Batteries not charging as expected

[Tony Brooks]

6 minutes ago, DShK said:

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...

 

If that 50Ah is 50% of a 100Ah lithium battery, then the only 50% discharge "rule" no longer applies. You are unlikely to get ;lithiums to 100% very often because of the possibility of damage, but you could take them down to close to fully discharged, so work on about 80% of battery capacity, but then you need to factor in the cost of the charging and protection systems you will need to prevent damage to lithium cells.

[DShK]

Yeah, I was looking at a smaller bank of maybe 300-400aH for a lithium setup, working on that I can use 80% rather than 50% of their capacity. It's the safety/protection systems I think I would need the most input on. EG, how do I stop my solar panels keeping them at 100% too much (perhaps I can set something up to dump load into my water heater), is a BMS alone good enough for most cut-offs, and if not what other systems should I look to have.

 

I'd look to wire my solar and charger into the lithiums, then use a DC-DC charger from the starter for the alternator. This would have the advantage that I could get rid of my smartbank, which I hate because the relay makes a horrendous squealing sound. I guess this setup still has the chance to overheat my alternator, but worst case is I can reduce the current pull of the charger. Perhaps not as good a solution as a proper alternator controller, but lots cheaper and I don't run my engine just to charge anyway.

[Tony Brooks]

Don't ask me, hopefully @nicknorman will be along to put you right.

 

 

[ditchcrawler]

2 minutes ago, DShK said:

Yeah, I was looking at a smaller bank of maybe 300-400aH for a lithium setup, working on that I can use 80% rather than 50% of their capacity. It's the safety/protection systems I think I would need the most input on. EG, how do I stop my solar panels keeping them at 100% too much (perhaps I can set something up to dump load into my water heater), is a BMS alone good enough for most cut-offs, and if not what other systems should I look to have.

 

I'd look to wire my solar and charger into the lithiums, then use a DC-DC charger from the starter for the alternator. This would have the advantage that I could get rid of my smartbank, which I hate because the relay makes a horrendous squealing sound. I guess this setup still has the chance to overheat my alternator, but worst case is I can reduce the current pull of the charger. Perhaps not as good a solution as a proper alternator controller, but lots cheaper and I don't run my engine just to charge anyway.

Why do people feel a third party device would be more reliable than what the manufacturers fit to protect their batteries 

[Tony Brooks]

2 minutes ago, ditchcrawler said:

Why do people feel a third party device would be more reliable than what the manufacturers fit to protect their batteries 

 

I suspect because people want to charge lithiums and LAs from one charge source whereas ideally they need different voltage settings, hence the need for intermediate gizmos.

[rusty69]

7 minutes ago, ditchcrawler said:

Why do people feel a third party device would be more reliable than what the manufacturers fit to protect their batteries 

Because some people believe the BMS should be used as a battery protection device, not a, charge controller. 

 

Some, of course, do not. 

[DShK]

Yeah I have read varying opinions on this on here. One guy wanted like 5 levels of security on top of the BMS. I'd just like to get an idea of what people consider sensible. I'd consider getting four counties marine to do an install for me if the sterling solution isn't safe/worthwhile. But I like to do my own work where I can 🙂

 

I noticed @TheBiscuits made a thread about installing the sterling power lithiums a year ago, I wonder how he's got on with them.

[MtB]

46 minutes ago, ditchcrawler said:

It's the safety/protection systems I think I would need the most input on. EG, how do I stop my solar panels keeping them at 100% too much (perhaps I can set something up to dump load into my water heater), is a BMS alone good enough for most cut-offs, and if not what other systems should I look to have.

 

You are right to be stressing about this. Li batts don't like being held fully charged for months on end, they like being cycled up and down. There are no proprietary products on the market to do this yet which puzzles me greatly as Li batts like being deeply discharged then almost fully recharged, over and over again as the normal usage cycle.

 

I think Rusty had configured a Victron AH counter thing to turn the solar charge on when the batts get down to a low SOC then off again once they are near fully charged, but I'm not clever enough to do that yet. Mebbe you are! 

 

Oh hang on, maybe it was Tony1.

 

 

[rusty69]

3 minutes ago, MtB said:

I think Rusty had configured a Victron AH counter thing to turn the solar charge on when the batts get down to a low SOC

Not me. I'm not that clever. 

[DShK]

I should be able to have my shunt and inverter communicate based on SoC (amp counting - seems better than voltage on lithium?) and turn on the second AC output for the water heater. I'd need to install a second RCD and a new socket.

[ditchcrawler]

1 hour ago, MtB said:

 

You are right to be stressing about this. Li batts don't like being held fully charged for months on end, they like being cycled up and down. There are no proprietary products on the market to do this yet which puzzles me greatly as Li batts like being deeply discharged then almost fully recharged, over and over again as the normal usage cycle.

 

I think Rusty had configured a Victron AH counter thing to turn the solar charge on when the batts get down to a low SOC then off again once they are near fully charged, but I'm not clever enough to do that yet. Mebbe you are! 

 

Oh hang on, maybe it was Tony1.

 

 

Mine get a 50% discharge every night, minimum

 

[TheBiscuits]

2 hours ago, DShK said:

I noticed @TheBiscuits made a thread about installing the sterling power lithiums a year ago, I wonder how he's got on with them.

 

Very well, although I had to replace one because the Bluetooth module packed up!  The battery was working fine but the communication module had failed. I didn't really care as I have other battery monitoring, but it was an expensive battery and is still under the 5 year warranty.

 

Sterling gave their usual no quibble replacement -  I happened to be passing Droitwich so I called in with the broken battery, they threw it on their test rig, confirmed the battery was fine but the Bluetooth bit wasn't and swapped it for a brand new one that they opened the box and tested in front of me.

 

I did ask how much they wanted for the "broken" one to buy back after they had given me a new one ....

[IanD]

17 hours ago, Tony Brooks said:

 

If that 50Ah is 50% of a 100Ah lithium battery, then the only 50% discharge "rule" no longer applies. You are unlikely to get ;lithiums to 100% very often because of the possibility of damage, but you could take them down to close to fully discharged, so work on about 80% of battery capacity, but then you need to factor in the cost of the charging and protection systems you will need to prevent damage to lithium cells.

With an accurate and properly configured BMS (not always easy for DIY, manufacturers like BMS do it) which controls both charging and discharging from *all* sources in the boat, there is no reason not to take LFP batteries all the way up to 100% SoC or down to 0% regularly, some manufacturers recommend this and it doesn't reduce lifetime.

 

Keeping them at 100% for extended periods is not recommended, but this won't happen on any boat that's being lived on where they get discharged daily. If the boat is laid up for any length of time around 50% SoC is recommended, but this is not critical, anywhere from 30% or so to 70% or so is fine.

Edited February 26, 2023 by IanD

[DShK]

I'll come back to the lithium discussion - just disconnected all but 2 (+ starter) of my batteries.

 

A quick test - solar disconnected, generator putting in 20 amps, seems to be stuck at 13.9v

Solar connected, generator disconnected - solar happy to put in 30 amps, voltage 14-14.4v

 

I think I might have both a duff battery AND a duff combi. My boat is cursed 😄 I think it's time to load up the credit card and just rip it all out... I was planning to redo a lot of it over the next 2 weeks between jobs anyway, I wasn't expecting to have to replace all of the costly bits...🙃

[rusty69]

1 minute ago, DShK said:

I'll come back to the lithium discussion - just disconnected all but 2 (+ starter) of my batteries.

 

A quick test - solar disconnected, generator putting in 20 amps, seems to be stuck at 13.9v

Solar connected, generator disconnected - solar happy to put in 30 amps, voltage 14-14.4v

 

I think I might have both a duff battery AND a duff combi. My boat is cursed 😄 I think it's time to load up the credit card and just rip it all out... I was planning to redo a lot of it over the next 2 weeks between jobs anyway, I wasn't expecting to have to replace all of the costly bits...🙃

Is the starter battery in circuit in good condition?

[DShK]

Couldn't test it before as it seems to be sealed. I'll remove it from the circuit and try again. However it seems to me that if removing the other batteries doesn't change anything, the fact the solar and alternator seem to have no trouble seems pretty damning on the charger to me...

[MtB]

37 minutes ago, DShK said:

I think I might have both a duff battery AND a duff combi. My boat is cursed 😄 I think it's time to load up the credit card and just rip it all out... I was planning to redo a lot of it over the next 2 weeks between jobs anyway, I wasn't expecting to have to replace all of the costly bits...🙃

 

I'd say it is time to stop being a bull-in-a-china-shop about it and do some structured fault-tracing. Actually diagnose and isolate the fault(s) before making the decision to rip it all out.

 

But if you do just rip it out, can I have all bits please? I'm sure most of it will be fine! 

[DShK]

I think I have diagnosed it? I have both a duff battery (could be put off dealing with fully now by removing it) and a charger which needs looking at by a professional. The solar and alternator charge fine so it's clearly this unit that is problematic.

 

I could bodge it but considering I already am sort of paying for the electrical work to be done by not having employment for 2 weeks anyway (specifically to rework the rats nest electrics) And I want to get this system done so I can actually start continuously cruising without -too- much worry after almost a year in the marina.

 

The only thing I would be doing that I wouldn't do eventually anyway is swapping the combi unit. I'll have it looked and, repaired and sell it on.

 

Do let me know what I've missed in terms of diagnosing the issue though. 

 

Oh I removed the starter battery and still no better

Edited February 26, 2023 by DShK

[ditchcrawler]

25 minutes ago, DShK said:

I think I have diagnosed it? I have both a duff battery (could be put off dealing with fully now by removing it) and a charger which needs looking at by a professional. The solar and alternator charge fine so it's clearly this unit that is problematic.

 

I could bodge it but considering I already am sort of paying for the electrical work to be done by not having employment for 2 weeks anyway (specifically to rework the rats nest electrics) And I want to get this system done so I can actually start continuously cruising without -too- much worry after almost a year in the marina.

 

The only thing I would be doing that I wouldn't do eventually anyway is swapping the combi unit. I'll have it looked and, repaired and sell it on.

 

Do let me know what I've missed in terms of diagnosing the issue though. 

 

Oh I removed the starter battery and still no better

So what is the DC voltage AT the battery charger terminals and what is the rating of the battery charger

[DShK]

1 hour ago, ditchcrawler said:

So what is the DC voltage AT the battery charger terminals and what is the rating of the battery charger

13.87 at the charger, 13.85 at the batteries. Charger is rated at 150a but is currently set to 100a

 

 

 

 

 

 

I removed the bridges home made busbar that was bolted into the inverter, to try and remove some more variables. No improvement.  🙃

19 hours ago, TheBiscuits said:

 

Very well, although I had to replace one because the Bluetooth module packed up!  The battery was working fine but the communication module had failed. I didn't really care as I have other battery monitoring, but it was an expensive battery and is still under the 5 year warranty.

 

Sterling gave their usual no quibble replacement -  I happened to be passing Droitwich so I called in with the broken battery, they threw it on their test rig, confirmed the battery was fine but the Bluetooth bit wasn't and swapped it for a brand new one that they opened the box and tested in front of me.

 

I did ask how much they wanted for the "broken" one to buy back after they had given me a new one ....

Good to hear. Can I ask about your setup? One thing I'm not sure about is how solar plays into this. I was worried about the BMS cutting off the MPPT controller when it's fully charged (I read this can blow up the victron controllers) but apparently it shouldn't happen as long as you set the charge voltage to under the cutoff voltage? But then, I'm not sure about sterling's warranty - it says you HAVE to use their DC-DC charge to get the warranty. But I'm not sure if this is just for alternator charging - if I have to put both solar and alternator through the DC-DC charge, I am worried I will have to micro-manage the output % to protect the alternator from overheating, but also getting the most out of the solar when not moving.

 

7 hours ago, IanD said:

With an accurate and properly configured BMS (not always easy for DIY, manufacturers like BMS do it) which controls both charging and discharging from *all* sources in the boat, there is no reason not to take LFP batteries all the way up to 100% SoC or down to 0% regularly, some manufacturers recommend this and it doesn't reduce lifetime.

 

Keeping them at 100% for extended periods is not recommended, but this won't happen on any boat that's being lived on where they get discharged daily. If the boat is laid up for any length of time around 50% SoC is recommended, but this is not critical, anywhere from 30% or so to 70% or so is fine.

This BMS that can control all charge sources - it sounds like a victron battery, which are well out of my budget!

Edited February 26, 2023 by DShK

[TheBiscuits]

2 hours ago, DShK said:

But then, I'm not sure about sterling's warranty - it says you HAVE to use their DC-DC charge to get the warranty. But I'm not sure if this is just for alternator charging

 

Yes, a solar controller set to an appropriate profile is fine by Sterling.  The B2B is for the alternator charging side.

 

I simply followed the installation instructions for the Sterling batteries and B2B - I might monkey about with the system when the warranty has expired but not before then.

 

Alternator - lead acid bank - B2B - lithium bank. 

 

Solar is permanently connected to lead acid bank.

 

The lithium bank is automatically paralleled with the lead acid bank when the engine is not running, there's an isolation switch linked to ignition live that automatically separates the two banks when the key is turned, forcing any alternator charge to go via the B2B to the lithiums. There's also a manual isolator in series with this so I can choose if I want the lithium bank in circuit or not, depending on state of charge of the lithium bank.

 

 

 

[DShK]

1 hour ago, TheBiscuits said:

 

Yes, a solar controller set to an appropriate profile is fine by Sterling.  The B2B is for the alternator charging side.

 

I simply followed the installation instructions for the Sterling batteries and B2B - I might monkey about with the system when the warranty has expired but not before then.

 

Alternator - lead acid bank - B2B - lithium bank. 

 

Solar is permanently connected to lead acid bank.

 

The lithium bank is automatically paralleled with the lead acid bank when the engine is not running, there's an isolation switch linked to ignition live that automatically separates the two banks when the key is turned, forcing any alternator charge to go via the B2B to the lithiums. There's also a manual isolator in series with this so I can choose if I want the lithium bank in circuit or not, depending on state of charge of the lithium bank.

 

 

 

 

Okay thanks for explaining! So Sterling are okay with solar being connected directly to their lithiums. You 're connecting to the lead acid. Can I ask why? And why you are paralleling the banks when the engine is not running? To make sure the starter stays topped up when moored up for long periods?

Okay, so I read this article about "Practical Characteristics" of Lithium Iron batteries. It seems pretty damn difficult to manually switch charging off effectively at say 90%. Even worse, that if you hold it there, you also ruin your batteries. It seems like a super difficult situation to deal with. However, the article concludes that "the only place for realistically determining charge termination in a lithium battery system is at the BMS and the BMS should supervise the charging process." Given that sterling give a 5 year warranty on their batteries, I'm thinking that their BMS must be pretty happy terminating charge and re-engaging when appropriate? I think I will ask them, and also make sure it's okay to connect a MPPT controller to them directly.

 

https://nordkyndesign.com/practical-characteristics-of-lithium-iron-phosphate-battery-cells/

[DShK]

Just spoke to Sterling. They reckon lithium iron batteries are perfectly fine to sit at 100% unless you are leaving them for months. Odd! Perhaps because of how the BMS functions? Not sure. Hard to argue with the 5 year warranty though.

[magnetman]

I think a slightly longer warranty would be desirable.

 

with daily cycling 5 years would only be about 1800 charge cycles. LFP batteries can do a lot better than that. Pylontech batteries advertise a cycle life of 7000 cycles. These are 48v "solar system" batteries and require proper install to obtain the warranty. Probably for a good reason.

 

I think because they are 'drop in' replacements there is a compromise on lifespan of the cells with products such as the Sterling batteries.

 

It makes sense. Could be wrong about this but I think sub optijmal conditions will probably shorten the battery life.

 

A lot of people would not be putting daily cycles on their batteries.

Edited February 28, 2023 by magnetman

[rusty69]

Last I looked fogstar were offering 10 years.