correct battery

[Sloppy 2000]

People suggest either an 069 0r 096.

My car is a mk1 (68) and has a dynamo.

I find it doesn't turn over from cold well but will after a run, obviously when warm when it needs less cranking power.

My question is that as a dynamo has less output, is there a limit to the Ah and CCA cranking power when choosing a battery with a dynamo? Should I use or is the highest units the best for both Ah and CCA? The car gets used once a week. I think mine is week and about 60Ah. I have had the car for about 18 months and the battery is a vauxhall one weirdly, so has probably had a previous car running on it at some point.
By the way the Ammeter in the car stays in the middle between C and D when idling and when running slightly more to the charge, but only a bit. Obviously draining initially when turning lights on, hence moving the needle a bit, so I think dynamo is working.
Jeff

[Dave B]

I used to have a similar problem with my mk2 a few years ago, going through several batteries that seemed to lose their efficieny quite quickly. I decided to have my starter motor reconditioned by a local auto-electrics company and..............result! The starter now turns the engine over a lot faster than before and the battery has been on for over three years. Perhaps worth a thought?

[Clifford Pope]

Electrically you can use any 12 volt battery that will fit. A higher capacity battery is no harder to charge than a small one, it just takes longer. ( A bit like having a larger watering can - you can fill it with the same tap at the same water pressure, it just takes longer to fill and is heavier to carry, but waters for longer )

Arguably a big capacity battery is especially useful with a dynamo because it gives you more leeway in which to balance-up periods of charge and discharge. In theory by contrast a high output alternator could supply virtually all your current needs immediately, so apart from starting the engine you could get away with a tiny battery.

[Sloppy 2000]

Both thanks, good advice,

I have a decent starter motor and with sufficient power and when warm works fine. I gave my battery a really good charge (new halfords ring charger with jump start facility), because I only had a trickle charger on it and perhaps with short journeys have not been really depositing much charge at all. It definitely made a difference and the starter spun respectfully so when there is decent charge starter is not an issue, although I will keep this in mind. The question is whether it hold a decent charge now over a few days with the inevitable cold. If it doesn't and starting is weak, I will put a new one on. This eliminates any concern about the alternator as it hasn't been engaged in any work. It is just a question of whether it holds charge. To use the watering can analogy, it may have a few holes in it or high evaporation and be losing power. If this is the case, I will put a bigger battery on it, with decent cranking power and reserve. I have to understand that the car is not used a couple of times a day, which if was my first line vehicle, it would.

I have given the earth strap anchorage a decent clean as well as the battery terminals. It is a nice feeling when every thing is working. Jonny dog told me to put some contact servicol spray into my side light switch as it is temperamental and that seems to be better too. Possibly a bit of 50 year corrosion in it.

[tony]

Tend to agree with Clifford, use the biggest battery as is practicable ,and well charged, all terminals clean and shiny, starter motor in good nick ant not drawing too much current and motor in a good state of tune. I don't see there's much more that you can do. Jap cars in general tend to use small batteries and large alternators.
Tony.

[johnnydog]

As yours is a Mk1, it could be either positive or negative earth, so the terminals of the battery would need to be on the side to get the earth terminal nearest the relevant battery post.
As most manufacturers use standard size battery cases, the physical size doesn't necessarily indicate a more powerful battery. Small size batteries can sometimes deliver more power - it's the amphere hour figure, and CCA (cold cranking) figure that needs to be considered, as well as terminal layout.
After my Mk1 had been in hibernation for 25 yeas, although it turned over reasonably well with a replacement battery, I felt it was a little sluggish. I fitted a re con starter motor, and it now spins over very fast! I leave the batteries on my Triumphs for reasonably long periods without any use, and they always turn the cars over quite well, but I charge them periodically with a Smart charger.
You mention 'giving the battery a really good charge'.
To just put a conventional charger on a battery and then leave it for a 'considerable' length of time can do more harm than good if continuously charging which can 'cook' a battery.
Is your Ring charger a 'smart' charger? Smart chargers go through a number of different cycles in the charging process, rather than just firing a continuous charge as with a conventional charger, and only charge the battery to its optimum capacity before stopping the charging process. They can actually 'rejuvenate' a battery that has been left in a partially discharged state, which isn't good for any battery, but conventional chargers can't do this; they just fire a continuous charge into the battery, although at a reducing amp rate as the battery becomes charged, but they never actually stop charging. Smart chargers can also be left connected on the vehicle permanently, and when the state of charge falls below a certain level, it will then trickle the battery back to its full capacity before switching the charge off again.
Ctek are considered to be one of the better makes, although the better Ring smart chargers are pretty good too. I have both so can comment on how they perform.

[Clifford Pope]

If there is nothing drawing any charge, such as a glove box light not turning off or a door slightly adjar, then a good battery will hold its charge for weeks if not months.

My LandRover has a large battery and a dynamo, and I start it perhaps once a month. It always turns and starts the engine without any difficulty. Rather than priming the petrol pump I just let it turn over on the starter for as long as it wants before the fuel arrives, reckoning that getting the oil pressure up before firing is probably a good thing.
Watching the ammeter I can see that it has replenished its starting drain within a few minutes of starting.
I think this legend about "needing a good run" or frequent charging is a myth - a good battery of generous capacity and a dynamo and regulator in good order will cope with periodic usage. We once had a boat with a heavy diesel engine and a bus battery. It would start the engine in the spring after lying unused since October.