Battery Monitor Shunt Wiring Best Practise

[Robbo]

1 hour ago, Keajre said:

If I put a 1kwh load on the genny (it has two outputs), THEN try to draw a load through the inverter, its fine.  It does pass through.  My theory here is that the inverter calls for far more than the genny can give, expecting an induction load (very high peaks at the start etc) and the genny immediately powers off.  Strange as usually you’d get a red overload light on the genny for 6 seconds before it switches off.  Here, its just switches off straight away.  

If you have a victron combi (as well as other makes) they have a remote that that you can dial in the shore/genny max current provided.   In this case it will dial down the charger amps or assist with power onboard if more power is required then the shore/genny can provide.

Edited February 18, 2018 by Robbo

[nicknorman]

On the fuses, it is abnormal to have a fuse between the domestic battery and the alternator, although not unheard of. Your diagram shows the alternator connected via the switchable side of the domestic isolator, which is BSS compliant. However bear in mind it means that if the engine is running, all the circuits are live (from the alternator) even the isolator has been turned off, say in an emergency eg smoke coming from wiring somewhere. On our boat we have the alternator connected direct to the batteries, albeit via a large 500A fuse. So I think the choice is alternator direct to batteries via fuse, or alternator to the isolator not via own fuse. An alternator fuse rating should be determined by what the cable can take, not the max alternator current. You don’t want the fuse operating near its rating as it will get thermal fatigue and may eventually blow, destroying the alternator in the process.

On the horn wiring, using hull return is a BSS failure. Bearing in mind the horn is only used very occasionally and for short periods, I don’t think it is an issue in practice, but some jobsworth BSS chap might fail you

[nicknorman]

2 hours ago, Keajre said:

Oh the starter battery charge cable coming from the inverter / charger is only a 4amp float current on 4mm cable.  I was going to put a 10a fuse in there, but is it really needed? 

 

Ref starter connection to start batt, I decided to do it via isolator, someone told me it was best practise but I didn’t actually check that myself

Yes it should be fused near the battery. The point is not about the float current, it is about the possibility of 1000 Amps or more that could flow out of the batteries if that wire were to somehow contact hull. Anything connected to a battery +ve is a potential source of huge currents if it should get shorted to hull, so for the same reason the solar wiring +ve should be fused near the batteries.

[nicknorman]

4 hours ago, Keajre said:

Yes I recognise and agree.  Resting voltage after several hours (24 ideally) shows SoC (or the amount of sulphuric acid in the electrolyte).  With a large load being draw, it would go below 12.2 I get that, and that’s ok.  I think 11.8 is too high, I’ll be honest I haven’t checked it recently, I think it is actually lower for those very reasons. 

 

The Trojan manual says to maximise lifespan, don’t discharge to more than 80%.  I assume that means 80% discharged, ie 20% left.  The suggestion seems to be as they are traction batteries you can safely dischartge down to 11.66 volts (resting voltage of course).  I was planning on not discharging below 20% SoC.  So 12.5 if I can help it.  I have seen the graph data showing the massive reduction of cycles you get when discharging to these lower percentages.  

 

The inverter is 3kw.  I generally never pull more than 20-30 amps.  I have a washing machine but I’ll be running a generator for that when I am out cruising.  There are some times when 200 - 250 amps will be pulled, as the Inverter performs its ‘power assist’ mode.  Takes a few seconds to kick in, initially the entire load (iron or washing machine) comes from the inverter as its starts to grab power from the generator.  Genny is a pure sign wave 2.2 (bursts to 2.5) khw.  For some reason, when I have it connected through the shore power line into the inverter, even though it could happily power said device on its own, and even though the inverter is doing ‘pass through’ only at that time, it causes the genny to stall immediately.  If I plug the same load (say washing machine) DIRECTLY into generator, its no problem.  So I have to use the power assist function and do some from batteries and some from Generator, even that sometimes causes the genny to stall.  In those cases I have to setup a separate load to pull from the genny, enough to get its RPM up and delverying current, then try again which usually does it.  Its a real pain. Sorry, going off topic here.

 

Good, my battery box sounds compliant then, thanks.

I think you have mixed up SoC and DoD up a bit there. If you really mean not taking the batteries below 20% DoD (= 80% SoC) that is perhaps not the best strategy, surprisingly. If you look at Trojan’s graphs of cycle life vs discharge depth and do some maths, you will find that unless you discharge beyond 40% SoC / 60% DoD, it is much of a muchness. So for example discharging to 80% SoC gives 3000 cycles. Discharging to 60% SoC (extracting twice as much) gives you 1500 cycles (half as many) and discharging to 40% SoC (three times as much) gives you 1000 cycles (one third as many).

So from the point of view of life, nothing in it. But each time you have to fully charge the batteries, you spend a long time running the genny etc to put in charge at a slow rate (an inevitable function of battery chemistry). So you increase the recharging costs. Of course if all the recharging is done by solar, it doesn’t matter.

[Richard10002]

If it takes a week to discharge to 40% SOC, thus recharging only every 7 days, the batteries will be sulphated in short order.

 

[TheBiscuits]

2 minutes ago, Richard10002 said:

If it takes a week to discharge to 40% SOC, thus recharging only every 7 days, the batteries will be sulphated in short order.

Or the glass is too big (Too much battery capacity for usage profile) 

[Dr Bob]

2 minutes ago, TheBiscuits said:

Or the glass is too big (Too much battery capacity for usage profile) 

Nope. Our bank is 660Ahr and we typically drop to 85% SoC overnight. It is a good solution. This was discussed a few days ago on another thread. For me, the bigger the bank the better.

[nicknorman]

12 minutes ago, Richard10002 said:

If it takes a week to discharge to 40% SOC, thus recharging only every 7 days, the batteries will be sulphated in short order.

 

True, but every other day would be OK.

[Keajre]

22 hours ago, Keajre said:

Other small issue, it says NO circuits should return by the earth (via the hull).  All wires should have two cables for positive and negetive.  Fine, 99% do.  My horn however doesnt.   It comes back via the hull through the earth cable and back to the batteries that way.  Can’t see how that could ever cause an issue.  It states about ‘electolytic’ and suggests about personal safety.  Can’t see the harm in it personally 

Any thoughts on this?  (IGNORE, Already answered by Nick Norman . . . . 

Edited February 19, 2018 by Keajre

[Keajre]

17 hours ago, nicknorman said:

On the fuses, it is abnormal to have a fuse between the domestic battery and the alternator, although not unheard of. Your diagram shows the alternator connected via the switchable side of the domestic isolator, which is BSS compliant. However bear in mind it means that if the engine is running, all the circuits are live (from the alternator) even the isolator has been turned off, say in an emergency eg smoke coming from wiring somewhere. On our boat we have the alternator connected direct to the batteries, albeit via a large 500A fuse. So I think the choice is alternator direct to batteries via fuse, or alternator to the isolator not via own fuse. An alternator fuse rating should be determined by what the cable can take, not the max alternator current. You don’t want the fuse operating near its rating as it will get thermal fatigue and may eventually blow, destroying the alternator in the process.

On the horn wiring, using hull return is a BSS failure. Bearing in mind the horn is only used very occasionally and for short periods, I don’t think it is an issue in practice, but some jobsworth BSS chap might fail you

Ye I’ll leave the horn, its 55ft away and veery old wiring, I agree with your sentiment on this, probably an ok one to leave as it.

OK, its a 75 amp alternator with a 50mm2 cable.  If the isolator was on and the alternator cable somehow touched earth, then the 400A fuse would protect it.  If the isolator was in the off position however, then nothing protects it, but its an incredibly unlikely scenarios I’m thinking.

11 hours ago, Richard10002 said:

If it takes a week to discharge to 40% SOC, thus recharging only every 7 days, the batteries will be sulphated in short order.

 

Ye I agree,  I would never leave my batteries at 40% SoC.  In fact, I would never let them get that low intentionally. 

11 hours ago, Dr Bob said:

Nope. Our bank is 660Ahr and we typically drop to 85% SoC overnight. It is a good solution. This was discussed a few days ago on another thread. For me, the bigger the bank the better.

I agree, I have 520 AH, was 330 before.  I think the more you have, the less you have to deep cycle the batteries.  Trojan say you can discharge down to 20% (80% depth of discharge) but I just cant see how that is a good idea.  Just asking to sulphur the plates surely? 

[nicknorman]

10 minutes ago, Keajre said:

I agree, I have 520 AH, was 330 before.  I think the more you have, the less you have to deep cycle the batteries.  Trojan say you can discharge down to 20% (80% depth of discharge) but I just cant see how that is a good idea.  Just asking to sulphur the plates surely? 

Sulphation occurs over time with discharged batteries. So if you take the batteries down to 20% SoC over a day or two then recharge, then there won’t be any significant sulphation. But if you leave it like that for a week, there would be. So it just depends on how much charge you use daily. For example, if you intended to use 40% of capacity in a 24 hr period, it would be wasteful to discharge to 80%, recharge in the morning, then discharge to 80% again and recharge in the evening. Better just to take it down to 60% and then recharge once a day.

Edited February 19, 2018 by nicknorman

[Keajre]

17 hours ago, nicknorman said:

I think you have mixed up SoC and DoD up a bit there. If you really mean not taking the batteries below 20% DoD (= 80% SoC) that is perhaps not the best strategy, surprisingly. If you look at Trojan’s graphs of cycle life vs discharge depth and do some maths, you will find that unless you discharge beyond 40% SoC / 60% DoD, it is much of a muchness. So for example discharging to 80% SoC gives 3000 cycles. Discharging to 60% SoC (extracting twice as much) gives you 1500 cycles (half as many) and discharging to 40% SoC (three times as much) gives you 1000 cycles (one third as many).

So from the point of view of life, nothing in it. But each time you have to fully charge the batteries, you spend a long time running the genny etc to put in charge at a slow rate (an inevitable function of battery chemistry). So you increase the recharging costs. Of course if all the recharging is done by solar, it doesn’t matter.

Interesting, so 80% SoC (20%DoD) means you get circa 3000 cycles, but then you pay out having to run engine / genny which also has its own assigned running costs to consider.  If your practise is to discharge down to 60% SoC (40% DoD) then you’d only get 1500 cycles, but you dont run the genny / engine as much and you get to pull more amps out each time.  There is a fine balance there.  Like you say, if you’re solar and its summer, then shallow cycles are best.  But if you are charging with an engine of some kind, then having to run for long periods through the absorbion cycle has a cost (and annoyance) implication.  

 

It says don’t discharge below 80% DoD which would be 20% SoC, 11.66 volts (resting).  Is that right?  It cant be!  See the statement from Trojan above.  Def says 80% DoD which is 20% SoC.

5 minutes ago, nicknorman said:

Sulphation occurs over time with discharged batteries. So if you take the batteries down to 20% SoC over a day or two then recharge, then there won’t be any significant sulphation. But if you leave it like that for a week, there would be. So it just depends on how much charge you use daily. For example, if you intended to use 40% of capacity in a 24 hr period, it would be wasteful to discharge to 80%, recharge in the morning, then discharge to 80% again and recharge in the evening. Better just to take it down to 60% and then recharge once a day.

OIC, so its a gradual thing ok.  I kind of thought even one day of say 40% SoC would damage batteries.  Trojan say to equalise once a month, but doesnt that also wear out the plates and cause the insulation between them to fall to the bottom of the battery?

[Keajre]

18 hours ago, Robbo said:

If you have a victron combi (as well as other makes) they have a remote that that you can dial in the shore/genny max current provided.   In this case it will dial down the charger amps or assist with power onboard if more power is required then the shore/genny can provide.

Yes I have confgured all of these settings via Ethernet connection to the unit.  Makes no difference, even spoken to Victron who weren’t able to solve the problem.

[Alan de Enfield]

11 minutes ago, Keajre said:

Interesting, so 80% SoC (20%DoD) means you get circa 3000 cycles, but then you pay out having to run engine / genny which also has its own assigned running costs to consider.  If your practise is to discharge down to 60% SoC (40% DoD) then you’d only get 1500 cycles, but you dont run the genny / engine as much and you get to pull more amps out each time.  There is a fine balance there.  Like you say, if you’re solar and its summer, then shallow cycles are best.  But if you are charging with an engine of some kind, then having to run for long periods through the absorbion cycle has a cost (and annoyance) implication.  

As far as I know, if you have used (say) 200Ah then 200Ah +15% must be replaced, the charge time for the last 10% will be pretty much the same (many hours), and it will take longer to get from 40% SoC to 80% SoC than it would from 60% SoC to 80% SoC (but not twice as long)

On purely financial grounds I am sure you can work out the costs of 'battery life' Vs generator / fuel costs, but is it worth it ?

Batteries are disposable items and there is no need to adapt your life around the batteries - accept that if you want a 'life' then you will need to replace them, if your idea of fun is crawling in the engine hole every few hours to talk to them, give them a bed-time story and wrap them up then that's what you should do.

If you can get (say) 2 years out of 5x £60 batteries (and £10 each from the scrap man when you dispose of them) that's a cost of £2.50 per week.

[nicknorman]

30 minutes ago, Keajre said:

Interesting, so 80% SoC (20%DoD) means you get circa 3000 cycles, but then you pay out having to run engine / genny which also has its own assigned running costs to consider.  If your practise is to discharge down to 60% SoC (40% DoD) then you’d only get 1500 cycles, but you dont run the genny / engine as much and you get to pull more amps out each time.  There is a fine balance there.  Like you say, if you’re solar and its summer, then shallow cycles are best.  But if you are charging with an engine of some kind, then having to run for long periods through the absorbion cycle has a cost (and annoyance) implication.  

 

It says don’t discharge below 80% DoD which would be 20% SoC, 11.66 volts (resting).  Is that right?  It cant be!  See the statement from Trojan above.  Def says 80% DoD which is 20% SoC.

OIC, so its a gradual thing ok.  I kind of thought even one day of say 40% SoC would damage batteries.  Trojan say to equalise once a month, but doesnt that also wear out the plates and cause the insulation between them to fall to the bottom of the battery?

Yes you can discharge to 20% SoC / 80% DoD if you want to. Battery life will be reduced if you do it repeatedly, but not drastically so. This is the point of semi traction “deep cycle” batteries. But as we’ve said, the important thing is not to leave the batteries in a low SoC for a prolonged period.

Trojan publish some contradictory advice about equalising, depending on which of their documents you read. In another document, it says to equalise only when the fully charged specific gravity fails to reach 1.277 or there is excessive split between cells (>0.030 IIRC). So I don’t equalise routinely, only when necessary. And if you recharge properly, it is rarely necessary. I find it is necessary in winter occasionally as we mostly charge via the alternator which is not temperature compensated. If we charged at the correct voltage for the battery temperature, I doubt it would ever be needed.

The only other thing to bear in mind is that the SoC and DoD we are talking about, is not a direct analogue of energy extracted. So the energy obtained by going from 100% to 90% SoC is much more than that obtained by going from 30% to 20% SoC - because in the latter case, the voltage is much lower and the energy is the charge multiplied by the voltage. Another way of looking at it is that for a constant power device like a fridge or an inverter, the SoC will fall off more rapidly at lower SoCs, for a given load.

17 minutes ago, Alan de Enfield said:

As far as I know, if you have used (say) 200Ah then 200Ah +15% must be replaced, the charge time for the last 10% will be pretty much the same (many hours), and it will take longer to get from 40% SoC to 80% SoC than it would from 60% SoC to 80% SoC (but not twice as long)

On purely financial grounds I am sure you can work out the costs of 'battery life' Vs generator / fuel costs, but is it worth it ?

Batteries are disposable items and there is no need to adapt your life around the batteries - accept that if you want a 'life' then you will need to replace them, if your idea of fun is crawling in the engine hole every few hours to talk to them, give them a bed-time story and wrap them up then that's what you should do.

If you can get (say) 2 years out of 5x £60 batteries (and £10 each from the scrap man when you dispose of them) that's a cost of £2.50 per week.

Your “15%” is a bit pessimistic, but anyway a relevant point is that most of that inefficiency is towards the end of the charging process. So charging from 60% to 80% is more efficient than charging from 80% to 100%.

[Robbo]

1 hour ago, Keajre said:

Yes I have confgured all of these settings via Ethernet connection to the unit.  Makes no difference, even spoken to Victron who weren’t able to solve the problem.

If you use the shore power input for your genny and set the settings for the genny it doesn’t make a difference as you need the remote control, and Auto Transfer Switch to automatically set the limit.

[Dr Bob]

1 hour ago, Alan de Enfield said:

Batteries are disposable items and there is no need to adapt your life around the batteries - accept that if you want a 'life' then you will need to replace them, if your idea of fun is crawling in the engine hole every few hours to talk to them, give them a bed-time story and wrap them up then that's what you should do.

If you can get (say) 2 years out of 5x £60 batteries (and £10 each from the scrap man when you dispose of them) that's a cost of £2.50 per week.

My strategy is to read them a bed time story and have a cost of £1.00 per week. The duck likes the stories as well. Kills two birds with one stone.

[Alan de Enfield]

18 minutes ago, Dr Bob said:

Kills two birds with one stone.

RSPB notified and now looking for a boat called K. Harris skippered by a 'muppet'

[Dr Bob]

4 minutes ago, Alan de Enfield said:

RSPB notified and now looking for a boat called K. Harris skippered by a 'muppet'

I donate the other £1.50 a week saved to the RSPB!

[Keajre]

 

3 hours ago, Alan de Enfield said:

As far as I know, if you have used (say) 200Ah then 200Ah +15% must be replaced, the charge time for the last 10% will be pretty much the same (many hours), and it will take longer to get from 40% SoC to 80% SoC than it would from 60% SoC to 80% SoC (but not twice as long)

On purely financial grounds I am sure you can work out the costs of 'battery life' Vs generator / fuel costs, but is it worth it ?

Batteries are disposable items and there is no need to adapt your life around the batteries - accept that if you want a 'life' then you will need to replace them, if your idea of fun is crawling in the engine hole every few hours to talk to them, give them a bed-time story and wrap them up then that's what you should do.

If you can get (say) 2 years out of 5x £60 batteries (and £10 each from the scrap man when you dispose of them) that's a cost of £2.50 per week.

Depends how you pull those 200 amps out I guess.  Peukerts equastion and all that.  Take 200AH’s out with 50 amp load and you’ll be putting a lot more amps back in during the charge phase than if your initial load was only 10 amps (hence the C ratings).  The higher the load the less capacity can be withdrawn but also the lower the SoC will be at the end of the load phase for a given number of amps (200 eg).  I suppose you mean a standard draw with lights and water pump, typical usage conditions.  

I wasn’t planning on working out costings down to that level of detail.  I think trying to avoid a DoD of no more than 40% (60% SoC) sounds about good to me (around 12.2 resting voltage).  

No plans to read them a bedtime story, but I think its useful to properly understand batteries in order to help preserve them.  I have had many conversations with boaters about batteries over the years.  Seems there are two main paradigms  A) Buy cheapies and dont care too much, replace after 2 years B ) get decent ones, spend a few more quid and get a few more years out of them.  Some people think the traction batteries are a myth, no better etc, I think they are mis-informed. 

I started with cheapies, lorry batteries actually (the previous owner) which was completely wrong as they have a different plate structure, no good for remaining in a discharged state (well neither are leisure’s / domestics really, but they cope a little better due to a thicker plate construction) .  Then I had three cheapies which I bought to replace the lorry ones.  They were crap.  £80 each x3 110AH each.  After no time at all, I was down to less than 50% capacity.

So now I have x4 Trojans (260AH for a pair) so we’ll see as they are brand new, and not finished the cabling yet.  But I think they will last me a good few years, even without bedtime stories 

Edited February 19, 2018 by Keajre

[Dr Bob]

20 minutes ago, Keajre said:

 

Seems there are two main paradigms  A) Buy cheapies and dont care too much, replace after 2 years B ) get decent ones, spend a few more quid and get a few more years out of them.  Some people think the traction batteries are a myth, no better etc, I think they are mis-informed. 
 

There is another option. Buy cheapies and look after them. It doesn't take too much effort to keep an eye on them so they last longer. Buy double the amount and they need far less attention and the DoD is far less.

[nicknorman]

56 minutes ago, Keajre said:

 

Depends how you pull those 200 amps out I guess.  Peukerts equastion and all that.  Take 200AH’s out with 50 amp load and you’ll be putting a lot more amps back in during the charge phase than if your initial load was only 10 amps (hence the C ratings).  The higher the load the less capacity can be withdrawn but also the lower the SoC will be at the end of the load phase for a given number of amps (200 eg).  I suppose you mean a standard draw with lights and water pump, typical usage conditions.  

I wasn’t planning on working out costings down to that level of detail.  I think trying to avoid a DoD of no more than 40% (60% SoC) sounds about good to me (around 12.2 resting voltage).  

No plans to read them a bedtime story, but I think its useful to properly understand batteries in order to help preserve them.  I have had many conversations with boaters about batteries over the years.  Seems there are two main paradigms  A) Buy cheapies and dont care too much, replace after 2 years B ) get decent ones, spend a few more quid and get a few more years out of them.  Some people think the traction batteries are a myth, no better etc, I think they are mis-informed. 

I started with cheapies, lorry batteries actually (the previous owner) which was completely wrong as they have a different plate structure, no good for remaining in a discharged state (well neither are leisure’s / domestics really, but they cope a little better due to a thicker plate construction) .  Then I had three cheapies which I bought to replace the lorry ones.  They were crap.  £80 each x3 110AH each.  After no time at all, I was down to less than 50% capacity.

So now I have x4 Trojans (260AH for a pair) so we’ll see as they are brand new, and not finished the cabling yet.  But I think they will last me a good few years, even without bedtime stories 

No - to your description of Peukert. You don’t lose charge when you discharge fast, some capacity is merely temporarily unavailable. If you take out 200AH fast, you have to put back the same charge as if you took out 200AH slowly (ie 200AH plus about 5%). Well possibly there is a tiny difference due to gassing, but insignificant.

Peukert describes a loss of capacity that is only relevant if you continue to discharge the batteries at a high rate until they are notionally flat. But the “lost” charge is not lost, it is just sleeping! If you let it rest for a while, the “lost” charge can be recovered.

What is different between fast and slow discharge is the energy available. So 200AH taken out fast, gives you less energy than 200AH taken out slowly, because in the former case the voltage was lower (and as I said earlier, Energy = charge x voltage).

Edited February 19, 2018 by nicknorman

[David Mack]

On 2/18/2018 at 10:32, Keajre said:

The one thing I might have a problem with is the ventilation.  Batteries are in a newly made battery box.  The back is open, so lots of ventilation there, but the no actual vents anywhere in the engine bay. 

So where does the engine get its combustion air from?

I suspect that in reality you have more than enough ventilation.

23 hours ago, nicknorman said:

On the horn wiring, using hull return is a BSS failure. Bearing in mind the horn is only used very occasionally and for short periods, I don’t think it is an issue in practice, but some jobsworth BSS chap might fail you

No, its only an advisory, not a failure. So while it is not to be recommended,  the jobsworth doesn't have grounds to fail you.  That said, how difficult would it be to isolate the horn from the boat steelwork and provide a separate earth connection?

[WotEver]

12 minutes ago, David Mack said:

No, its only an advisory, not a failure. So while it is not to be recommended,  the jobsworth doesn't have grounds to fail you.

Not according to 3.7 of the BSS check list:

”Is the electrical system insulated from the hull?

Check any wiring that can be seen to a suitable device such as a horn, headlamp, or navigation light for the presence of a two‐wire insulated cable.

Electrical systems using the hull as a conductor will not pass this check.”

Edited February 19, 2018 by WotEver
Extra info

[Keajre]

30 minutes ago, David Mack said:

So where does the engine get its combustion air from?

I suspect that in reality you have more than enough ventilation.

No, its only an advisory, not a failure. So while it is not to be recommended,  the jobsworth doesn't have grounds to fail you.  That said, how difficult would it be to isolate the horn from the boat steelwork and provide a separate earth connection?

The engine breaths through the gaps in the deck boards, there are 4 boards and non are air tight so hopefully there is plenty of ventilation. 

 

Well its just getting to the wiring that’s the tricky part.  Not sure where the earth bus bars are, behind walls probably.  Could run a length of cable for its return but it would be 15 metres long.  Probably just leave it.

21 minutes ago, WotEver said:

Not according to 3.7 of the BSS check list:

”Is the electrical system insulated from the hull?

Check any wiring that can be seen to a suitable device such as a horn, headlamp, or navigation light for the presence of a two‐wire insulated cable.

Electrical systems using the hull as a conductor will not pass this check.”

My last BSS survey merely lifted up the deck boards, had a brief 10 second look and passed it all hahaha

55 minutes ago, nicknorman said:

No - to your description of Peukert. You don’t lose charge when you discharge fast, some capacity is merely temporarily unavailable. If you take out 200AH fast, you have to put back the same charge as if you took out 200AH slowly (ie 200AH plus about 5%). Well possibly there is a tiny difference due to gassing, but insignificant.

Peukert describes a loss of capacity that is only relevant if you continue to discharge the batteries at a high rate until they are notionally flat. But the “lost” charge is not lost, it is just sleeping! If you let it rest for a while, the “lost” charge can be recovered.

What is different between fast and slow discharge is the energy available. So 200AH taken out fast, gives you less energy than 200AH taken out slowly, because in the former case the voltage was lower (and as I said earlier, Energy = charge x voltage).

I stand corrected, I dont mind being wrong