watercraft
Member
Hi I have come across Roamer Batteries selling lifep04 drop in batteries at a reasonable price. Has anyone had any experience with this brand?
Roamer Lifep04 Batteries
- Thread starter watercraft
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Poey50
Well-Known Member
Apologies for repetition but 'drop-in LFP batteries' as a replacement for lead acid used in a marine installation is a simple marketing lie. Drop-ins could form part of an 'LFP system' but as the term implies, it means taking a whole-system approach. Drop-ins seem to offer simplicity and that is the deceit. It is more complicated to make a safe system with them than by other methods. You will need to research and this is the best starting point. And along the way you may find you are betting off sticking to one of the varieties of lead acid.
LiFePO4 Batteries On Boats - Marine How To
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watercraft
Member
Thanks yes I'm aware there needs to be some serious upgrading to my charging system. However they are stating the internal battery management system will do all the cell balancing stuff etc and I'd need to ensure the alternator is protected using something like battery to battery charging. I'm still leaning towards Super Cycle Victron AMG's as they do a 170ah version that fits my 110ah battery box space.
cheers
Poey50
Well-Known Member
This is my three-part thought experiment for people to test the safety of their LFP system. You are crossing a busy shipping lane at night and your BMS isolates your house battery leaving you without power.
1. How will you know that it is about to happen?
2. How could you prevent it?
3. How could you mitigate the effects?
An internal BMS will look after your LFP battery, a B2B will look after the alternator on sudden disconnect if properly matched but neither will look after you or your boat. Drop-ins are great for RVs since, if you lose power to your induction hob you can drive down to the chip shop. Marine installations needed greater layers of safety.
1. How will you know that it is about to happen?
2. How could you prevent it?
3. How could you mitigate the effects?
An internal BMS will look after your LFP battery, a B2B will look after the alternator on sudden disconnect if properly matched but neither will look after you or your boat. Drop-ins are great for RVs since, if you lose power to your induction hob you can drive down to the chip shop. Marine installations needed greater layers of safety.
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watercraft
Member
Yes indeed and I'd concluded the same ... all fine and dandy when working but what is the backup system. Bow thruster bank switchover was my first thought. Modes of failure, probability, impact of failure etc a typical RCM engineering approach would be needed. I'm still talking myself into AMG's!
Poey50
Well-Known Member
There is only one drop-in which provides any kind of warning of imminent disconnect and that is Lithionics. This matters because there is an emerging standard for LFP installations (initially via the ABYC) requiring warning of BMS disconnect. That standard is likely to be taken up by surveyors and then insurers so, worst case scenario, anyone buying drop-ins for a 10-15 year investment may find themselves unable to get insurance in a few years time. There are hybrid systems emerging in which a lead acid battery is alway kept in the system or dual systems in which all essential services are powered by lead acid and the non-essential by lithium. But the best systems that are in financial reach are the DIY ones but that is not for the faint-hearted. The link in my signature can take you down that rabbit hole.
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Travelling Westerly
Well-Known Member
Can you expand on properly matched please
Poey50
Well-Known Member
I could have expressed that better. The appropriate sizing is to have say a minimum of 60 amp alternator with 30 amp B2B. Adding a Sterling Alternator Protect is also recommended to deal with a sudden disconnect even with a B2B.
Travelling Westerly
Well-Known Member
Thanks, thought I'd missed something there.
I've fitted a Sterling protect and am just in final stage of connecting my Victron B2B, got worried about the term matching.
Ian_Edwards
Well-Known Member
I installed 4 LiFos 105 LIFePO4, “drop in” batteries in May this year.
I also installed a Victron BtoB to charge the stater battery, a 110amp hour sealed lead acid battery, a Victron 120amp/3KVA inverter charger, a new Balmar 120amp alternator and a Wake Speed WS 500 alternator controller.
The BtoB looks after the starter battery with the correct charging profile,
The WS500 stops the LiFePO4 taking too much current from the alternator (and cooking it), it has a shunt in the alternator output and temperature sensors on the alternator.
The Victron inverter/charger is programmed for LiFePO4 batteries.
I have had one unexpected automatic shutdown of the LiFos batteries, caused by a faulty relay in the Bow Thruster circuit, which put a constant drain on the house bank, but not enough to blow any fuses.
All the lights and instruments went out, and after a “What the **^%$ going on here” moment, I checked the Lifos Batteries using the mobile phone app, realised that, for some reason, the house bank was dead. Manually switched out the house bank and switched in the starter battery. Everything came back up.
I then had the option of starting the engine or the 5KVA generator to keep starter battery charged.
I don’t see that the situation would have been any different if the house bank had been Lead Acid, the dropout would have happened a lot sooner, and it would probably have been more progressive. The Raymarine MFD, would have dropped out first, and I may have noticed the lights going dim, but the workaround would have been exactly the same.
The Lifos batteries give me a lot more usable energy, charge a lot faster, are maintenance free, and are nearly 100kg lighter than the 4 @ 130 amp hour AGM’s.
It didn’t take long to start the generator, switch it to charge the Lifos Batteries and restore normality, if such a thing can exist on a yacht.
So, I don’t see the problem with installing “drop-in” lithium batteries, I could take the lithium batteries out and drop the old AGM’s back in, tweak the inverter/charger and the system would function in exactly the same way.
I also installed a Victron BtoB to charge the stater battery, a 110amp hour sealed lead acid battery, a Victron 120amp/3KVA inverter charger, a new Balmar 120amp alternator and a Wake Speed WS 500 alternator controller.
The BtoB looks after the starter battery with the correct charging profile,
The WS500 stops the LiFePO4 taking too much current from the alternator (and cooking it), it has a shunt in the alternator output and temperature sensors on the alternator.
The Victron inverter/charger is programmed for LiFePO4 batteries.
I have had one unexpected automatic shutdown of the LiFos batteries, caused by a faulty relay in the Bow Thruster circuit, which put a constant drain on the house bank, but not enough to blow any fuses.
All the lights and instruments went out, and after a “What the **^%$ going on here” moment, I checked the Lifos Batteries using the mobile phone app, realised that, for some reason, the house bank was dead. Manually switched out the house bank and switched in the starter battery. Everything came back up.
I then had the option of starting the engine or the 5KVA generator to keep starter battery charged.
I don’t see that the situation would have been any different if the house bank had been Lead Acid, the dropout would have happened a lot sooner, and it would probably have been more progressive. The Raymarine MFD, would have dropped out first, and I may have noticed the lights going dim, but the workaround would have been exactly the same.
The Lifos batteries give me a lot more usable energy, charge a lot faster, are maintenance free, and are nearly 100kg lighter than the 4 @ 130 amp hour AGM’s.
It didn’t take long to start the generator, switch it to charge the Lifos Batteries and restore normality, if such a thing can exist on a yacht.
So, I don’t see the problem with installing “drop-in” lithium batteries, I could take the lithium batteries out and drop the old AGM’s back in, tweak the inverter/charger and the system would function in exactly the same way.
Poey50
Well-Known Member
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Poey50
Well-Known Member
I took down my detailed critique of the Lifos since they are no better or worse than most other drop ins. Of course you can use them in a marine LFP system. You pay a lot for a little for a cruder system but I understand people like the convenience.
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ckris
Well-Known Member
Not yet on lithium but been thinking hard about how to. These would be my answers:
1. Low voltage alarm on battery monitor would be set above the lithium bms disconnect voltage, so alarm would sound in advance.
2. Start the engine and charge when the low voltage alarm goes off ( before the bms disconnect)
3. If it did happen, switch domestic load over to the agm engine start battery (then start the engine)
Curious how these answers stack up?
sailaboutvic
Well-Known Member
My two penny worth.
If your using lithium dropping for the run of the mill equipment, what every BMS are inside these dropping I doubt you going to have a lockout because of low voltage and if you did it would had happen a lot earlier if you was using LA batteries.
We run some heavy stuff with our 400AH cells and we got no where near a voltage that would disconnect the power.
After saying that I wouldn't want to use droppings using the power we use at times over 210A .
Our30A b2B as been very rarely used throughtout the summer our solar keeps the batteries up nicely but we are finding now we having to turn on the charger thought the B to B to top up the batteries after five days of over cast weather .
If your really concean that at some point your going to have a disconnecion then fix a isolate switch so you can easily switch to your LA starter battery if need be .
The only problem we have had in the year we been using lithium was our starter battery died and I had to jump off the lithium tostart the engine , winter job m fit a switch in case the problem happen again .
If your using lithium dropping for the run of the mill equipment, what every BMS are inside these dropping I doubt you going to have a lockout because of low voltage and if you did it would had happen a lot earlier if you was using LA batteries.
We run some heavy stuff with our 400AH cells and we got no where near a voltage that would disconnect the power.
After saying that I wouldn't want to use droppings using the power we use at times over 210A .
Our30A b2B as been very rarely used throughtout the summer our solar keeps the batteries up nicely but we are finding now we having to turn on the charger thought the B to B to top up the batteries after five days of over cast weather .
If your really concean that at some point your going to have a disconnecion then fix a isolate switch so you can easily switch to your LA starter battery if need be .
The only problem we have had in the year we been using lithium was our starter battery died and I had to jump off the lithium tostart the engine , winter job m fit a switch in case the problem happen again .
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sailaboutvic
Well-Known Member
what some have complained about is the BMS cuts in when X amps is being used ,
I think that's the point poey making, you don't have to be below voltage cut off fot thus to happen if say the BMS has a 50A breaker and you happen to go over that it will disconnect the batteries even if your batteries are fully charge , so the low voltage alarm won't be much good ,
But as I said in my other posting , if your using dropping for the run of the mill stuff that's not going to be a problem .
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sailaboutvic
Well-Known Member
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Poey50
Well-Known Member
One of the several problems with drop-ins is that the MOSFET based BMS can disconnect for a whole variety of reasons
Amperage overload
High or low cell temp
Excessive voltage difference between cells (can’t keep up with balancing)
Cell high voltage (not to be confused with 'pack voltage')
Cell low voltage
Mosfet temp
Circuit board temp
Error in the chip/BMS computer
Not only is no warning given in advance and, even if Bluetooth enabled, there may not be any information provided at cellular level - only at pack level so if will be impossible to understand what is happening. In any circumstance like that then your number 3 is the only immediate solution available to you assuming you have a three-switch system with an emergency linking switch (not a paralleling switch system). You do need to have thought it through in advance as otherwise to lose all power at night in a shipping lane might be a shocking and brain-freezing event. But that is the purpose of the thought experiment. This is the reason that some people ensure that a lead acid battery is permanently kept in the system, in parallel, although keeping it sufficiently charged can be a challenge. It is certainly true that lead acid can run out of power but the voltage sag as lead acid empties is much more noticeable whereas for a low power disconnect LFP will stay perky until nearly empty and then drop off a cliff (the lower 'knee' of the discharge curve).
Risk is less for two or more drop-ins in parallel since there is loss of capacity rather than total power if one goes down although there could be issues with an isolated battery coming back on stream if there is a massive disparity between states of charge given how quickly current flows between these low-resistance cells. For a single string in series to create a nominal 24 volts, the risks are doubled.
I might offer a small prize to anyone who finds this kind of warning given by companies marketing LFP to boaters or in sailing magazine articles doing comparative tests on LFP. The single exception is Rod Collins' company - Compass Marine. This, for example (below), is his solenoid solution to managing sudden disconnect when motoring. It also maintains the battery without need of a battery to battery charger.
A much greater range of options is available to those building packs from raw cells using an external BMS in which heavy current does not pass through MOSFETs but instead is managed by external relays controlled from the BMS. It also makes possible a 'dual-bus' set-up in which all charging circuits are separated from all load circuits. So if the BMS triggers a shut-down because of a high voltage event then only the charge circuit is isolated, the load circuit is unaffected. And vice versa, for a low voltage event, the loads will be temporarily shut down but the charging circuit remains open. Unlike the Bluetooth of typical drop-ins there is detailed information on each cell available so any imbalance can be picked up early. High quality external BMSs will control charging sources directly on the basis of cellular level information making high voltage disconnects highly unlikely. Some also can warn of disconnect and this will be a more commonly found feature as the ABYC will eventually demand it.
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Poey50
Well-Known Member
Aside from considerably higher cost, larger sizing, mosfet-based internal BMS, and absence of communication with external devices, there is a further downside to drop-ins which is the need to regularly charge them to full or near-full. Technical data for the Roamer 100ah Smart batteries shows a balance current of just 30mA. (LIFOS don't even publish a figure for this which I find concerning.) I have a 123SmartBMS on my pack which is not especially well featured but has 1 amp of balancing current - 30 times the amount of the Roamer. Many external BMSs have more than this and some will actively transfer current between cells rather than passively burn it off. Balancing takes place near the top end of a charging curve above a threshold voltage. With such limited balancing current then the battery must be brought regularly above the threshold otherwise the battery may never catch up if it goes out of balance. For this reason, with drop-ins you have to follow the manufacturers charging recommendation - which in this case is 14.6 volts. For LIFOS it is 14.4 to 14.6 volts.
14.6 volts is 3.65 volts per cell (as long as charging is halted as soon as this target voltage is reached), a maximum figure that should not be exceeded on any kind of regular basis since to do so is progressively to allow irreversible lithium plating which reduces the capacity of the cell. However the longest life from LFP is to opt for a more conservative charging range - say 20 - 85% - perhaps charging to full occasionally when needed. But this more limited range means that the drop-in does not get charged in order to balance and, given the low balancing current available, may overwhelm the ability to balance when attempting to charge to full. So to keep them healthy they have to be charged 90-100% but that means a trade-off of a shorter life that can be obtained with batteries that will sit more happily at mid-ranges.
If not kept well balanced then although 3.65 +3.65 +3.65 +3.65 = 14.6 volts, which is perfectly healthy, a very imbalanced battery might have cells of 3.1 + 3.2 + 3.2 + 5.1 = 14.6 volts. Cell number 4 will be having its life shortened despite the pack voltage looking normal. Bluetooth communication - such as found in LIFOS and no doubt others - does not give individual cell voltages so it would not be possible to pick up this problem early. Of course the other problem here is that one cell getting so high (even with less gross disparity) would trigger a high voltage disconnect well before this figure. For this reason, these internal BMSs have rather high figures for voltage cut-off. For the LIFOS this is 3.85 volts. The reasoning here is that it will be better to risk over charging (from 3.65 to 3.85 volts) than have nuisance disconnects and to give the poor balancing capacity a chance to bring down the cell differences.
For these reasons, the US experience is that drop-ins are being found to lose capacity faster than anticipated since it is hard to manage the ideal charging conditions that may allow them to live a full life. Well-matched cells in a DIY system with external BMS with good cell voltage information and robust balancing capability - if needed - can be kept better in balance, at more conservative ranges of charge, can have a lower and therefore safer high voltage cut-off (mine is 3.7 volts) and can be charged at a lower rate (mine are charged at 13.8volts) and provide much better information to the owner to make those choices.
14.6 volts is 3.65 volts per cell (as long as charging is halted as soon as this target voltage is reached), a maximum figure that should not be exceeded on any kind of regular basis since to do so is progressively to allow irreversible lithium plating which reduces the capacity of the cell. However the longest life from LFP is to opt for a more conservative charging range - say 20 - 85% - perhaps charging to full occasionally when needed. But this more limited range means that the drop-in does not get charged in order to balance and, given the low balancing current available, may overwhelm the ability to balance when attempting to charge to full. So to keep them healthy they have to be charged 90-100% but that means a trade-off of a shorter life that can be obtained with batteries that will sit more happily at mid-ranges.
If not kept well balanced then although 3.65 +3.65 +3.65 +3.65 = 14.6 volts, which is perfectly healthy, a very imbalanced battery might have cells of 3.1 + 3.2 + 3.2 + 5.1 = 14.6 volts. Cell number 4 will be having its life shortened despite the pack voltage looking normal. Bluetooth communication - such as found in LIFOS and no doubt others - does not give individual cell voltages so it would not be possible to pick up this problem early. Of course the other problem here is that one cell getting so high (even with less gross disparity) would trigger a high voltage disconnect well before this figure. For this reason, these internal BMSs have rather high figures for voltage cut-off. For the LIFOS this is 3.85 volts. The reasoning here is that it will be better to risk over charging (from 3.65 to 3.85 volts) than have nuisance disconnects and to give the poor balancing capacity a chance to bring down the cell differences.
For these reasons, the US experience is that drop-ins are being found to lose capacity faster than anticipated since it is hard to manage the ideal charging conditions that may allow them to live a full life. Well-matched cells in a DIY system with external BMS with good cell voltage information and robust balancing capability - if needed - can be kept better in balance, at more conservative ranges of charge, can have a lower and therefore safer high voltage cut-off (mine is 3.7 volts) and can be charged at a lower rate (mine are charged at 13.8volts) and provide much better information to the owner to make those choices.
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Poey50
Well-Known Member
Finally, it is easy to be reassured by attractive marketing that some drop-in LFP batteries now come with Bluetooth so you can see what is happening inside. I want to illustrate the difference between Bluetooth information from a typical drop-in LFP and that from a mid-range external BMS with Bluetooth capability.
First the LIFOS app information.
As you can see this provides the same kind of information as if it were a lead acid battery. That is it only provides pack-level information, not information about the individual cells. There is no means of making user-adjustment.
These are the 123Smart BMS screens
This allows the user to choose their own parameters.
This shows the individual cell voltages and cell temperatures so, crucially, it is possible to see imbalance (although the main imbalance will not show up until higher states of charge). It also shows which cells are subject to balancing once charging is above the threshold value.
The next shows pack-level information in the pack itself and current load and charge information.
Finally, the shows state of charge information over 7 days. There is also an error screen (not shown).
First the LIFOS app information.
As you can see this provides the same kind of information as if it were a lead acid battery. That is it only provides pack-level information, not information about the individual cells. There is no means of making user-adjustment.
These are the 123Smart BMS screens
This allows the user to choose their own parameters.
This shows the individual cell voltages and cell temperatures so, crucially, it is possible to see imbalance (although the main imbalance will not show up until higher states of charge). It also shows which cells are subject to balancing once charging is above the threshold value.
The next shows pack-level information in the pack itself and current load and charge information.
Finally, the shows state of charge information over 7 days. There is also an error screen (not shown).
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