Lead Carbon Batteries, Experience, Observation.

Targus100

New Member
Joined
Oct 2, 2019
Messages
8
Hi all,

Firstly some experience and secondly a question on lead carbon batteries, as it seems to be very hard to get a straight answer on these things!! Quick background is that I have been living totally off grid for 5 to 6 years and have relied on 2 2x6 volt 430 ah FLA battery banks in series to get 12 volts which I have then inverted to 240 to run computer and lights, I also run three camp fridges but they all have their own circuits.
Now that the money situation has eased somewhat (dont get divorced peoples:eek:) and I had been looking to upgrade my systems a bit, here in Australia there is a company called Commodore Solar that are selling their own branded 2v 1000ah lead carbon batteries which are a drop in replacement for my FLA system (did not want lithium as I would have to replace the whole system) Sooo I went ahead and purchased 6 of these to create a 12 volt bank to run my little abode, now first of all WOW I now have real power!! Second, I have them hooked up to 2 x 250watt 24v panels through a cheapy (Kickass) MPPT charge controller with the intention of connecting another 2 panels that I have as my charge controller can theoretically take 1050 Watts of 24v panels but as I have been watching what is going on I may have to change my mind.
The charge controller is rated at 40amps and the other day where I had run the batteries hard for the first time overnight the next day the charge controller was showing it was pulling 32amps off the 2x250 watt 24v panels!!..........First of all is that even possible?? And second of all I have noticed that on a regular basis I am getting anywhere between 26 to 28 amps charge rate showing through the charge controller and to the point it was heating my wiring up from the solar panels to the controller (which I have since replaced)
Now here is the question, are these batteries capable of pulling more power in to recharge than a FLA? Because I have an identical set up on one of the FLA banks and the most I have ever see it pull was 18 amps with a total of 102amp hours for the day whereas the lead carbon bank was pulling a maximum of 32amps and 177 amp hours for the day then it hit float charge with another hour or so of sun to go!
I have the charge parameters set manually for the lead carbon bank as a gel battery bank as that appears to be the closest charge rate match but again this took quite a while to even get that information (come from the victron forum) Are these batteries really the super capacitator batteries as they have been touted as? I have to say I have only had these now for a month or so but their performance is eye opening compared to my other system especially their ability to "pull in power" and it looks like I am going to have to upgrade the charge controller before I add the other panels otherwise things could get a little messy!!
 

fratermus

Solar Addict
Joined
Mar 19, 2021
Messages
264
Glad to see the carbon-doped battery subject come up. I was considering something like the Trojan version, the T-105RE.

are these batteries capable of pulling more power in to recharge than a FLA?

Trojan's promotional materials for their carbon (RE) line claim "improved charge acceptance" and "Faster recharge in PSOC applications".

Firefly, the leader in this space AFAIK, claims: "higher energy density; faster charge and discharge times,"

A quick google search shows academic articles that seem to support the idea. Sample blurb: "Carbon materials are widely used as an additive to the negative active mass, as they improve the cycle life and charge acceptance of batteries, especially in high-rate partial state of charge (HRPSoC) conditions"

This Sandia Labs paper is about carbon in VRLA, but it says: "[researchers] attributed the dramatic improvement they observed in charge acceptance to the capacitive effect. the effect of the carbon is to increase the overall electrochemically active surface area within the negative plate, thereby increasing its capacity and facilitating more complete recharge" and "the effect of the carbon is to increase the overall electrochemically active surface area within the negative plate, thereby increasing its capacity and facilitating more complete recharge." They note that a battery with carbon in parallel with the negative lead plate "exhibits a dramatically improved cycle life over traditional VRLA batteries, as well as increased charge power and charge acceptance"

So I think it is (or can be) a real effect.

dont get divorced peoples

The play is at first base; don't get married peoples! :)
 

Targus100

New Member
Joined
Oct 2, 2019
Messages
8
Yaa, bit more research says that 32amps off 500watts of solar @12v is possible in good conditions which it was ie cold day yet full sun.
Since I have a simple monitoring system on both banks I have been comparing them and the carbon bank is now consistantly out performing the FLA bank, granted the FLA bank is older but the lead carbon bank is pulling nearly double the amps at any given time compared to the FLA yet I have deliberately loaded both banks near enough to equal load. Again understand not really comparing apples with apples due to the differing size and age but the lead carbons seem to be able to get more of what is on offer from the panels..................in short very happy until my next shed goes up then I will put a big system in play....................lead carbon or lithium? We will wait and see.
 

Substrate

Solar Addict
Joined
Apr 28, 2021
Messages
675
Location
SoCal
FLA is usually rated for no more than about 0.15C charge current, where C is the 20-hour capacity rating.

Lead-Carbon is usually a form of improved AGM. Conventional AGM's around about everywhere can accept about 0.2 to 0.3C charge current. So yes, they are an improvement over FLA since you can have larger panels to push more recharge current in.

The promise of lead-carbon is usually touted as being "PSOC", or partial-state-of-charge capable. Unlike normal AGM's, which tend to be UNDER-charged via solar and quickly sulfate and walk themselves down in usable capacity, the lead-carbon supposedly won't hard sulfate *as fast* if you do partial charges - common with solar.

That means you might get more life out of them as compared to a conventional agm. Note that this does NOT relieve one from achieving a full charge on a regular basis!

The majority of the lead-carbon psoc application is seen in "Start-Stop" vehicles, that actually turn off the engine at stoplights and such and quickly fire back up when the light goes green. This is prone to leaving the batteries in a partial state of charge by not running the alternator to charge full time. Lead carbon helps here.

So it can also help in a solar situation too. Just keep an eye out for weasel-word marketing trying to make you think that you can do PSOC full time and never achieve a full charge on lead-carbon and just "fuggetaboutit". :)

So really, the lead-carbon usually being a variation of a conventional agm, which has always had more charge aceptance than an fla to begin with, is simply able to charge faster.

When you really want to push it you either have to do one of two things: 1) Upgrade to pure-lead agm's, OR 2) change chemistry altogether to LiFeP04.
 
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