small starting battery

[smeaks]

At present I sart a 1GM via my single dual purpose battery. I always start cranking with the decompressor pulled and load the engine once turnig to start. I am considering fitting a smaller battery through a 1/2 both switch to use specifically as an engine starter. My thoughts are to use a 12v wet (sealed) motorcycle engine (20-40ah ish) - employing the same starting regime. If one of these batteries can crank an 1000 cc + motorcycle then I imagine a soflty started Yanmar should be ok.. weight, space and cash saving idea or am I courting disaster through folly? I welcome your opinions....

 

[Cloven]

Best option for a small starter battery is the Red Flash 1000. Not cheap but do the job.

Hope this helps

 

[bdsweeting]

A smallish motorcycle battery may not come cheaply.

Replaced the 20ah on my bike recently, cost £70 !

A bit like Swiss watches I suppose.

 

[Aja]

Have you priced against diesel starter batteries from Halfords?

Donald

 

[LadyInBed]

For (cold) starting it's the cold cranking amps (CCA) that counts.
See here

When I had a 1GM I had two 70 a/h through a 1,2,Both. Even then, when cold it seemed to struggle a bit even using the decompressor!

 

[smeaks]

I only have the one at the moment and it does not turn the engine when compressed hence I run her up decompressed however I never have to run it for more than 3 or 4 seconds and once the compressor bangs in she fires up no prob in about two cycles.... perhaps I should add so far! Joking aside I am confident with her starting.

 

[Talbot]

cheapest answer is a car battery from Macro.

 

[Gin]

redflash batteries are slim and specifically for engine start with high CCA capacity, at a price.

Google for Merlin who, I think, sell them but otherwise looke here

http://www.dmstech.co.uk/redflash.htm

 

[macd]

1000cc motocycles are much easier to turn over than your 1GM. We used to kick 'em, remember? Petrol m/cycle engines have far less resistance than diesels (compression ratio is about half), and this is usually spread over four small friendly cylinders, whilst yours is in one big hefty lump. Don't even think about using a bike battery.

 

[steve6367]

If it wont turn the engine without being decompressed are you sure you dont have another problem. Wireing? Started etc etc ...........

 

[Pye_End]

Or indeed the current battery?

If it is a leisure battery of that sort of size then it should have no problem starting a 1GM without using the decompression lever.

Before you fit a second battery (which is usually worth doing if you have the space) I would solve this problem first.

 

[Evadne]

I'll second that suggestion. My 1GM has only one battery attached, a 70Ah leisure battery that does starting, vhf and an nav. lights, and it has no problems turning the engine over. For many years I ran it with a battery from ATS or Halfords "for a diesel Mondeo" which did the job as well. You need a heftier battery to turn over a diesel than a petrol engine, but something isn't right if you're struggling with the current setup.

 

[smeaks]

without a doubt it is the current battery that is flagging... hence my intrest in options available. As stated I have confidence in the current battery but do recognise it is flagging. Thanks to all for some excellent advice... I would go the red flash route but I think the prudent route may be too replace my current battery and then experiment using the old one as the second unit... thanks again too evryone who has contributed.

 

[Gunfleet]

You can put a switch in the field/excitor side of the alternator to cut that out when cranking. Depends how powerful the alternator is but it can absorb 1/2 hp. Just switch in in when the engine's started.

 

[michael_w]

Another vote for the Red Flash 1000; it's the dog's danglies of engine start batteries.

 

[pvb]

I don\'t think so...

[ QUOTE ]
Depends how powerful the alternator is but it can absorb 1/2 hp.

[/ QUOTE ] The alternator can't absorb anywhere near that much power at cranking speed!

 

[BAtoo]

Re: I don\'t think so...

Rd Flash 1000 - v good - does my 28hp fine; small and mount in any position; £85ish delivered. Then used my old engine battery to add to my domestic bank - same type b4 anyone says.

 

[Gunfleet]

Re: I don\'t think so...

I know you know a lot abt this. The nice man at Adverc suggested the change to me because my 1gm10 with a big alternator was difficult to start when the battery was a bit run down. I did it and it works. QED, except I may not have the Q bit right, if you see what I mean.