Thread: Problem Charging Aux Batteries with Smart Charger

Landoman, this is just a suggestion, next time you try to charge your batteries via the Anderson plug, set your charger to the AGM mode. If the charger does not go into float, try connecting it to either battery and then see if it will go into float.

I suspect the thinner cable may be part of, if not the very reason your charger is not going into float.

Again, I suspect the changing of the charge setting from AGM to NORMAL may be changing the voltage level and current draw at which the charger monitors to determine when it should go into float and while it is AGM, the voltage is right on the boarder line but the voltage drop in the thinner cable is just enough to keep the current draw just too high and stops the charger getting to the level it needs to be able to change to float mode.

By moving the charger directly to the batteries, you remove the voltage drop and this may be enough to cause the charger to go into float while set to AGM.

This is just a suggestion but I base the possible outcome on the fact I have many people doing exactly what you are doing, with many different types of chargers and none are having your problem ( that I am aware of ) and the only difference is that they are all charging via 6B&S ( 13.5mm2 ) instead of your 8B&S ( 7.9mm2 ).

Drivesafe, I think you’re spot on. It seems like the charger is just not seeing the voltage get high enough to tell it the batteries have absorbed enough and it’s ready for float. It could be cable thickness or possibly poor connections in the Anderson plugs or battery ends too.

Originally Posted by DiscoJeffster

Drivesafe, I think you’re spot on. It seems like the charger is just not seeing the voltage get high enough to tell it the batteries have absorbed enough and it’s ready for float. It could be cable thickness or possibly poor connections in the Anderson plugs or battery ends too.

Ok chaps .....this is a frustrating problem indeeed

put the charger in normal mode on both the wet crank and the optima ....and they go to float pretty much straight away so the batteries are in a good state of charge .

go to the back and plug in and again can get it to go to float in normal mode

Go back a gain to batteries and can get it to float in normal mode .....
try to get it to float on both batteries in AGM mode ...but no go

funny thing is ...IF I CHANGE MODE WITH OUT UNPLUGGING BACK TO NORMAL MODE IT GOES TO FLOAT ...THEN AGAIN CHANGE TO AGM MODE IT NOW GOES TO FLOAT

If I unplug and wait 10 minutes then try to get to float in the AGM mode it just sits on absorption and this is at the batteries ,....same behaviour I get when plugged in at the back ....
....not sure the problem is the wiring from the back because it is 6 AWG think

I am beginning to think the charger I bought is a lemon .....but given I have put anderson plug in one of the leads probably can't return it so will call it the expense of learning

can you reccomend a good charger for this set up ....OEM Battery crank ,optima second battery
to anderson at the back and both batteries linked by SC80

many thanks

Originally Posted by landoman

Ok chaps .....this is a frustrating problem indeeed

put the charger in normal mode on both the wet crank and the optima ....and they go to float pretty much straight away so the batteries are in a good state of charge .

go to the back and plug in and again can get it to go to float in normal mode

Go back a gain to batteries and can get it to float in normal mode .....
try to get it to float on both batteries in AGM mode ...but no go

funny thing is ...IF I CHANGE MODE WITH OUT UNPLUGGING BACK TO NORMAL MODE IT GOES TO FLOAT ...THEN AGAIN CHANGE TO AGM MODE IT NOW GOES TO FLOAT

If I unplug and wait 10 minutes then try to get to float in the AGM mode it just sits on absorption and this is at the batteries ,....same behaviour I get when plugged in at the back ....
....not sure the problem is the wiring from the back because it is 6 AWG think

I am beginning to think the charger I bought is a lemon .....but given I have put anderson plug in one of the leads probably can't return it so will call it the expense of learning

can you reccomend a good charger for this set up ....OEM Battery crank ,optima second battery
to anderson at the back and both batteries linked by SC80

many thanks

It won't be the wire thickness. Thinner gauge means LESS current from charger, so if anything it will drop into float more easily. (It goes to float when current drops enough). Almost certainly the extra current drawn by the Traxide is stopping it float in AGM mode. Make the effort, remove the Traxide earth, temporarily bridge the batteries and I betcha it goes into float. Long term, get a charger rated at a higher current - it will drop into float at a higher current level than your 5 amp job.

It’s not frustrating. Don’t let it be..
It’s a cheap charger and thin cables...

Be happy they’re charged and move on, life’s too short to worry!

Originally Posted by Tombie

It’s not frustrating. Don’t let it be..
It’s a cheap charger and thin cables...

Be happy they’re charged and move on, life’s too short to worry!

Guess I just like things tidy and to work reliably

If it doesn't go to float and it stays too long in absorption can you damage the battery ?

Run it it Wet and it drops in ok... so no it won’t do damage..

As per my earlier post, my Ctek MXS 5A charger works perfectly for your exact setup. Note that my cable to the rear Anderson came with the D4-5S Traxide kit so it may be a larger gauge than yours and if so this would be the only difference to you. I don’t disconnect the Traxide and it doesn’t cause any issues for the charger getting to float.

Scott