Morning all, it's been a while since my last post.I need a bit of advice regarding the battery in a Ford diesel van.
My Dad's Ford Escort diesel van has just failed its MOT in a big way so looks like it will be on its way to the scrap yard very soon. I will be removing the battery as it was new just before Christmas. My question is:
Will I be able to use this battery in my Mum's Fiat Motorhome - 2.0 litre petrol - as the battery in it is dead? The motorhome is due its MOT new week so need to get it sorted over the weekend.
thanks in advance.
Mart
|
The way I see it:
- If it's undersized for the Motorhome (unlikely) you may have the problem of the battery running low.
- If it's oversized for the Motorhome then the sentiment is that the battery won't go through it's charge/recharge cycle because the car will be drawing a lower current on startup than the battery's designed for. This might shorten the longevity of the battery.
- If it's got Ford "square" terminals on it and the Motorhome has round ones, then it certainly won't fit, but I think you can get adaptors.
--------------
Mike Farrow
|
Thanks Mike,
I hadn't thought about the teminals! suppose that needs checking first.
I was under the impression that a battery for a diesel engine "has a bit more power/kick" than one for a petrol engine. Isn't it something to do with turning the engine over on startup?
Mart
|
I was under the impression that a battery for a diesel engine "has a bit more power/kick" than one for a petrol engine. Isn't it something to do with turning the engine over on startup?
It's because diesels have a higher compression ratio than petrols, so it takes more effort from the starter motor to get them turning over.
--------------
Mike Farrow
|
|
|
|
The way I see it: - If it's undersized for the Motorhome (unlikely) you may have the problem of the battery running low. - If it's oversized for the Motorhome then the sentiment is that the battery won't go through it's charge/recharge cycle because the car will be drawing a lower current on startup than the battery's designed for. This might shorten the longevity of the battery. - If it's got Ford "square" terminals on it and the Motorhome has round ones, then it certainly won't fit, but I think you can get adaptors. -------------- Mike Farrow
One more thing to add; make sure the terminals are the same way round on both vehicles.
|
The thing I was worried about was that the diesel battery will be to powerful for the petrol starter-motor/engine and cause damage that way.
If the terminals are the correct shape do you think the battery will be ok? at least for next weeks MOT
thanks again
|
It won't be too powerful. It'll be fine for the MoT.
But I doubt the terminals are the same, Ford didn't revert to the standard ones until early this decade IIRC. So if your van's older than this I'm afraid you might be unlucky.
--------------
Mike Farrow
|
I think there is a bit of public misconception about what is meant by the "power" of a battery. All (12 volt) batteries have the same voltage, so are compatible with any electrical system that uses 12 volts. That is their "potential".
What a component actually draws in current depends on its own resistance, so if connected to any 12 volt battery it will draw the same current.
How long a battery can sustain such a current depends on its capacity, which is basically related to the size (not number) of its cells, plus a few other design factors. Diesels are heavier engines with higher compression ratios, so draw a higher starting current. A higher capacity battery will be better able to supply that current for a longer period.
Fitting a battery with a higher capacity than specified won't overload anything - batteries do not "pump" power into anything - they allow power to be drained according to the load applied to them. The only difference will be that a higher-rated battery will have a bigger reservoir of stored electrical energy. It can give out more, but it will also take longer to charge. That won't matter because you will not be taking any more out than with the old battery.
As for the correct cycle of charge and discharge, thinking now is that a battery lasts longest if it is kept as near as possible to fully charged all the time, and it seems to me that if anything that is more easily achieved with a bigger than a smaller battery.
Apart from the terminal issue (easily overcome, I'd have thought, for a lot less than the price of a new battery) you will be better off, in all respects, not least in having a bigger reserve, especially useful in a motorhome.
|
Cheers Cliff, makes it all clearer now.
Mart
|
If people don't know what volts-voltage or amps-current are, well, we were taught at school...
VOLTAGE is the potential difference between two points, ie, the potential for the electrical charge to jump gaps (spark) or flow through materials. So with a battery of 12 volts, there is a potential difference of 12volts between the + and - terminal, or in a thunderstorm, there may be a potential difference of 1,000,000 volts between a cloud and the ground. In an ignition system, there may be a potential difference of 5,000 volts between the earth and centre electrode of a spark plug. You can see here, that voltage or 'potential difference' is what makes the electricity able to flow from point A to B.
CURRENT is measured in Amperes (amps) this is the 'payload'.
If the voltage was a measure of how powerful a coal train's engine was, the current (amps) would be a measure of how many ons of coal it's carrying to the destination. If we look at a 12 volt car alarm keyfob battery, we may think it could be used to start a 12volt car engine, but it wouldn't at all. The small battery in the keyfob may be 12v, but it can only deliver a small current the electricity has the potential to get there, but when it gets there it has no payload (current).
However, if we powered the car alarm fob by a couple of wires from a car battery, it would work fine, in fact the battery wouldn't even notice. It is 12 volts so will be enough potential difference but not too much to make the electricity go bursting in and burning it out. Even though the battery is capapble of delivering 400amps, the key fob will only take a miliamp or so, as it was designed for 12v use, so it's resistance which is right for 12v will make it only take a miliamp.
|
I don't think the analogy with the coal in the engine is quite right. The work the engine can do, measured in terms of the amount of coal it has on board, is actually better compared with the wattage of the electrical component times the length of time the battery can run it before its stored energy has been consumed.
I think a good analogy for electrical potential (voltage) is the difference in height between the water level in a dam and the bottom of the valley below. If there is no pipe between, no water and hence no current flows. If you connect a garden hosepipe you will get only a small flow (low current) but if you put in a ten foot pipe with a turbine you will get an enormous flow (high current) and be able to power a factory with it.
But the dam will empty faster, and if not recharged with rain will finally empty. A larger lake behind the dam (bigger battery) will keep up the flow for longer and be less subject to mismatches between rainfall and demand.
But no matter how big the lake, the potential (voltage) will remain the same, and hosepipe will not flow any faster.
|
|
Good analogy, if 617 squadron came along you would have a massive flow, but not for long!
|
|
|
|
|
