Thread: Dual Battery Charging Behaviour

Originally Posted by DiscoJeffster

I assume you lock the car when you leave it? They can be known to drain faster if not locked

Yes, double locked and keys upstairs other end of house.

Originally Posted by winglen

Tim,

Since sorting the loose aux earth point so the batteries are linked and both BM2s giving identical readings, I’ve been doing a reconditioning charge for the last week, 12 hours on and off each day. Settled SOC after a couple of hours is about 12.8V.

Have also done the cranking battery load test (aux disconnected, ignition and headlights on) for 5 minutes. Dips below 12 for a few seconds then settles unmoving on 12.13V, screenshot below. I assume from this the cranking battery health is ok.

My last question relates to the whether I have a problem with rate of discharge, about 0.10V per day. My configuration is at #11 of this thread, and after a full charge, the batteries isolate after a week.

Mate, something is not quite right.

What position do you have the switch on the In-Cab set at?

Originally Posted by drivesafe

Mate, something is not quite right.

What position do you have the switch on the In-Cab set at?

Is a 2017 version of your kit, so no in-cab switch on the SC80.

Try disconnecting the thin earth wire on the SC80 and then see if the batteries discharge so quickly.

I have the same Traxide kit in my 2013 D4.
Main battery (Delkor) is 3.5 years old.
Aux (Optima) is 1.5 years old.
Rate of drain looks about the same as yours, but isolates at about 14 days.

Hi Tim,

I have one of your Traxide D3-BD kits in my L320. It isolates the aux after ~3.5 days of no use, seemingly irrespective of voltages. Is there a way I can set/reset it to remain linked a lot longer or (ideally) indefinitely until the main battery drops enough to warrant disconnection? Also I see fairly aggressive discharge rates when the vehicle is just sitting there (double-locked) until the batteries isolate at which point both recover to a higher voltage (?!) and then hold a relatively steady state. You can see that in a typical trace below. It has exhibited this behaviour as long as I've had it fitted with the D3-BD.

L320 dual batt.jpg
Orange trace is the main and blue is the aux. Horizontal scale is in days. First part of the main trace is missing data however both sensors read within ±0.05V of each other when connected to the same source.

The starting battery is an SSB SS88Ti and the aux is an Optima D34 yellow - both AGM VRLA. Both are similar ages (less than three years old). There are no external loads placed on the system (nothing plugged in or drawing power apart from the base vehicle itself and dual batt system).

Disconnected the SC80 earth lead, separating the batteries.
The main battery voltage stabilised, and no leakage over the last 36 hours.
The aux battery continued to leak voltage at a lesser rate.

So I then disconnected the lead to the rear of the vehicle at the mini Anderson plug just in front of the firewall.
The aux battery then stopped leaking volts.

Conclusion: seems both the SC80 and the ABG25 are dragging the batteries down at a rate of up to 0.1 volts per day. Not a big drama if I’m out touring, but is an issue if the D4 spends a lot of time parked in the garage ie The shopping cart syndrome Tim talks about.

I’m currently thinking about removing the ABG25 to asses what happens.

Originally Posted by RHS58

Disconnected the SC80 earth lead, Conclusion: seems both the SC80 and the ABG25 are dragging the batteries down at a rate of up to 0.1 volts per day. Not a big drama if I’m out touring, but is an issue if the D4 spends a lot of time parked in the garage ie The shopping cart syndrome Tim talks about.

Exactly what the SC80 did in the D4,and the DT 90 does in our current vehicle.

I had an underbonnet switch in the earth wire from the SC80,which i would use when necessary.

With the DT 90,i havent fitted one yet,but i will.Even in storage mode,it drains some current from the battery.

I put a Cteck charger on the batteries every month or so overnight,and find they seem to charge better separated,which is why i installed the switch.