LiFePO4 Lithium Batteries - the lazy way

[Naughty Cal]

On 26/02/2022 at 07:15, Naughty Cal said:

Our aim for today's outing in the van is to use as much power as possible and see if we can get ours to actually register a cycle 😀

Funny this post has popped back up again. 

 

We are over 18 months later and still have not clocked up a single cycle according to our Sterling Amps battery!

 

It performs brilliantly for how we use the van but seems to be chronically under used for 3 months of the year.

[wakey_wake]

37 minutes ago, nicknorman said:

Correct, however the powers that be don’t seem to like hybrid systems and my worry is that at some point in the future they will be disallowed by the BSS.

 

Oh, interesting! Do they give any reasons for this? I'm rashly assuming it's rational.

 

I'm uneasy about LFP∥LA, but not in a rational way.  I've stared at the discharge curve of this particular LFP for a while and it matches LA remarkably well... at least at 20°C, and temperature is an important complication.

 

 

37 minutes ago, nicknorman said:

In any case a lead acid battery is not the only means of absorbing the load dump, for example Sterling make a load dump absorber which I presume is just a bank of transient absorbing diodes. And also modern alternators tend to be fitted with avalanche diodes that will also absorb the worst of this transient (but it will still peak at around 30v)

 

I also maintain that a properly constructed charging system doesn’t rely on the battery’s BMS to protect it from overcharging, rather the charging system should cut off or go into a zero current float before the “ultimate protection” of the BMS shut-off kicks in. The latter is then just the emergency backup protection, not the day to day means of charge control.

 

Causing and absorbing load dumps isn't something I want to be doing. It would be sensible to have some safety protection - like having a fuse but less risk of starting a fire without one - but AIUI the transorbs aren't rated for regular repeat performances?

 

And so yes, it makes sense to stop charging before the BMS. Even if only to avoid stressing the battery chemistry, because I suspect the eking out of the last few watt-hours is a false economy; the battery manufacturer hitting the performance rating at minimum cost?

 

So then I need a new alternator already, and this is escalating. If it's going to escalate then I would rather design it in the direction I prefer which is probably B2B charging, instead of patching safety systems on top of each other and hoping they don't "Swiss cheese" on me. https://en.wikipedia.org/wiki/Swiss_cheese_model

 

17 minutes ago, Tony1 said:

If I've understood it (which is by no means certain), there is a question mark over whether a B2B setup will still be acceptable under future regs, even when/if the direct parallel link via long wire gets banned. 

 

🤯 so how does one use a modern battery, in that scenario? Can't run LFP∥LA and can't run LA-B2B-LFP.

 

But the powers that be do want to move us over to electric?

[magnetman]

6 minutes ago, wakey_wake said:

 

 Even if only to avoid stressing the battery chemistry, because I suspect the eking out of the last few watt-hours is a false economy; the battery manufacturer hitting the performance rating at minimum cost?

 

 

I don't think it is eking out the last watt hour I think it is to be able to deceive people into thinking they are a 'drop in' replacement by advertising the maximum charge voltage as similar to LA maximum charge voltage.

 

In reality you don't ideally want to take LFP anywhere near 14.4 volts BUT it will probably be okay until the the warranty runs out after which the supplier is not at all bothered what happens to your batteries. 

 

Cynic? Moi?

 

 

I have small LFP banks as well as some LTO batteries on the boats. I set the LFP to charge (solar is the only charging source) to 13.6v. 

 

 

[Tony1]

11 minutes ago, wakey_wake said:

 

🤯 so how does one use a modern battery, in that scenario? Can't run LFP∥LA and can't run LA-B2B-LFP.

 

But the powers that be do want to move us over to electric?

 

I can only assume that if any type of parallel setup is banned (which to be fair, is far from certain), we will still be permitted to use the alternator controller method- but alternator controllers are maybe £500 or more, plus the cost of fitting- so its easy to imagine people paying £700 or more to get the job done. 

 

But tbh I personally am optimistic that B2B setups will be permitted.

For me, the bigger worry is whether insurance companies or BSS are going to insist on 'professional' installation. Mine was done by two different companies, and added to by me, so its not a straightforward answer, and in any case I no longer have any receipts to prove it was installed by a pro. 

I can only hope that if a 'pro install' requirement emerges, it does not apply retrospectively.

 

Ultimately, if they make it too difficult to have lithiums on board, I have the option of taking out the lithiums and buying lead carbons or something similar, and hopefully in a few more years the panic will have died down and I can put them back in place. 

 

 

[wakey_wake]

9 minutes ago, magnetman said:

I don't think it is eking out the last watt hour I think it is to be able to deceive people into thinking they are a 'drop in' replacement by advertising the maximum charge voltage as similar to LA maximum charge voltage.

There may be several reasons. I was going by the area under this (one cycle discharge only) test I ran:

 

...oh. "There was a problem uploading the file.

Please contact us for assistance."

 

I have a nice discharge curve for a Kepworth 12V 100Ah running 25A±2A into an inverter, a variac to control the draw, and then the immersion heater. The area under curve between 13.8ish and 13.15V is really quite small and the quick and dirty summing up of coulombs tells me the cells in the battery are just big enough to meet the spec. But it was cheap.

 

 

9 minutes ago, magnetman said:

In reality you don't ideally want to take LFP anywhere near 14.4 volts BUT it will probably be okay until the the warranty runs out after which the supplier is not at all bothered what happens to your batteries. 

 

Cynic? Moi?

 

I have small LFP banks as well as some LTO batteries on the boats. I set the LFP to charge (solar is the only charging source) to 13.6v.

 

Another good reason for not letting the BMS terminate the charge, yes.

 

On LTO vs LFP, what are your thoughts?

 

I would prefer LTO because they're even less likely to firework on me, but I'm not seeing them in the cheapskate price range.

[nicknorman]

29 minutes ago, wakey_wake said:

 

Oh, interesting! Do they give any reasons for this? I'm rashly assuming it's rational.

 

One has to bear in mind that people involved in this sort of thing don’t really know what they are talking about and have no practical experience. I suspect it comes from some Li battery manufacturers who specify that the their product must not be mixed with batteries of a different chemistry. A blanket arse covering statement, obviously, and probably aimed at not mixing different types of Li chemistry. Personally I don’t see a problem with mixing Li and LA but it’s not up to me!

[magnetman]

19 minutes ago, wakey_wake said:

There may be several reasons. I was going by the area under this (one cycle discharge only) test I ran:

 

...oh. "There was a problem uploading the file.

Please contact us for assistance."

 

I have a nice discharge curve for a Kepworth 12V 100Ah running 25A±2A into an inverter, a variac to control the draw, and then the immersion heater. The area under curve between 13.8ish and 13.15V is really quite small and the quick and dirty summing up of coulombs tells me the cells in the battery are just big enough to meet the spec. But it was cheap.

 

 

 

Another good reason for not letting the BMS terminate the charge, yes.

 

On LTO vs LFP, what are your thoughts?

 

I would prefer LTO because they're even less likely to firework on me, but I'm not seeing them in the cheapskate price range.

 

Yes they are usually expensive. There was a geyser selling some unused bankrupt stock electric bus LTO modules and he did me a very good deal on them (40Ah nominal 14.4v blocks £80 each). They are Toshiba SCiB cells. He had a shed load of them but I only got a dozen. He sold the rest quite quickly maybe not surprising. 

 

They seem very good. No BMS they seem fine but I've only had them a couple of yars and other than during summer when I am using the electric canoe a lot they don't get many cycles. 

 

Interestingly I wired 5 together and put them to 15.2v about 12 months ago and they still show 15.18. Very little self discharge and good temperature tolerance. 

 

No BMS is a risk but I've run them down to about 6v before and they charge up and take the correct capacity so they seem pretty tolerant. 

 

They are higher voltage I charge them to 15.2v (max is 16.8v).

 

This can be a bit high for some DC equipment but is well within normal inverter voltage ranges. 

 

Also brilliant engine start batteries. 

 

I could have got more to sell later but I doubt other people would want them due to lack of BMS or warranty. 

 

Funny chemistry is LTO. Not light batteries and rather unusual but my impression is they are pretty good. Time will tell. 

 

 

 

 

 

Edited November 4, 2023 by magnetman

[Tony1]

1 hour ago, wakey_wake said:

 

🤯 so how does one use a modern battery, in that scenario? Can't run LFP∥LA and can't run LA-B2B-LFP.

 

But the powers that be do want to move us over to electric?

 

Just another thought- I haven't got much of clue about electrics to be honest, but I believe Nick's suggestion of the Sterling alternator protection device would allow you to charge a B2B directly from the alternator, thus removing the need for a lead acid battery in parallel. 

To my ignorant eye that device seems a bit riskier than using a lead acid battery in parallel, but on the plus side it doesnt cost too much, and it would cope with the surge when the B2B switches itself off (or goes into float). 

I'm tempted to get one and try it out instead of replacing my failing lead acid battery, but one never wants to be the guinea pig in these situations- and especially not when one's alternator might need replacing if it all goes wrong. 

 

There's an old youtube video in which Sterling demo the thing, and tbh it looks pretty good:

 

Edited November 4, 2023 by Tony1

[peterboat]

23 minutes ago, magnetman said:

 

Yes they are usually expensive. There was a geyser selling some unused bankrupt stock electric bus LTO modules and he did me a very good deal on them (40Ah nominal 14.4v blocks £80 each). They are Toshiba SCiB cells. He had a shed load of them but I only got a dozen. He sold the rest quite quickly maybe not surprising. 

 

They seem very good. No BMS they seem fine but I've only had them a couple of yars and other than during summer when I am using the electric canoe a lot they don't get many cycles. 

 

Interestingly I wired 5 together and put them to 15.2v about 12 months ago and they still show 15.18. Very little self discharge and good temperature tolerance. 

 

No BMS is a risk but I've run them down to about 6v before and they charge up and take the correct capacity so they seem pretty tolerant. 

 

They are higher voltage I charge them to 15.2v (max is 16.8v).

 

This can be a bit high for some DC equipment but is well within normal inverter voltage ranges. 

 

Also brilliant engine start batteries. 

 

I could have got more to sell later but I doubt other people would want them due to lack of BMS or warranty. 

 

Funny chemistry is LTO. Not light batteries and rather unusual but my impression is they are pretty good. Time will tell. 

 

 

 

 

 

James?

[magnetman]

It was his friend Roland. 

 

 

[nicknorman]

1 hour ago, Tony1 said:

 

Just another thought- I haven't got much of clue about electrics to be honest, but I believe Nick's suggestion of the Sterling alternator protection device would allow you to charge a B2B directly from the alternator, thus removing the need for a lead acid battery in parallel. 

To my ignorant eye that device seems a bit riskier than using a lead acid battery in parallel, but on the plus side it doesnt cost too much, and it would cope with the surge when the B2B switches itself off (or goes into float). 

I'm tempted to get one and try it out instead of replacing my failing lead acid battery, but one never wants to be the guinea pig in these situations- and especially not when one's alternator might need replacing if it all goes wrong. 

 

There's an old youtube video in which Sterling demo the thing, and tbh it looks pretty good:

 

 

I don't know enough about the Sterling device to know if it is up to repeated use. Probably depends on how close to the diodes' limits a disconnect event gets.

[Naughty Cal]

6 minutes ago, nicknorman said:

 

I don't know enough about the Sterling device to know if it is up to repeated use. Probably depends on how close to the diodes' limits a disconnect event gets.

We have one fitted on the van. I believe it is one use only.

 

We fitted one on the off chance it might save the alternator given that you can't even see the alternator and fitting a new one involves dismantling the front end of the van! 

[Tony1]

5 minutes ago, nicknorman said:

 

I don't know enough about the Sterling device to know if it is up to repeated use. Probably depends on how close to the diodes' limits a disconnect event gets.

 

On that video it looks quite robust- he disconnects the live cable and the current falls to zero, then a few seconds later he reconnects it (just by touching, not securely) and the alternator comes back to life and is charging again. 

I think before I consider using one of these instead of a lead acid, I'll give Sterling a call and see how they feel about repeated use.

Mine is a cheap alternator, but it would still cost £150 plus labour to replace, so I am a bit wary of fixing something that isnt broken and then having a problem. 

But for those who currently have parallel steups, using one of these might offer a solution that will be acceptable to BSS and possible future insurance requirements, so its worth having a look at it. 

 

What encourages me is that test was done when the alternator was putting out I think 160 amps, whereas my alternator would be putting out 50 amps at most.

 

 

[nicknorman]

Just now, Tony1 said:

 

On that video it looks quite robust- he disconnects the live cable and the current falls to zero, then a few seconds later he reconnects it (just by touching, not securely) and the alternator comes back to life and is charging again. 

I think before I consider using one of these instead of a lead acid, I'll give Sterling a call and see how they feel about repeated use.

Mine is a cheap alternator, but it would still cost £150 plus labour to replace, so I am a bit wary of fixing something that isnt broken and then having a problem. 

But for those who currently have parallel steups, using one of these might offer a solution that will be acceptable to BSS and possible future insurance requirements, so its worth having a look at it. 

 

What encourages me is that test was done when the alternator was putting out I think 160 amps, whereas my alternator would be putting out 50 amps at most.

 

 

 

Yes I think it will depend on how much stored energy there is in the alternator vs the capability of the device. A smaller output alternator is going to have less stored energy and so the energy dumped into the device will be less. However (and I suppose depending on what they say) I would be inclined to get another LA battery, maybe a smaller one, and keep the load dump device in a memory reserve for when/if BSS disallows LA Li paralleling.

[Tony1]

6 minutes ago, Naughty Cal said:

We have one fitted on the van. I believe it is one use only.

 

We fitted one on the off chance it might save the alternator given that you can't even see the alternator and fitting a new one involves dismantling the front end of the van! 

 

If you look at the end of the video, he reattaches the charging cable and the alternator comes straight back to life, so it looks encouraging at least- but I would want to have a lot more assurance than a youtube video before I got one of them. 

 

 

1 minute ago, nicknorman said:

 

I would be inclined to get another LA battery, maybe a smaller one, and keep the load dump device in a memory reserve for when/if BSS disallows LA Li paralleling.

 

Yes, I'm sure that's the sensible thing to do.

I would really like to have a definite answer to the question of whether this device is good for repeated use, just in case parallel lead acids are banned even with B2B chargers. 

But such a ban, in the unlikely event that it happens, is still many months away. 

 

My ignorance here is going to make you groan, so I can only apologise, but how about this- could the live feed from the alternator be split into two directions?

So instead of one cable going through a lead acid and thence to a B2B and lithium, instead there would be one cable feeding direct to the B2B, and another cable feed a lead acid? 

So the lead acid in that case is not in parallel, is it?

But could it still act as a buffer for charge if the B2b was disconnected? 

I have a sinking feeling that if it were that simple, it would already be a thing- but its at least worth knowing why my suggested setup wouldnt meet the purported coming regs. 

 

[peterboat]

31 minutes ago, Tony1 said:

 

If you look at the end of the video, he reattaches the charging cable and the alternator comes straight back to life, so it looks encouraging at least- but I would want to have a lot more assurance than a youtube video before I got one of them. 

 

 

 

Yes, I'm sure that's the sensible thing to do.

I would really like to have a definite answer to the question of whether this device is good for repeated use, just in case parallel lead acids are banned even with B2B chargers. 

But such a ban, in the unlikely event that it happens, is still many months away. 

 

My ignorance here is going to make you groan, so I can only apologise, but how about this- could the live feed from the alternator be split into two directions?

So instead of one cable going through a lead acid and thence to a B2B and lithium, instead there would be one cable feeding direct to the B2B, and another cable feed a lead acid? 

So the lead acid in that case is not in parallel, is it?

But could it still act as a buffer for charge if the B2b was disconnected? 

I have a sinking feeling that if it were that simple, it would already be a thing- but its at least worth knowing why my suggested setup wouldnt meet the purported coming regs. 

 

Tony my BSS inspector had a look over my setup, checking for fuses in the correct place, my 2 cutoffs for the drive batteries, one electric one manual and was happy. He knew of nothing in the pipeline about Lithium batteries. My insurance are happy with my Lifepo4s and know it was self installation, I suspect its because they don't burst into flames, I think we are safe for a few years yet

[PeterF]

32 minutes ago, Tony1 said:

 

If you look at the end of the video, he reattaches the charging cable and the alternator comes straight back to life, so it looks encouraging at least- but I would want to have a lot more assurance than a youtube video before I got one of them. 

 

 

 

Yes, I'm sure that's the sensible thing to do.

I would really like to have a definite answer to the question of whether this device is good for repeated use, just in case parallel lead acids are banned even with B2B chargers. 

But such a ban, in the unlikely event that it happens, is still many months away. 

 

My ignorance here is going to make you groan, so I can only apologise, but how about this- could the live feed from the alternator be split into two directions?

So instead of one cable going through a lead acid and thence to a B2B and lithium, instead there would be one cable feeding direct to the B2B, and another cable feed a lead acid? 

So the lead acid in that case is not in parallel, is it?

But could it still act as a buffer for charge if the B2b was disconnected? 

I have a sinking feeling that if it were that simple, it would already be a thing- but its at least worth knowing why my suggested setup wouldnt meet the purported coming regs. 

 

I am not sure that you can run an alternator direct into a B2B, there are many posts on the Victron Community of people trying this and failing as the alternator delivery current and voltage swing about as the dynamics of the B2B charger are faster than those of the alternator causing oscillation. The battery damps all this out by acting as a large capacitor. This is why Sterling do the Alternator to Battery charger which is more costly but has stuff in to mange the alternator current draw without having the battery in place.

[nicknorman]

51 minutes ago, Tony1 said:

 

So instead of one cable going through a lead acid and thence to a B2B and lithium, instead there would be one cable feeding direct to the B2B, and another cable feed a lead acid? 

So the lead acid in that case is not in parallel, is it?

But could it still act as a buffer for charge if the B2b was disconnected? 

I have a sinking feeling that if it were that simple, it would already be a thing- but its at least worth knowing why my suggested setup wouldnt meet the purported coming regs. 

 

 

There is no difference from an electrical point of view, they are still in parallel!

[Tony1]

1 hour ago, PeterF said:

I am not sure that you can run an alternator direct into a B2B, there are many posts on the Victron Community of people trying this and failing as the alternator delivery current and voltage swing about as the dynamics of the B2B charger are faster than those of the alternator causing oscillation. The battery damps all this out by acting as a large capacitor. This is why Sterling do the Alternator to Battery charger which is more costly but has stuff in to mange the alternator current draw without having the battery in place.

 

Thanks for the heads up Peter, its worth knowing that this idea is not going to be an option.

Tbh any ban on parallel Li/LA batteries is probably a few years away anyway (if it happens at all) as PeterB says- so there's no need to rush finding a solution. 

I can say the Sterling A to B charger is not the solution though. I had one, and after I installed the lithiums I found that the A2B did not limit the current to the lithiums in any way, and my alternator overheated.

 

[wakey_wake]

1 hour ago, Tony1 said:

[...] how about this- could the live feed from the alternator be split into two directions?

So instead of one cable going through a lead acid and thence to a B2B and lithium, instead there would be one cable feeding direct to the B2B, and another cable feed a lead acid? 

So the lead acid in that case is not in parallel, is it?

But could it still act as a buffer for charge if the B2b was disconnected? 

I have a sinking feeling that if it were that simple, it would already be a thing- but its at least worth knowing why my suggested setup wouldnt meet the purported coming regs.

 

Your "split in two directions" is basically a small domestic battery with its own alternator, then a B2B off that to charge the LFPs.

That's what I was considering - a third battery bank of LFPs. I would use it for the inverter, which the current LA domestics are not going to enjoy... and to keep the LAs charged.

 

(Wish I could scribble a diagram. Any idea why image uploads don't work? Is that just me? Last one was a 100kb .png )

 

 

1 hour ago, nicknorman said:

There is no difference from an electrical point of view, they are still in parallel!

 

I disagree, there is a B2B between the LA(+) and the LFP(+). They will have a common (-) like everything else on the boat. If the B2B isn't sending current either way, the LA and LFP are disconnected. When it is sending current, they don't have to be at any particular voltage with respect to each other.

 

However if I try to future-proof myself against putative new regs, I may never get off my shoreline!

[nicknorman]

13 minutes ago, wakey_wake said:

 

 

I disagree, there is a B2B between the LA(+) and the LFP(+). They will have a common (-) like everything else on the boat. If the B2B isn't sending current either way, the LA and LFP are disconnected. When it is sending current, they don't have to be at any particular voltage with respect to each other.

 

However if I try to future-proof myself against putative new regs, I may never get off my shoreline!

Yes ok you’re right, but what was under discussion was a proposed change in the way these things were wired up, and my point was that the proposed change in fact made no difference.

[wakey_wake]

37 minutes ago, wakey_wake said:

That's what I was considering - a third battery bank of LFPs. I would use it for the inverter, which the current LA domestics are not going to enjoy... and to keep the LAs charged.

 

Another benefit to 3rd bank: if I make too many cups of tea and carelessly empty the LFPs, I'll still have enough in the LA bank to keep the freezer froze and the lights on for a couple of days. Meanwhile hopefully the sun would shine a bit, and I would've got some panels up to catch it.

 

The downside is complexity (which I'm terrible with) and inefficiencies of B2B charging (in % efficiency of transfer, and in capital outlay) and not wanting to afford a large enough B2B to shift 50A per LFP unit = maybe 200A.

 

Third bank is a bit off the topic of "the lazy way". Replacing the B2B box with a fat (1,2,1+2) isolator switch or contactor to put them in parallel is probably a stepping stone in my plan and hits the lazy spot nicely.