Flat Christmas battery

[MLW]

Left the 430 with a 2 1/2 year old Battery on the drive for 20 days over Christmas. Checked it today and the interior light looks weak. Tried to start, what is normally a great starter, and nothing but a whirling fuel pump. Even the steering wheel would not move.

On the charger and all should be well tomorrow morning.

How common is this?

[The-Acre]

13 minutes ago, MLW said:

Left the 430 with a 2 1/2 year old battery on the drive for 20 days over Christmas. Checked it today and the interior light looks weak. Tried to start, what is normally a great starter, and nothing but a whirling fuel pump. Even the steering wheel would not move.

On the charger and all should be well tomorrow morning.

How common is this?

I think it's quite common, its happened on my past LS's. The security system seems to cause a fair drain.  A solar charger is a good solution. Surprised the alarm didn't go off.

[Britprius]

13 hours ago, MLW said:

Left the 430 with a 2 1/2 year old battery on the drive for 20 days over Christmas. Checked it today and the interior light looks weak. Tried to start, what is normally a great starter, and nothing but a whirling fuel pump. Even the steering wheel would not move.

On the charger and all should be well tomorrow morning.

How common is this?

Leave the car on the charger for at leased 24 hours or even more if it's charge rate is below 5 amps. The Battery will be of at leased 70 amp hours capacity, and the charge efficiency is only about 60%.

This means at a constant 5 amp charge rate the Battery would need to be on charge for 14 hours plus 40%. Another 6 hours. Unfortunately lead acid Battery charge acceptance falls dramatically as it's level gets above 80%, and many chargers although rated at 4 amps only charge at half of that rate.

Using the cars alternator to compensate is asking for early retirement of it.

John. 

[RgrWynne]

Never leave mine longer than 14 days, because the Battery drain means it will be flat. Just replaced a Toyota/Lexus battery after under 3 years, because I think allowing it to run down shortens it’s life, so just ordered a CTek charger, or as has been mentioned use a solar charger.

[MLW]

UPDATE

17 hours on my AA 1 amp trickle charger was OK, and it started. A one mile drive to the petrol station  to fill up, involved another start. This was OK but 'not quite' normal. 110 miles on the motorway to Birmingham and a stop, gave 'all back to normal sound'. 300 more miles over 3 days, and I have forgotten about it as all is very normal.

Next year a slow slow trickle charge after 10 days me thinks.

[Britprius]

12 hours ago, MLW said:

UPDATE

17 hours on my AA 1 amp trickle charger was OK, and it started. A one mile drive to the petrol station  to fill up, involved another start. This was OK but 'not quite' normal. 110 miles on the motorway to Birmingham and a stop, gave 'all back to normal sound'. 300 more miles over 3 days, and I have forgotten about it as all is very normal.

Next year a slow slow trickle charge after 10 days me thinks.

A trickle charge over the Christmas period or any other extended period of non use is a good idea.
The problem with only charging a flat Battery at 1 amp for 17 hours is that it will have acquired in that time only about 12 amp hours of charge or about 18% of it's capacity. Charging is not 100% efficient. Although this is enough to start the car it can put a lot of extra strain on the alternator, and could cause early problems with it if it has to make up the difference.
Charging at 1 amp a 70 AH Battery from fully discharged  would require something in the region of 90 hours to fully charge.
Bear in mind the alternator cost of replacement with labor is perhaps 3 to 4 times the cost of a Battery apart from the inconvenience of time lost off the road.

John.

[RgrWynne]

I think that is sound advice, but I would add, having recently replaced a Toyota/Lexus Battery at under 3 years old, that allowing the Battery to run down in the first place, will prematurely age the Battery. LS430’s have a constant drain on the Battery to run the various electronics, alarm etc., so you are much better charging the Battery to full, and then putting a trickle charger on to replace the drain from the car. I have just invested in a CTek charger, which will boost the charge, then lower to trickle to maintain. I was quite shocked to find just how much is taken out on starting in cold weather, and unless you then do a decent mileage to recharge from the alternator, next time you start from a reduced Battery state, and so it goes on. That ruins batteries. Good luck, Roger 

[MLW]

All good advice. I normally have a thing about Battery charging. In the past every winter I took the Battery out and clean it, topped it up and a long 4 amp charge. Seem to do less now, but next year charger on. I would have done more than 17 hours but had to use the car. Hopefully not too much damage. 

4 hours ago, Britprius said:

A trickle charge over the Christmas period or any other extended period of non use is a good idea.
The problem with only charging a flat battery at 1 amp for 17 hours is that it will have acquired in that time only about 12 amp hours of charge or about 18% of it's capacity. Charging is not 100% efficient. Although this is enough to start the car it can put a lot of extra strain on the alternator, and could cause early problems with it if it has to make up the difference.
Charging at 1 amp a 70 AH battery from fully discharged  would require something in the region of 90 hours to fully charge.
Bear in mind the alternator cost of replacement with labor is perhaps 3 to 4 times the cost of a battery apart from the inconvenience of time lost off the road.

John.

 

[MLW]

In the last few days topped up and charged my 430 and wife's Mercedes SLK (with a 74 amp battery), Both were 'fully charged' in my view after a 300 mile run each. Both took about 20 hours at 1amp and were 'fully charged'. I bought an AA Battery trickle charger last year. For the price it is a real winner.

https://www.amazon.co.uk/AA-Battery-Charger-Maintainer-Batteries/dp/B00DW6RHN2/ref=sr_1_3?ie=UTF8&qid=1547331257&sr=8-3&keywords=car+battery+charger+for+aa