Thread: Battery Charger - not enough Float cycle time?

Originally Posted by scarry

I have the same charger and the SC80.
If you have it connected to the main battery,as i do,you are effectively charging both batteries.

Mine will often take a good few hours before it goes on float,which is normal and depends on how flat the batteries are.

Does it charge both if you have it connected to the auxiliary battery?

Originally Posted by Aaron40

Does it charge both if you have it connected to the auxiliary battery?

Yes, unless the SC80 has isolated the aux due to low voltage. Then you would need to bring the cranking battery voltage up first so that the SC80 re-connected.

Scott

dont forget that when charging with a smaller charger on a large battery with a traxide that it'll take some time to charge the first battery to the point where the isolator will rejoin the batteries and then you have the additional delay of charging the second battery before it will kick to float, If you have a load on or for some reason some of the vehicles systems are staying awake in a higher power mode due to the higher voltage thats going to blow the time out as well.

For example if you have one of the cheaper low voltage cutout only peltier cooler sytled drinks coolers plugged in and it draws 4 amps and you need to charge 100Ah worth of battery its going to take the best part of a week

All good points posted but I'm not worried about how long it takes to charge per-se, only that it makes it difficult for me to actually achieve the 8 hours on float advised by Tim in my circumstances (single vehicle household) with this charger.

But if any time on float is helpful then I'm happy.

Thanks,
Scott

Have a Sunday sleepin

Hi again Scott, and sorry for both taking so long to reply and for the long reply.

Don't worry about how long your charger is in any given mode, it is the total time on the battery that counts.

With a high current charge, your batteries would reach a "fully charged" state in a shorter time than your small current charger, but both would then go into float mode.

This is just basic math.

But a "fully Charged" battery means that the battery capacity that can actually be charged, is fully charged. This does not mean the whole battery is charged.

The problem with any type of lead acid battery is that as time goes by, the battery will loose capacity. This can be caused by a number of different factors.

The most common is continually undercharging the battery, closely followed by leaving batteries for long periods of time between chargers.

I won't go into these causes in detail now as charging is the subject of this thread.

To FAST charge any lead acid battery, you need both high voltage and high current capacity.

With a charger the size of LandyAndy's, a 25 amp charger, he will charge low batteries to a fully charged state in a short time.

There is a potential problem once the battery is fully charged, that the high voltage will, if allowed to continue to be applied to the fully charged battery, will eventually cook the battery.

This was the primary problem with older type battery chargers, like the good old 4 amp Arlec battery chargers. If you forgot to check them, they would just boil the battery dry.

All modern battery chargers charge at there maximum current till the charger reaches it's maximum charge voltage.

This is usually when the battery's State of Charge ( SoC ) reaches around the 80%, and from this point on, as the battery continues to charger, the current it draws from the charger tapers off.

Once the battery gets to a fully charged state, it will draw very like current. At this point, the charger determines the battery is fully charged, so the charger steps back the voltage to the pre determined FLOAT charger voltage level.

THEORETICALLY, the FLOAT charge voltage level is supposed to stop the battery from self-discharging and maintain the battery in a fully charged state.

This it does, but over a period of time, if the FLOAT charge is permanently
maintained, the battery will eventually dry out.

Now back to your small current charger and not being able to get into FLOAT for long enough.

With your small current charger, you are actually achieving the same results while in the long Charge mode as what is be achieved in Float mode with any size charger.

It is the actual total time the charger is on that is of benefit and will help condition the battery, no matter what mode it is in.

So with your small current charger, you may find it needs to be used three or four nights in a row before the charge goes into float mode for any length of time.

But once it does, each night, it will go into float mode sooner than the last charge.

If this is what you are finding, then your battery is getting both a good charge and a good conditioning.

I came across info on this type of charging about 8 or 10 years ago, from some RELIABLE source in the USA. I have carried out this type of recovery charging on too many batteries I have failed to maintain properly, but in the most part is works very well at recovering most if not all of the lost capacity, just takes time.

For an extreme example, my RR has been stored at a service company in Brisbane and has not turned a wheel in over two years.

I forgot to go up and retrieve the batteries ( 1 x brand new Varta cranking battery + 1 x brand new Optima ) when I first decided not to bother to fix the RR.

It was 14 months before I finally brought the batteries back to my workshop.

The Varta had a terminal voltage of 0.7v and the Optima had a voltage of 9v

While I was sure the Varta was unrecoverable, I was confident that the Optima would still have some use once charged.

The first charge of both batteries gained a 10% capacity in the Varta, which I was surprised it would charge at all and the Optima had about a 60% of it's original capacity.

After many conditioning charges and a couple of high voltage charges ( 17+v using an unregulated 80w solar panel ) I managed to get the Varta up to 55%, which while the battery was still stuffed, it was surprising it could still be charged and would hold the charge.

The Optima eventually regained 85% of it's original capacity, which is not bad.

So again, this type of conditioning charge does have good benefits.

Originally Posted by drivesafe

With your small current charger, you are actually achieving the same results while in the long Charge mode as what is be achieved in Float mode with any size charger. It is the actual total time the charger is on that is of benefit and will help condition the battery, no matter what mode it is in.

So with your small current charger, you may find it needs to be used three or four nights in a row before the charge goes into float mode for any length of time. But once it does, each night, it will go into float mode sooner than the last charge. If this is what you are finding, then your battery is getting both a good charge and a good conditioning.

Thanks Tim for the extra detail, it's appreciated .... and at 2am, that's dedicated. What you have described is exactly what the Ctek is doing, a bit earlier to float stage each night.

Scott

Just a single calcium battery in my D4, but I’d like to make it last as long as possible. So a simple question: do I just put my 6A smart charger straight onto the battery terminals or is there some other place that one or both clips need to go?

Thanks in advance...