is my battery ruined

[robertbruce]

im wondering if my battery is ruined....

vehicle always starts on first crank...
i've charged it with a good charger...
then removed high tension wire for testing...
it cranks my V8 fine, 4-8 seconds 12-15 times before tiring..

so i fully charge it again...
drive it for 15 minutes and then the bloomin' thing wont crank more than 3 seconds...
alternator is charging fine...
wiring is all ok...
i have dual fuel and i use LPG mainly...

battery holds charge after charging but not after driving,
something is draining it whislt the car is running,
could it be electronic ignition, gas leads or something else in a lpg system?

can anybody advise where do i start to look for or how to find problem
how do i find the fault with the ignition on and alternator outputting?

[CNM67]

Check out the voltage regulator that's mounted to the rad. support its what was wrong with my charging system.

[robertbruce]

ta's CN, will do

[CNM67]

Let us know if that's not it

[robertbruce]

will do...

[fordman]

turn off everything on the truck. remove the negative battery cable. put a test light between the negative battery cable and the negative post. if the light lights up you have a leak or short in the system some place. to find the leak or short. you remove one fuse at a time until the light goes out. once the circut the fuse controls is found. then you look in that circut of wiring to find the leak or short. it coul deven be in the alternator or the regulator. the regulator tells the alternator how much to charge. it basically turns it off and on or regulates the output power of the alternator.

[robertbruce]

many thanks for your post FM....

and now i am going to admit something that will have your eyes rolling and mind thinking, "oh noooo, he really has a nightmare on his hands".....

the said wiring is in a motorhome.... it has a four box rotronics battery charging sytem on it, three batteries, 5 solar panels, a big dial to switch batteries, wired in inverter, relays galore, fuses a plenty. several positive strip teminals, cutout switchs, relay switchs, solar panel regulators. a disconnected alarm, a panel full of switchs with guages. It has been done well with most joins insulated and shink-wrapped....
So im not a sparky but i feel if i am persistant and patient and forum i will find what the problem is before replacing the battery..

a test light to the negatives was one test i had forgotten about....

[fordman]

most of that crap is kind of isolated from the rest of the truck i think. so it shouldbe be too hard to find.

[Nitekruizer]

You said that your battery can start it no problem but after you drive it for a while and shut it off then try to restart it is when it won't start? Has this happened more than once? Did it happen during daylight or at night with all of the lights on? IMHO it sounds to me like your battery is not being charged or getting enough of a charge when you're driving. It could be just too much of an electrical load on the charging system with all of those accesories or it could be caused by a defect in the charging system. A bad VR,as mentioned above or a burned out alternator diode or stator winding would cause a weak charge. A defective VR,a burned out alternator field coil or even bad brushes could cause no charge at all. First thing I would do is check the charging voltage at the battery with the accesories turned off and then with them turned on. Then test the alternator and the VR. If everything is working okay you may need to go to a higher amperage alternator.

[robertbruce]

many thanks for your reply NK...
yes, it happened more than once, day or night, it happens every time....
it's such a bummer to patiently fully charge all three batteries on a charger only to have the crank flatten within minutes of running the alternator...

i've got some days off coming up which will give me enough time to remove inspection covers, floor plates, wall panels and the like so i can get down to the systems....
I've been reading my rotronics intructions the last few days. To confuse matter for me, In them I've found an instruction to switch the charge selector to "main" for short city runs and whilst the crank does seem a little better with this switched, it is still discharging dramatically.... there is all these diodes and fusable link fuses everywhere, it really is a well done spagatti

many thanks for your reply, ill be back in a day or so..

[bill69f100]

Another thing to do is to isolate the batteries. Charge them, let them sit for a while (about an hour) to let them settle down from the charging. Get a multi meter and set it on 20VDC. Get 2 paper clips, with 1 paper clip on 1 lead and the other on the other lead. Test each cell. Cell to cell you sould get 1.89vdc to 2.15vdc. Make sure you don't touch the lead inside the battery or it might throw off your readings. When you add the readings you should get near 12vdc. That way you can tell if your batteries are going bad or if they are bad.

[robertbruce]

many thanks for that Bill...
where do i touch the paperclips to test each cell?

[fordman]

when you said diodes the first thing i thought of was the diodes in the alternatro being bad and letting the power flow out instead of stopping the power from leaving. you might have the alternator tested.

[robertbruce]

ive started this today and found +11.99 volts on the negative lead/negative post... (8(
ive pulled my easy to get to fuses and got a slight drop, +11.72 on two of the smaller negative leads which prolly means i got ywo problems...(8((8(
it going to take me 24hrs to go thru it all ... the whole thing is just darn sad......

i agree about the diodes, will have to test them all...
when i bought this i was already a convert of manaully managing my batteries with a big switch, or even just swapping lead over. That this unit has the upper range model of battery charger system and is capable of independently charging each battery rather than parallel charging the two accessories battery i thought, ok, ill give it a go...it can only be a limited number of things wrong...
manys thanks to forum for the assist...

[robertbruce]

could someone please confirm i have used the multileter lead correctly...

ive been testing the voltage between the disconnected negative lead and negative post holding the positive wire to the lead and the negative wire to the post..using this method it is giving me a positive reading.... if it was the other way around and considering the charging sytem i have, that a negative reading wouldn't in be a totally bad thing

is postive lead of mutlimeter to the negative lead or should it be the other way around??