Lithium LifePo4 12v Batteries - Time For An Upgrade?

Hi folks, my lucas 125ah AGM battery is discharged after 30 hours running my fridge and lights so need to replace.
First year with the van and I have been shamefully poor at looking after my battery when I get back from trips, thinking that the alternator and solar would put enough charge in when depleted.

Currently I have a Ring RSCDC battery to battery charger and a CBE CB516 240v charger.

Will they work with a lifepo4?
 
stanyd said:
Hi folks, my lucas 125ah AGM battery is discharged after 30 hours running my fridge and lights so need to replace.
First year with the van and I have been shamefully poor at looking after my battery when I get back from trips, thinking that the alternator and solar would put enough charge in when depleted.

Currently I have a Ring RSCDC battery to battery charger and a CBE CB516 240v charger.

Will they work with a lifepo4?
Click to expand...

No the RING RSCD doesn't have a Lifepo4 profile.

the closest setting would be GEL 14.2v / 13.2v



1690830171863.png


and the :

CBE CB516 240v charger.


is just a basic Dumb charger for Lead Acid batterys.. . .


++++++++++++++++++++++++++++++



so no, your existing setup is not lithium compatible, but its an easy fix.

++++++++++

1#

fit a 100ah lithium battery:


EG the Renogy 100Ah,




1690830399132.png





++++++++++++++

2#

swapout the RING 30A charger, for a CTEK or RENOGY 30A charger.






1690830462627.png




+++++++++++++++++

3#

then add a decent EHU charger -

eg like the Victron 15A unit. . .










1690830526815.png




++++++++

4#


make sure all cables and fuses are correct and suitable (if you stick with under 30A chargers you existing cable install should be good - assuming you have a RING 30A charger)
 
Last edited:
stanyd said:
Okay cheers mate. I was trying to understand the price about using the AGM mode if it had the right voltage
Click to expand...
technically you can use a AGM charger etc . .

provided that the voltage limits are enforced.

normally 14.2v bulk and 13.2v float. for most lithium's with internal BMS, will help charge it.

but . . .

all lifepo4 battery manufactures will stipulate that you use a suitable charger fit for purpose,

ie - a modern smart charger with a dedicated Lifepo4 profile and safety features.

so, NOCO, Renogy, CTEK, Victron etc etc etc .

The RING is an older tech from previous days before Lifepo4,

and the CBE is just a basic SLA old skool charger.

++++++++++++


so the official word would be - ripout/sell then replace with lifepo4 spec kit


++++++++++++


as a side note, where all lithium's will pull MAX current from any charger, most older gen SLA chargers will just overheat and cut out.



.
 
Browsing around Fogstar seem to strongly hint that their batteries can be charged as lead acid at 14.4v - just wondering if anyone has tried that...

From the manual:
Screenshot_20230731-202011-01.jpeg

If the BMS can regulate the charge that's a significant saving for a simple basic 100ah system.

I'm just a bit suspicious, especially with the wildly varying voltage in smart alternator based system...
 
well I've played with SLA chargers and lithiums. . .

++

but i deffo would not connect to a cars alternator. . .

a flat lithium will easily draw 200A from an alternator and smoke it.


1690832221206.png



victron done some tests . . .


1690832290402.png


see the video here -->





.



they cooked it. . . .


1690832409311.png
 
I was certainly surprised to see it there in the manual.

Theoretically something like a BMS should be in a position to regulate charge as none of these batteries are really "bare" lithium cells, after all they are capable of talking between themselves to balance things, I've just not seen it done. But if they evolve to be completely drop in it would be the next step.

Might drop Fogstar a line and see what they mean.

But yes I'm not going to experiment directly...
 
@Dellmassive tad off tooic here but you seem to know your stuff!

just having a look at my dumb ac dc charger and it is currently set to lead acid and not to gel.

should it be set to gel for an AGM battery?

Looks like it would then charge it to 13.8 instead of 13.5v and keep charging for longer once that threshold was reached
 
sure,

but most battery BMS will allows up to the max current, most are 100-200A on a 100Ah battery. ( most will NOT allow you to regulate the incoming current within the BMS settings - they just use MOSFETS to switch the current flow ON or OFF)

(but some CHARGERS allow to set a current limiter (Victron & Renogy spring to mind))

so a battery pulling 100-200A is way more than most alternators will handle.

the T6 has a 140A or 180A alternator,

running the engine could take +40A alone,

so adding a unregulated lithium will pull max current.

plus a T6 alternator under regen outputs 15.0V which is more that most lithiums can handle - this will trigger the battery BMS over voltage alarm.

and a smart alternator will freewheel at 12.6v most of the time - which again is no good for a lithium and wont charge it.


........



charge rate and current flow is directly related to the source voltage and circuit resistance. so a direct connection to a T6 Alternator and starter battery is NOT A GOOD IDEA.


..........


so my advice, and many battery makers is to use a DC-DC charger on a vehicle as a buffer between the engine/alternator and any lithium battery bank.
 
Those are exactly the reasons I was surprised, and to be clear to other readers I'd certainly second the DC-DC advice.

I've dropped Fogstar a line to clarify quite what they mean by that line as the engineer in my head is intrigued.
 
stanyd said:
@Dellmassive tad off tooic here but you seem to know your stuff!

just having a look at my dumb ac dc charger and it is currently set to lead acid and not to gel.

should it be set to gel for an AGM battery?

Looks like it would then charge it to 13.8 instead of 13.5v and keep charging for longer once that threshold was reached
Click to expand...
+++

looking at the manual for that, id agree that the GEL setting would offer better charge levels for your AGM battery. . . 13.8v will be better.

( you will need to check the real voltages at the battery terminals as you will have volt drop from the supply cables and install. so you will get a lesser voltage at the battery, compounding the low charge rate, your current 13.5v charger may be down to 12.8v by the time it gets to the battery)


SLA - 14.1v / 13.5v

GEL - 14.3v - 13.8v

1690833696086.png1690833751996.png


www.jacksonsleisure.com

CBE CB-516 Campervan Caravan 16 Amp Switch Mode Battery Charger

The CBE CB-516 is a 16 amp campervan caravan battery charger
www.jacksonsleisure.com www.jacksonsleisure.com


+++


more info here:


check out the CHARGER, MONITORING, DC-DC and Lithium sections



*****************************************************

POWER:







******************************************************
 
Thanks for advice.... sorry state of bought it not built it here....

A couple of hours and I'm finding all sorts of rabbit holes. Dc dc set for solar priority mode preventing any alternator charging and CBE set to lead acid.

Poor old AGM battery wasn't getting a chance to impress
 
Dilbert said:
The Fogstar Drift batteries currently do NOT use ACTIVE balancing. The JBD BMS uses PASSIVE balancing.

I have built a battery using Fogstar Prismatic cells with a JK BMS which has ACTIVE balancing for this very reason.
Click to expand...
Got some pics of your build @Dilbert.

I love a DIY pack.
 
Pauly said:
Be interested to hear how it works out price wise compared to buying the built package
Click to expand...

4 x EVE LiFePO4 230Ah Prismatic Cell (Grade B) @ £99 each
1 x Smart BMS JK-B2A8S20P with Active Balancer 200A (4S-8S) @ £95

Plus case materials, cable, crimp connectors, etc. This will give me a 230Ah seat base battery for about £500. I am not worried about an internal heater. The main motivation was availability/lead time of the complete batteries plus I wanted to do it!

(NOTE: The Grade B cells are still excellent cells. Read more hear: The REAL difference between EVE Grade A and Grade B LiFePO4 Prismatic Cells).
 
I like watching Jehugarcia on YouTube although I struggle to keep up however on his website jag35.com he has new Samsung 18650 cells in 100 boxes at 99 US dollars and various projects showing these built into different size and voltage packs.
I find it really interesting but struggle to follow the various package architecture and BMS specs but like the idea of an off grid beefy house battery and inverter setup.
 
Two items not worth cutting corners or saving money on; batteries and chargers.
Best case it’s salad for breakfast.
Worst case your van has gone up in smoke and the insurer is asking questions.
 
I'm potentially interested in DIY because I have a close enough parallel background to know what I'm doing, but I'm also self aware enough to know that's a big warning sign :rofl:

I do it in small scale in RC models, and I've done some for event kit in the garage similar to Dellmassive's tool box batteries (but with ex UPS lead acid gel blocks) but I think actually in the van I'd rather just stick to plumbing the wires between off the shelf kit.

I haven't had a reply from Fogstar querying the charging details in the manual, which is a bit off putting given the prices are pretty keen and they talk a good talk in the blogs.
 
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