LiFeP04 battery charging

Hi Guys .

I have had a few people interested in researching Lithium batteries, private message me.

I think it would be best if this topic was discussed here on the open forum, as it may benefit all who are interested.

And I know there are people here who have different set ups , ideas and knpwledge
and some who have concerns,hopefully all are willing to discus it here.

So why not, if you are using lithiums tell us what ya got and how it is going,
or why you wouldn't change to them.


To answer one query, of concern about, why I said "forget what ever you know about AGMs" ,is the charge and discharge of LIFeP04 is completely different to that of other batteries, in my opinion once set up right they are much more user friendly.
And yes you will probably lose 100kgs and save space

Hope this gets of the ground Cheers Ken

Hi Ken
Good thread
Just wondering about these batteries not liking trickle charging from a battery charger. How does that equate to solar charging where they might go for days in bad weather with only 3-4 amps going in.

Like braggy I went with the Thundersky/Winston cells This one. when I installed them 1 year ago. Purchased fromHere.... I used 8 100ah cells linked to make 4 packs of 2.Image Could Not Be Found This will allow me to increase the size of the pack by 100a/h if needed by adding 4 cells and making a 4x3 configuration. If you use 4 200a/h cells and want to increase capacity you would have to go to 400a/h.
So far I think 200 is enough and an increase in solar would be more beneficial.
I retained the BTI Omegalec solar controller (set to GEL @ 13.9v) and already had a Pronautic 50 amp charger which has a setting that can be customised.
I prefer not to use the type of monitoring/balancing system which bolts across the +/- terminals of each cell as to me it just introduces a point of failure and is not necessary on a 12v pack. Most failures of these batteries are caused by these modules failing.
I use a victron BM600 (from site sponsor Enequest) to monitor the SOC and use this to operate the disconnect solenoid at 15% SOC and sound an alarm at 20% SOC. I also have a unit which shows me the individual cell voltages and also has a contact to operate the disconnect solenoid if any individual cell goes over 3.6V

We have been using this set up now for the past year and am very happy with the results. I have not had to do any rebalancing of the cells since the initial conditioning and balance charge.

Just to add some thoughts on this subject.
When I first started down this track I found that most of the knowllage on these batteries was from their use in electric vehicals which have a different usage and charging pattern to house batteries. They use high amp 240v charges as their primary (only) source of charge, charge them fully and than use most or all of the charge before the next recharge. We on the other hand use solar as our primary charging system which is for these batteries a very slow low amp charging. We than need to keep them as full as we can because we never know how much charging capacity we will have in the imeadiate future. (no sun, next spot under shade)

Charge voltages.
The battery is fully charged at 3.45v per cell which is13.8v if all are exactly the same. Any voltage over this is only surface charge and will quickly be lost as soon as a load is applied so there is no need to go higher.
As others have said these batteries are very robust. The only thing that will affect them is running flat (not remotely likely with a good low voltage cut off) or overcharging which is very possible if you are using high charge voltages and the cells get a bit to far out of balance. From what I have found for our usage 14.4v may be OK for a high amp 240v charger that switches off as soon as it reaches 14.4v .It needs to go that high because the high amps are holding the terminal voltage high. If it was lower, the charger would have to have a short absorption stage to let the battery catch up. It is much to high for solar charging where the terminal voltage rises slowly and with low amps coming in may sit between 14.0 &14.3v for a long period before getting to 14.4 and switching to float. Seeing as the battery was already full back at the 13.8 v mark, all further amps are just generating internal heat that may shorten its life. Also at 14.3v the cells are very close to the critical 3.6v which is from my understanding the point where longevity really starts to decrease. Held at these voltages only a small difference in cell balance could put one cell over. Why take the chance for no gain.

240v battery charges.
As others have said, these batteries dont need to be regularly fully charged and are best to be discharged to 50/60% for long term storage (AGM users have to get their head around that one). This means we only need the charger to put in a quick 40/50 a/h when they are too low to get through the night and rearly if ever use it to fully charge the battery, so pretty much any charger will do the job.
A recent example is last week when we spent 2 nights in a van park at lightning ridge for a get to gether with Gone Bush. We arrived at 10am with 50% SOC but did not bother with the charger till we went in for the night about 7.30 and switched of at bed time when it was at 95%. Next day rained all day so no solar but did not turn charger on. Next morning we turned on charger when we got up and ran it till we packed up at 9.30. Left with 95%SOC and solar had it at 100% when pulled up for lunch. Compare this with a dedicated charger that it turned on at arrival and left running. It would charge the battery than turn off and wait till it droped to 13v. Unless a large load was applied to drop the voltage and turn it back on the battery could be down to 30/40% SOC when you left in the morning. At 40%SOC and just the fridge running mine are still at 13.1-13.2V

I am in contact with a good number of people who use these in vans & motorhomes and none use a dedicated Lithium charger.

Again, just my thoughts so take from it what what you will

Do any of you have a recommendation for a DC to DC charger that will suit my current AGMs and future Lithiums?

Hi John & Heather, Yes have purchase a MCB 1225L it's on the way to WA for Rodney to set up with my lithium battery , he will give me a full report on it when he is done. I have been in touch with Luke from GSL he has given me 3 names of distributors in Tassie , but none of these stock the MCB 1225L sooooo I have purchased from else where all good now.
Jim emailled me last night with a full extraction from the KK site about setting up this system.

Cheers Dave.

Hi Dave

Sounds like you have it all just about sorted now. (with a little bit of help from our friends)

It would be great if when all up and going, you could let us know what the final set up is.

It does seem like a long road, but the knowledge gained a long the way makes it all the better to understand how these LiFeP04s perform, and how to look after them . More satisifing researching and deciding for yourself, anyway

Bet you can hardly wait to connect it all up now, LOL

Good on ya Ken


Hi ,Grumpy Old John,

Why the 240V charger, when in storage, ?
I thought the go was to just leave lithiums at about 50%, when storing ,
and check and charge every few months.
Do you know something we don't ?

PS... The kids have conquered the Cape, pick up the van, and headed off the long way to your place, LOL


Cheers Ken