AGM Batteries

[Greg2]

I never experienced nor heard of a real benefit going for AGM,

but imo more importantly,
use a high quality charger with multi stage charging algorithm; for me I would only use Victron or Mastervolt
install a battery monitor, and never discharge below 50% (i've set the alarm at 60%)
use a known brand for the battery's sa Varta, Victron, Bosch, ...
don't pay a premium for the supposedly "high end " brands

Your comment on no real benefit of AGM is intersting.
We have a Sterling battery charger that I installed last year. I looked at both Victron and Mastervolt but the Sterling compared well if memory serves.

Whatever we go for I think a battery monitor is a good shout.

 

[Greg2]

Is there a zero maintenance angle to factor in the choice?

It’s just the ER s get hot esp in the Med and maybe FLA need regular topping off with distilled water that’s extra evaporating in the heat = shorter than expected life .

AGM s are sealed maintenance free I understand so that’s one less thing ( to water level check ) to go wrong .
And things do go wrong on boats as we all know !

Definitely want sneaked batteries as a minimum - the battery bank sits between the engines so topping them up would be tricky.
.

 

[Tranona]

Your comment on no real benefit of AGM is intersting.
We have a Sterling battery charger that I installed last year. I looked at both Victron and Mastervolt but the Sterling compared well if memory serves.

Whatever we go for I think a battery monitor is a good shout.

Yes, a monitor is a good idea. As I suggested earlier understanding your pattern of usage is key to making a sensible decision on battery choice. Proponents of different types of batteries tend to concentrate on the specific characteristics of their favourite types without going back a stage and finding out what your user requirements actually are. So saying no benefits of AGMs over gel FLAs for use in outside broadcast vans is of little help in deciding what would best suit your boat. You can see this most clearly with the snake oil salesmen promoting lithium on youtube. They tell you how wonderful they are but never in what situations they are worth considering. Vast majority of boaters cannot use the properties of lithium and converting the 12v system to use them is a complete waste of money.

For most "light" users of 12v power, good FLAs are perfectly adequate and if properly looked after (not discharged too deeply which means having a large enough bank in relation to your consumption) regularly charged up to full capacity and not allowed to self discharge over long periods on non use will last between 5-7 years. The real gamechanger that brings AGMs into play for this type of usage is the adoption of AGMs for automotive use, primarily to support stop-start operation. This has resulted in massive drops in prices, crucially expressed in £s per discharge cycles. This is the measure of potential life. The premium in price %age is now substantially less than the %age increase in number of discharge cycles. These cheaper automotive derived AGMs do not have the life of the better and more expensive "marine" AGMs which are much more suited to heavy users such as liveaboards.

 

[Greg2]

Thanks for your helpful input @Tranona

On the use of battery chargers do you think it is it better to leave the (smart) charger on whenever on shore power and the boat is in use or is it better to cycle the batteries within recommended parameters? I have assumed the former.

 

[BartW]

just to bring this up again,

don't know for other makes,
but Victron chargers can stay connected permamenetly, when the battery's are full, and have not been discharged for 24hrs, the charger goes in "storage mode, "
and after a week or so (driven by the algorithm) the charger does a bit of recharging, to copensate for the self discharge.
(see online for more info on Victron Adaptive charging...)

 

[AndieMac]

just to bring this up again,

don't know for other makes,
but Victron chargers can stay connected permamenetly, when the battery's are full, and have not been discharged for 24hrs, the charger goes in "storage mode, "
and after a week or so (driven by the algorithm) the charger does a bit of recharging, to copensate for the self discharge.
(see online for more info on Victron Adaptive charging...)

Thanks for both your responses to this thread Bart, I’m also at the stage of battery system replacement and appreciate your input. After seeing your own boats DC system, I’m following your advice!

 

[Daydream believer]

Voltage on its own won't tell you the battery's state.
To fully check a battery, you need to put it under load and see how the voltage then responds.
There are modern, more technical, testers but I use the crude old method - a tester like this:-

Battery Drop Tester 6/12V | BT91/7 | 1 Year Guarantee | Sealey

Generally, I connect it up, switch the load on for about 5 seconds - if the battery voltage drops to 9v or less - that battery is dead and needs replacing.
You have to be careful with load testers - you don't want to damage a good battery so don't use too often and don't load for too long.

Since posting on this thread I have spoken to the battery manufacturer. I saw your post & then looked at some you tube vids. I noted that the type you show ( & this with no disrespect to you) was a bit inaccurate as it just shows a block for the results. So I started looking at digital load testers & nearly bought one. These give a more positive digital reading as a % etc.
However, when reading a review of the one I chose, a person noted that it did not have a facility to enter the battery amperage. That got me wondering. It is OK knowing the cranking amps for a few secs, but I want to know the storage capacity of the battery.
So I rang the battery manufacturer & asked the tech dept for advice. It was confirmed that I would be wasting my money buying such item. This because cranking amps are not a measure of long term supply. I think I got that right; he got very technical. I pointed out that I was stuck, as the batteries were out of warranty & I needed to be certain that I had good batteries, as I was sailing at night, using autopilot, nav lights etc & needed to be able to rely on them.
He has sent me a warranty form to arrange for them to be collected & said that if they are out of warranty, but shown to be dodgy, they will still change them. So now they are parcelled up ready for return to them. They will be run down to zero, re charged then the cycle repeated & the results analysed
So I will either have a bill for that - but they will be certified as OK- or I will have 2 new batteries. At least I will not have wasted my money on a load tester. Fair dues to a company that is prepared to change them; even out of warranty, albeit only by 3 months

 

[BartW]

Thanks for both your responses to this thread Bart, I’m also at the stage of battery system replacement and appreciate your input. After seeing your own boats DC system, I’m following your advice!

Hi, Callum, I'm just discussing the replacement of the battery's on P's old boat, (Ant)
the new owner wanted advice from P and myself, and now he's ordered the new batt's
Let me know if I can help,
kind regards !

 

[BartW]

Since posting on this thread I have spoken to the battery manufacturer. I saw your post & then looked at some you tube vids. I noted that the type you show ( & this with no disrespect to you) was a bit inaccurate as it just shows a block for the results. So I started looking at digital load testers & nearly bought one. These give a more positive digital reading as a % etc.
However, when reading a review of the one I chose, a person noted that it did not have a facility to enter the battery amperage. That got me wondering. It is OK knowing the cranking amps for a few secs, but I want to know the storage capacity of the battery.
So I rang the battery manufacturer & asked the tech dept for advice. It was confirmed that I would be wasting my money buying such item. This because cranking amps are not a measure of long term supply. I think I got that right; he got very technical. I pointed out that I was stuck, as the batteries were out of warranty & I needed to be certain that I had good batteries, as I was sailing at night, using autopilot, nav lights etc & needed to be able to rely on them.
He has sent me a warranty form to arrange for them to be collected & said that if they are out of warranty, but shown to be dodgy, they will still change them. So now they are parcelled up ready for return to them. They will be run down to zero, re charged then the cycle repeated & the results analysed
So I will either have a bill for that - but they will be certified as OK- or I will have 2 new batteries. At least I will not have wasted my money on a load tester. Fair dues to a company that is prepared to change them; even out of warranty, albeit only by 3 months

this battery tester is not a device that you would use for knowing "exact" value's,
but rather be able to compare the condition of individual battery's in the same bank, or compare with similar battery's from somewhere else,
as long they are all more or less withing the same range, you're good,
One can test and compare when the battery's are fully charged, and again after a discharge.
In practice I'm not so much concerned about the remaining capacity in a battery, rather if all battery's in one bank are OK, and are behaving more or less the same.

But there are a few indications that give it away when a battery is bad;
- after charging a battery, wait for 30..60min, and if the voltage is below 12V, the battery is BAD
any battery with a floating voltage (disconnected) below 11,5V must be considered BAD
- charge a battery and leave it alone for a couple of day's, (disconnected), again, the voltage may not go below 12V, if it does, its warn.. below 11.5V its BAD.

as has been said before the voltage doesn't tell much about the charge conditions,

 

[limecc]

Technology moves on and EFB batteries are replacing AGM, I think they are also cheaper.
AGM & EFB Automotive Batteries Explained - Yuasa battery

 

[Daydream believer]

this battery tester is not a device that you would use for knowing "exact" value's,
but rather be able to compare the condition of individual battery's in the same bank, or compare with similar battery's from somewhere else,
as long they are all more or less withing the same range, you're good,
One can test and compare when the battery's are fully charged, and again after a discharge.
In practice I'm not so much concerned about the remaining capacity in a battery, rather if all battery's in one bank are OK, and are behaving more or less the same.

But there are a few indications that give it away when a battery is bad;
- after charging a battery, wait for 30..60min, and if the voltage is below 12V, the battery is BAD
any battery with a floating voltage (disconnected) below 11,5V must be considered BAD
- charge a battery and leave it alone for a couple of day's, (disconnected), again, the voltage may not go below 12V, if it does, its warn.. below 11.5V its BAD.

as has been said before the voltage doesn't tell much about the charge conditions,

With due respect--I AM concerned how much is left in the battery. I want to know if my engine is going to start or if my nav lights are going to last the night etc. As for charging- My batteries show 13 V after charging They stayed at that throughout the winter. However, if used for 4 minutes at 5 amps they drop very rapidly. That is not right & It does not tell me what is going on. I would never let them drop below 12 V
It is not so much a case of BAD but a case of not giving me a nominal 100 amps, or anywhere near 50% of that, which one might expect

 

[BartW]

With due respect--I AM concerned how much is left in the battery. I want to know if my engine is going to start or if my nav lights are going to last the night etc. As for charging- My batteries show 13 V after charging They stayed at that throughout the winter. However, if used for 4 minutes at 5 amps they drop very rapidly. That is not right & It does not tell me what is going on. I would never let them drop below 12 V
It is not so much a case of BAD but a case of not giving me a nominal 100 amps, or anywhere near 50% of that, which one might expect

If your battery's stayed at 13V all winter, you must have had the charger permanently installed,

if there wasn't
you could connect a small load, such as a light bulb, (from which you know the power / consumption)
and after a couple of hours, or a day or so, measuring the voltage at the batt terminals that would give you a indication of whats going on,

if your battery's behave as you discribe, they are bad,
and pls test them with a accurate voltmeter,

 

[Tranona]

Technology moves on and EFB batteries are replacing AGM, I think they are also cheaper.
AGM & EFB Automotive Batteries Explained - Yuasa battery

EFB is positioned between FLA and AGM in both potential life and price - again driven by automotive demand. You will see EFBs fitted to cheaper cars and AGMs to more upmarket cars. For example my Ford C Max has an EFB whereas Jaguar and Land Rover fit AGMs. However they are not necessarily cheaper . I have just bought 2 Exide AGMs 95Ah capacity each (for a Jaguar XF) at £115 each, the same price as the 75Ah EFB for my C Max.

As ever it pays to do research about what is on offer to determine what is suitable for your use and offers the best value.

 

[Portofino]

Thanks for your helpful input @Tranona

On the use of battery chargers do you think it is it better to leave the (smart) charger on whenever on shore power and the boat is in use or is it better to cycle the batteries within recommended parameters? I have assumed the former.

Most modern marine chargers are smart enough to be left on full time at the dock .In fact it’s designed in the sulphating phase , and other maintenance phases .
I use this kit .There’s a bit on batts too regarding different types .

Marine Chargers, Batteries | Dolphin, the best for your boat

 

[Hurricane]

Since posting on this thread I have spoken to the battery manufacturer. I saw your post & then looked at some you tube vids. I noted that the type you show ( & this with no disrespect to you) was a bit inaccurate as it just shows a block for the results. So I started looking at digital load testers & nearly bought one. These give a more positive digital reading as a % etc.
However, when reading a review of the one I chose, a person noted that it did not have a facility to enter the battery amperage. That got me wondering. It is OK knowing the cranking amps for a few secs, but I want to know the storage capacity of the battery.
So I rang the battery manufacturer & asked the tech dept for advice. It was confirmed that I would be wasting my money buying such item. This because cranking amps are not a measure of long term supply. I think I got that right; he got very technical. I pointed out that I was stuck, as the batteries were out of warranty & I needed to be certain that I had good batteries, as I was sailing at night, using autopilot, nav lights etc & needed to be able to rely on them.
He has sent me a warranty form to arrange for them to be collected & said that if they are out of warranty, but shown to be dodgy, they will still change them. So now they are parcelled up ready for return to them. They will be run down to zero, re charged then the cycle repeated & the results analysed
So I will either have a bill for that - but they will be certified as OK- or I will have 2 new batteries. At least I will not have wasted my money on a load tester. Fair dues to a company that is prepared to change them; even out of warranty, albeit only by 3 months

Couple of points to make here.
I assume you have standard flooded cell batteries.

First - Years ago, I tried to make a warranty claim and the result was that we aren't using FLA batteries in the way that they were intended to be used (starting engines for example).
They weren't designed to be used for long periods of low current draw.
So my warranty claim was immediately rejected.

Secondly, the instrument that I use for "testing" isn't intended (in my view) to be used to determine how much charge is left in the battery.
I use it to decide in the battery is BAD (as Bart says).
If a battery passes the crude load test, it will go on to be used in my system.
If it doesn't pass the crude test - thats it - it is ?ucked!! and gets replaced.

If you really want to know how much is left in your battery bank, get a battery monitor - the Victron BM one is dead cheap and does the job for me.
They usually come with their own shunt so you don't need to work out what shunt to use.
My one is a bit old now - the new ones connect with your mobile phone and report ststistics.
Battery monitors usually incorporate Peukert's law which is widely regarded as a way of measuring battery capacity in lead acid batteries.
See here Peukert's law - Wikipedia
I tend to use my Victron battery monitor's % left display to determine the capacity of my battery bank - my batteries are charged using a mains charger, the engines and solar panels.
I also keep an eye on the current drain (again using the Victron monitor)
As I said above, the voltage doesn't really give you an idea of the capacity left - there are too many other variables.

But when the battery is BAD - that it - just change it and move on.

 

[Daydream believer]

If your battery's stayed at 13V all winter, you must have had the charger permanently installed,

No battery charger. & tested with digital tester & on board NASA BM1 both agreed

 

[Daydream believer]

I assume you have standard flooded cell batteries.
Secondly, the instrument that I use for "testing" isn't intended (in my view) to be used to determine how much charge is left in the battery.

If you really want to know how much is left in your battery bank, get a battery monitor - the Victron BM one is dead cheap and does the job for me.
They usually come with their own shunt so you don't need to work out what shunt to use.
My one is a bit old now - the new ones connect with your mobile phone and report ststistics.
Battery monitors usually incorporate Peukert's law which is widely regarded as a way of measuring battery capacity in lead acid batteries.
See here Peukert's law - Wikipedia
I also keep an eye on the current drain (again using the Victron monitor)
As I said above, the voltage doesn't really give you an idea of the capacity left - there are too many other variables.

AGM batteries
Monitor is a NASA BM1 so one assumes it knows how to calculate what is left & It does display an alarming drop in capacity in a short time. - something like 50% in 4 minutes of use with the fresh water pump running.
However, my experience of NASA instruments does give me concern. I have calibrated it as per instructions at regular intervals, checking temperature etc.

 

[BartW]

Is your water pump ok ? (I've had one ones making a short cirquit, but that would blow the fuse)

when the BM shows a big drop of capacity, it could only be that a hi curent is drained through the shunt.
the BM does not "know" the real capacity of your bank, it just counts what goes in and goes out.
you have to "set" the nominal batt capacity in the unit,
(at least it is like that in Victron and Mastervolt BM's)

 

[Daydream believer]

Is your water pump ok ? (I've had one ones making a short cirquit, but that would blow the fuse)

when the BM shows a big drop of capacity, it could only be that a hi curent is drained through the shunt.
the BM does not "know" the real capacity of your bank, it just counts what goes in and goes out.
you have to "set" the nominal batt capacity in the unit,
(at least it is like that in Victron and Mastervolt BM's)

More than satisfied with the pump. It was new a few years ago & works well.
One does set the capacity of the batteries with a BM1

 

[Assassin]

So with regard to some of the cheaper products on the market such as “Energy Expedition Plus” or ”Leoch” , some of which are offering 4 and 5 year warranties, what is the general opinions of these - reasonably good buys, or stay well away?

I would stay well away for one reason, their warranty is worthless and they know it and what they do is exactly the same practise as Chinese manufacturers do and that is to include "extras" in their deal and it works quite simply.
Battery Outlet orders 1000 batteries of the same style and type from Wong Tung Chung in China and he gets his order and when he checks it there are 1050 batteries in his order and this is to cover warranty claims, if 10 batteries are defective when new you have 10 batteries to replace them as its cheaper than returning them to China and then sending 10 batteries out, they know many people wont adhere to their conditions such as registering them online and they can discount their warranty claims when they fail at 4 years and they know many people wont actually bother to make a warranty claim and those that follow the registration completed correctly and they fail at 4 years will be small and they hope the remaining 40 batteries will cover them.