LiFePO 12v 200a/hr battery charging

[Neeves]

This one for those who have been keeping up to date on battery usage and application. Paul Rainbow comes to mind.

Is there in absence of running engines, a wind gen, a hydro gen, solar panels (thinking more in terms of no sun), no dedicated charger what contribution would a cheap and cheerful automotive battery charger make to a, say, 50% depleted LiFePO 200a/hr battery. Basically having relied on solar and rejected other options and not wanting to run the engines, disturbs the neighbours, not ideal for engine but have access to mains power....... So access to 240v (marina) and a nearby Halfords.

Dangers, length of time to recharge, or near re-charge, other options (like a better battery charger) or.....

Jonathan

 

[gregcope]

Is this for long term storage or just a top up?

If you mean "Halfords" as as high street supplier sell "standard" chargers they are unlikely to have a LifePo4 profile for either as LifePO4 needs lower voltages for either a full charge - (3.6V per cell * 4 = 14.4V) or long term storage (3.3V * 4 = 13.2V).

Depending on the state of charge; standard charge rates are 4A-8A which might need 200Ah * 20% SOC = 160Ah/6A = 26 Hrs to take to "full" 200Ah.

Dangers, or rather issues, as none of these should be catastrophic are;

• Over charging -ie cells above 3.65V. The battery Should have a decent BMS that prevents this. You can mitigate this by manual monitoring at high states of charge. This might take a while.
• Without a LifePO4 float profile they will charge the batteries to 100% SOC set by the hopefully sensibly configured BMS. This will be a high SOC and is not suitable for longevity. LifePO4 loves to be kept between 40-60% to deliver epic (10k+ ) number of cycles, I store mine at this SOC. Again you can manually monitor voltages to mitigate or may accept the risk.
• Temperature - LifePo4 will not like being charged below 0C. Again a sensible BMS should prevent this. Charging below 0C damages most types of cells (there are some with heaters or chemistries that are okay below eg Roamer Extremes or Wilson cells). Again can be mitigated with monitoring temp.

What would be better? Any charger that is either configurable or have a lifePo4 profile that makes sense. You could use a desktop power supply and set a cuttoff or get a dedicated Lifepo4 charger from Victron or Renogy. Other brands also available. I use Victron.

With a search I do note that Halfords do have this charger that has a lithium profile; https://www.halfords.com/motoring/b...d-smart-battery-charger-plus---6a-238350.html. However I cannot tell what they mean by "Lithium" (Lifepo4 or LIpo). More details required.

For long term storage the suppliers charge them to 3.28V or similar per cell and then just leave them. The self discharge is tiny that they can be left like this for months, even with a BMS connected. See my post here on long term self-discharge of around 1% per month; Lithium 304Ah Build

In terms of an LifePo4 profile Battery to Battery charger depends on what you want to do. If your charging off an engine start battery that will be quickly be depleted assuming its smaller AH wise than the LifePo4 unless it has a supply that keeps up. You could have a B2B to charger the lifePo4 when running the engine OR when ashore charge the Start battery, assuming its FLA or AGM off an off a Halfords charger and let the B2B charge the LifePo4. I have a Victron LifePo4 profile B2B and this tops up the LifePO4 batteries when it senses the running engine/alternator. My FLA charger is still on board but not connected.

 

[Neeves]

Is this for long term storage or just a top up?

If you mean "Halfords" as as high street supplier sell "standard" chargers they are unlikely to have a LifePo4 profile for either as LifePO4 needs lower voltages for either a full charge - (3.6V per cell * 4 = 14.4V) or long term storage (3.3V * 4 = 13.2V).

Depending on the state of charge; standard charge rates are 4A-8A which might need 200Ah * 20% SOC = 160Ah/6A = 26 Hrs to take to "full" 200Ah.

Dangers, or rather issues, as none of these should be catastrophic are;

• Over charging -ie cells above 3.65V. The battery Should have a decent BMS that prevents this. You can mitigate this by manual monitoring at high states of charge. This might take a while.
• Without a LifePO4 float profile they will charge the batteries to 100% SOC set by the hopefully sensibly configured BMS. This will be a high SOC and is not suitable for longevity. LifePO4 loves to be kept between 40-60% to deliver epic (10k+ ) number of cycles, I store mine at this SOC. Again you can manually monitor voltages to mitigate or may accept the risk.
• Temperature - LifePo4 will not like being charged below 0C. Again a sensible BMS should prevent this. Charging below 0C damages most types of cells (there are some with heaters or chemistries that are okay below eg Roamer Extremes or Wilson cells). Again can be mitigated with monitoring temp.

What would be better? Any charger that is either configurable or have a lifePo4 profile that makes sense. You could use a desktop power supply and set a cuttoff or get a dedicated Lifepo4 charger from Victron or Renogy. Other brands also available. I use Victron.

With a search I do note that Halfords do have this charger that has a lithium profile; Halfords Advanced Smart Battery Charger Plus - 6A | Halfords UK. However I cannot tell what they mean by "Lithium" (Lifepo4 or LIpo). More details required.

For long term storage the suppliers charge them to 3.28V or similar per cell and then just leave them. The self discharge is tiny that they can be left like this for months, even with a BMS connected. See my post here on long term self-discharge of around 1% per month; Lithium 304Ah Build

In terms of an LifePo4 profile Battery to Battery charger depends on what you want to do. If your charging off an engine start battery that will be quickly be depleted assuming its smaller AH wise than the LifePo4 unless it has a supply that keeps up. You could have a B2B to charger the lifePo4 when running the engine OR when ashore charge the Start battery, assuming its FLA or AGM off an off a Halfords charger and let the B2B charge the LifePo4. I have a Victron LifePo4 profile B2B and this tops up the LifePO4 batteries when it senses the running engine/alternator. My FLA charger is still on board but not connected.

Thanks for the detailed reply.

As may be obvious from my post - I'm not in any way familiar with 'lithium'. I suspect, maybe wrongly - its so easy to misjudge - my lack of knowledge is not unusual.

I am aware the the word 'Lithium' covers a range of technologies.

In answer to your queries.

Top up, not storage - I want to be able to use and rely on the batteries as my store of 'amps'.

I chose Halfords as a common supplier of battery maintenance (or it was) 'equipment' - considering that lithium uptake is becoming 'commonplace' in the UK. I also chose Halfords as I think it is common place, lots of branches. I'm in Australia and we are 5 years behind you in Lithium uptake. It appears that Lithium is maybe not common place, enough, yet in the UK. Here it very much an exotic - but changing rapidly. You mention that Halfords do have a lithium charger - but the implication is that it might not be specifically focussed at LiFePo4 - you are saying - check and check again.

Victron are an obvious source but here hardly commonplace - if you go into a chandler (a market on which Victron focus) or the Oz equivalent to Halfords - they will not have a row of Victon kit on their shelves - here it would be specially order (not off the shelf like a lead acid battery charger).

One redeeming feature, accidental rather than planned - charging at below 0 deg C would be unlikely.

The key seems to be a sensible battery management system and a LiFePo4 specific charger - which may be a real exotic (and hence expensive) item here.

Now, along with my research on a 'on demand' instant, gas, hot water heater - I'll look for 'off the shelf' battery charges LiFePo4 specific.

You did add to my meagre knowledge base - you define that the ideal is maintaining charge at 40%-60% to deliver those 10k cycles. I had naively believed lithium was quite comfortable at much less than 40%.

Our engine start battery is too small to consider as part of any configuration.

Again very many thanks

Jonathan

 

[mattonthesea]

Hi Nerves,
Just starting on this journey myself. Was recently guided (by one of this parish) to 'The Off Grid Garage' Utube channel where an Aussie based chap guides you through all the stuff in an highly entertaining way. You need to be a bit selective on which videos as there are lots and not all are relevant to boats. He does experiments to test ideas and some myth busting.

Just have a few hours spare!

 

[Neeves]

Hi Nerves,
Just starting on this journey myself. Was recently guided (by one of this parish) to 'The Off Grid Garage' Utube channel where an Aussie based chap guides you through all the stuff in an highly entertaining way. You need to be a bit selective on which videos as there are lots and not all are relevant to boats. He does experiments to test ideas and some myth busting.

Just have a few hours spare!

Thanks Matt,

Will have a look. It was so simple when there was just lead based batteries - it has become complicated and moving fast. Sodium batteries might replace.....

No-one can know everything about everything - the forum is a great introduction.

Good luck

Jonathan

 

[Pete7]

You did add to my meagre knowledge base - you define that the ideal is maintaining charge at 40%-60% to deliver those 10k cycles. I had naively believed lithium was quite comfortable at much less than 40%.

Jonathan

Johnathan, I think you will find calendar aging finishes off your LifePO4 (LFP) battery before you reach the thousands of cycles. Our BMS reports 15 cycles in two years so far. Plan on staying between 90 - 20% SOC and a storage of 40 - 60% if you are away from the boat for a few days and you will be fine. Just be aware that the % SOC display isn't particularly accurate and more of an estimate. The voltage isn't much help either as it has a very flat charge curve from 20 - 90% so 3.3v per cell is a bit meaningless, it could be 30% or 70%. Counting Ah in and out better which is what the Victron gauges with shunts do, but again they need setting up properly and re-setting regularly.

Do you have the slightly more expensive NOCO range in Halfords down under?

https://www.halfords.com/motoring/b...battery-charger-230286.html?recType=OCWOTBRec

The manual says suitable for LFP which would be good. Whilst a full LFP cell will be 3.65, you really don't want to charge to that level. Andy on Off Street Garage show in a number of videos that anything above 3.5 is a tiny fraction of capacity and not worth stressing the battery on a regular basis and certainly don't float it at that voltage. Here is the manual for a NOCO, but it isn't clear about the LFP settings. You may have to manually switch on and disconnect what ever charger you go for from Halfords. The BMS being used as a safety item of last resort.

Do you plan to fit any form of battery monitoring in addition to any bluetooth app that connects to the BMS? That would be useful if the budget allows.

Could you order a Victron or Sterling charger by Amazon?

Ours is a slightly different hybrid LFP and FLA house bank. However, we had the advantage of a 40A Sterling multi stage battery charger and their battery monitor. So in winter we use this to charge the engine start battery and from there charge the hybrid house bank with a DC>DC charger. This would be expensive to set up for what you want though.
Finally choose a LFP battery that has bluetooth that will show each individual cell voltage, which is really useful to see if one cell is misbehaving.

Pete

 

[gregcope]

As @Pete7 Suggests you can run LifePo4 between 10-90% SOC without much issue. That is one of the things that is great, ie much more usable capacity. 40-60% SOC is the ideal cycle, if you want 10K cycles, which for boat owners would be many decades.... irrelevant in practice.

You might find victron or others are easily available in Oz. LifePO4 is popular in the RV/Camper space. Another youtube channel - Project Brupeg also have a few videos on LifePO4.

If you are considering "Lithium" then you will need to consider all charging sources. I documented where I started here; Lithium 304Ah Build. Its worth a read of Marinehowto or Nordkyndesign. Basically, in my view, our charging sources are optimised for Flooded Lead Acid (FLA) or AGM over the last 100 years. LifePO4 is new, but slightly different...

It is amazing to have 500Ah usable on my boat, compared to 120Ah with FLA. In the same space, with half the lifetime cost.

 

[Neeves]

Pete 7 and gregcope thank you both.

I had not identified that 'lithium' was so popular in other markets - but have defined this now. There is a Camping and Caravan show (I think the biggest in Australia) on now and we we went yesterday. Lithium, specifically LiFePO4, is available as standard or as an option on virtually every caravan here on the market. We did not look at motorhomes - but suspect its no different. We have niche areas - for people who venture off grid - and lithium again is standard or common place. Sometimes there is an AGM option, rather than lithium, but that is unusual. Some caravans do not offer batteries - the assumption being you plug into mains at the site (and I assume this is similar in the UK). Because distances can be huge in Australia and because some main roads have few caravan sites - there is a demand for batteries (solar on the caravan roof), and that demand increases if you intentionally go off grid.

Marine usage is lower, because buying a new yacht is not an everyday purchase for many, and chandlers have not caught up yet. If you go to a caravan dealer and retail item for 'extras', lithium is on the shelf.

An answer to my opening post is, don't bother with the local equivalent to Halfords or West Marine - go to your nearest caravan and/or 4 wheel drive shop - and they have lithium batteries and chargers on the shelf.

Cross referring to my thread on instant hot water heaters (and I'm surprised at the numbers who have used them on a yacht (I thought we were an exception) then instant hot water heaters may be like hens teeth at a chandlers but are common place at caravan retail outlets etc - and the devices sit alongside (well almost) the lithium batteries and lithium battery chargers ( + solar panels, regulators and gen sets).

And as an aside - those same retail outlets offer gas hobs (though without gimbals) fridges, freezers, small reverse cycle A/C units, ovens - offering a much better range than anything I see in chandlers.

What is lacking at 'caravan' retail outlets is the technical background - which fortunately is available here.

Now whether the UK, or European, caravan retail market has developed in the same way as here - I obviously don't know - but I do note reference to caravan/camping as an option for a source in this thread (and it has been mentioned in the past in answer to 'similar' questions).

In answer to two specific questions - we have an existing Adverc BMS and independently have a Xantrex monitor/display. I am aware that the display gets out of sync and needs to be re-set every so often (presumably errors creep in terms of amps input and output).

Jonathan

 

[Pete7]

Jonathan,

You mentioned in another thread a bread maker. LFP is of course ideal for supporting a pure sine wave inverter for electric cooking and why we have switched to LFP. However, I had assumed you were a lower power user, lights, laptop and tv etc. If you go down the LFP route ideally you will need to do a power audit to work out how much you need each day and therefore what size of battery charger you need to replace this power from shore supply. Equally, that during the summer, your solar can keep up. This is worth playing around with:

https://en.sunware.solar/systemsize/daily_yield#tabelle

Now that yo have found a better outlet for this sort of stuff, I would go back and look at Victron, Sterling, Mastervolt equipment. Yes its more expensive, but if you're living on board you really want equipment that is reliable and lasts. Our 40A Sterling charger is 15 years old and still doing sterling service.

 

[GHA]

Lots experience here
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