Batteries not charging as expected

[DShK]

Okay here are the results. I think I can see the problem.... battery 3 cell 1 is not happy... it was barely above the waterline. Guess that battery is knackered. Is that cell shorting or something else? I think batt3 was the one reading a low voltage compared to it's partner battery. Also I believe it had the most corroded terminals...

 

Also, what am I measuring here? Specific gravity or something?

[Tony Brooks]

If there is a difference of more than 0.03 (Lucas said 0.025) then the battery should be considered as faulty as it should if any cells had coloured liquid in them. However, I would try giving them a good long charge with a mains charger off the boat and retest (because I don't like spending money). So it looks to me as if battery 3 is faulty.

 

Also, a fully charged set of good cells should show between 1.27 and 1.3 so if your batteries are well charged the lower readings suggests they are also sulphated. If you know how, compare the rested voltage implies state of charge with that indicated by the hydrometer/refractometer. The greater the discrepancy, the more the cells are sulphated.

[DShK]

The boat and I are not the marina right now, so they are not currently fully charged. Not deeply discharged but could account for the values being lower. However, between batteries there is a difference between 1.19 and 1.26 - clearly some of them are more healthy than others at least.

 

Unfortunately it's going to be quite hard for me to test on a mains charger off the boat - I live aboard and the nearest house I could do it at is a bit of a journey. Perhaps I could ask the marina if they could do it for me. What do you think the chances of this "sorting" that battery out? And would this cause the symptoms with the charger do you think? Ideally don't want to spend £1000 on new batteries to then need to spend £1500 on a new inverter (sellweb have a 4 week lead time, I can't wait that long - I'd fit a new inverter and sell on my old one when repaired).

[ditchcrawler]

6 minutes ago, DShK said:

The boat and I are not the marina right now, so they are not currently fully charged. Not deeply discharged but could account for the values being lower. However, between batteries there is a difference between 1.19 and 1.26 - clearly some of them are more healthy than others at least.

 

Unfortunately it's going to be quite hard for me to test on a mains charger off the boat - I live aboard and the nearest house I could do it at is a bit of a journey. Perhaps I could ask the marina if they could do it for me. What do you think the chances of this "sorting" that battery out? And would this cause the symptoms with the charger do you think? Ideally don't want to spend £1000 on new batteries to then need to spend £1500 on a new inverter (sellweb have a 4 week lead time, I can't wait that long - I'd fit a new inverter and sell on my old one when repaired).

are 1&2 in series 3& 4 in series 5&6 in series by any chance?

[DShK]

18 minutes ago, ditchcrawler said:

are 1&2 in series 3& 4 in series 5&6 in series by any chance?

Indeed they are

[Tony Brooks]

44 minutes ago, DShK said:

The boat and I are not the marina right now, so they are not currently fully charged. Not deeply discharged but could account for the values being lower. However, between batteries there is a difference between 1.19 and 1.26 - clearly some of them are more healthy than others at least.

 

Unfortunately it's going to be quite hard for me to test on a mains charger off the boat - I live aboard and the nearest house I could do it at is a bit of a journey. Perhaps I could ask the marina if they could do it for me. What do you think the chances of this "sorting" that battery out? And would this cause the symptoms with the charger do you think? Ideally don't want to spend £1000 on new batteries to then need to spend £1500 on a new inverter (sellweb have a 4 week lead time, I can't wait that long - I'd fit a new inverter and sell on my old one when repaired).t

 

Not great I fear (sorting the battery). I would take   3 and 4 out of circuit and see if that sorts the battery charger.

 

You say "off the scale", I assume this something like 1.00 so the difference is 1.26, 3 is faulty.

 

Accepting it is a risk and you are likely to run into more problems sooner rather than later, if removing that pair solves the charger problem you could just replace battery 3.

[magnetman]

I would scrap the batteries then put one battery in there and see how it goes. 

 

At the end of the day it is only batteries. Not a life or death situation and they are all basically nackered.

 

Worth considering a single 100Ah LFP battery. Whatever anyone says, it is an inescapable fact that power you draw from a battery will need to be replaced.

 

 

[DShK]

I'll remove them and see what happens 🙂 If it sorts it I am tempted to take the opportunity to just go lithium. The sterling ones look like they might be a good solution but there are some question marks there in terms of setup - the other option is to get something professionally done - in which case replacing the one battery (or just using the remaining 4) might be a good idea in the meantime.

 

Thanks again for the help!

[magnetman]

Large battery bank is a red herring.

 

At the end of the day all you need to do is have a battery which will supply the daily loads. Nothing more and nothing less.

I'm pretty sure that almost everyone could work their day with about 100Ah of good quality LFP. 

 

The hair dryer and the air fryer and the other tryers may well need a diesel ting.

 

It doesn't actually make any difference what size battery you have as you still need to recharge it. Nothing comes for free here. 

[IanD]

6 minutes ago, DShK said:

I'll remove them and see what happens 🙂 If it sorts it I am tempted to take the opportunity to just go lithium. The sterling ones look like they might be a good solution but there are some question marks there in terms of setup - the other option is to get something professionally done - in which case replacing the one battery (or just using the remaining 4) might be a good idea in the meantime.

 

Thanks again for the help!

Going lithium has many advantages, but also many pitfalls -- especially if you try and do it on the cheap without much knowledge...

 

There are plenty of people on here who can give you invaluable advice if you decide to do this 🙂

[magnetman]

I like the look of the Fogstar battery. 

 

No connection and I don't have one but it looks like an interesting solution.

 

Personally I have quite a lot of Toshiba LTO batteries which will last for a life time but these are knot normal. 

 

Commercially available LFP are worth looking at but I would not wish to comment on Sterling products on account of causing the boat to be boat rocking.

 

[rusty69]

33 minutes ago, magnetman said:

I would scrap the batteries then put one battery in there and see how it goes. 

 

At the end of the day it is only batteries. Not a life or death situation and they are all basically nackered.

 

Worth considering a single 100Ah LFP battery. Whatever anyone says, it is an inescapable fact that power you draw from a battery will need to be replaced.

 

 

Pleeeeease talk me out of buying more cells:

 

 

https://www.ebay.co.uk/itm/364146249565?

 

 

[magnetman]

Just now, rusty69 said:

Pleeeeease talk me out of buying more cells:

 

 

https://www.ebay.co.uk/itm/364146249565?

 

 

I don't advocate DIY battery production. 

 

Don't go there.

 

 

[rusty69]

1 minute ago, magnetman said:

I don't advocate DIY battery production. 

 

Don't go there.

 

 

No, ok. Thanks.

[magnetman]

I did say a "single 100Ah battery" but assumed not all that many people have a 3.25v lighting and domestic appliance system on their boat.

 

If they did then the world would be a better place..

[rusty69]

Just now, magnetman said:

I did say a "single 100Ah battery" but assumed not all that many people have a 3.25v lighting and domestic appliance system on their boat.

 

If they did then the world would be a better place..

Obvs, the OP would need two of these to replace his existing 6V setup <rolls eyes in a southerly direction>

[magnetman]

Can you imagine the joys of not needing a top and bottom balance, LVC, HVC and that is not to mention the awful anxiety of burning the boat to scrap value just because of the batteries. 

 

Anyone who can get all the gear working on 3.25 volts is going to be a rich kid. 

Know what I'm sayin?

 

 

 

[rusty69]

NO. What are you sayin?

[magnetman]

3 minutes ago, rusty69 said:

NO. What are you sayin?

I was like "make 3.25v the line voltage and avoid all the nonsense" 

 

Know what I'm sayin' ?

[rusty69]

No, What are you sayin?

 

 

Sorry, OP, just ignore us, we are a pair of fools. Well, he is. Ignore everything he says, and you'll be fine.

[magnetman]

 

3 minutes ago, rusty69 said:

No, What are you sayin?

 

 

I was pointing out that you don't want to make batteries up from individual cells without being very careful.

 

Maybe I should have elucidated.

 

[DShK]

51 minutes ago, magnetman said:

Large battery bank is a red herring.

 

At the end of the day all you need to do is have a battery which will supply the daily loads. Nothing more and nothing less.

I'm pretty sure that almost everyone could work their day with about 100Ah of good quality LFP. 

 

The hair dryer and the air fryer and the other tryers may well need a diesel ting.

 

It doesn't actually make any difference what size battery you have as you still need to recharge it. Nothing comes for free here. 

Well, I use a fairly powerful PC to do my job. I have a fridge and freezer. A router that is always on, and a hungry combi inverter/charger. I budget about 250aH/day so my 600aH bank is about right.

50 minutes ago, IanD said:

Going lithium has many advantages, but also many pitfalls -- especially if you try and do it on the cheap without much knowledge...

 

There are plenty of people on here who can give you invaluable advice if you decide to do this 🙂

I will definitely ask on here before going that route! Thank you. I was looking at using a B2B charger to avoid the expensive or dodgy alternator charging issues. I don't run my engine just to charge, I use a generator. So I can live with less output from the alternator. I think the things on my mind are is - is a BMS as the only safety feature reasonable - and will my solar keep them at 100% too much? Plus, all the things I haven't thought to consider, I guess

[rusty69]

4 minutes ago, magnetman said:

 

 

I was pointing out that you don't want to make batteries up from individual cells without being very careful.

 

Maybe I should have elucidated.

 

Yea, point taken. Only an idiot would use more than one cell to make a battery bank.

 

Edited February 25, 2023 by rusty69

[magnetman]

2 minutes ago, DShK said:

Well, I use a fairly powerful PC to do my job. I have a fridge and freezer. A router that is always on, and a hungry combi inverter/charger. I budget about 250aH/day so my 600aH bank is about right.

It doesn't make any difference how much power you use. Unless you can replace this using solar panels or a mains electric hookup you will need to use an infernal combustion engine of some sort to get the energy back in to the batteries.

My philosophy is "that which is" and it is an inescapable fact that energy out must be counteracted by energy in.

 

Solar panels do mess with the math as they can provide surplus but don't let them rule your life. 

 

[DShK]

43 minutes ago, magnetman said:

It doesn't make any difference how much power you use. Unless you can replace this using solar panels or a mains electric hookup you will need to use an infernal combustion engine of some sort to get the energy back in to the batteries.

My philosophy is "that which is" and it is an inescapable fact that energy out must be counteracted by energy in.

 

Solar panels do mess with the math as they can provide surplus but don't let them rule your life. 

 

Right, disregarding the solar panels (which when it's sunny more than power everything). If I charge up my batteries with my generator in the morning. I need enough battery capacity to last until the next morning. 50aH available will not last just powering my fridge/freezer, let alone the other bits. I would have to have the generator running the entire day, which I'd rather not do...