Redarc BCDC1225 charging issue lifepo4

Unfortunately not, the Redarc is not setup up for Lithiums.

I'm curious though, the Redarc will charge to 14.6V which I consider to be very high, it should stay at that voltage till the current drops to around .5A, at these levels your Lithiums will most likely be over charged.

Generally Lithiums will be very low if they get down to 13.1V, so what are you actually trying to achieve?

If the charger is bringing the batteries upto full in typical days driving then what are you running off the batteries that you need the charger to start charging again?

The only set and forget solution using that charger would be to only charge the batteries from it and run all loads via another means ie a separate power circuit from the car but it would be easier to replace the Redarc will a unit that can handle Lithiums and personally I would steer clear of the Redarc Lithium unit as it doesn't allow user settings, and if your going to upgrade then may as well upgrade to one that does.

There is much more to a charge profile than just hitting a couple of target voltages and moving on. And this is true of any battery chemistry, to really do it properly and get the best performance.
So you need a charger with specific design and settings for Lithium; the AGM settings can only do so much

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Hi Sam,

Redarc do market a charger for Lithium batteries.
It is the LFP1225 and is two-stage compared to the three-stage BCDC.
I imagine this being the reason that Redarc "didn't want to know".
The LFP list price is around $130 dearer than the BCDC although I cannot figure why so.

The charging algorithms of the two models is below but I make no comment on their suitability for the relative batteries, although others are likely to do so!

Sam39

I have the same brand cells as you, CALB, but 180Ah capacity. I bought mine from Ev Power in WA. The proprietor told me quite definitely not to use the Redarc (and some other) lithium products due to the voltage being too high either in the bulk cut-off voltage, maintenance voltage or both.

According to his advice to me when I was setting up, the voltage of 14.6 that you are using on your Redarc lead acid charger is too high for CALB cells. If you are going to persist with the Redarc, you need 14.2 to 14.4V, with 13.6V float if that is possible. I don't know if it is. If it is not, then I think it would be wise to change to a more suitable charger..

For economic reasons I have taken the same route as yourself, using lead-acid solar, DC-DC and mains chargers which I already owned. All have suitable voltages available and all work as you wish your Redarc to work - that is, they bulk charge to, in my case, 14.2V, have a short but unnecessary for lithium absorption phase then drop into float of 13.6V.

Like yours, though, they all need to be tricked into commencing a bulk charge. This is because the discharge curve of the lithium batteries is so flat - almost a constant 13.3V across most of the useable capacity. Here's the discharge curve for 180Ah cells. For your 100Ah ccells it will be similar but the drop-off would obviously occur earlier:

The voltages are per cell, so multiply by four. The Amp-hours are amp-hours removed.

You might take out 50% or more of capacity, but the lead acid chargers see a relatively high13.3 volts or so and think that a bulk charge is not needed. The mains and DC-DC chargers I have get their reset, or "trick", each time input power is applied. My solar reg has to be manually reset each morning to force it into bulk mode - a small inconvenience that I am prepared to put up with rather than spend $300 plus to eliminate it.

In regard to the displayed voltage on your Victron BMV - I have found that displayed voltages on my BEP battery monitor and my devices can vary significantly. You might need to calibrate the voltage display on the Victron if that is possible (it is on the BEP). You'll need an accurate multimeter for that. The Victron's displayed 13.1V may not be what the Redarc is seeing. Equally the Redarc could be seeing a slightly higher voltage than is actually present. 0.1V variations will make all the difference.

Cheers

The BCDC1225D and 1240D have a Li profile but you still need a BMS.
LI does not require a 'float' charge.

Do you have any BMS or are you relying on the charger ceasing its AGM charging in order to save the Li cells from over charging?

Suggest you do it right and avoid destroying expensive Li cells.

So if Redarc sold the product and you say it's not doing what it's meant to do and the product in it's warranty period have you asked for them to take it back and test it which they should be obligated to do if their product has a suspected fault with it. Asking for a refund would be the next thing if they refuse call an ombudsman to help sort the issue out I expect things will happen pretty fast once their involved. After all they are not a cheap device to just toss in the bin you should keep a record of the conversation you had with Redarc if you have to pursue this matter.