Battery Testing

IDAMAY

IDAMAY

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Piers' thread has made me think about battery testing but not wishing to hijack it. I have two linked 12V 180ah AGM batteries. They don't hold charge for more than a couple of hours once off external power from shore or generator. Their base load is a fridge and freezer through an inverter, plus lighting which is almost all LED. When new three seasons ago they would comfortably keep all this running overnight.

It seems clear that one or both batteries are past it. Is there any way in which I can easily find out if it is just one or both that need replacement? For instance would one of the more sophisticated battery testers enable this. For example the Ancel BA101. Or are their other methods?


Thanks for your help.
 
By "linked", do you mean that they are in series to get 24V?
Anyway, my understanding is that having all "equivalent" batteries in the same bank is crucial for the longevity.
In other words, also assuming that just one battery is shot, I don't think it's a good idea to replace just that and connect the new one together with a 3 years old battery, which even if still good, is bound to be nowhere near the capacity of the new one.
 
MapisM said:
By "linked", do you mean that they are in series to get 24V?
Anyway, my understanding is that having all "equivalent" batteries in the same bank is crucial for the longevity.
In other words, also assuming that just one battery is shot, I don't think it's a good idea to replace just that and connect the new one together with a 3 years old battery, which even if still good, is bound to be nowhere near the capacity of the new one.
Click to expand...

Thanks. MapisM. They are in Series as the boat is all 12V. I take your point about possible false economy.
 
IDAMAY said:
I take your point about possible false economy.
Click to expand...

Not possible. Fact. The batteries need to be balanced and if not at best you are playing to the lowest capacity. It's also worth bearing in mind electricity is lazy. i.e. you may not be balanced across a bank but actually feeding from / or mostly from, one battery if not balanced.
 
There are modern battery testers but I still use the old style.
That is a tester where you apply a large load and watch the voltage.
If the voltage holds over a 10 second time period, the battery is good - otherwise I replace it.
And, yes all the batteries in that connected together should all be replaced.

More importantly, you don't seem to have a way of monitoring the battery bank.
I suggest that you fit a Victron BMV monitor.
I fitted one 10 years ago when there was only one option but these days there are a number of Victron battery monitors available.
Essentially, they do the same thing.
Once set up you can then monitor the % full value.
IMO, well worth the small cost of fitting.
Here is a link to a supplier - after a quick Google so you may find a better deal.
https://www.es-store.co.uk/product_...eRZOHZqHQdjp1DtJrbXxCk_n1LkFPaBhoCBi0QAvD_BwE

Do you have a method of determining how much power the fridge freezer consumes - if not, one of these Victron monitors would help.
 
Hurricane said:
There are modern battery testers but I still use the old style.
That is a tester where you apply a large load and watch the voltage.
If the voltage holds over a 10 second time period, the battery is good - otherwise I replace it.
And, yes all the batteries in that connected together should all be replaced.

More importantly, you don't seem to have a way of monitoring the battery bank.
I suggest that you fit a Victron BMV monitor.
I fitted one 10 years ago when there was only one option but these days there are a number of Victron battery monitors available.
Essentially, they do the same thing.
Once set up you can then monitor the % full value.
IMO, well worth the small cost of fitting.
Here is a link to a supplier - after a quick Google so you may find a better deal.
https://www.es-store.co.uk/product_...eRZOHZqHQdjp1DtJrbXxCk_n1LkFPaBhoCBi0QAvD_BwE

Do you have a method of determining how much power the fridge freezer consumes - if not, one of these Victron monitors would help.
Click to expand...


I used a Bosche drop tester.

All passed with flying colours.

No way!

Left if for an hour under load with chargers off. One was far lower than the others - replaced all good.

So testing is not an exact science!
 
IDAMAY said:
Thanks for the advice folks. As Hurricane says I don't have any info on battery condition apart from the very basic voltage meter so I will definitely look at the Victron or similar system. In the meantime it looks like two new batteries are in the offing.
Click to expand...

Are these the batteries you bought in Jersey in 2016 Richard? If so - why dead so soon - charger or shore supply issues?
 
IDAMAY said:
Piers' thread has made me think about battery testing but not wishing to hijack it. I have two linked 12V 180ah AGM batteries. They don't hold charge for more than a couple of hours once off external power from shore or generator. Their base load is a fridge and freezer through an inverter, plus lighting which is almost all LED. When new three seasons ago they would comfortably keep all this running overnight.

It seems clear that one or both batteries are past it. Is there any way in which I can easily find out if it is just one or both that need replacement? For instance would one of the more sophisticated battery testers enable this. For example the Ancel BA101. Or are their other methods?


Thanks for your help.
Click to expand...

Hi Richard. The lessons I've learned over the 16 years we've had Play d'eau, is:

1) An intelligent battery charger is key
2) The charger to have the correct setting for the type of batteries it's charging
3) The batteries all bought at the same time, from the same supplier (so you have batts form the same manufactured batch) - i.e., don't mix and match. Why? The one which is less good will demand a greater charge from the charger which will be applied to all batts, potentially over-charging the better batts

Piers
 
Piers said:
Hi Richard. The lessons I've learned over the 16 years we've had Play d'eau, is:

1) An intelligent battery charger is key
2) The charger to have the correct setting for the type of batteries it's charging
3) The batteries all bought at the same time, from the same supplier (so you have batts form the same manufactured batch) - i.e., don't mix and match. Why? The one which is less good will demand a greater charge from the charger which will be applied to all batts, potentially over-charging the better batts

Piers
Click to expand...

Hi Piers,

Thanks for the advice of your experience. The charger is at least a semi intelligent one being a Mastervolt of roughly 2003 vintage and the batteries are all of the same type and supplied at the same time. However, I take your point about keeping that commonality. They replaced a very funny set up which combined AGM and lead acid which didn't strike me as very smart, particularly as they are located under the bench in the dinette!


Richard.
 
IDAMAY said:
Thanks for the advice folks. As Hurricane says I don't have any info on battery condition apart from the very basic voltage meter so I will definitely look at the Victron or similar system. In the meantime it looks like two new batteries are in the offing.
Click to expand...

The 700 is for a single bank, 702..you guessed..for two banks, I guess for the starter bank. The standard shunt is 500A which they say is adequate for most situations, but they do a larger one if needed. The 712 has bluetooth if you want to use their App.
Doesnt seem many people make this sort of thing?
 
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