Thread: Battery charging

Originally Posted by Redtail

My plan is to have it run for 6-8h a night for all of the 32 days I'll be away.
It'll be thru the rear Traxide plug, topping up the crank and the recently fitted SSB HVT70D.

Is doing it every night is too much?
I can switch out the basic timer for a weekly one and do it say 3 or 4 nights a week with a day off in between.

Have even a 25 amp charger connected like you are planning will be fine.

Regardless of how big the charger is, once your batteries are fully charged, they themselves will govern how much current they will draw on each charge cycle.

A fully charge lead acid battery, whether it be a wet cell or an AGM, will only draw about 100 to 200ma, even if the charge is capable of supplying sat 100 amps.

SPECIAL NOTE, do NOT use this type of charge maintenance with any lithium batteries. They need special charging or they will be damaged.

What are the consequences of just disconnecting the battey/ies if leaving the vehicle for an extended period?

I'd happily do it with my 95 Defender if I had a parasitic drain that I was worried about, it would lose the radio settings, but it has no other electronics.

I have done it to my old Suzuki as well as taking the rotor button with me when leaving it in the airport parking for 2 weeks, yes a soft top so not really lockable.

Tony

Originally Posted by TonyC

What are the consequences of just disconnecting the battey/ies if leaving the vehicle for an extended period?

I'd happily do it with my 95 Defender if I had a parasitic drain that I was worried about, it would lose the radio settings, but it has no other electronics.

I have done it to my old Suzuki as well as taking the rotor button with me when leaving it in the airport parking for 2 weeks, yes a soft top so not really lockable.

Tony

Hi Tony and two weeks is fine, PROVIDING the batteries are fully charged when you disconnect them.

Anything over a month and batteries can self discharge and if the batteries are not in a real good condition, they could self discharge quite quickly and this can lead to flat batteries, even if they were fully charged at the time you disconnect them.

Thanks for all the advice and feedback.

It doesn't suit, nor is it convenient in my situation to:
1) permanently connect a maintenance charger - I already have the one and it gets used on multiple vehicles and battery boxes,
2) disconnect the batteries - the housesitter may need to move the car, and simply unplugging a powerpoint is way easier. :-)

And once I'm sitting atop a mountain in Bavaria downing a Korbinian, I won't be thinking about it at all (unless I run into Vera & Christian).

Originally Posted by drivesafe

Hi Tony and two weeks is fine, PROVIDING the batteries are fully charged when you disconnect them.

Anything over a month and batteries can self discharge and if the batteries are not in a real good condition, they could self discharge quite quickly and this can lead to flat batteries, even if they were fully charged at the time you disconnect them.

Hi Tim.
The question was more about the D4 or other very electronically complex vehicle, are there things that will have a hissy fit being left unplugged.

A quick web browse says the self discharge of a lead acid battery is about 5% a month.

My Defender often goes 2 or 3 weeks with out being started, and the Haflinger a month or more, but neither could be described as complex 🙂

Tony

Originally Posted by Redtail

......And once I'm sitting atop a mountain in Bavaria downing a Korbinian, I won't be thinking about it at all (unless I run into Vera & Christian).

They'll be the ones looking at their shoes while everyone is discussing Toyota's

Originally Posted by TonyC

A quick web browse says the self discharge of a lead acid battery is about 5% a month.

This as I posted, if your battery is in good condition.

The problem is that this is usually NOT the case.

So playing it safe is better that playing Russian Roulette.

Originally Posted by Redtail

Thanks for all the advice and feedback.

It doesn't suit, nor is it convenient in my situation to:
1) permanently connect a maintenance charger - I already have the one and it gets used on multiple vehicles and battery boxes,
2) disconnect the batteries - the housesitter may need to move the car, and simply unplugging a powerpoint is way easier. :-)

And once I'm sitting atop a mountain in Bavaria downing a Korbinian, I won't be thinking about it at all (unless I run into Vera & Christian).

OK here is an expensive fix and this does work.

If you connect a fully charged 100Ah lithium battery in parallel with your cranking battery, just before you leave, the lithium battery will actually keep your cranking battery fully charged for around 3 months.

By then, the lithium battery will have slowly discharged into you cranking battery.

Once the lithium battery discharges down to around 10 to 15% SoC, both the lithium battery and your cranking battery will collectively slowly discharge down to around 12.0v, which will probably take at least another 2 to 3 months.

At around this time, the lithium battery's BMS will shut down, protecting the lithium battery from being over discharged by the cranking battery.

So this will give you at least 6 months without needing to do anything to your cranking battery and will allow who ever needs to move the vehicle to do so without the need to do anything out of the normal.