Joined: Aug 2017 Posts: 613 Threads: 19
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Location: Hampshire UK
02-04-2021, 09:30 AM
One for the experts in electro-chemistry ?
My Pearl hasn't been out for 6 months, but a couple of days ago I decided it was high time for a run out. Came to start the engine, ignition light on, pull starter, light goes out and absolutely nothing from the starter motor. Further check shows battery voltage collapsing to near zero when a start attempted. The battery is a traditional style rubber cased one with exposed lead links, and probably 4 years old.
Now I know what you are thinking - this idiot has just left it and allowed his battery to go flat. However, the whole of the 6 months it has been dutifully connected to a stabilised power supply set at 6.9 volts i.e. a normal float charge setting. Nothing "smart" about it.
With nothing to lose, I gave it a 24 hour charge at 10 amps (tapering down to 3 amps). It now seems OK, with terminal voltage of over 6 volts (all individual cells very similar voltage) and only dropping to about 5 volts when cranking.
Rather than putting off the inevitable, I have ordered a new battery anyway. But I'm mighty curious to know what's going on. Does prolonged float charging cause a high resistance film to build up on the plates ? Unfortunately my hygrometer disappeared years ago so I don't know what the SG is up to.
Joined: Aug 2017 Posts: 254 Threads: 3
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Location: Shropshire, UK
John, I have had a virtually identical experience, 2 year old battery on the vehicle, left on maintaining charge on a ALDI smart charger, max current 0.8A attempting to start vehicle - no starter motor action. I have tried boost charging the battery several times with intervals between; no joy. I no longer leave the maintaining charger permanently connected but have reverted to my earlier practice of a "top-up" charge once per month.
I have had plenty of experience with wet lead acid batteries over the last 50 years but I am at a loss to explain this.
Joined: Aug 2017 Posts: 178 Threads: 1
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John & Ian, I too use an Aldi smart charger (only smart on 12v) but do not leave on all the time.I just use for about 8to 10 hours a day 3or 4 times a week. No problems.
Joined: Aug 2017 Posts: 1,018 Threads: 53
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Location: The delightful town of Knaresborough, North Yorkshire
John Cornforth wrote "...the whole of the 6 months it has been dutifully connected to a stabilised power supply set at 6.9 volts i.e. a normal float charge setting."
6.9 sounds high to me. I'm more familiar with 12 volts, double 6.9 is 13.8 volts. My Lidl smart charger seems to hold it at 12.9
On the other hand, batteries do fail. Plenty fail within a one year warranty. Others fail at 4, 5, 6 years old. I had one that lasted for 17 years.
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02-04-2021, 01:07 PM
(This post was last modified: 02-04-2021, 01:08 PM by Edgar Lowe.)
I have 3 Halford smart chargers on my three cars heavy duty 12v batteries connect at all time. They all start first time, even today I tried to start one after 6 months it started immediately. It looks that the 6v battery cannot handle the permanent Smart charger.
Joined: Aug 2017 Posts: 926 Threads: 22
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Location: Near Cambridge, UK
Car type: 1928 tourer (mag type), short chassis Gould Ulster
I have always suspected that the intelligent part of Aldi and similar 'smart' chargers is not so good on the 6v setting. Although I use this type of charger I check after 24 to 48 hours, and disconnect if full, recharging every 6 weeks or so.
Joined: Feb 2018 Posts: 128 Threads: 13
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When I connect my battery to my Aldi charger it reads 6.4 volts after half an hour it reads 7.4 volts but it turned my cars engine over for three or four second and that"s it but it can start easily on the starting handle. What is it about six volt batteries that they fail far more often than 12 volt ones, because I use two six volt batteries in series on other cars I have had seven fail in as many years, with the development of small 12 volt batteries that last the only six volt ones I need are for my sevens regards to all Rob.
Joined: Aug 2017 Posts: 1,018 Threads: 53
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Location: The delightful town of Knaresborough, North Yorkshire
robert regan wrote "What is it about six volt batteries that they fail far more often than 12 volt ones"
it could be with such little demand for 6 volt that batteries have stood a few years when you buy them.
Joined: Feb 2018 Posts: 128 Threads: 13
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I do have one that came to me on my chummy three or four years ago its now on my cabriolet and its power seems to be endless I will look to see the make of it tomorrow and let you know what it it regards to all Rob.
Joined: Aug 2017 Posts: 1,647 Threads: 23
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Location: The village of Evenley
Car type: 1934 Austin Seven RP Deluxe
I bought an MGB spec 6 volt Exide battery for the Old old Chummy and it performed faultlessly without top up charging for six years and although the car was used at least three times a week commuting to and from work, there were occasions when it was left in the garage for a couple of months at a time.
However, I bought a new 6 volt battery for the box saloon 18 months ago and I’m having exactly the same problems as you John, I’m going to buy another MGB battery!
