battery charging voltages

[clartsonly]

Hi

After putting my engine back in again I am not sure the battery is charging properly.

When the engine is running the voltage on the battery is 13.8v and when the engine is off the voltage is 13.3v I am sure it is supposed to be 14.5 when charging, after a week it has started turning over slowly, is it likely to be the batteyr at fault or the alternator or maybe the wiring for the alternator from the starter motor?

I do have another battery I am borrowing at the moment from a ford diesel transit, if it is the battery would I be better off getting one of these or will it demand too much from the alternator during charging?

[kevtherev]

whatever the battery it should be over 14 volts

I would say the rectifier brush pack is not working properly. Alternators rarely fail but the brush pack has a limited life

[eatcustard]

Both my batteries only charge at 13.75v

[toomanytoys]

what happens when you turn all electrical stuf on.. ie headlamps, heater fan, rear demister etc... if it holds 13.8, I wouldnt be so worried.. if it drops at idle, then its weak.. pick up a few revs and comes back up?

[Red Westie]

Bosch/Beru regulators are stamped with 14Volt but have a charge tollerance from 13.9 to 14.2volts.
You are very slightly low and I would be tempted to pop the pack and check the length of the brushes....pattern packs are less than a tenner posted.
Martin

[clartsonly]

the thing is...

I got a new starter motor a couple of years ago and had some strange setup where there is the big red wire (charging wire I assume) was already joined to the starter wire. I cut through the seized connector and simply put a ring connector on the wire to continue the circuit when putting the engine back in the wire seemed a little dry and brittle and I moved the ring connector up the lead a little.

I am sure the battery used to charge at 14.5v a year or so ago?! now when it starts the first thing it does isa squeal like mad whereas it rarely squealed before I took it apart. (sqeal = fanbelt = alternator asking for one million amps / volts / watts???)

[toomanytoys]

Squealing means the belt isnt tight enough... that would drop the voltage as it load on the alternator...

back to basics...
make sure the connections from alt to starter to battery are nice and clean and don up.. adjust belt tension correctly.. check the voltage...

if its still low, then take the brush pack out and take a look.. if the brushes are very worn and hardly any length, that wont help..

[Red Westie]

Squeeling is actually a good sign that the alternator is trying to charge (obviously the belt needs tightening or replacing if cracked/worn)
However, if this is happenig without lights/heaters etc being turned on it is indicating a discharged battery from the last time the engine was run.
Could there be something discharging the battery?
Martin

[ghost123uk]

Mine charges at 13.84 - checked after a slight run, just to make sure this is the "trickle charge" level from the alternator. This is a fairly new alternator, less than 10,000 miles anyway.

Battery voltage settles at 12.1 after a 12 hour rest ( is this a bit low compared to others ?)
Van starts ok even on LPG, (tho doesn't turn over as briskly as it did a year ago !!)

My Aux battery, a std car battery and a bit newer, settles at 12.45 Volts after a rest.

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I would be interested in finding out from a as many folks as possible, what their battery load (in milliamps) is when everything is switched off and no engine running.

It does seem to vary a lot.

The memory for the radio will use a few milliamps. (modern radios seem to use more - some use stupid amounts, even when off) The clock will use a few too. The alarm (if fitted) will use some too, even when not armed.

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My tests =

Our campers old style Blaupunkt radio uses 250 milliamps (1/4 of an amp) which I think is a bit high. This equates to 3 watts - (12 volts divided by 1/4 amps) - a little less than 1 side light bulb. This is enough to drain the battery if not used for over a week (which hardly ever happens !) Disconnecting the radio gives 1 milliamp (i.e. virtually nothing)

Our Scirocco uses 110 milliamps with radio connected (but off of course) and 3 milliamps with no radio connected.

Anyone fancy checking and posting theirs ?

NOTE = if not sure how to use your digital meter to do this, either don't or ask me, you can damage the meter if you do it wrong, and for goodness sake don't try to start the van with the meter connected !!

[clartsonly]

I was considering doing this too but am a little paranoid as everytime I start trying to measure volts etc from one wire to the next the fuse box catches on fire