. It sounds as though I’ll just have to be taking a few big gulps here. The purchase contract called for the owner to produce his maintenance records within a certain period of time. When nothing materialized, we asked him for the records. A week later, he responded that he had no records but that he’d look for receipts. We told him to skip the receipts, and asked him to simply provide us with a list of maintenance tasks that he’s performed over the last three years along with the approximate date of performance. Still waiting on that one week later. He says that he has the oil changed on the main and genset each year, and it may be that he doesn’t do much more than that. He has no oil sample analyses to offer. Admits that it’s probably time for a bottom job, but that his diver says it “looks OK.” (We’ll see about that when it’s hauled.) If the boat weren’t so attractive in other respects, one of us might well have walked by this point. But perhaps I’m being overly sensitive and careful, because this is my first boat purchase and it’s in the $500k range.

Sheesh! Is it unusual to expect maintenance records when you’re up at that level?

Sorry about the thread drift. I’m starting to vent.

Kawini said:

Thanks again all. It sounds as though I’ll just have to be taking a few big gulps here. The purchase contract called for the owner to produce his maintenance records within a certain period of time. When nothing materialized, we asked him for the records. A week later, he responded that he had no records but that he’d look for receipts. We told him to skip the receipts, and asked him to simply provide us with a list of maintenance tasks that he’s performed over the last three years along with the approximate date of performance. Still waiting on that one week later. He says that he has the oil changed on the main and genset each year, and it may be that he doesn’t do much more than that. He has no oil sample analyses to offer. Admits that it’s probably time for a bottom job, but that his diver says it “looks OK.” (We’ll see about that when it’s hauled.) If the boat weren’t so attractive in other respects, one of us might well have walked by this point. But perhaps I’m being overly sensitive and careful, because this is my first boat purchase and it’s in the $500k range.

Sheesh! Is it unusual to expect maintenance records when you’re up at that level?

Sorry about the thread drift. I’m starting to vent.

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Some owners have no records, some have extensive records.

To me, maintenance log books if they exist are something to be looked at pre-offer. A boat with good log book style records would be an indication of the maintenance style of the owner. I would be more inclined to make an offer on a boat with good records, and would scan the records pre-offer to see what work has been done. A lack of records is not necessarially bad, but having records is good.

As far as having the owner write down maintenance activity, that has zero value. I’d bag it and continue with your due dilligence.

ksanders said:

I would look at the date.

Any battery over 5 years old should be replaced as part of your new owner fitting out process.

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Good advise on any newly-acquired boat.

I don't keep any records except oil changes and fuel purchases, receipts for purchased equipment and services (including batteries) are also kept. I got 6 years on my AGM batteries, with probably 100 cycles a year average, so I expect I got my money worth ($300 a year to have electricity). I consider it to have been money well spent, and will replace them with identical batteries next season.

I agree they are just a maintenance item, as are water heaters and eventually refrigerators. New water heater this season also, the last one went for 20 years, six of them for me. It only had an anode in it for the last two years, before that I didn't know there was the option for it.

Some things wear out, with warning or without.

Kawini:


You are focusing on the wrong things. For $500-1000 you can replace all of those batteries. Focus on the really expensive things, like the engine(s).


David

David- The problem, I think, is that I am thinking of too many things! Believe me, I’ve got my eyes on the engine too!

But I hear and appreciate the advise about not sweating the small stuff at this stage. It’s been given by others to others before here on TF, and I’m sure it makes sense. Thanks for the reminder.

I understand that you want to feel like you got a good deal by getting a discount for older batteries, but will you be happy if you loose the boat over the cost of batteries? I know if the boat was what I wanted and checked out ok otherwise, I would be really upset with myself if I lost the boat over that.

Heck our Lindell 36 had 4 13 year old Lifeline 8ds when we bought it. They were still doing ok at 17 years but we decided it was time to replace them as our generator run times where creeping up at year 17 when we were anchored out for extended periods. If you like the boat don’t sweat the batteriesEric

Kawini
Would you care to expand this to the engines. What brand and model? is this the original owner?

To fully check the batteries would require so much survey time it is just not worthwhile. I`m looking at something with 3 recently replaced sealed start batts.The 4 house 8Ds have screwcaps,any life left in them is a bonus.
I`d be more concerned about a 500K boat where the owner can`t be bothered to hole punch the service invoices and put them in a ringbinder(or electronic equivalent). There may be a reason you are not seeing any maintenance records, it may be good,bad,or indifferent.

Consider fuel in the tanks you are probably not being charged for a wash on the age and condition of the batts.

It is good to know if the batteries are an immediate concern. I have seen plenty of times where the time it took for a short haul was enough to cause worn batteries to struggle restarting or not starting engines. Problem is that larger battery banks will start engines even when in poor condition.

I bought a Midtronics battery tester a few years ago and it is a quick and has proven to be a reliable indicator of battery condition. The one I have has a printer so I can "show" the results. Single batteries are easy to test and large banks usually have one or more that can be separated by removing only one cable without disabling the entire system. If one or more of a gang of siblings fails one can pretty well count on the rest being in the same shape.

One other low tech test is to observe the temperature of the batteries. If they are warm that may indicate they are shorted internally. If they are covered you will know as soon as you raise the lid. A quick touch will tell you where the heat is coming from.

Kawini said:

I’m under contract on a 2007 boat, and about to go to surveys. Of my many concerns is the current state of the batteries (house, starter, genset, and thrusters) and whether they will need to be replaced relatively promptly.

Can I get some feedback, please, on whether it’s possible to assess the current quality and expected future longevity of the batteries during a survey? Is this possible during a day, or does it require a longer discharge/charge/discharge cycle.

Thanks very much in advance.

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Based on your statements on how much you like the boat and soft selling the sellers shortcomings on maintenance, records and responsiveness, I am guessing you want buy the boat regardless and are looking for some reinforcement. There are a lot of fish in the sea and probably of the same make/model you are looking at. Too many red flags to spend that kind of money.

You must be a little on the new side of T.F. to talking of buying a $500,000 boat and not include any pictures for us. Shame on you.

Sometimes when I buy something new for my boat I do it because it just makes me feel good. Batteries are one of those things. I get a warm fuzzy feeling knowing I have 7 or 8 brand new batteries below. All the others are right, treat the batteries like they are junk and buy new ones. Personally I like low tech, lead acid batteries from a reputable manufacturer and dealer but the choice is yours.

Probably of more concern would be the 15 year old electronics, toilets, lines, fenders,canvas, etc. All these things need to be inspected and probably replaced, given the age of the boat.
Rather than nit pick the present owner about one or two items that are questionable like batteries or a radio or gps. Just tell him all the items I have listed above are acceptable but are showing their age and you would like to have a few dollars left in your pocket to replace them. He sure should come down at least enough to cover half of the items.

If all of those aging items are in Bristol condition it shows he is keeping the boat up well and just bite the bullet on the batteries and maybe a few other items and write the check. ( you know you want to)

pete

Expensive boat.

The owner did all the work himself? Does he seem like a mechanic or hands on guy? He probably paid someone to perform something. He may not have receipts, but whoever did the work likely does. Ask for permission to get access. Did he keep the boat in one place. Ask that marina who has been working on the boat. Just looking over the boat carefully will show what is newer versus older. Bolt heads with missing paint or scratches from wrenches. Mismatching gaskets or sealants. Look for one engine having anything the other does not. Newer clean hoses versus dirty older ones. Wires not inside a bundle or zip strip. Non matching paint. Almost every bit of service leaves a tell tale sign. Records exist, if you cannot find them you should ask yourself why. Also, you can ask for the owners signature on a questionnaire that covers important questions such as “ has the boat ever partially or completely been submerged” “ has it ever been the subject of an insurance claim or legal proceeding” “ and any other concern you want an answer to. Do your due diligence and then let it go. You can only do so much. Batteries are not something I would spend much time on and only as an indicator of how the boat was kept up. I hope it works out well for you.
I spoke to my neighbor over the fence yesterday. His purchase of a 60 hour , new 46 sea ray was held up by issues such as what you are struggling with. He got everything checked professionally and all legal documents the way he wanted. On the way home one of the cummins lost oil pressure. Oil filter full of metal. Had to truck it home from there. The trucks trailer broke down on the way home and it sat in a parking lot for a few days while the rig was fixed. My point- you can do everything right and still face major issues. All part of being a boat owner.
Ps- I sold my Bertram with very single receipt since it’s purchase new in 1976. The file was over a foot thick, the other half was at the servicing shop who keeps ALL receipts.

moparharm brings up an interesting point. Almost all repairs and service leaves some sign. It may be obvious, like the owner telling you all the batteries are brand new. They look new and are dated and he hands you the receipt. Good, no need to question it.

There may be a paint chip on a heat exchanger, does it need to be questioned? Probably not, it might have been checked, replaced, tightened or removed for some other reason. Maybe an injector pump is a different color than the other. So what, who cares? It failed and was replaced. Even brand new parts fail. Don't read too much into it.

Just buy the boat already, you know you want it.

pete

I don’t disagree with Pete, but

You are reviewing your purchase and want to know as much about the boat as you can possibly learn. In the end you will either accept the condition or reject it. But.......
“ I see one cylinder head is painted differently from the rest of the motor”. “ was there head work?”
Oh yeah I forgot to mention I had an overheat last year and blew a gasket.
1. Who did the work?
2. Was the repair just a gasket?
3. Did you deck the head?
4. How much did you deck the head?
5. What thickness head gasket did you use?
6. Did you do a valve job?
In this regard I do not agree with “who cares”. These are important questions that effect the current, and future operation of the boat.
Knowing as much as you can is fun, prepares you for the future, and in this purchase tells you a lot about who you are buying your boat from.

Kawini said:

I’ll just have to be taking a few big gulps here. If the boat weren’t so attractive in other respects, one of us might well have walked by this point. But perhaps I’m being overly sensitive and careful, because this is my first boat purchase and it’s in the $500k range.

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IMO, batteries are about the last thing you need to worry about. A big gulp is if you miss the need to overhaul a main engine or genset, or if you fail to discover wet coring, delamination, or blistering.