Battery Charger - not enough Float cycle time?

[LRD414]

I have a Traxide SC80 dual battery setup with an Optima Yellowtop aux and a CTEK MXS5.0 charger.
http://www.ctek.com/Image/Small/Archive/Product/MXS%205.0_2.jpg
Charger purchased to improve the battery SoC due to lots of short city drives, like quite a few other people on here.
I have not suffered any problems or warning messages, just trying to be proactive and also follow Tim's advice in this thread (page 5, post 44):
http://www.aulro.com/afvb/d3-d4-rrs/206464-d4-2nd-battery-charging-5.html

Advice summarised as follows:
"...it is the FLOAT cycle that is needed to condition the batteries. To get the best benefit from any charging, you need to leave the batteries on a FLOAT cycle for 8 to 10 hours. Then turn the charger off for at least 10 to 12 hours and repeat. By turning the charger off for 10+ hours, you let the battery's electrolyte settle. The initial BULK charge cycle will stir up the electrolyte, then the float mode will have fairly evenly mixed electrolyte and this helps to recondition the battery ..."

The D4 gets driven nearly every day so the only opportunity for the float cycle is overnight. I have noticed the charger takes a few hours to get the battery up to float mode, so I'm not getting 8 hours in float. I'm getting 10-12 hours of charging but I'm guessing only ~5-6 hours of float (not sure exactly). And this is even when it has been charged up to float mode on the night before. It seems that a few starts and short runs during the day runs the battery down enough to require bulk/absorbtion mode again that night.

So is 5-6 hours (or possibly less) of float achieving anything? Do I need a faster charger to get to float quicker? Bit reluctant to do that because its new and working well.

Cheers,
Scott

[Tombie]

Stop worrying...

I haven't put a charger on my D4 in 4 1/4 years...

I have Tims USI-160, 3 batteries and do some long trips...

But most trips during the week are sub 4 minutes and sub 4 km...


What you are doing will certainly help...

[scomac]

Scott,I just bought the MXS 7.0 today from Repco for $149. I think I can manually select the float mode? Havn't got it out of the box yet, will find out soon.
Cheers
Scott

[LandyAndy]

I would have thought the batteries need to be fully charged before the float mode can happen.
I have the 25 amp CTek,definaitley wont do float until they are full.
Andrew

[Eevo]

Scott,I just bought the MXS 7.0 today from Repco for $149. I think I can manually select the float mode? Havn't got it out of the box yet, will find out soon.
Cheers
Scott

ive got the mxs 5.0 and you cant select float mode
but if the battery is already fully charged, it will skip the charge section and go to float.

[LRD414]

ive got the mxs 5.0 and you cant select float mode
but if the battery is already fully charged, it will skip the charge section and go to float.
Yep and that's what I'm seeing, so it's all working ok. I was more wondering about getting the 8 hours on float because it takes some time to get back to fully charged before going into float.

As Tombie said, even a short time on float is beneficial given that the battery gets to fully charged first. But how useful/beneficial is the extra long time on float etc as per Tim's advice.

Scott

[Blknight.aus]

dont forget that sometimes with the vehicles electrics hooked up, and your batteries linked the values the charger is looking to measure will be changed so it may not flick from its boost/absorption/pulse mode to its float/maintenance charge mode.

very generally this is more likely to happen with lower amp chargers than higher ones.

[LRD414]

Well that's interesting, I didn't know that. It is going into float mode each time, just takes a few hours to get there, so could be related.

Scott

[LandyAndy]

Scott.
Its only a 5 amp charger so the times you are quoting would be fine.Even my 25amp charger takes time to get to float.On the trip we just did I was running a 80lt fridge freeze engel on freeze and a 40lt waeco on fridge all day.When back at the camp I plugged into the camper trailer that had 2 120amp deep cycles with the Ctek on full time fully charged in float.It would take 20 mins to an hour to get back to float after plugging the D4 back in.
Andrew

[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.

[Eevo]

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

exactly.

over simplified example: if you have a 100Ah battery that's completely flat and a 5A charger, it will take 20hours to change.

[Aaron40]

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?

[LRD414]

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

[Blknight.aus]

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

[LRD414]

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

[AndyG]

Have a Sunday sleepin

[drivesafe]

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.

[LRD414]

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

[TB]

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...

[Tombie]

Pos and Earth point near battery..

[LRD414]

I added a ctek lead connected to the positive terminal and earth stud as Tombie said.
This makes charger much quicker to connect with no need to remove battery cover.

https://www.aulro.com/afvb/images/imported/2015/12/286.jpg

Scott

[Tombie]

Ive got a 12S plug with the Ctek socket on it.
In the middle of that I have Powerpole connector so that I can change devices!!

[LRD414]

Ive got a 12S plug with the Ctek socket on it.
In the middle of that I have Powerpole connector so that I can change devices!!
That's a good idea, would have saved me making two leads ....
https://www.aulro.com/afvb/images/imported/2017/06/261.jpg

[TB]

If there is a specific ground point I should be using, could somebody please help me identify it? The picture in the manual looks nothing like the engine bay – it has the battery on the RHS and appears to indicate a bolt at the top of a suspension mount, none of which are visible anywhere near the battery in my D4.

There are a couple of smaller bolts into the chassis which are being used as ground points for the Redarc isolator. If those are suitable, I'm all set.

Thanks again.

[LRD414]

There are a couple of smaller bolts into the chassis which are being used as ground points for the Redarc isolator. If those are suitable, I'm all set.
That's the ones. There should also be some factory earth wires using the same bolts.

Scott

[scarry]

I added a ctek lead connected to the positive terminal and earth stud as Tombie said.
This makes charger much quicker to connect with no need to remove battery cover.

https://www.aulro.com/afvb/images/imported/2015/12/286.jpg

Scott

Mine has been exactly like that for years, i use the Ctek alligator clips to charge the optima,if needed.
I also have a switch on the earth wire from the SC80.so i can charge the batteries separately,for whatever reason.