Battery Charger - not enough Float cycle time?

**LRD414** · 13th January 2016, 02:22 PM

I have a Traxide SC80 dual battery setup with an Optima Yellowtop aux and a CTEK MXS5.0 charger.

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/...harging-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 · 13th January 2016, 03:13 PM

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** · 13th January 2016, 08:06 PM

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** · 13th January 2016, 08:09 PM

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** · 13th January 2016, 08:15 PM

Originally Posted by 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

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** · 13th January 2016, 08:22 PM

Originally Posted by Eevo

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** · 13th January 2016, 09:00 PM

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** · 15th January 2016, 05:24 PM

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** · 15th January 2016, 07:24 PM

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** · 15th January 2016, 08:32 PM

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.

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