Redarc BCDC1225 charging issue lifepo4

Submitted: Thursday, Nov 09, 2017 at 14:58
ThreadID: 135847 Views:10596 Replies:6 FollowUps:15
This Thread has been Archived
Hi, our Redarc BCDC1225 in the 4WD is charging using the AGM/GEL profile, max charge 14.6v, float 13.3v, it does not have Lithium battery profile to use. The issue is that the Boost or Bulk charge phase is finishing early and going into Absorption and then Float mode and it doesn’t come out of Float mode unless I reset the Redarc by disconnecting the power from the car battery. The issue appears to be the consistently high voltage level of the lithium batteries compared to lead acid.

Redarc don’t want to know about the issue as it’s a lithium battery even though I suspect their charger is not doing what the manual says it will do. Redarc told me it should go back to Boost at <13.1v for 30mins or 12.7v for 2 secs. Its less than 13.1v on my Victron BMV and its not doing this. If current being accepted drops below 25amps goes into "Absorption" when current being accepted < 4amps for 30 secs. Boost should restart if "off" 4 hours or more, it is not doing that.

Any ideas, how to work around this issue with the current Redarc unit used to charge from the engine only or a simple device to replace it with given a similar charge profile to the above that will not overcharge Lithium batteries (don’t need Solar capability) ?
Back Expand Un-Read 0 Moderator

Reply By: HKB Electronics - Thursday, Nov 09, 2017 at 15:15

Thursday, Nov 09, 2017 at 15:15
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.

Lifetime Member
My Profile  Send Message

AnswerID: 614866

Follow Up By: Sam39 - Friday, Nov 10, 2017 at 08:51

Friday, Nov 10, 2017 at 08:51
Thanks, I thought my problem also would be the risk of overcharging with the Redarc but this has not been the case as after about an hour at 72% SOC it had gone into Float and it stays in Float unless the unit has been reset by unpowering it from the car cranking battery. There is a fridge running on the same circuit so there is some draw likely happening at the same time.
My plan was to monitor closely via bluetooth while driving and potentially disconnect manually at about 95% SOC as per the Victron BMV700 (if I still have a long drive ahead of me). I have not got this far and I have a few hour drive on Sunday that will give me another opportunity to test again. The batteries are newly installed as I was doing my first several hour drive and was hoping to get the battery close to fully charged when arriving at my destination.
My goal is to get the Redarc to keep charging to 14.6v (or thereabouts) or until I manually disconnect the unit from the battery.

I have 8 of these cells making up at 200AH 12v battery. Cells
FollowupID: 885585

Follow Up By: HKB Electronics - Friday, Nov 10, 2017 at 21:48

Friday, Nov 10, 2017 at 21:48
I assume you have fully charged the Lithium pack using a manual charger setup then set the Victron for 100% charged?

Typical BMS have many parameters that need set so that the BMS knows what percentage of power has been drawn from the battery, have you setup the BMS?

In other words are you sure the batteries were discharged to below 72%, ie monitored the amp hours in and out of the batteries?

Lifetime Member
My Profile  Send Message

FollowupID: 885603

Follow Up By: Sam39 - Saturday, Nov 11, 2017 at 11:33

Saturday, Nov 11, 2017 at 11:33
The BMV 700 should be correct as the parameters have all be set.
I set it up with the supplier of the LFP batteries and he had done several BMVs and had charged/tested my battery to 100% before we installed it.
I also spoke to him when I first had the issue and he assured me that the battery voltage level and SOC would be very close to correct, I will be able to do a bit more testing with the 240v charger next week when we are home again to see how it handles my batteries. I can see all the cells are balanced so this should not be an issue.

I have now also read on other forums about people having the same issue with the Redarc BCDC1225.
FollowupID: 885613

Reply By: CSeaJay - Thursday, Nov 09, 2017 at 15:50

Thursday, Nov 09, 2017 at 15:50
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
AnswerID: 614867

Reply By: Allan B (Sunshine Coast) - Thursday, Nov 09, 2017 at 19:00

Thursday, Nov 09, 2017 at 19:00
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!


My Profile  My Blog  My Position  Send Message

AnswerID: 614869

Follow Up By: PhilD - Thursday, Nov 09, 2017 at 20:47

Thursday, Nov 09, 2017 at 20:47
It depends on what lithium battery you have. I charge my Winston cells at 14.2 volts, as the 14.6V used by Redarc exceeds specs. I have a Sterling charger with 9 different settings charging at 100 amps as lithium cells will accept a high charge/discharge rate.
FollowupID: 885577

Follow Up By: Frank P (NSW) - Thursday, Nov 09, 2017 at 23:17

Thursday, Nov 09, 2017 at 23:17
Redarc's 14.6V exceed the specs for my CALB cells too. Redarc's lithium profile is by no means a generic, one-size-fits-all algorithm. It's a shame they don't incorporate some voltage selection in their lithium profile - they make good stuff, but this lets them down a bit, IMO.

If the OP wants to change to a lithium DC-DC device, Enerdrive's DC2DC product is very good and worth a look. Lithium profile is adjustable or you can program your own profile. Has solar, but you don't have to use it.


Lifetime Member
My Profile  My Blog  My Position  Send Message

FollowupID: 885582

Follow Up By: Keith B2 - Friday, Nov 10, 2017 at 07:01

Friday, Nov 10, 2017 at 07:01
Sterling Power have a 60 amp BB1260 DC-DC unit which has a number of charging profiles that may suit your batteries. But I was advised to check my battery specs first. Their website is down at the moment.
FollowupID: 885583

Follow Up By: Sam39 - Friday, Nov 10, 2017 at 08:55

Friday, Nov 10, 2017 at 08:55
I have 8 of these cells making up a 200AH 12v battery Cells
FollowupID: 885586

Reply By: Frank P (NSW) - Friday, Nov 10, 2017 at 10:20

Friday, Nov 10, 2017 at 10:20

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.


Lifetime Member
My Profile  My Blog  My Position  Send Message

AnswerID: 614880

Follow Up By: Sam39 - Friday, Nov 10, 2017 at 10:46

Friday, Nov 10, 2017 at 10:46
Thanks Frank, As yet I haven't tested the Projecta 240v charger (will do that next week) and my Solar regulator is new so it show be fine although I haven't got enough solar at the moment to more than "break even" on a good day at the moment. I am reasonably confident by BMV is accurate but will need to keep an eye on this.

My first longer drive only got to 72% SOC before it went into float, I would like it to go much higher, I will see what happens on my trip home on Sunday. I would be happy to "trick" it to start again if it was charging into the 90% plus percent range but 72% is not going to work when we go on longer trips.
FollowupID: 885588

Reply By: Malcom M - Friday, Nov 10, 2017 at 11:28

Friday, Nov 10, 2017 at 11:28
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.
AnswerID: 614883

Follow Up By: Sam39 - Friday, Nov 10, 2017 at 12:20

Friday, Nov 10, 2017 at 12:20
We have basic BMS with LVD and HVD and additional LVD or HVD using the Victron BMV (currently set for LVD).

If the Redarc is simply having an issue with the Voltage being to high (which it seems to) and then going into Float. I was hoping to identify a simple device that would act as a diode so the Redarc continues to charge in Bulk mode and then maybe just disconnects at 14.2v or appropriate level so as not to damage the battery so I could continue to use my existing gear. I do not mind if there is no Float mode. If there is an appropriate device I am not sure how to find it but I am happy to be pointed in the right direction.
FollowupID: 885589

Follow Up By: Frank P (NSW) - Friday, Nov 10, 2017 at 12:33

Friday, Nov 10, 2017 at 12:33
Follow-up deleted. The OP's follow-up posted while I was writing makes mine unnecessary :-)

Lifetime Member
My Profile  My Blog  My Position  Send Message

FollowupID: 885591

Follow Up By: Malcom M - Friday, Nov 10, 2017 at 13:09

Friday, Nov 10, 2017 at 13:09
I can't see you going much further without spending some cash.

I'd be ditching the Redarc in favor of the BCDC1225D with Li and no float.
Then maybe some BMS modules with HVD as well as LVD. Maybe these-
FollowupID: 885592

Follow Up By: Sam39 - Friday, Nov 10, 2017 at 14:52

Friday, Nov 10, 2017 at 14:52
The other thought was to maybe put in an on/off switch in the 4WD to enable me to disconnect the power on the Redarc while driving to "force" it back into Bulk or Boost charge mode. If I did this a few times I might get to a SOC level I am happy with, not sure this will work and I might test it a few times manually before installing a switch.

The other advantage might be that once charged to the level I want then I can just power off the Redarc which terminates Float mode that is not really needed anyway.

Does this sound like a reasonable approach?
FollowupID: 885594

Follow Up By: Malcom M - Saturday, Nov 11, 2017 at 18:13

Saturday, Nov 11, 2017 at 18:13
How upset will you be when you have destroyed the cells?

Why spend all that money on cells when you wont spend anything on correctly managing things?
FollowupID: 885626

Reply By: Batt's - Saturday, Nov 11, 2017 at 01:36

Saturday, Nov 11, 2017 at 01:36
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.
AnswerID: 614902

Follow Up By: Allan B (Sunshine Coast) - Saturday, Nov 11, 2017 at 08:28

Saturday, Nov 11, 2017 at 08:28

Sam's Redarc is a BCDC1225 which is designed for use with "Standard Lead Acid, Calcium Content, Gel & AGM type only" according to Redarc documents. Sam has it set to the "AGM/GEL profile" on a Lithium battery which requires a different algorithm and voltage thresholds.
Redarc make a model LFP1225 specified for Lithium batteries.

Sam says that "Redarc don’t want to know about the issue as it’s a lithium battery.....".
I assume that Redarc have told Sam that his BCDC is unsuitable but it's Sam who doesn’t want to know about the issue and persists in wanting to use the BCDC on a Lithium battery.

Others above have pointed out the need to use a correct charging profile on Lithium batteries but Sam persists in finding a way to employ his BCDC.


My Profile  My Blog  My Position  Send Message

FollowupID: 885610

Follow Up By: Batt's - Saturday, Nov 11, 2017 at 11:13

Saturday, Nov 11, 2017 at 11:13
Ah yes I miss read it I thought it wasn't selecting the correct battery my mistake. Then that makes it so much easier unless I'm wrong get the correct charger so you don't ruin expensive lithium batteries or cause them to explode or catch fire if that sort of thing can happen.

4wdextreme sell them cheaper than redarc I bought mine from them last yr you could sell the current charger while it's still working and buy another for around $700 or look at other brands.
FollowupID: 885611

Sponsored Links