Lithiums only beat LA if you don't have enough solar

[rusty69]

....and turning off the charge source should the temperature fall below zero if you are away from the boat and it is unheated.Though I hear Dr Bob actually sleeps with his batteries in the bed, and checks them in to an adjoining hotel room if they ever go away.

Edited October 7, 2019 by rusty69

[Dr Bob]

26 minutes ago, rusty69 said:

....and turning off the charge source should the temperature fall below zero if you are away from the boat and it is unheated.Though I hear Dr Bob actually sleeps with his batteries in the bed, and checks them in to an adjoining hotel room if they ever go away.

No, they are under the bed. 

The BMV battery monitor isolates the bank at 5 deg C so they cannot be charged at these low temps. 

If I leave the boat and the Li's get too much below zero then I will be in a mess as all sorts of water pipes will freeze. I will have the stove on double quick time when I return to the boat.

Temperature is just not an issue.

[plato]

Hi Ivan 

i don’t know if you’re aware of the 12 volt boating group on face book? If you join you are able to get around 35% discount on victron kit. That might make a difference in your costings in regard to SLA v Lithium. There are a few very knowledgeable people on there that are specialists in lithium installs.Also go to Nordkyn Design .com it’s a saltwater boating site that  has extensive information on lithium installations.

 

[Constant Cruise]

Batteries under the bed???!!! In a fully ventilated compartment as per BSS?

 

If a battery compartment is ventilated, as per my understanding of said regs, then not impossible for inside ambient temperature to be very close to outside ambient, which could be tricky in winter.

 

Ventilation essential for lithiums as they can get hot and if you're au fait with warranties then you'll know the terms.

 

Ventilation essential not just for gassing, lithiums don't, but cooling of the batteries.

 

And further are your insurers happy with batteries under the bed  if not in fully ventilated compartment as per BSS?

 

Strikes me you are pushing it a bit,  still it's your boat.

[MtB]

14 minutes ago, Constant Cruise said:

Batteries under the bed???!!! In a fully ventilated compartment as per BSS?

 

If a battery compartment is ventilated, as per my understanding of said regs, then not impossible for inside ambient temperature to be very close to outside ambient, which could be tricky in winter.

 

Ventilation essential for lithiums as they can get hot and if you're au fait with warranties then you'll know the terms.

 

Ventilation essential not just for gassing, lithiums don't, but cooling of the batteries.

 

And further are your insurers happy with batteries under the bed  if not in fully ventilated compartment as per BSS?

 

Strikes me you are pushing it a bit,  still it's your boat.

 

 

For people frightened of their own shadow, lithiums are not a good option.

 

 

[rusty69]

2 minutes ago, Mike the Boilerman said:

 

 

For people frightened of their own shadow, lithiums are not a good option.

 

 

That is why I haven't installed them.Oh, and I just ain't smart enough.

[MoominPapa]

20 minutes ago, Constant Cruise said:

Batteries under the bed???!!! In a fully ventilated compartment as per BSS?

 

If a battery compartment is ventilated, as per my understanding of said regs, then not impossible for inside ambient temperature to be very close to outside ambient, which could be tricky in winter.

 

Ventilation essential for lithiums as they can get hot and if you're au fait with warranties then you'll know the terms.

 

Ventilation essential not just for gassing, lithiums don't, but cooling of the batteries.

 

And further are your insurers happy with batteries under the bed  if not in fully ventilated compartment as per BSS?

 

Strikes me you are pushing it a bit,  still it's your boat.

Lithiums don't need ventilation. They don't gas, and they don't get hot under normal circumstances with fractional-C charge or discharge. I can charge my 480Ah bank all day at 60A and the temperature stays within a couple of degrees of ambient. You do need to monitor the temperature, but the correct action if they get hot is to treat it as a fault and to stop charging/discharging , not to waft air over the things.

 

I can't be bothered to look at the BSS to see if it restricts the ventilation requirements to battery types which can gas, as it should. It probably doesn't, because Lithium batteries were not common when it was written, and it is, to be frank, a fairly low quality document anyway. I've yet to need to subject my installation to a BSS examination. I'm expecting it to be an interesting experience.

 

MP.

 

ETA, last winter which wasn't cold, the battery temperatures under the bed stayed above 5 Celsius, which is the conservative limit I've set for charging. If it dropped below that, the BMS will disallow charging until it increases again. I have no experience as to whether this is likely to  be an inconvenience when living aboard in very cold weather. Ask me again in the spring, if this winter is cold.

Edited October 7, 2019 by MoominPapa

[cuthound]

5 hours ago, Mike the Boilerman said:

 

Thems going so slow because there is not much room lefts in them batt trees. They are having to queue up and shuffle about to get in.

 

 

 

Doesn't that big red "C" mean it needs calibrating? ?

[MtB]

4 minutes ago, rusty69 said:

That is why I haven't installed them.Oh, and I just ain't smart enough.

 

Just be grateful you have a shadow at all. If you don't, there is something gravely wrong.

 

Or do I mean a reflection in the mirror...?

 

?‍♂️

[rusty69]

2 minutes ago, cuthound said:

 

Doesn't that big red "C" mean it needs calibrating? ?

It is a calibration countdown timer in days. Calibration is required when it reaches zero.

[MtB]

3 minutes ago, cuthound said:

 

Doesn't that big red "C" mean it needs calibrating? ?

 

I thought it stood for "clot", but you're probably right.

 

But even once calibrated they still don't tell you the right SoC, apparently....

 

 

 

[rusty69]

See, its things like this that worry me ( from link above), especially the last sentence.Lots of reading and understanding is required before attempting a homebrew Lithium system imo. Probably why it is only being adopted by the clever buggers on the forum.

Quote

Cell Voltage Monitoring

The need for monitoring the individual cell voltage is the main point of distinction between a lithium battery bank and a lead-acid one, where total battery voltage only is ever considered. It is made necessary by the fact that voltage excursions quickly become destructive with lithium cells and lithium cells stop accepting current when fully charged, which prevent a battery from self-equalising the way lead-acid ones do.

In order for a LiFePO₄ cell not to fail, its own voltage must be remain at all times with a prescribed range, above 2.0VDC in all cases and below about 3.65VDC. Practically, cell destruction occurs at about 4.2VDC, when the electrolyte is decomposed, but voltages in excess of 3.55VDC don’t make much sense and the cells are sensitive to the maximum instantaneous voltage they are exposed to, not just the average. Many charging sources deliver a voltage superimposed with a ripple and the peaks from the ripple can destroy the cells even if the average value as reported by a multimeter appears acceptable.M

 

[cuthound]

10 minutes ago, Mike the Boilerman said:

 

I thought it stood for "clot", but you're probably right.

 

But even once calibrated they still don't tell you the right SoC, apparently....

 

 

 

 

Another possibility is that the temperature inside of your boat is at 96°C ?

[Dr Bob]

10 minutes ago, MoominPapa said:

Lithiums don't need ventilation. They don't gas, and they don't get hot under normal circumstances with fractional-C charge or discharge. I can charge my 480Ah bank all day at 60A and the temperature stays within a couple of degrees of ambient. You do need to monitor the temperature, but the correct action if they get hot is to treat it as a fault and to stop charging/discharging , not to waft air over the things.

 

I can't be bothered to look at the BSS to see if it restricts the ventilation requirements to battery types which can gas, as it should. It probably doesn't, because Lithium batteries were not common when it was written, and it is, to be frank, a fairly low quality document anyway. I've yet to need to subject my installation to a BSS examination. I'm expecting it to be an interesting experience.

 

MP.

 

ETA, last winter which wasn't cold, the battery temperatures under the bed stayed above 5 Celsius, which is the conservative limit I've set for charging. If it dropped below that, the BMS will disallow charging until it increases again. I have no experience as to whether this is likely to  be an inconvenience when living aboard in very cold weather. Ask me again in the spring, if this winter is cold.

I agree with all MP has said.

I see very little variation in temperature. They rise a couple of degrees on fast charging over 3 to 4 hours. They have only been between 15 °C and 23 °C as the under bed temperature is largely controlled by the water temperature.  The Li's disconnect if they go over 30°C or under 5°C,

Not a clue about the BSS. They dont need ventilation for the purpose of using them.

33 minutes ago, Constant Cruise said:

 

Ventilation essential for lithiums as they can get hot and if you're au fait with warranties then you'll know the terms.

 

 

Not a clue about warranties. I dont have warranties for my Li's.

I do know about Lithium batteries. I am director of a company that is involved in a large EU aerospace project reseaching standards for transportation of Lithium batteries. We have now a years experience of trying to destroy them with heat, nails etc etc so I am well aware of their limits, what you can do to them and what you can't. A canal boat is a very friendly environment compared to what is found in electric cars/vans. I have done a full risk assessment of my set up and am happy the Li's are safer than my lead acids which are potentially dangerous beasts (acid spills, explosion hazard, failure due to lack of maintenance, mechanical failures).

 

 

[MoominPapa]

9 minutes ago, rusty69 said:

See, its things like this that worry me ( from link above), especially the last sentence.Lots of reading and understanding is required before attempting a homebrew Lithium system imo. Probably why it is only being adopted by the clever buggers on the forum.

 

If the voltage-per-cell, as read by your multimeter, is 3.55 or below, than you'd need 20% ripple to exceed the 4.2v never-exceed voltage at the peak of the waveform. That's a LOT of ripple. Read the above as advice not to go to the limit, lest such things bite you, and advice that you don;t need to go to the limit.

 

MP.

 

[MoominPapa]

On the BSS and ventilation, I thing the following quote is probably definitive:

Quote

NOTE ‐ if batteries of a ‘sealed’ type are stored in a non‐ventilated space verify that storage in
unventilated spaces meets with the battery manufacturer’srecommendations by reference to presented
documentation from the manufacturer.

Worst case scenario is showing the examiner a datasheet for the batteries.

 

MP

[Dr Bob]

Just now, MoominPapa said:

If the voltage-per-cell, as read by your multimeter, is 3.55 or below, than you'd need 20% ripple to exceed the 4.2v never-exceed voltage at the peak of the waveform. That's a LOT of ripple. Read the above as advice not to go to the limit, lest such things bite you, and advice that you don;t need to go to the limit.

 

MP.

 

Which is why I aim for 80% where my cell voltage is then less than 3.4V per cell so no chance of a ripple voltage getting it to 4.2V.

I have an audible alarm when cell voltage gets to 3.6V and an auto disconnect when it gets to 3.8V.

I also have a total bank audible alarm at 13.7V and and auto disconnect at 13.8V which will be triggered if more than one cell goes high.

 

In normal operation, I am in the ball park 20-60% SoC at the start of each day so I know given the charge sources I have that I will not get over 90% charged so avoid all the bad things that can go wrong when you get over 100%.

The alarms and autodisconnects will come into action IF something bad goes wrong ie the MPPT or Alternator decides to output 55V, but having an audible alarm (which requires attention when you hear it) and then an autodisconnect via 2 separate sources give you a couple of levels of redundancy.

 

CC, Please also note that if it does go tits up, you may destroy a cell but it isnt going to explode. LiFePo4s are very robust. Have you seen the video of the two chinese guys trying to set fire to a bank of them.....They failed. Keeping them at 80% reduces the opportunity for catastrophic failure. For the more fragile Li type batteries, ie your phone battery, when at 100% SoC they can go on fire in a spectacular way. When at 50% charge, they hardly make any flames. LiFePo4s are far far more robust.

[tree monkey]

23 minutes ago, Dr Bob said:

We have now a years experience of trying to destroy them with heat, nails etc etc so I am well aware of their limits, what you can do to them and what you can't. 

 

 

Some people have the best jobs but a slightly disappointing result, did you run a comparison test of things you could blow up, I like to see things blow up

[peterboat]

1 hour ago, Constant Cruise said:

Batteries under the bed???!!! In a fully ventilated compartment as per BSS?

 

If a battery compartment is ventilated, as per my understanding of said regs, then not impossible for inside ambient temperature to be very close to outside ambient, which could be tricky in winter.

 

Ventilation essential for lithiums as they can get hot and if you're au fait with warranties then you'll know the terms.

 

Ventilation essential not just for gassing, lithiums don't, but cooling of the batteries.

 

And further are your insurers happy with batteries under the bed  if not in fully ventilated compartment as per BSS?

 

Strikes me you are pushing it a bit,  still it's your boat.

LifePo4s dont ventilate, as they are never going to be used hard enough to do that. I had 10 on my drive system on the boat, even drawing 23KW they didnt get warm! I have now fitted 30 x 36 volt ones as drive batteries and have six of the 12 volt ones under the step next to the central heating pipes, no issues in the last year at all, The thing is I have been doing this for over a year, my mate James has been doing it for 3 years with no problems, so in our type of light usage problems arnt likely to arise

[peterboat]

25 minutes ago, Dr Bob said:

Which is why I aim for 80% where my cell voltage is then less than 3.4V per cell so no chance of a ripple voltage getting it to 4.2V.

I have an audible alarm when cell voltage gets to 3.6V and an auto disconnect when it gets to 3.8V.

I also have a total bank audible alarm at 13.7V and and auto disconnect at 13.8V which will be triggered if more than one cell goes high.

 

In normal operation, I am in the ball park 20-60% SoC at the start of each day so I know given the charge sources I have that I will not get over 90% charged so avoid all the bad things that can go wrong when you get over 100%.

The alarms and autodisconnects will come into action IF something bad goes wrong ie the MPPT or Alternator decides to output 55V, but having an audible alarm (which requires attention when you hear it) and then an autodisconnect via 2 separate sources give you a couple of levels of redundancy.

 

CC, Please also note that if it does go tits up, you may destroy a cell but it isnt going to explode. LiFePo4s are very robust. Have you seen the video of the two chinese guys trying to set fire to a bank of them.....They failed. Keeping them at 80% reduces the opportunity for catastrophic failure. For the more fragile Li type batteries, ie your phone battery, when at 100% SoC they can go on fire in a spectacular way. When at 50% charge, they hardly make any flames. LiFePo4s are far far more robust.

Virtual greenie Bob, remember when I first said I was installing LifePo4s, and said I was going to control the problems by never going above 80% charge? its over a year ago now and I had the same response from people on here like we have just had from that new poster. Well a year down the line some of us are staying at the 80% mantra and the batteries are staying naturally balanced, I am very pleased with the performance of my Valence batteries, they were an excellent buy and relieve me of so much hassle trying to charge my old tractions up to 100% weekly, I dont think I could cope with LAs far to much hassle and so dangerous as well?

Edited October 7, 2019 by peterboat

[Dr Bob]

16 minutes ago, peterboat said:

Virtual greenie Bob, remember when I first said I was installing LifePo4s, and said I was going to control the problems by never going above 80% charge??

I remember it well.

Great advice.

35 minutes ago, tree monkey said:

Some people have the best jobs but a slightly disappointing result, did you run a comparison test of things you could blow up, I like to see things blow up

I'll see if I can find the video of our lab blowing up some lithium phone batteries.

[rusty69]

25 minutes ago, Dr Bob said:

I'll see if I can find the video of our lab blowing up some lithium phone batteries.

Got any jobs going?

[tree monkey]

Just now, rusty69 said:

Got any jobs going?

Oy I asked first, well sorta asked, I was being subtle I was

[rusty69]

1 minute ago, tree monkey said:

Oy I asked first, well sorta asked, I was being subtle I was

Pah! I'll fight ya for the job monkeyman. Exploding lithium batteries at dawn?

[tree monkey]

1 minute ago, rusty69 said:

Pah! I'll fight ya for the job monkeyman. Exploding lithium batteries at dawn?

See how limited the beagle is, there's more to blow up than lithiums.