Discussion
Sounds like it may be terminal but this link at bottom of post suggests that you may be able to get some juice back into the battery with a dumb charger that doesn't try and detect the battery.
https://www.aussiebatteries.com.au/blog/how-to-tro...
https://www.aussiebatteries.com.au/blog/how-to-tro...
Edited by indigochim on Tuesday 11th August 07:23
According to Odyssey the reason that your battery won’t charge is because the voltage is too low for the charger to recognise the battery. To get around this problem you connect a good fully charged battery in parallel with jump leads to your flat battery and then connect the charger to the combined pair. The charger will then recognise that a battery is connected.
It's probably an Odyssey, but we need Daz to tell us.
I am puzzled by the 8.5 volts - that suggests that the charger did recognise the battery as being present, but suggests 2 failed cells.
I am on my third Odyssey battery now. One was allowed to go too flat, one was faulty from the factory, and the third one has never missed a beat, but I now have a cut-off switch for then the car is not in use for long periods - after 9 months with the switch turned off over the winter (engine fubarred), the battery still had 75% charge when it was turned on again. Which just goes to show that they are good batteries, but that the alarm etc drains them if the car isn't driven.
Daz, I have an intelligent charger/tester that has a recovery mode, and some decent jump leads. Give me a call and I can pop over and see you and see if we can identify the problem or solve it.
I am puzzled by the 8.5 volts - that suggests that the charger did recognise the battery as being present, but suggests 2 failed cells.
I am on my third Odyssey battery now. One was allowed to go too flat, one was faulty from the factory, and the third one has never missed a beat, but I now have a cut-off switch for then the car is not in use for long periods - after 9 months with the switch turned off over the winter (engine fubarred), the battery still had 75% charge when it was turned on again. Which just goes to show that they are good batteries, but that the alarm etc drains them if the car isn't driven.
Daz, I have an intelligent charger/tester that has a recovery mode, and some decent jump leads. Give me a call and I can pop over and see you and see if we can identify the problem or solve it.
There’s a technique, involving a second battery, to get it to a stage from where you can then hook up a normal charger and charge up as normal.
I’m a numpty with electrics so that’s as technical as it’s going to get from me.
If you type something like recover AGM battery into YouTube there will be a few pop up.
I’m a numpty with electrics so that’s as technical as it’s going to get from me.
If you type something like recover AGM battery into YouTube there will be a few pop up.
QBee said:
I am on my third Odyssey battery now. One was allowed to go too flat, one was faulty from the factory, and the third one has never missed a beat, but I now have a cut-off switch for then the car is not in use for long periods - after 9 months with the switch turned off over the winter (engine fubarred), the battery still had 75% charge when it was turned on again. Which just goes to show that they are good batteries, but that the alarm etc drains them if the car isn't driven.
Sound odd to me Anthony 
Odyssey batteries are first class quality in my experience, I've had my Odyssey PC1500 for 8.5 years now and it's as good as new!
It is of course a proper full sized Odyssey, you cant beat physics so I don't believe in those half sized Odyssey batteries.
AGM is just like any other battery "use em or lose em" storing them with anything less than 90% charge is asking for long term trouble 
and the stuff about "I managed to fully recover my battery from flat no voltage" etc trust me you didn't you will pay for that f
k up batteries dont like to be left discharged for long periods old new Gel AGM conventional lead acid or otherwise , I'm four years in with my Odyssey no issue at all and when I hit the battery cut after winter lay-up I'm displaying 12.5 volts and yes I charge fully before lay-up and I dont mean running the car or driving it round the block 
like Dave said they are good units
and the stuff about "I managed to fully recover my battery from flat no voltage" etc trust me you didn't you will pay for that fk up batteries dont like to be left discharged for long periods old new Gel AGM conventional lead acid or otherwise , I'm four years in with my Odyssey no issue at all and when I hit the battery cut after winter lay-up I'm displaying 12.5 volts and yes I charge fully before lay-up and I dont mean running the car or driving it round the block like Dave said they are good units Hedgehopper said:
According to Odyssey the reason that your battery won’t charge is because the voltage is too low for the charger to recognise the battery. To get around this problem you connect a good fully charged battery in parallel with jump leads to your flat battery and then connect the charger to the combined pair. The charger will then recognise that a battery is connected.
Or just use the second battery to jump start the car and go for a good drive. The alternator will then shove plenty of charge in.
(Take the good battery with you in case you stall or have to stop and need to jump it again)
Try to connect another battery in parallel whist charging either on or off the vehicle like you would doing a jump start 
connecting the batt charger just to one battery Daz, better to trickle charge that battery from discharged/flat then using the cars charging circuit, in this weather your alternator wont thank you for that stunt
connecting the batt charger just to one battery Daz, better to trickle charge that battery from discharged/flat then using the cars charging circuit, in this weather your alternator wont thank you for that stunt TwinKam said:
Hedgehopper said:
ChimpOnGas said:
Odyssey batteries aren't gel, they're absorbed glass mat (AGM).
What battery construction does Daz actually have.
He seems to have gone......What battery construction does Daz actually have.
It's only about 15 miles, so I will expect him some time next week, as the route between us is quite hilly for Nottinghamshire.
I am imagining he has an Odyssey 925 or similar, one of the half size AGM batteries.
ChimpOnGas said:
QBee said:
I am on my third Odyssey battery now. One was allowed to go too flat, one was faulty from the factory, and the third one has never missed a beat, but I now have a cut-off switch for then the car is not in use for long periods - after 9 months with the switch turned off over the winter (engine fubarred), the battery still had 75% charge when it was turned on again. Which just goes to show that they are good batteries, but that the alarm etc drains them if the car isn't driven.
Sound odd to me Anthony Odyssey batteries are first class quality in my experience, I've had my Odyssey PC1500 for 8.5 years now and it's as good as new!
It is of course a proper full sized Odyssey, you cant beat physics so I don't believe in those half sized Odyssey batteries.
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