battery condition guide

[haydn callow]

I read a comment by one of our members recently, He said he thought his battery was ok cos it gave a voltmeter reading of 'just over 12 volts'
I really got into battery management when we lived on a narrowboat for 6 years and volts/amps became a fixation. Te following may be of interest:-
Battery voltage % of battery charged specific gravity
11.64 0% 1.10
11.88 20% 1.14
12.09 40% 1.175
12.30 60% 1.21
12.51 80% 1.245
12.72 100% 1.28
With engine running voltage should read about 14volts
The above voltage readings should only be used when the battery has settled ie. about an hour after switching off engine.

[adam]

Every days a school day on this forrum i thought that as long as the battery had anything over 12 v it was fully charged. Yesterday i went to the bongo and it was a pain to start it took around 5 attemps. Once it did start it sounded a bit rough for about 30 seconds then all of a sudden as if by magic it ran like a dream.left it about 3 hours after a 3 mile trip same problem happened.

My first thought was glowplugs or relay- checked them and all okay.

Slept on it last night.

Same problem twice today thats when i thougt about this post that hcallow had written. So I checked battery voltage and its just under the 12.3v mark so I am now thinking that as for the last 2 weeks the bongo has not done more than 3 mile trips each day that maybe the battery is not getting enough charge or its not holding its charge as it should.

If i am correct about the above would the lumpy running after start up be due to the fact that there is to much fuel in the engine as its taken so many attempts to start .

Any thoughts anyone

P.S
And to make matters worse got a puncture in my bike, washing machine broke and the cooling hose above the starter motor on bongo split gushing water all down the street.Luckily on walking up the road and following the water marks i found that the leak only happened 50meters from home.So fingers crossed no damage to engine Its been a crap day

[haydn callow]

Battery could be cause of poor starting but doubt it causes lumpy running. Someone on here will come up with something!!

[adam]

Battery could be cause of poor starting but doubt it causes lumpy running. Someone on here will come up with something!!

Could i have flooded the engine with fuel cranking it over so much- to much fuel leading to a cough and a splutter bit of smoke then no problems

[johnzbenson]

While the advice about measuring the specific gravity of the battery and the readings is undoubtedly correct I doubt whether this has any practical benefits to a 1 or 2 battery vehicle other than telling you what you already know. you may wish to view this link http://www.igmaynard.co.uk/bongo/forum/ ... c110#58132
which in principle states that a battery in a healthy state of charge with engine switched off should read 12.25 volts with a standard voltmeter-this should also remain a steady reading for at least 15 minutes- if you can wait that long.
with the engine running the voltage across the battery terminals should read around 13. 8 volts representing a charge being delivered to the battery. -Whats the age of your battery? I could go into detail about electrolytic action and gradual positive pillar decay however suffice to say without too much abuse most modern batteries wil give good service for three to four years after that depends alot on the demands on the battery and after 6 years the first cold snap often shows poor battery performance. a good test without any special tools is to have your battery fully charged and with the engine switched off leave your headlights on for 15 minutes. if the lights go progressively dimmer then you have a battery that while often good enough for immediate starts while being regularly being re-charged by the alternator. it is a battery that will not sustain a long duration of cranking capacity. as for your original comment about lumpy running i would guess you may have one or 2 dodgy Glowplugs. as with the engine running the battery demand is negligible