Hi, I have a question re charging a spare car battery.
I have a spare battery that I leave on charge via a timer,which I allow a 15 minute charge twice a day, therefore having a fully charged spare battery, (reason being that my car,parked in the garage,can be sat there for a week or more without being used and I have had a flat battery on the odd occassion,and also as I have this battery there is no point in leaving it flat),is it OK to do this and do I need to leave the filler caps off/loose, as obviously they are not loose when the car is charging a battery when on the move,and leaving them loose evaporates the water.
Might sound a silly question but hey it might also help others.
Thanks
|
|
One used to leave the tops loose so that the gases could escape whilst charging. I think you would be better off with one of those mains operated starters. A battery should not go flat in less than a month anyway. I've left my car for three weeks before in the cold and it's started first time.
|
Yes I know the reason for the tops left off, but as I am only charging for 2x 15 minute periods do the tops need to be left off/loose as this will evaporate the water, whilst the engine is running the battery is charging but the tops are tight? what is the difference for the amount of time I am using the battery charger.
Maybe the battery going flat when left could be due to the alarm mobilised? and drawing power?
|
|
I know it would mean disabling your alarm but if you leave a car unused for a time - particulary in Winter, disconnecting the battery negative terminal will prevent any battery drain. Even with no alarm/immobilise system I understand a battery will gradually drain if left on a completed circuit. I imagine doing this puts the battery in the same state as if in storage waiting to be sold.
|
You surely don't have to leave the tops off when charging a battery? What happens then when the battery is charged normally in the car by the alternator? Batteries are vented to allow for escaping gases.
A decent battery will hold its charge for weeks, even months. What you are describing is one, or possibly two, ageing batteries. I agree they will go on for years in this state, and it makes sense to have the spare, if you happen to have it anyway, kept in a state of readiness.
|
|
Usually a battery is put on charge because it is flat,a lot of hydrogen is released so it is advisable to remove the caps.When it is charging on the vehicle it is being topped up,electrically,so no extra venting is needed.
|
Best bet is a battery tender, not a charger. Is connected all the time and delivers a tiny floating charge whenever the battery falls slightly below full charge, then shuts off. Can't overcharge. Got 3 and swear by 'em in a hot climate where unattended batteries discharged very quickly if the vehicle is not used. Electrical consumption is minimal, mine run about 20watts.
|
Sorry, meant to add that leaving caps off is unnecessary with a tender.
|
|
|
|
Yes that is what I am trying to get at, the battery is fully charged and I want to trickle charge it twice daily for 15 minutes a time via a timer, so as when being charged electrially on the vehicle it is being charged electrically via the charger, my main concern is that if leaving the caps loose that it will evaporate the water covering the plates.
I don't want to go to the expense of purchasing a "battery tender" as suggested by THe Growler, as surely a charged up battery trickle charged twice daily,(keeping the battery fully charged) via a timer does the same job as with the "tender" therefore leaving the caps on should be the should be the same with the "tender" or charge, or am I still missing something?
One of the batteries is 2½ years old and the other one (spare) is unknown but probably less than 5 years.
Re islandman and disconnecting therefore immobolising alarm, this is a big no as the insurance stipulates the car should be left with alarm/immobilser on or insurance for theft/damage is void, not worth the risk re the question I am posing.
Thanks
|
|
|
|
