Battery/alternator question

[petedg]

I have to replace my starter battery, the current one is 90Ah and the alternator is 50amp. Would replacing with a 100Ah or 105Ah battery both of which are freely available be likely to cause premature failure of the alternator?
Those with more knowledge and experience than myself would be much appreciated.

 

[pampas]

No.

 

[VicS]

I have to replace my starter battery, the current one is 90Ah and the alternator is 50amp. Would replacing with a 100Ah or 105Ah battery both of which are freely available be likely to cause premature failure of the alternator?
Those with more knowledge and experience than myself would be much appreciated.

No but some VP manuals specify a max battery size.

Reasons not known but I suspect more to do with the current that could be delivered to a stalled starter motor than with the alternator output.

 

[pvb]

No but some VP manuals specify a max battery size.

Reasons not known but I suspect more to do with the current that could be delivered to a stalled starter motor than with the alternator output.

Not sure that's the reason - Ah capacity need not indicate the ability to deliver current. Having said that, I have no idea why Volvo Penta specified max battery size; it may just have been a translation error, maybe it meant min battery size!

 

[ghostlymoron]

The max battery size in the MD1 manual is ridiculously small - but the so is the output from the generator. I've ignored it and have a 100ahr leisure and a 55ahr starter battery.

 

[VicS]

Not sure that's the reason - Ah capacity need not indicate the ability to deliver current. Having said that, I have no idea why Volvo Penta specified max battery size; it may just have been a translation error, maybe it meant min battery size!

Pretty sure its not a translation error. I appears across quite range of older manuals.

I have seen the explanation posted elsewhere .... but there is always a danger than its my own theory, which I have posted before, doing a full circle and coming back to me from another direction.

 

[Momac]

I have to replace my starter battery, the current one is 90Ah and the alternator is 50amp. Would replacing with a 100Ah or 105Ah battery both of which are freely available be likely to cause premature failure of the alternator?
Those with more knowledge and experience than myself would be much appreciated.

'Ah' is a measure of the total amount of energy that the battery can store and has no detrimental affect on the alternator.
For a starter battery you should look for a CCA rating which is cold cranking amps. That is a measure of the ability of the batter to deliver a big current over a short period such as demanded by a starter motor. The higher the CCA the better . Look for a battery with greater than you really need . 900CCA would be good and I don't think it would be hard to find if you can accommodate a large battery. But I dare say 500CCA would do the job.

 

[VicS]

The max battery size in the MD1 manual is ridiculously small - but the so is the output from the generator. I've ignored it and have a 100ahr leisure and a 55ahr starter battery.

60 Ah in the manual I'm looking at!

A typical 60ah automotive battery should be more than capable of starting an MD1. IIRC the battery in my car (1.5 litre diesel) is smaller, certainly no larger.

 

[VicS]

'Ah' is a measure of the total amount of energy that the battery can store and has no detrimental affect on the alternator.
For a starter battery you should look for a CCA rating which is cold cranking amps. That is a measure of the ability of the batter to deliver a big current over a short period such as demanded by a starter motor. The higher the CCA the better . Look for a battery with greater than you really need . 900CCA would be good and I don't think it would be hard to find if you can accommodate a large battery. But I dare say 500CCA would do the job.

Yes we know all that....time travel back to the 1950s ans tell Volvo Penta!

You dont need a 900 CCA battery to start an MD1. Its aonly a single cylinder 445 cc engine with a Dynasarter.
The battery in my 1.5 litre diesel car is no bigger than half of that and its been starting the engine regularly and reliably for 10 years.

 

[Momac]

You dont need a 900 CCA battery to start an MD1. Its aonly a single cylinder 445 cc engine with a Dynasarter.

in that case it sounds like pretty much an starter battery will be sufficient.
or may be worth spending a bit more to get something that will last .
http://www.halfords.com/motoring/bu...-12v-silver-car-battery-hsb063-5-yr-guarantee


.

 

[VicS]

in that case it sounds like pretty much an starter battery will be sufficient.
or may be worth spending a bit more to get something that will last .

.

Some people just get a second hand one from a scrappy!

 

[single]

No idea why, but when i had this question with my engine suppliers, they said don't go above 450CCA (1.5 diesel, 50Ah alternator, x3 110Ah domestics)

 

[ghostlymoron]

If you buy from a scrappie, how can you tell if it's any good?

 

[sailorman]

If you buy from a scrappie, how can you tell if it's any good?

I would suggest by scrapie he means breakers yard where there would be written off vehicles for dismantling

 

[ghostlymoron]

Yes I understood that but is there a way you can test them before you buy?

 

[VicS]

Yes I understood that but is there a way you can test them before you buy?

I think they do test them. You take a chance I suppose but on balance seems to serve some people well.

IIRC it was former forumite Nigel Luther, aka Refueller who always advocated this.