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MG MGA - Battery Life

I just tried to start my car earlier this week and had no luck. It's cranking very slowly (Vrrump... Vrrump... Vrrump... ). I put a charger on it (the type that varies its output depending on the batteries' output) and after a few days it still cranks too slow to start. Looks like I'll be buying the MG a new set of batteries this spring. So that's two sets since the restoration was completed in 2004. Is it normal for a set of batteries to only last three seasons? I try to start and run the car once a month, even if the weather isn't good enough for driving, but in this instance I hadn't run it since October.
David Breneman

I routinely get 6-7 years on a 60 month battery in my DD's here in northern Illinois. I just replaced the 10 year old factory OEM battery on my '99 Buick. Not because the chemistry was worn out, but because the battery terminal broke off in the case. I used to get about 6 years on my 1x12 volt battery in my MGA coupe. I am on the 8th year on my 12 volt battery in my roadster. I generally put up the car in mid November and don't touch it till the end of march/ early April. The battery just sits in the car for that time with no charger at all.

For the biggest bang for the buck, I buy the mid grade batteries at Walmart, not the big-name battery stores. So to say 3 years is a normal life, nope- no way!

Batteries have a shorter life in hot climates. Just due to the nature of the beast. Washington state does not qualify as a Hot climate.

But my experiences are all single 12 V batteries, It sounds like you are running the original setup 2x6 volt bateries. This is less effective due to 2 reasons: 1) the 6 volt batteries are built of an older technology and do not benefit from the newer designs. 2) there are more interconnects in a 2-battery system. Each wire-to-terminal connection is an opportunity for failure.

I would think you should still get 5-6 years on your setup if the regulator is set right and you maintain the terminals on the batteries. Not just the batttery terminals but the wire-to-terminal clamp corrosion; engine ground strap; switch-to-starter wire; etc.

Sorry to hear you are getting such poor life on your $$ batteries. Check your regulator, if it is set too high, it will overcharge the batteries and dry them out....if it is set too low, then it will not charge fully. Either way, it is not good.

Chuck Schaefer

David, do you lay your car up for the winter? If you do, you need to give it a refresher charge every month to keep it in good condition. If a battery sits idle for 6 months, the plates get covered with lead sulphate which reduces their efficiency. When the battery is used again, this sulphate falls off and forms a sediment in the bottom of the cells which will, when it builds up enough, short out the plates and render cells useless. This could possibly be your problem.
Lindsay Sampford

David, I just purchased "battery tenders" for my cars to prolong their battery life. I was beginning to sense some starting strain on the batteries. I'm using 2 x 6 vlots as well on 2 of my cars. The batteries are always fully charged, they can't be overcharged and it is supposed to prolong the battery life. Just type in Battery tender on Ebay and you'll get lots of choices. I'm very happy with them and it's great knowing the car will start.

60 MGA Coupe
67 MGB
Andy Preston

David, first of all check all the connections, clean and refit the clamps to batteries, but also check the cable to clamp connections.

Also I have brought some pretty dead batteries back to life with CTEK conditioners. They can even repair partly sulphated batteries.

I have a number of different battery conditioners and maintenance/trickle chargers for my cars and business. I use a CTEK XS3600 for initial charging and maintenance of the battery and then connect to an XS700 or other (less expensive) trickle charger.

Neil McGurk

I had problems with a couple of batteries failing early and traced it eventually to a low output from the dynamo meaning that the batteries were never being completely charged. There were no obvious symptoms and everything electrical appeared to work OK. Adjusting the voltage regulator back into range fixed it.
Malcolm Asquith

I restored my 1600 Roadster in 1995. Since then I have only changed the batteries (two 6 volts original type from Moss) twice, plus the originals. That's seven years each time. The last change was this last summer. As I don't drive it much, especially in the winter, I bought a Sears Diehard automatic charger. I hook it up and leave it on all the time when I'm not driving the car. Of course I check the water level in the bateries every couple of months and add Distilled Water when low. It has worked for me all of these years so I'm sticking with it.
Joe Wiley

David - As several people have already stated, batteries don't like to sit unused for long periods of time and running the car once a month qualifies as leaving them sit unused. Do as Andy suggests, get one of the battery tenders (aka battery managers, battery tenders, etc.) and hook it up to the battery when the car is sitting unused in the garage. I did this with out TD and it brought the 8 year old battery in it back to life. The battery tender monitors the battery charge state and uses a trickle charge to bring it back to full charge, then goes back into the monitor mode until the battery discharges to a set voltage, then repeats the cycle. This is a much better situation than just using a trickle charger, which will over charge the battery and cause the electrolite to boil if left on permanently. The other thing that I would suggest is to check and clean all the battery terminals, cables and terminations at the far end of the cables to insure that you don't have a high resistance connection somewhere in the path. Pay particular attention to the connection between the cable and the terminal at each end. It is not uncommon for the cable to develop corrosion under the insulation near the crimps at the terminals, which will cause a high resistance that will cause problems when drawing a heavy current, such as when trying to start the car. Cheers - Dave
David DuBois

Thanks everyone for all the replies. I do have a conditioning charger (sorry I worded that awkwardly in the original post). The car was starting fine in October; now it's turning very slowly. A week on the charger didn't help. This is the wrong week to debug this further as I'm having my annual yuletide soiree Saturday and setting up for that is taking all my time. After Christmas I'll go through and check all the wiring, and check the batteries with a hydrometer. I tend to discount generator or regulator problems because everything in the car was replaced or rebuilt 5-1/2 years ago, but of course that is a definite possibility. When the first set of batteries went gunnybag after three years, they were genuinely dead. They would not take a charge even with a professional charger. They also failed with little notice. The car started fine all summer, sat for maybe a couple weeks, and the ability of the batteries to start it diminished greatly over the course of a single day the next time I drove it.
David Breneman

David, do you have a radio with a station memory connected to your car? These can wind your battery down over a few weeks, they can also flatten your battery much quicker if they go faulty. Similarly, a car alarm that is hooked up to the battery can do the same thing. As others have said, it could be a bad connection on the battery leads, I had a bad earth connection to the chassis at the back recently which stopped mine from getting enough juice to start. A way of finding bad connections is to hit the starter with the ignition off for a few seconds and then quickly feel all battery connections, including the ones on your starter switch, a hot connection is a bad one. Don't forget the engine earth strap on the left hand engine mount.
Lindsay Sampford

This thread was discussed between 15/12/2009 and 17/12/2009

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