Lithium battery ??

Submitted: Thursday, Aug 19, 2021 at 18:01
ThreadID: 142410 Views:1341 Replies:6 FollowUps:10
Hi All : question regarding lithium battery's . Which battery is considered the better , cylindrical or prismatic cell or doesn't it matter ?
regarding charging the lithium battery ? i understand they like a fast charge , So how would you go with solar and what are the options for charging I.E vehicle alternator ?
Looking at changing from deep cycle to lithium for camping & boat etc NOT cranking or under bonnet .
Any comments on what i need to know . cheers
Cheers Nick b
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Reply By: RMD - Thursday, Aug 19, 2021 at 19:06

Thursday, Aug 19, 2021 at 19:06
Nick
I have only used small prismatic cells but prefer those over cylindrical. I have both types and two dedicated chargers which vastly slow the charge after initial bulk delivery. While one type has many cells banked in parallel circuits the prismatic is more like each cell of a conventional battery, in my view, others may differ. Although they will accept high charge rates I am not so sure they like it, as many believe. Acceptable rates ,yes. Bill Shortens 8 minutes would ensure a short life, ie, Shorten'ed.
There are many alt powered switch mode chargers to suit. Most also accept solar which will be less charge rate anyway. Lithium seems to be the way to go but check the cell balancing/ management and discharge draw ability is suited to your application with whatever you choose.
Seeing they hold their voltage until very near the end, a monitor to read ins and outs is a good thing to include.
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Reply By: Member - McLaren3030 - Friday, Aug 20, 2021 at 07:33

Friday, Aug 20, 2021 at 07:33
Hi Nick,

It is my understanding that you need a DC/DC Charger with a high amperage output to take full advantage of a LiFePo4 battery’s ability to rapidly recharge. Something like a Redarc 1240. Trying to charge one battery from another battery is really not ideal, as once the voltage of the two batteries equalises, you have two not fully charged batteries.

The set up in the back of my wagon is that I have a 100 AmpHr LiFePo4 battery being charged from the vehicle alternator via a Redarc 1240 DC/DC charger. I have a seperate solar input into the Redarc via an Anderson plug on the back of the car.

I would humbly suggest that you seek the advice of a competent Auto Elec.

Macca.
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Follow Up By: Phil G - Friday, Aug 20, 2021 at 08:17

Friday, Aug 20, 2021 at 08:17
Macca,
The LiFePO4battery specs usually quote maximum charge rate. And if you want to recharge the battery quickly, then sure go for the bigger DC-DC charger. But there is nothing wrong with charging at lower rates which is what always happens when you are just charging off solar and it may prolong the life of the battery.

I like a DC-DC charger where you can easily vary the settings - I use the Enerdrive DC2DC where you change the charge rate to anything between 5 and 50 amps. So when I am camped up for a few days I can put it on the max charge rate so it does a quick recharge when you go for a drive, but most of the time I use a lower charge rate of 20-30A. Less work for the alternator first thing in the morning (I also have a DC-DC in the van pulling similar current) and better for the battery.
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Follow Up By: Allan B (Sunshine Coast) - Friday, Aug 20, 2021 at 15:19

Friday, Aug 20, 2021 at 15:19
Macca, I think you may have misread Nick's "change" as 'charge'.
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Follow Up By: Member - McLaren3030 - Saturday, Aug 21, 2021 at 10:00

Saturday, Aug 21, 2021 at 10:00
Hi Allan,

Yep, my bad, I read it as charge.

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Reply By: Phil G - Friday, Aug 20, 2021 at 07:49

Friday, Aug 20, 2021 at 07:49
I only know what I've read and take no notice of what a battery seller says to promote their batteries.
Just dug this up if you want a summary: https://blog.epectec.com/lithium-batteries-cylindrical-versus-prismatic

For RV use I don't think it matters whether they are cylindrical or prismatic. The performance and longevity is similar. Cylindrical can be cheaper but not as easy to assemble as prismatic.

I have cylindrical - 100Ah and 125Ah Sunyee batteries (I trust the brand because they have been around for 16 years) and because they were cheap. I have 4 batteries spread between my Troopy, caravan and tvan.
I prefer good brand chargers that you can put custom charge settings into - so use Enerdrive DC2DC and a Victron IP22 240V chargers.

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Reply By: Allan B (Sunshine Coast) - Friday, Aug 20, 2021 at 08:55

Friday, Aug 20, 2021 at 08:55
.
Hi Nick,

For the user there is little difference between cylindrical and prismatic cells. The choice is made by the manufacturer based on his preference of manufacturing. In essence, a cylindrical cell is a prismatic one rolled up! Because a pack of cylindrical cells leaves spaces between, they occupy a larger final case volume than would equivalent prismatic construction.... but not much. Some may falsely argue that this assists heat dissipation but heat in the spaces has no ventilation so....?

Lithium batteries do not "like a fast charge" but they will 'accept' higher charge rates than lead-acid batteries. Mind you, higher charge rates mean higher cell temperatures which contribute to cell degradation and shorter life, so it is wise to use a charging system that limits the charge current to protect both the battery and vehicle alternator. To that end, a dc-dc charger with both alternator and solar input ability is appropriate. Some people have arranged for their lithium battery to be charged directly from the alternator or from a dc-dc charger designed for lead-acid batteries, but that is not my way of treating an expensive lithium battery.

Lithium batteries are expensive so there is the temptation to buy a cheaper brand but that can be a greater cost in the long term due to inferior build quality. My philosophy is to protect my investment by purchasing a reputable brand even if at a greater initial cost. Then use a quality dc-dc charger and battery monitor system.
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Allan

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Follow Up By: Member - nickb boab - Friday, Aug 20, 2021 at 11:05

Friday, Aug 20, 2021 at 11:05
Thanks Allan ' can a lithium battery be charge safely w 240 volt conventional battery charger at home or do you need a charger with lithium profile for a full charge . what brand and price are the lithium batteries you might use ?
Cheers Nick b
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Follow Up By: Allan B (Sunshine Coast) - Friday, Aug 20, 2021 at 14:45

Friday, Aug 20, 2021 at 14:45
.
It may depend on what you mean by "conventional" Nick. If you mean the brute force chargers from yesteryear then I would be unlikely to use one on even a lead-acid battery. But if, more likely, you mean the modern multi-stage charger not programmed for lithium, then I would say yes, with reservations.
The reservations are that it delivers no more than 20A and that you terminate the charging when the lithium battery was fully charged so to not leave the charger on 'float phase' indefinitely. Certainly do not allow the charger to operate in 'Reconditioning' mode at any time if it has such option.

I purchased an Enerdrive B-TEC 200Ah at $2400 for the Sprinter motorhome that I am building. All my auxiliary power components are also from Enerdrive. I like the company and their products but they are not the cheapest!


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Follow Up By: Phil G - Friday, Aug 20, 2021 at 16:08

Friday, Aug 20, 2021 at 16:08
Nick,
The characteristics of the BMS will vary so there is no correct answer to your question. Have to go by teh manufacturer's recommendation.
I use both ammeter and voltmeter on my Lithium in the Troopy and its interesting to see what goes on. The Lithium recharges very quickly at full current from the DC-DC - most of the time the voltage is in the 13's then it rises quickly to 14.4 by which time the Lithium battery's BMS has already cut the current to the battery even though the charger is still hitting it with 14.5V. The battery claims to have "overcharge protection" and I guess that is what it's doing.
As such I do wonder whether a Lithium profile is of any use on my Lithium batteries because it looks to me that the BMS protects it from higher float voltages or lower absortion voltages.

I've also noticed the default Lithium profiles for chargers vary a lot - Absorption voltage on my Victron is 14.2V while on others its usually 14.5 to 14.6V. And float voltages are usually 13.5, but some have slightly higher.

And as Allan said, never use desulphation or recondition mode on a Lithium.
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Reply By: Member - LeighW - Friday, Aug 20, 2021 at 10:09

Friday, Aug 20, 2021 at 10:09
Hi Nick,

I have been trialing two 100Ah built up batteries for a few years and for the past 2 years or so an 80Ah drop in my car.

The 100Ah are mounted in a camper and charged by an Enerdrive DCDC which does has a Lithium profile, a MPPT with a Lithium profile and the existing Projecta AC charger. However I do not use the Lithium profiles in the chargers that have them, I use user parameters that are basically the same as the Gel profile on the Projecta charger which does not have a Lithium profile. Note the Lithium settings on the other two chargers are more or less the same as their Gel profiles anyway. If AC is available I generally just charge the batteries using the power supply settings as it brings them very close to fully charged. If cycling daily then I use settings similar to the GEL settings to bring them up to fully charged a bit quicker.

The 80Ah in the car is directly charged off the alternator via a VSR, via 6B&S cable. With a modern alternator your not likely to get more than 60A flowing into the battery, less if it is an unboosted low output voltage type.

With my setup power to the van is taken off the VSR, power to the aux in the car is taken off the same point, I have done this to control the max current draw from the alternator. When the van batteries are low the DCDC in the van draws around 50A, this pulls the charge voltage to the aux in the car down so it will only charge at around 10A - 15A until the batteries in the van are charged then it increases.

After several years of use the van batteries still test over their specified Ah capacities. The car aux still tests over its specified capacity, actually it is exactly the same as the Ah capacity shown on the test sheet when I purchased it. It is also mounted in the engine bay and so far it has not been affected by the heat.

To date I have found the Lithiums much easier to maintain than lead acids, they will happily accept whatever I throw at them and aren't fussed about not being fully charged, I used to spend considerable time managing the old lead acids, chasing sun etc but with the lithiums I just glance at their SOC in the morning to check the chargers are keeping up with the demand and that's it.

Once a year I fully charge them and let the cell balancers do their thing.

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Follow Up By: Member - nickb boab - Friday, Aug 20, 2021 at 10:41

Friday, Aug 20, 2021 at 10:41
Thanks leigh' what brand of batteries are you using & type of cell are they ?
Cheers Nick b
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Follow Up By: Member - LeighW - Friday, Aug 20, 2021 at 15:50

Friday, Aug 20, 2021 at 15:50
Van batteries are EV power units built up using prismatic cells.

Under bonnet is a DCS battery, no idea what is in it, could be prismatic, pouches or cylindrical cells.

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Follow Up By: Phil G - Friday, Aug 20, 2021 at 16:10

Friday, Aug 20, 2021 at 16:10
Leigh, DCS use cylindrical cells
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Follow Up By: Member - LeighW - Friday, Aug 20, 2021 at 17:48

Friday, Aug 20, 2021 at 17:48
When I purchased it I didn't really care what was in it, it was rated for under bonnet temps which was what I was mainly interested as generally it is believed that all Lithium batteries will fail in a short time when housed under bonnets so thought I would give it a go and find out how long it lasts.

So far it still test same as when supplied, the previous four lead acids I had as aux's were already down on capacity at the same point in time.

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Reply By: Bazooka - Friday, Aug 20, 2021 at 20:02

Friday, Aug 20, 2021 at 20:02
Nick, as suggested above, there's not a great difference between prismatic or cylindrical cells in performance or reliability. There's a HUGE amount of good and easily found info on the web regarding these two cells types, and proper charging of them. Here's another comparing cell types you mention: https://www.lithiumion-batteries.com/cylindrical-vs-prismatic-cells.php

In general, the recommended charging rate for a 12V LFP is 0.3C, ie 30% of battery capacity.

High charge rates = more heat, and heat will reduce battery life over time. Solar charging is fine, if obviously a little slow.

Some batteries will have their recommended and maximum charge (and discharge) rates listed. [Not that you asked but higher discharge rates are often a decent indicator of BMS, cell and build quality. Always ask what the cell grade is - A grade being the by far the best. ]

If charging from 240V ideally you should use a charger with an LFP profile. LFP's charge differently from LA batteries (higher voltage, no float etc). As has already been stated, the critical thing is that once charged your battery should not be put onto a float stage.

Again there is plenty of useful and easily understood info around regarding charging, eg https://offroadliving.com.au/blogs/12-volt/can-i-charge-my-lithium-battery-with-a-lead-acid-charger
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