The earth lead was slightly warm when I took the old one off but I'm not sure that means anything?
it might be a clue ... if the other end of it is connected to a bit of body that's rusting. never looked at mine so if it goes to engine and not body, check it's tight.
7th Jul 2019 9:21 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8072
omg! wrote:
Thanks for all your help guys.
The car wouldn't start after it was apparently fully charged so I swapped the battery out for a spare I have. It started fine and ran at 14.4v with the engine running initially and dropping to 13.98v after a short time. So that looks as if the alternator is OK?
Engine off it settled at about 12.8v after 15 minutes.
I can't see any date markings on the battery but my Tayna account says I bought it 29/12/2014
Funny thing is that the battery I took off increased it's voltage while lying on the garage floor! I'm guessing that's because while it was connected there was some drain on it by the systems that hadn't gone to sleep?
The earth lead was slightly warm when I took the old one off but I'm not sure that means anything?
The cold cranking amps(CCA) cannot be tested with a Multy Meter (MM), only the voltage , it is the CCA that provide the power to turn the engine over, but you need the voltage to get the CCA.
It is quite common for an old battery to show over 12.75 volts on a mm but will not have sufficient CCA to turn the engine over, a good battery showing 12.75 volts is only half charged.
If the earth connection is warm it has a poor connection, clean the battery post and inside the cable terminal if it still gets warm after cranking with the new battery, starter motors use more power than all the other electrical devices put together.It can when others can't,
It will when others won't,
It goes where others don't.
8th Jul 2019 8:21 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13604
Hi M3DPO
Do u think these apps are any good plse, reason I ask is I fitted a box to mine to monitor the battery voltage , allowing me to know when I need to plug my ctek back in
Battery was low and went through it and done there crank test
Just wondered if that can be considered an accurate test plse
Apologises as always for asking the daft questions but just know ur very knowledgeable and always prefer to ask
Enclosed some screen shots when the battery was low
Then rechecked it whilst charging and soon after I removed the charger , have twin batteries so don’t know if that makes any difference
Many thks as always in advance
8th Jul 2019 9:18 am
Globetrotter448
Member Since: 21 Mar 2017
Location: Londonderry NSW
Posts: 1782
I would have expected the cranking voltage to be higher on a good battery
8th Jul 2019 9:59 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13604
Hi
Must admit Battery was quite low when I done that , to be fair really need to do it again with fully charged batteries to see how they compare
8th Jul 2019 3:54 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8072
I’ve no experience or knowledge of these apps, the information it is giving is interesting but probably no more accurate than a simple £5ish plug in the power socket(cigar lighter) volt meter that usually also have 1 or 2 usb charger outlets and can be left plugged in permanently.
The battery figures look ok, the only comment is if the voltage whist cranking drops below 9 volts it will throw faults up in the system, i.e. special programs off, clock time lost, normal height only, etc. an engine restart and/or a hard reset after the engine has had a few minutes to put some power back into the battery will usually clear them.
It is unlikely for a battery charged with the alternator to show more than a 12.8volts, to go above this figure it needs to be on a smart battery charger, but a battery showing these charge rates will not necessarily have full specified CCA.It can when others can't,
It will when others won't,
It goes where others don't.
Last edited by M3DPO on 8th Jul 2019 10:27 pm. Edited 1 time in total
8th Jul 2019 10:14 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13604
Many thks
Will be interesting to see what figures I get after I fully charge the batteries
Funny enough these are the readings I’m getting with the engine running, aux battery wire isn’t connected to the gauge yet , I did plug the cheap volt meter in and surprised of how accurate it is
With the engine off it reads 12.8 Vdc
Many thks as always and very interesting about the fault below 9Vdc
Ps, that box just works via Bluetooth via my iPhone , just helps me monitor the main battery and when to recharge it
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