Lithium checklist

[lustyd]

Hi all, someone recently posted a checklist for moving to Lithium batteries (may have been @geem?) and I can't find it any more. If anyone has such a list please post it here, just bought a LiFePo4 to replace the two AGMs* that have deteriorated on the boat.

Pretty sure I have most of it covered, but starting to look at charge parameters and realised that I leave the charger on 24x7 and probably need to change that, and want to make sure there's nothing else I've missed.

 

[Trident]

It rather depends on the charger - if you can set the charge parameters then you can set float charge to 13.2v which is lower than the resting state of the LifePo4 and leave it on 24/7 as it simply won't do anything until the battery runs down a bit and the charger reverts to bulk.

For longevity you may wish to set the charger to actually only charge the batteries to around 85% anyway as a maximum rather than let them get full.

Make sure you have good connections, good fuses (ideally T class but with a smaller bank and depending on the C rate of discharge on the BMS it may not be necessary to go to that expense.) and connect the alternator to a LA battery first or some other system like an Alternator protector to protect it from a spike if the BMS shuts off. You can if needed connect the LA starter battery to the Lithium with either a DCDC (best bet) or a VSR (but get a good one as it will always be closed circuit with the LifePo4 at over 13.2v so basically constantly trickle charging you LA when the alternator is off.)

Watch out that there is no charging at 0 degrees C or lower

 

[Kelpie]

It may have been @Poey50 who posted it?

 

[Poey50]

It may have been @Poey50 who posted it?

Not a checklist as such but a PowerPoint presentation on LFP systems that I did for the Cruising Association. PM me with an email address for a copy.

 

[Poey50]

It rather depends on the charger - if you can set the charge parameters then you can set float charge to 13.2v which is lower than the resting state of the LifePo4 and leave it on 24/7 as it simply won't do anything until the battery runs down a bit and the charger reverts to bulk.

For longevity you may wish to set the charger to actually only charge the batteries to around 85% anyway as a maximum rather than let them get full.

Make sure you have good connections, good fuses (ideally T class but with a smaller bank and depending on the C rate of discharge on the BMS it may not be necessary to go to that expense.) and connect the alternator to a LA battery first or some other system like an Alternator protector to protect it from a spike if the BMS shuts off. You can if needed connect the LA starter battery to the Lithium with either a DCDC (best bet) or a VSR (but get a good one as it will always be closed circuit with the LifePo4 at over 13.2v so basically constantly trickle charging you LA when the alternator is off.)

Watch out that there is no charging at 0 degrees C or lower

Same idea as above but I leave a single Victron Smart Solar in charge when I leave the boat with storage settings of 13.2 volts for both absorption and float, having first run the capacity down to around 60%. One unexpected part of managing an LFP system is aiming to leave the boat at around mid-range state of charge. It just needs a bit of forward planning and the ability (switches) to isolate charging sources - especially alternator charging.

 

[lustyd]

Thanks PM sent.

Yes I think between switches and software controls I have everything needed to control the system. The alternator will be behind a Victron B2B so easy to disable, and the charger is on a switch but is also Victron so easy to change and/or disable and same for solar.

 

[geem]

If you are using Victron or Sterling B2Bs to charge lithium from the engine battery, I suspect you will be disappointed with the output. Once they get warm, their output is miserable. Fitting a computer fan to the rear such that you blows air across the fins does maintain a reasonable output.

 

[lustyd]

Thanks, yes I'll be using a Victron 30A Orion and currently contemplating where to mount it for best cooling. Realistically I don't think alternator charging will be a huge issue as the new battery should last (with a bit of solar) between shore hookups for us. We run the engine for 30 minutes each morning for hot water and I imagine that's short enough to get some charge in before heat becomes a huge issue. I'll certainly keep an eye on it though

 

[geem]

Thanks, yes I'll be using a Victron 30A Orion and currently contemplating where to mount it for best cooling. Realistically I don't think alternator charging will be a huge issue as the new battery should last (with a bit of solar) between shore hookups for us. We run the engine for 30 minutes each morning for hot water and I imagine that's short enough to get some charge in before heat becomes a huge issue. I'll certainly keep an eye on it though

I am not sure since we are running ours in a high ambient, but ours would drop its output considerably after about 10mins.

 

[lustyd]

Blimey that is quick. Perhaps I'll do some experimenting before choosing a location. Realistically the only place with "fresh air" is the engine compartment but that has the engine in it which is also hot

 

[geem]

Blimey that is quick. Perhaps I'll do some experimenting before choosing a location. Realistically the only place with "fresh air" is the engine compartment but that has the engine in it which is also hot

Mine was mounted in a compartment with other victron kit but with two fans discharging air in to the compartment to provide ventilation. The compartment has three grille outlets for exhaust air. This did nothing to keep the B2B cool. I mounted the B2B on a bulkhead with a void behind. A drilled a 4" diameter hole behind the B2b and mounted the fan over the hole, blowing across the fins. Another hole from the void allowed air in. Much improved.

 

[Trident]

You can always look at the Renogy DCDC with a built in double fan cooling system - I have two of the 60A and they don't reduce output at all as far as I can tell though I've only used them for about an hour at a time

 

[geem]

You can always look at the Renogy DCDC with a built in double fan cooling system - I have two of the 60A and they don't reduce output at all as far as I can tell though I've only used them for about an hour at a time

I did. Couldn't see a 24v version

 

[Trident]

I did. Couldn't see a 24v version

Sorry that was aimed at the OP but Renogy have finally brought out LifePo that can series link (their earlier BMS could do parallel up to 8 - the new one can do 4s4p ) so hopefully 24v versions of the DCDC will follow

 

[Neeves]

Slight thread drift.

For cooling computer fans are the way to go. But there is little point in cooling an item in a closed locker - you need to, positively, extract the warm air which in most cases means another fan attached to a vent. The coolest air, unless like Geem you are in the Caribbean (or any other delightful part of the tropics) will be the anchor locker and if you can extract air from the locker with ducting to the item needing to be cooled that is probably the best you can do. Ducting used for diesel heaters in yachts might fit the bill.

We wired our fans to come on when the compressor on the fridge cuts in simply used the same terminals as the fan on the compressor.

We used domestic extractor fan ducting from the anchor locker to the saloon, then (in our case) the fridge/deep freeze compressors and then to the engine bay. We have plenty of space for ducting it will be more of a challenge in a yacht - but through the bilges seems a first bet.

'Computer fans' are something of a misnomer as they are used in many other applications, like fridge compressors, and come in sizes from 30mm square upto 150mm square (and maybe bigger and smaller) - their single important characteristic is they usually operate at 12v and use very little power.

Apologies for the drift

Jonathan

 

[geem]

Slight thread drift.

For cooling computer fans are the way to go. But there is little point in cooling an item in a closed locker - you need to, positively, extract the warm air which in most cases means another fan attached to a vent. The coolest air, unless like Geem you are in the Caribbean (or any other delightful part of the tropics) will be the anchor locker and if you can extract air from the locker with ducting to the item needing to be cooled that is probably the best you can do. Ducting used for diesel heaters in yachts might fit the bill.

We wired our fans to come on when the compressor on the fridge cuts in simply used the same terminals as the fan on the compressor.

We used domestic extractor fan ducting from the anchor locker to the saloon, then (in our case) the fridge/deep freeze compressors and then to the engine bay. We have plenty of space for ducting it will be more of a challenge in a yacht - but through the bilges seems a first bet.

'Computer fans' are something of a misnomer as they are used in many other applications, like fridge compressors, and come in sizes from 30mm square upto 150mm square (and maybe bigger and smaller) - their single important characteristic is they usually operate at 12v and use very little power.

Apologies for the drift

Jonathan

For cooling a B2B, ducting is not an issue. The Victron B2Bs are finned on the rear. The computer fan is simply increasing the heat flow from the fins. They get very hot to the touch. The computer fan makes a noticeable difference.
The other way that often possible to increase cooling effect if a ducted solution is not possible, is to create a chimney. Our main fridge/freezer has the compressor/condenser combo mounted in a narrow tunnel close to the cabin floor, that has an air inlet at the bottom and a larger air exhaust at the top. The tunnel is about a metre high. Cool air comes in at the bottom and warm air escapes at the top. No fan, but great airflow. You need about double the exhaust air ventilation area as inlet area, ideally

 

[B27]

Slight thread drift.
.....

'Computer fans' are something of a misnomer as they are used in many other applications, like fridge compressors, and come in sizes from 30mm square upto 150mm square (and maybe bigger and smaller) - their single important characteristic is they usually operate at 12v and use very little power.

Apologies for the drift

Jonathan

More generally those square fans are 'equipment fans'.
Some of them do not 'use very little power', you can get some powerful fans in the format, which look at first glance exactly like the one in the back of a PC, but draw a lot more power and shift a lot more air.

I guess a 3A fan is not a 'lot of power' to the inverter afficionado with a masssive battery bank, but it is to me!

 

[Kelpie]

I'm using 200mm server fans as cabin fans. €11, and very quiet and low power.

 

[mattonthesea]

Our Sterling B2B is mounted 1cm away from the panelling against the hull, below the water line. It doesn't drop power but, by Jove, the fans run fast and make a racket.

Sterling are very good on support

M

 

[Pete7]

Our Victron DC>DC is mounted on the outside of the nav seat with a 3" hole behind it, but that isn't enough. I have a small ex computer fan to fit at some point. The Victrons do drop from 30A to about 27A over a period of time and then level off. However, since solar is our primary means of charging the house bank, a single Victron unit is fine for us.

Temperature reading after an hour, and that's the outside of the plastic case.