Cheap LiFePO4 BMS?

[jetzi]

1 hour ago, nicknorman said:

Yes. The technical term is “knackered”.

 

I think the recent Betas tend to have 45A engine battery alternators, so you probably can’t go up much. Still, 50% is 22.5A which will make a difference. But the cheapest solution would be to get it overhauled and get yourself 50% of 40A, ie 20A extra for you Li battery charging.

 

Presumably it is on the same belt that drives the water pump, so you need something there to keep the water pump spinning, which would mean you can’t run the engine with that alternator away at the repair shop.

The new Beta 38s still have a 40A alternator as standard, the larger engines have bigger. I'm going to ask Beta if it's possible for me to squeeze anything bigger in there (I'm guessing I can't, though). Perhaps they'll also be able to tell me what voltage they're regulated at.

 

Yes the belt is driving something else - I'll take your word for it that it's the water pump, makes sense.

 

What flavour of repair shop would I need to take the alternator to? An auto electrician? Thanks to the solar I could get away with a few days of not running the engine, but I'll also consider replacement which would not leave me up the cut without a paddle. I'd be curious to know how much a repair would save over getting it replaced, a ballpark figure for repair vs replace would be helpful - otherwise I'll call around in the morning.

 

I'm wondering if the overheat problem on the alternator is maybe overblown. A 70A alternator surely should be able to sustain 70A output. So perhaps the correct way really is just ducting and fans to keep them cool, and an emergency alarm / shutoff of course

[nicknorman]

1 hour ago, ivan&alice said:

The new Beta 38s still have a 40A alternator as standard, the larger engines have bigger. I'm going to ask Beta if it's possible for me to squeeze anything bigger in there (I'm guessing I can't, though). Perhaps they'll also be able to tell me what voltage they're regulated at.

 

Yes the belt is driving something else - I'll take your word for it that it's the water pump, makes sense.

 

What flavour of repair shop would I need to take the alternator to? An auto electrician? Thanks to the solar I could get away with a few days of not running the engine, but I'll also consider replacement which would not leave me up the cut without a paddle. I'd be curious to know how much a repair would save over getting it replaced, a ballpark figure for repair vs replace would be helpful - otherwise I'll call around in the morning.

 

I'm wondering if the overheat problem on the alternator is maybe overblown. A 70A alternator surely should be able to sustain 70A output. So perhaps the correct way really is just ducting and fans to keep them cool, and an emergency alarm / shutoff of course

Yes sorry, 40A for a Beta 38 and 45A for a Beta 43. I notice that the current Beta 38s come with a 100A secondary alternator.
 

Yes an auto-electrical place. Sorry I don’t know how much a repair would cost but I wouldn’t think it a lot if you take the alternator to them and collect it again. But piece of string territory I suppose, and it will depend on whether they want work or not. As you say, phone around a bit.

 

No, perceived wisdom is that if you try to take 70A from a 70A alternator for long periods, it won’t last very long. But of course it will last longer if it is spinning fast and in cool ambient air. An engine bay usually doesn’t have nice cool air in it!

Edited May 17, 2020 by nicknorman

[jetzi]

9 minutes ago, nicknorman said:

I notice that the current Beta 38s come with a 100A secondary alternator.

I noticed that too, but I've heard that you can't drive something that large from a V belt like my pulleys are set up for. Also it's a bit harder to justify replacing a working alternator

 

11 minutes ago, nicknorman said:

No, perceived wisdom is that if you try to take 70A from a 70A alternator for long periods, it won’t last very long. But of course it will last longer if it is spinning fast and in cool ambient air. An engine bay usually doesn’t have nice cool air in it!

Is it just the temperature that is the problem? If so, then ducting cool air should be adequate provided the fan is large enough, right?

[Dr Bob]

5 minutes ago, ivan&alice said:

 

 

Is it just the temperature that is the problem? If so, then ducting cool air should be adequate provided the fan is large enough, right?

Small frame alternators like the beta one are not designed to run at full whack for any length of time. They are designed For automotive duty not deep discharge batteries. Read all about them on the marine how to site. 

MP and T&B both burnt their alternators out last year. I stilll hold that you will be safe at 50% of rated value. Cooling helps but will not allow you to run at high output for hours.

If your engine start alternator has gone and you are in RCR, then call them out and get them to fit a new one free, then repair the old one! They don't fix or replace the domestic alternator without charging you.

[Keeping Up]

I'm tempted to limit my Beta 43 domestic alternator by changing to thinner wires. It's rated at 170 amps but gives up to185 amps for a couple of minutes at the moment. It often gives over 100 amps for up to an hour. I've got 4x110 Ah batteries and I'm sure that such a high current shortens their life.

[Dr Bob]

7 minutes ago, Keeping Up said:

I'm tempted to limit my Beta 43 domestic alternator by changing to thinner wires. It's rated at 170 amps but gives up to185 amps for a couple of minutes at the moment. It often gives over 100 amps for up to an hour. I've got 4x110 Ah batteries and I'm sure that such a high current shortens their life.

Nah, that's only 0.25C. Charging at that rate is fine. Not getting back to 100% frequently is the killer. Get some lithiums and you'll be fine.

[nicknorman]

25 minutes ago, Dr Bob said:

Nah, that's only 0.25C. Charging at that rate is fine. Not getting back to 100% frequently is the killer. Get some lithiums and you'll be fine.

I agree with KU in that 100-150A for lead acid batteries does shorten their life somewhat. I certainly found that new LA batteries would take the full 175 (or more) amps for a short while, but after a few months this had dropped to more like 120-130A. As we’ve discussed, not much point in ramming the maximum current into your batteries if you intend to be cruising for 8 hours!
 

Trojan for example recommend 10-13% of capacity, which for our 450Ah bank would be 45 - 60A. Whereas I hit them with 130A+! What I need is a smart alternator controller to limit the current when the intention is to boat all day... And one day I may even be allowed to test it!

[Dr Bob]

10 hours ago, nicknorman said:

I agree with KU in that 100-150A for lead acid batteries does shorten their life somewhat. I certainly found that new LA batteries would take the full 175 (or more) amps for a short while, but after a few months this had dropped to more like 120-130A. As we’ve discussed, not much point in ramming the maximum current into your batteries if you intend to be cruising for 8 hours!
 

Trojan for example recommend 10-13% of capacity, which for our 450Ah bank would be 45 - 60A. Whereas I hit them with 130A+! What I need is a smart alternator controller to limit the current when the intention is to boat all day... And one day I may even be allowed to test it!

Well the high charge rate may have a detrimental effect but that's not the worst of KUs problem...although as I don't know what type of LAs he has, this may be a load of cobblers. If KU sees over 100A for an hour with a 440Ahr bank, then in that hour he is putting in 25-30% capacity less efficiencies. That indicates he must be down to 50% SoC to start with. The risk then is that you don't get back up to 100% as driving the '50%' sites - i.e. Those sterically hindered sites deep in the pores that give up their electroms when down to 50% - is difficult and needs lots of energy...hence the 14.4v or more when cold. If you finsih charge at 97% then getting that 3% back next charge cycle is even worse as sulphation sets in deep in the pores. Charging at a lower rate, i.e. With my 90A alternator putting out 50A will take many hours longer so risks not getting back to 100%. Which is worse? An hour at 100A or sulphation. 

On our boat it had 3 batteries when we got it which meant 50% SoC often. We bought 3 new ones which took it up to 660Ahrs so that was 75%. That would mean less time in bulk and batteries lasting much longer (more than twice as long?)as easier to get the last few percent in.

This of course could start a massive argument but the answer of course is to get some lithiums where all these problems instantly vanish.....which is I guess why we are all reading this thread.

Edited May 18, 2020 by Dr Bob

[peterboat]

17 minutes ago, Dr Bob said:

Well the high charge rate may have a detrimental effect but that's not the worst of KUs problem...although as I don't know what type of LAs he has, this may be a load of cobblers. If KU sees over 100A for an hour with a 440Ahr bank, the in that hour he is putting in 25-30% capacity less efficiencies. That indicates he must be down to 50% SoC to start with. The risk then is that you don't get back up to 100% as driving the '50%' sites - i.e. Those sterically hindered sites deep in the pores that give up their electroms when down to 50% - is difficult and needs lots of energy...hence the 14.4v or more when cold. If you finsih charge at 97% then getting that 3% back next charge cycle is even worse as sulphation sets in deep in the pores. Charging at a lower rate, i.e. With my 90A alternator putting out 50A will take many hours longer so risks not getting back to 100%. Which is worse? An hour at 100A or sulphation. 

On our boat it had 3 batteries when we got it which meant 50% SoC often. We bought 3 new ones which took it up to 660Ahrs so that was 75%. That would mean less time in bulk and batteries lasting much longer (more than twice as long?)as easier to get the last few percent in.

This of course could start a massive argument but the answer of course is to get some lithiums where all these problems instantly vanish.....which is I guess why we are all reading this thread.

The very reason why I dumped leisure batteries for tractions all those years ago, they can handle lower SOC without dying! As soon as I found LifePo4s at the right money I dumped the tractions, and for me its been a life changer 

[Col_T]

Apologies for the slight tangent, but do GEL and AGM batteries sulphate in the same way as wet lead acids? I suspect the answer is yes, but confirmation would be good.

 

As far as reading this thread is concerned, I read it out of pure curiosity - we're not live-aboards and don't use power hungry devices (coffee-makers, hair-driers, etc.) so lithiums don't make sense for us.

[nicknorman]

22 minutes ago, Dr Bob said:

Well the high charge rate may have a detrimental effect but that's not the worst of KUs problem...although as I don't know what type of LAs he has, this may be a load of cobblers. If KU sees over 100A for an hour with a 440Ahr bank, the in that hour he is putting in 25-30% capacity less efficiencies. That indicates he must be down to 50% SoC to start with. The risk then is that you don't get back up to 100% as driving the '50%' sites - i.e. Those sterically hindered sites deep in the pores that give up their electroms when down to 50% - is difficult and needs lots of energy...hence the 14.4v or more when cold. If you finsih charge at 97% then getting that 3% back next charge cycle is even worse as sulphation sets in deep in the pores. Charging at a lower rate, i.e. With my 90A alternator putting out 50A will take many hours longer so risks not getting back to 100%. Which is worse? An hour at 100A or sulphation. 

On our boat it had 3 batteries when we got it which meant 50% SoC often. We bought 3 new ones which took it up to 660Ahrs so that was 75%. That would mean less time in bulk and batteries lasting much longer (more than twice as long?)as easier to get the last few percent in.

This of course could start a massive argument but the answer of course is to get some lithiums where all these problems instantly vanish.....which is I guess why we are all reading this thread.

I think it will depend entirely on how long he runs the engine for. Maybe, like us, he tends to cruise for 8 or so hours a day in which case no problem.
 

LA batteries are strange beasts, normally we recharge fully every day because we are cruising. The current profile is thus familiar to me - starting off at 130-150A, reducing rapidly to perhaps 100A and then a gradual and steady decline. When properly “fully charged” the current will be down to below 1A (~0.25% capacity). If we stop for a couple of days and just give it a top-up charge in the interim, on the next full cruising day the current profile is much lower than usual, with a long period of time spent in the sub-30A range and painfully slow to get the last bit in. Your steric hinderance at play I’m sure (whatever that is, but I can guess!), due to the prolonged time spent not fully charged allowing some of the reaction to reach equilibrium deep inside the plates, vs a less deep reaction in the plates if is left in a low SoC for a shorter time.
 

In other words it’s not just about the lowest SoC reached, it is also about how long it spent at less than full charge.

[Keeping Up]

I'm just using cheap LAs at the moment. During the summer I use probably only 20% of the capacity and cruise most days for 6+ hours so not much of a problem there (and the high current is a shorter duration of course) but in winter yes I hammer them a bit by going down to about 60% before running the engine for hours & hours & hours! I notice all the cheapies seem to hold their capacity about 3 weeks then it declines steadily over the next few months until they stabilise at about 60% of their original. When I had a smaller alternator the capacity didn't start to drop for a few months. Still I get about 3 years from them usually so I'll probably just stick with cheap LAs.

[nicknorman]

11 minutes ago, Col_T said:

Apologies for the slight tangent, but do GEL and AGM batteries sulphate in the same way as wet lead acids? I suspect the answer is yes, but confirmation would be good.

 

As far as reading this thread is concerned, I read it out of pure curiosity - we're not live-aboards and don't use power hungry devices (coffee-makers, hair-driers, etc.) so lithiums don't make sense for us.

No I think gel and AGM batteries are less prone to sulphating, especially AGMs. Gel batteries are very expensive for what they give, their only advantage is that they can be installed in any angle and don’t spill, so good for seagoing boats.

 

Agm batteries in modern cars are typically not fully charged when you turn off the engine, due to the regenerative braking element of modern ECU controlled alternators, and yet they seem to survive.

[Dr Bob]

31 minutes ago, Keeping Up said:

I'm just using cheap LAs at the moment. During the summer I use probably only 20% of the capacity and cruise most days for 6+ hours so not much of a problem there (and the high current is a shorter duration of course) but in winter yes I hammer them a bit by going down to about 60% before running the engine for hours & hours & hours! I notice all the cheapies seem to hold their capacity about 3 weeks then it declines steadily over the next few months until they stabilise at about 60% of their original. When I had a smaller alternator the capacity didn't start to drop for a few months. Still I get about 3 years from them usually so I'll probably just stick with cheap LAs.

Allan, you may be missing the point here. You are likely to be saying to yourself, I replace my LAs every 3 years so around £1000 in a 10 year period. Li's will set me back £1000 ish (ok maybe £1200-£1400). Its a no brainer to stick with LA's.

BUT

you say you are running your engine for hours and hours and hours in the winter. How many hours per week? That's why I put Li's in. With your alternator, you can likely put 120Ahrs back in in 2 periods of engine running of 30 mins - so one hour a day. Lets say it normally takes 3 hours per day for 100 days a year on LA's. That is 200 hrs more engine running between LAs and LIs. That is likely £250 per year on fuel, oil and filters, or add another £100 if you get a little man in to service the engine. Your LA's will be paying back in 3-4 years, you wont have the excess 2hrs of engine noise per day (and neither will you neighbours!) and your electrics will be much happier when running at 13.2V rather than 12.2V.

Just get yourself 480Ahrs of lithiums and bolt them on in parallel to your existing set up. No major surgery required. No more worrying over "am I full"?  With your alternator you could easily get away with 320Ahrs of Li capacity which will bring the total cost to £1000 or less.

[Keeping Up]

It's a bit more complicated, we don't live on the boat during most of the winter - and some of the days even in the winter are spent cruising - so I reckon the payback period may be longer than my projected future boating capabilties. I'll think further on it though.

[peterboat]

2 hours ago, nicknorman said:

No I think gel and AGM batteries are less prone to sulphating, especially AGMs. Gel batteries are very expensive for what they give, their only advantage is that they can be installed in any angle and don’t spill, so good for seagoing boats.

 

Agm batteries in modern cars are typically not fully charged when you turn off the engine, due to the regenerative braking element of modern ECU controlled alternators, and yet they seem to survive.

They do survive well, 12 years and 136k miles is a recent example of a petrol XF the diesels arnt so well lived clearly the heater plugs and higher compression takes its toll. In S Types where it was LAs, petrols would do about 8 years and diesels about 3-4

2 hours ago, Dr Bob said:

Allan, you may be missing the point here. You are likely to be saying to yourself, I replace my LAs every 3 years so around £1000 in a 10 year period. Li's will set me back £1000 ish (ok maybe £1200-£1400). Its a no brainer to stick with LA's.

BUT

you say you are running your engine for hours and hours and hours in the winter. How many hours per week? That's why I put Li's in. With your alternator, you can likely put 120Ahrs back in in 2 periods of engine running of 30 mins - so one hour a day. Lets say it normally takes 3 hours per day for 100 days a year on LA's. That is 200 hrs more engine running between LAs and LIs. That is likely £250 per year on fuel, oil and filters, or add another £100 if you get a little man in to service the engine. Your LA's will be paying back in 3-4 years, you wont have the excess 2hrs of engine noise per day (and neither will you neighbours!) and your electrics will be much happier when running at 13.2V rather than 12.2V.

Just get yourself 480Ahrs of lithiums and bolt them on in parallel to your existing set up. No major surgery required. No more worrying over "am I full"?  With your alternator you could easily get away with 320Ahrs of Li capacity which will bring the total cost to £1000 or less.

Actually Bob 500 squids would have done it with 2 of my valence batteries

[cuthound]

6 hours ago, Col_T said:

Apologies for the slight tangent, but do GEL and AGM batteries sulphate in the same way as wet lead acids? I suspect the answer is yes, but confirmation would be good.

 

As far as reading this thread is concerned, I read it out of pure curiosity - we're not live-aboards and don't use power hungry devices (coffee-makers, hair-driers, etc.) so lithiums don't make sense for us.

In theory yes, because the chemistry is the same. However in practice premium brand AGMs (Lifeline, Rolls, Yuasa etc) seem to last longer than typical leisure batteries.

 

This may be because AGMs have a lower internal resistance and so give and receive higher currents better. They also have much lower self discharge currents

 

However these brands are not cheap, hence semi-traction wet cells like Trojan are better value, but require more maintenance.

My Lifelines are over 12 years old and still have 45% of their original capacity left, but I am not a liveaboard, so they are either on a landline or charged for 6 or so hours a day when we are cruising, hence little scope for sulphation to set in.

 

.

[jetzi]

20 hours ago, Dr Bob said:

If your engine start alternator has gone and you are in RCR, then call them out and get them to fit a new one free, then repair the old one! They don't fix or replace the domestic alternator without charging you.

Do you mean for free as in the labour? The part will be the hard bit to find / expensive bit to buy. I wouldn't have thought RCR would help me with this, since it's not really an emergency as I can charge my starter on my domestic alternator?

 

20 hours ago, Keeping Up said:

limit my Beta 43 domestic alternator by changing to thinner wires.

If this thread has proved anything it's that I'm no electrician but Shirley that won't work - won't the thinner wires just increase the resistance and heat up?

 

9 hours ago, Dr Bob said:

Just get yourself 480Ahrs of lithiums and bolt them on in parallel to your existing set up. No major surgery required. No more worrying over "am I full"?  With your alternator you could easily get away with 320Ahrs of Li capacity which will bring the total cost to £1000 or less.

Although I'm sold on the lithiums for my use case and absolutely cannot wait to take delivery (any day now...), I don't think they are for everyone, yet. They aren't as complicated as some would make out  but it's a little bit misleading to say it's that easy - yes the parallel dump load will help in an emergency cut off situation, but we haven't spoken for 43 pages in each of 3 threads about how easy it is to just bolt these batteries in parallel with your LA bank! There are all kinds of considerations here - over/undervoltage protection, alternator charging, alternator overheating, balancing, how to set up your BMS, even where to buy them - unless you're prepared to pay the big bucks for LiFePOs to have a competitive price point with new LAs they have to be either secondhand, ordered from China, or otherwise sourced, not to mention the DIY BMS and alternator control etc. Not wishing to put anyone off, I'd definitely encourage everyone to consider them.

 

3 hours ago, cuthound said:

This may be because AGMs have a lower internal resistance and so give and receive higher currents better. They also have much lower self discharge currents

 

However these brands are not cheap

Maybe it's that these more expensive technologies and brands just have a higher build quality?

 

[peterboat]

28 minutes ago, ivan&alice said:

Do you mean for free as in the labour? The part will be the hard bit to find / expensive bit to buy. I wouldn't have thought RCR would help me with this, since it's not really an emergency as I can charge my starter on my domestic alternator?

 

If this thread has proved anything it's that I'm no electrician but Shirley that won't work - won't the thinner wires just increase the resistance and heat up?

 

Although I'm sold on the lithiums for my use case and absolutely cannot wait to take delivery (any day now...), I don't think they are for everyone, yet. They aren't as complicated as some would make out  but it's a little bit misleading to say it's that easy - yes the parallel dump load will help in an emergency cut off situation, but we haven't spoken for 43 pages in each of 3 threads about how easy it is to just bolt these batteries in parallel with your LA bank! There are all kinds of considerations here - over/undervoltage protection, alternator charging, alternator overheating, balancing, how to set up your BMS, even where to buy them - unless you're prepared to pay the big bucks for LiFePOs to have a competitive price point with new LAs they have to be either secondhand, ordered from China, or otherwise sourced, not to mention the DIY BMS and alternator control etc. Not wishing to put anyone off, I'd definitely encourage everyone to consider them.

 

Maybe it's that these more expensive technologies and brands just have a higher build quality?

 

I am glad that my charging needs are done by solar, while it's handy having a diesel engine for moving my electric motor suits me fine, and charging with solar suits my way of life, which can be laxidasical to say the least 

[jetzi]

2 minutes ago, peterboat said:

I am glad that my charging needs are done by solar, while it's handy having a diesel engine for moving my electric motor suits me fine, and charging with solar suits my way of life, which can be laxidasical to say the least 

Oh yes, Peter, I am deeply envious of your electric motor. I can only imagine how peaceful it must be cruising without engine noises. One day when my ship comes in it will be a narrowboat - diesel-electric, every square inch covered in solar, plus a generator that I can run on red diesel for the winter months.

[Keeping Up]

46 minutes ago, ivan&alice said:

If this thread has proved anything it's that I'm no electrician but Shirley that won't work - won't the thinner wires just increase the resistance and heat up?

 

You are sort of right. The wires to my alternator would carry 600 amps before they got warm, apart from the Beta-provided wire from alternator to stud, which is probably only rated at 200 amps. If I changed it all for 200 amp cable it wouldn't warm up very much at all, but its resistance would drop some volts which would reduce the initial charge current. However when the battery is nearly full the current is low so there would be hardly any volts lost and the batteries would still reach almost the same one-point of charge (14.7 volts in my case)

[peterboat]

7 minutes ago, ivan&alice said:

Oh yes, Peter, I am deeply envious of your electric motor. I can only imagine how peaceful it must be cruising without engine noises. One day when my ship comes in it will be a narrowboat - diesel-electric, every square inch covered in solar, plus a generator that I can run on red diesel for the winter months.

I honestly think it was my best move ever, I have enough solar for winter when the drive solar is switched to domestic battery bank as well.  I have the whispergen purely as backup  it's done 20 hours this season and that was for heating mostly 

[TheBiscuits]

15 minutes ago, ivan&alice said:

One day when my ship comes in it will be a narrowboat - diesel-electric, every square inch covered in solar, plus a generator that I can run on red diesel for the winter months.

 

You had better hurry up then - that is going to go away soon, maybe even in the budget in November!

[jetzi]

22 minutes ago, peterboat said:

I have enough solar for winter when the drive solar is switched to domestic battery bank as well.

Is it necessary to separate your drive and your domestic bank? I realise that drive is going to take a lot more current but what are the advantages of separating them?

 

17 minutes ago, TheBiscuits said:

You had better hurry up then - that is going to go away soon, maybe even in the budget in November!

Huge off topic alert, I haven't been following this, every now and again I hear people saying that but is it really going to happen?

[peterboat]

33 minutes ago, ivan&alice said:

Is it necessary to separate your drive and your domestic bank? I realise that drive is going to take a lot more current but what are the advantages of separating them?

 

Huge off topic alert, I haven't been following this, every now and again I hear people saying that but is it really going to happen?

Yes my drive batteries run at 72 volts nominal, my domestic batteries are 24volts nominal so the MPPT controllers are set at different voltages.  The solar is two thirds to drive one third to domestic, I can switch it all to drive, all to domestic, are as it is at the moment, one third to domestic and two thirds to immersion heater. The system works for me and has proven reliable over the last few years,  and is now very cheap to run 

As for red diesel I can't see it surviving because it's to hard to patrol its usage, which is why I use kerosene for the bubble stove and whispergen 

Edited May 18, 2020 by peterboat