ok. My car came to me with a 41 ah , 360 CCA, Bosch battery in it. On investigation this is meant for a 1.1 clio...
But the custom fibreglass, rubber trimmed box will only fit this size of battery as a maximum. Leading me to think that Dax (who manufactured the car *kit car) intended this size battery.


I'm just getting it back on the road, and when I took it off in October the battery would run flat if I had headlights on.... and sometimes it went flat over a period of a weeks normal driving.
The guy who I bought it off had had loads of problems with the battery flattening and ended up leaving it on trickle charge. It was a 6 moth old battery on it when I got it.

So I tested it for current drain, and the readings were fine (cant remember them but read up on it at the time)
Charging voltage is fine , about 14volts with everything on iirc.

Now the new engine needs a 62ah battery (2 litre zt), the current 1.8 Zt still needs about this I think.

I know a lot of the power is for ancilleries and stuff, but the only thing my car doesn't have that I can think that a mondeo may have is air con.
It also has more gauges and a bigger fuel pump.

Could the low Ah be the cause of my problems? Its a bit of a PITA fitting a bigger battery as Im going to have to make a custom battery box so wanted to get some thoughts before I do it.

Im 99% sure its going to have to be done though.
Are there any other tests that will prove this?

 

Put a clamp Meter over the + terminal to read amps while everything is on including engine, that will tell you how much you are drawing, then get a battery to suit, have you checked the alternator too? Thought an engine that size would have a 75a battery

 

The first thing is to perform a test on the battery, you won't be able to do this, your best off taking it to a specialist as they have the equipment for testing it (when it's fully charged!), it may be the battery has had it.

The main thing with a battery is the CCA, with a bigger engine and higher compression this increases but in doing so does the AH figure as well.

This AH figure is how many amperes it can supply over an hour, theres far more to it than this, but as a rough guide if you had a 10A load, it would last four hours in your case.

Remember it's the charging system, i.e. alternator that provides the power, in addition to charging the battery.

If your battery is a little on the small side for turning over that engine as so this is killing it.

Martin

 

Not really, 1600 Zetec is 43AH.

Martin

 

Oh ok, i thought a mondeo 1.8 zetec was 75ah?

 

What alt are you running? And is the engine low comp?

 

It won't be your battery, either your alternator is too small or broken.

 

i would think a 360a battery would be fine, a 390a battery is pretty much standard fitment to most petrol focuses/fiestas.

 

I should think it is mate, but then I know bigger engined cars that have smaller capacity batterys than that, for example I know a Focus 1800 is 43.

Martin

 

.thanks for the help everyone!
Its a Fiesta RS1800 zetec engine, with stock alternator.
Will get the battery tested , but first Im going to retest all the stuff like current drain again tomorrow and will update then.

I don't have a clamp meter (yet) to test the dc current with engine running.

I have tightened the alternator belt up as it was a teeny bit slack, but not the problem I'm sure. After more research it could be the alternator is charging but also draining if the diode is faulty?

cheers

ps/ when its charged it turns the car over and it starts instantly. Doesn't seem to be underpowered going on ease of starting anway

 

Starting most engines is easy enough. If it does it, all good and well.

But when running, the alternator is providing all power, and any excess goes to recharging the battery.

So it's more about how capable your alternator is at maintaining an excess of power when driving than the battery itself.

 

Get your alternator tested, as Steve said the battery only starts the engine. Everything then runs off the alt. If the Alt has gone bandy, then the power will be pulled from the battery, killing it

 

As I say get the battery tested, if the battery has had it then it won't be able to hold a charge, hence after it's charged it's fine for a while, from what you have said so far I would say the charging system is ok and before you think it the fact it's not that old means nothing, if it's been deeply discharged a few times it will kill it!

The classic sign of a bad rectification is the battery light stays on when the ignition is switched off.

Martin

 

cheers Martin
Where will test it? do halfrauds do a service does anyone know?
I will get it done tomorrow if I can.
Interesting about the rectification tip... dont think it does that!

 

Your local motor factors should test your battery free of charge.

 

think I'm going to buy a proper battery tester.
My local motor factors are a right bunch of tw*ts

 

This, woulden't trust Halfords (if they can even do it), you can of course buy a tester, was going to do just this the other day, but for the amount of use it would get and the expense (Circa Ł75 from my research), I figured if ever I needed to do such a thing I would just go to the local factors.

Martin

 

It would be cheaper just to buy a new battery. Why not just make sure the alternator is charging ?

Simplest method other than going to an autospark. Stick a voltmeter onto it whilst driving. If it ever drops below 13.8v at the battery, I'd be concerned about the alternators ability to charge.

 

the battery on my rs1800 is only 16ah

 

OP has tested under load, as above.

Martin

 

if voltage is maintained all the time, then it pretty much is as simple as the existing battery being fucked.

What make is the current battery ? An awful lot of batteries out there are complete dung.

 

I was thinking this myself, im running a 20ah golf cart battery that has started my rx7 turbo with no problems and now is on my supercharged 1.8 lotus(so harder to turn over that yours) with no issues.

Mine weighs 5.3kg, have you weighed yours? what make etc is it? only way lighter I think would be a lithuim ion battery to take it under 2kg.

Its two options that i think is responsible for your problems, either alternator is on the way out or you have a bad earth which causes all sorts of starting issues.

Havent any of your friends got a voltmeter they can borrow you?

 

Bosch he said it came with, presume its same one still in it he is having the issues with

 

mines from a golf trolley too

 

this might be a good option

http://www.ebay.co.uk/itm/Liberty-Li...item2c6a412264

16ah and only weighs 2.2kg, not cheap but if its got the power to start a car it would be a nice weight saving, lithium iron is a type of lithium ion battery but looks like its the same as the Ł600 racing ones without the big price tag, but im not an expert on batteries.

alot of people forget about the large weight savings that can be done with batteries, trying to save grams with carbon body parts when stuff like this makes a nice cheap saving.

 

Cheers lads.
it seems the battery size should be fine for the car then. The battery is about 8 months old, a Bosch silver one.
I know the guy I bought it off had the battery fitted thinking it was the problem causing power loss. It clearly wasn't.
He had it on trickle charge all the time when it was on the garage so its never been deeply discharged as far as I'm aware, as when it has gone flat on me its only in terms of not starting the car and Ive charged it straight away.

Going to test voltage drop on alternator wiring in the morning, and might stick a new alternator on it if in doubt.
will update!

 

Only problem with small light batteries....if you have a problem and the car fails to start. How much scope do they give for cranking for long periods ?
Or how much capacity do they have for running fans whilst stationary ?

For a track car where support is nearby I can see the appeal. For a road car...I would never recommend a small battery.
I want peace of mind that my battery will work, and work for a very long time if things go wrong.

Ive been tempted many times by a race battery, but just cant bring myself to do it.

 

You have already said you have 13V +, so that is fine, imo I don't see this dropping as you have already tested it under load, the only other thing to do is check the draw, i.e. how many amps are being pulled, as voltage only gives half the story.

Do you have any extras on the car?

You can't do this with a meter though, you need an 'amp clamp', as said.

What you have said above defines a deep discharge.

Martin

 

13v is not fine.

Anything below 13.8v and something is wrong.

 

you are aware that most black batteries are made by UK batteries and they someones sticker is placed ontop of them

think there is only exide, bosch and maybe a few others but generally everything else is made by uk batteries,,,, hence we use uk battery codes

 

So is it the UK ones that are crap then ? lol or different brands ?

Ignoring colour, there are many small differences on some batteries, shape, terminal covers, handles, sight window, vent covers etc.
So are all of these variations even for the same size battery still made by a single manufacturer ?

 

Yes, I will recheck tomorrow as it was several months ago. I think it was about 14.3V which is fine , hence why I was puzzled..!

No real extras, apart from a load of gauges, standalone ECU, alarm/immo and such like.

Didn't realise that was a deep discharge
I thought that was when the battery was flattened and then left so that even dash lights and so on wouldnt come on. Hey ho, the battery might be knackered as well then

 

battery tester for under Ł25 from mc mart

http://www.machinemart.co.uk/shop/pr...battery+tester

 

as said the majority of batteries you see, "lion" from eurocarparts, motorcraft and ford silver from ford, halfords batteries from halfords are made by "uk batteries" and that is the norm as batteries are just batteries,,,, look at the construction and what they are made of,,, a form of metal plates, acid and plastic

no matter what you do it will be the same but some companys use calcium ect in there batteries ( which makes it a different battery) and even then they are the same

we just buy bosch as we feel we need to buy a better battery

same thing with oil too in this day and age with very few exceptions

 

Well that will be a potential downside that if your cranking for a long time then you do risk running out of juice.

Luckily its never happened to me when ive been somewhere, if ive built an engine and going for the first start to get oil pressure and also get it running I would be doing this at home anyway so ill hook up to a big battery to cover myself, after that your good to go on the little one.

I suppose for yourself(assuming your in the granada) running one would only reduce the your overall weight by 0.6% where for me its closer to 1.5% again small numbers but im aiming for 680kg from starting with 780kg so every little helps.

When you mention fans, I assume we are talking them running when the engine is off?

Ive had fans running for about 30seconds then start the vehicle, seemed ok, but then I cant guarantee that for everyone and different fans due different amount of amps

 

Yup, the likes of sitting in the fireup lane at a drag venue with the fans running. That would be minutes. or start stop driving only a few metres at a time, but lots of times.

I do agree that it is a good weight to save. But before doing so, you need to be sure about the reserve capacity you might need depending on exact usage.

 

No it's not, so long as the voltage is greater than the open circuit power of the battery then it's a charge, plenty of systems run less than 13.8V!

Yes car batteries, unlike "Leisure" battery's are not designed to be deeply discharged.

Martin

 

No road car will ever reliably charge and maintain charge with less than 13.8 volts. It may last a while and you may think its ok, but long term it is not. Even more so if electrical demand is high

 

13V with no load isn't good, it should be 13.5-14V say, with a heavy load if it drops to 13V that is no problem, even so it doesn't have to be 13.8V!

In actual fact a lead acid battery shouldn't be charged any higher than 14V +, it clearly states this on some battery's, hence one reason why Calcium battery's are used.

Martin

 

most newer alternators have resistors to prevent overcharging of batteries