How show battery is dead, warranty

[MickeyB]

Hey All,

So I have 2 90Ah batteries, that after 2.5 years have practically died.  From all the sun in Malta, they are fully charged by about 11 each day, but now the fridge dies about 2 or 3am due to insufficient voltage.

I took them to the battery seller with the 3yr warranty, and he put a 1 amp load on for an hour and said all good.

So how do I actually go about showing the batteries are not working? Naturally he won't visit the boat...

Mike

[SY Racer]

You can easily simulate more load with car light bulbs (head lights). The usually consume 55W each, so two of  them will result in roughly 10 amps load. 

[MickeyB]

Thanks for that -  my biggest problem is trying to convince a battery shop that they are wrong.

So If I have 1 full battery, and put 2 55W bulbs across it for an hour, what then do I have to do to prove deadness (is that a word?)

The big problem is, they are better at this than me, and obviously don't want to swap batteries (which to me is odd, as they would get a loyal customer if they did whereas now I wont go there again whatever happens).

I know this is a lot to ask, but something that drains like crazy, and the resultant voltage etc would be great if anyone knows what the numbers should roughly be.

Mike

[Zanshin]

Many boats and every car garage will have a cheap battery load tester for you to borrow. This puts a known resistance across the battery and shows the battery condition.

$40 on Amazon

I have one on board, but rarely use it.

But let's assume that the batteries are proven to be dead. Since you cannot prove that you never mistreated them, there is little chance of a shop accepting a warranty claim unless there are other indicators.

[sitara]

Hi Mike,

I had a similar problem, AGMs installed and connected to solar panels, never dropped below about 70% capacity when cruising and fully charged at all other times. They died after about four years. When sailing my boat draws about 8 amps (fridge and instruments etc) and I was loosing voltage on cloudy days when the solar could not keep up. I replaced them with more AGMs although I was tempted to go with lithiums. Maybe it is battery build quality?

[zaphod]

Jun 16, 2023 11:37:45 GMT MickeyB said:

Hey All,

So I have 2 90Ah batteries, that after 2.5 years have practically died.  From all the sun in Malta, they are fully charged by about 11 each day, but now the fridge dies about 2 or 3am due to insufficient voltage.

I took them to the battery seller with the 3yr warranty, and he put a 1 amp load on for an hour and said all good.

So how do I actually go about showing the batteries are not working? Naturally he won't visit the boat...

Mike

What is the brand of the batteries? Are they a major name brand, or an in-house brand that is exclusive to the battery shop you are dealing with? How long is the warranty? What does the fine print of the warranty say?

Do you have a battery monitor on your boat? If so, does it log total ah consumed? Are you sure there is no parasitic loads that could be running them down? The amp meter on your instrument panel may not tell the whole story.

I would be inclined to take the batteries to another shop and have a proper load test done.

[NZL50505]

A long shot just in case it helps…. I had a set of house batteries that died after less than 2yrs and I was able to get them replaced under warranty because I was able to prove they had not been mis-treated and had been charged correctly etc. How was this possible…? Luckily I had previously installed a new solar controller with Bluetooth connectivity that allows you to look at the charging / voltage history - showed this to the battery supplier and they conceded ‘defeat’ and replaced the batteries.

So… just in case you happen to have a solar panel connected to your batteries and just in case the controller is a modern unit with Bluetooth that allows you to access charging history via an App… if so you might be in luck and able to support your claim?

[Trevor]

Hello Mike,

Battery claims under warranty are tough but let’s establish some basics.

Battery capacity is pretty simple. The ampere hour rating of the battery gives you the amount of current the battery can supply for 20 hours. A 90 aH battery can supply 90/20 = 4.5 amps. 20 hours is selected as a general rule of thumb.

We could think that the battery could supply 90 amps for 1 hour. That makes perfect sense but a factor called the peukert factor will reduce the battery capacity significantly if that much current is drawn for an hour. The 20 hour discharge provides a good rule of thumb and reduces the impact of the peukert factor.

The process of discharging the battery at 1 amp for 1 hour would be a reasonable test for a 1 amp hour battery but not a 90 amp hour battery. The test would need 1 amp to be discharged for 90 hours for that small level of current to be valid.

Perhaps you may have to accept a pro rata warranty claim and try to negotiate a better price based on prorata warranty for replacements. If forced to replace them you may consider the opportunity to change to Lithiums.

Trevor

[MickeyB]

Hey, and many thanks for all the input.

I do have a battery monitor, but only the instant sort, it doesn't recall history.

I think I will have to accept that new batteries are required, and go to another shop.  Will check out drop in lithiums and see what they cost here in Malta.

Mike

[zaphod]

Before you drop the money on new batteries, you might want to spend some time trying to figure out why your old batteries died prematurely. That is assuming they are indeed bad.

It is sometimes possible to restore batteries that have lost capacity. A good battery shop should be able to do it. Just don't go to the one that thinks 1 amp for 1 hour is a good load test.

You say you have a battery monitor. It should be able to tell you how many amp-hours you used before your fridge shuts down. Knowing how many ah you are getting now compares to the rated ah of the bank.

[SY Racer]

Hi, when swapping to lithium make sure to check if your alternatator is capable of charging them. Lithium draw a much higher current and blown up alternator are the result. Perhaps you will need to add an DC/DC charger to come around that problem.
Very good article on the web, regarding Li*:


marinehowto.com/drop-in-lifepo4-be-an-educated-consumer/

cu

[SaltyDog]

Are you a 100% positive it is the batteries that die? It could also be that you have high resistance in the battery or fridge cabling or connections. Best is to have a volt meter over the poles of the battery to confirm the voltage is indeed too low to drive the fridge...