Dead battery?

[Hartley18]

I know some may think this an unusual question, coming from me, but I'd like to get the facts straight:

The situation: We have the usual battery set-up on our current Teredo Target, it's rather chilly outside and the engine (a Volvo with glow plugs) is being a right pain in the butt to start.

My usual procedure is to switch to Battery #1 (the start battery - topped up irregularly by shore-power float charger) use the glow for the recommended 10-15 seconds and push the start button. At this point, lately, all I get is a click, the cabin lights (LED's) black out and the VHF resets itself to Ch16. I then wander below, change to Battery #2 (the house battery - topped up by solar panel), repeat the procedure and can usually at least get the engine cranking....

I'll get the battery details later today, but they're very ordinary sealed lead-acid marine batteries, NOT identical and about 3 years old (dunno exactly - they came with the boat). All connections have been checked, are tight and smeared with Vaseline. Gut feeling tells me this engine requires plenty of grunt to crank over!!

The question: Battery #1's float voltage is currently 12.68V. I read somewhere that if the cabin lights dim significantly on cranking from a fully-charged battery, then said battery is likely stuffed. Is this correct?

Is there an easy way to verify the condition of a sealed battery?? (I guess I'm asking how to do a definitive load test without access to specialised gear). Ideas anyone??

Thanks,
Cameron

[tdw]

Originally Posted by Hartley18

I know some may think this an unusual question, coming from me, but I'd like to get the facts straight:
Ideas anyone??
Thanks,
Cameron

Some may think ? Give it a break Cameron, if you don't know how the fark do you expect anyone else to ?

Ideas ? Ya batteries are stuffed ya mug.

Seriously if they are at least three years old and not of any great lineage chances are they are rooted. Hard to tell though unless you disconnect from the charger and see how they hold a charge.

Well thats my take on it but wtf would I know ? hmmmm ??

[Hartley18]

Originally Posted by tdw

Seriously if they are at least three years old and not of any great lineage chances are they are rooted. Hard to tell though unless you disconnect from the charger and see how they hold a charge.

12.68 volts is what they seem to sit on without the charger hooked up - and have no problems running lights, radio, ignition, etc. - but engine cranking is something else entirely.

Originally Posted by tdw

Well thats my take on it but wtf would I know ? hmmmm ??

Probably quite a lot - for a Wombat.

[mitiempo]

Hartley

If they sit at 12.68 without a charger try putting a 10 amp load on the battery for a few hours and check the voltage again.

[Ilenart]

Me thinks the Wombat is right, ya starters stuffed.

I had the same issue on Amadeus, the starter battery was holding around 12.6-12.7v but died every time I tried starting. The new one was'nt that expensive, less than $200. I also went for one with a bit more grunt than recommended for my engine just in case I had trouble starting. As your engine sounds a bit diffcult to start you probably want to go for something similar.

Looking at my records I went for an Exide marine starter rated @ 700CCA for $180. This had no problems starting my old 20HP Yanmar. They also have a 600CCA, however for $10 more I went for the larger batttery. Only thing you have to check is the measurements to make sure it fits; the 700CCA is L303xW173xH225mm. The 600CCA is slightly smaller.

Ilenart

PS seems a bit weird giving you electrical advice

[tdw]

Originally Posted by Ilenart

Me thinks the Wombat is right, ya starters stuffed.

I had the same issue on Amadeus, the starter battery was holding around 12.6-12.7v but died every time I tried starting. The new one was'nt that expensive, less than $200. I also went for one with a bit more grunt than recommended for my engine just in case I had trouble starting. As your engine sounds a bit diffcult to start you probably want to go for something similar.

Looking at my records I went for an Exide marine starter rated @ 700CCA for $180. This had no problems starting my old 20HP Yanmar. They also have a 600CCA, however for $10 more I went for the larger batttery. Only thing you have to check is the measurements to make sure it fits; the 700CCA is L303xW173xH225mm. The 600CCA is slightly smaller.

Ilenart

PS seems a bit weird giving you electrical advice

The Wombat is right .... my oh my that has a nice ring to it ....

Cameron is quite obviously just another one of these armchair experts with no real practical ability. (thanks be he lives 1200km away)

[MarkSF]

Lead acid batteries can fail in a mode where they have normal voltage under no or light load, but can't provide much current. What you will see on a multimeter is that when you crank, the voltage drops right down - to 7, 6, or even less volts. A healthy battery should be able to produce at least 9 volts while cranking - the higher the better.

This is the basis of those battery testers they have in auto stores.

So if you have access to a meter, measure the battery voltage when cranking. Much less than 9 volts and they are done. If you have 2 in parallel the drop should be even smaller.

This would avoid guessing whether it's the batteries or the starter (or the charger)

My last car battery failed like this - just a click and you could see the voltmeter on the dash dropping to 6V. Off to the store for a new battery.

[Hartley18]

Thanks, Mark. Finally... some HELPFUL ADVICE!!!

I'll keep it in mind to check the cranking volts on the weekend.

Originally Posted by tdw

The Wombat is right .... my oh my that has a nice ring to it ....

Cameron is quite obviously just another one of these armchair experts with no real practical ability. (thanks be he lives 1200km away)

[tdw]

Originally Posted by Hartley18

Thanks, Mark. Finally... some HELPFUL ADVICE!!!

I'll keep it in mind to check the cranking volts on the weekend.

pshaw .... first reply "ya batteries are stuffed" ... what more did you need ?

[Hartley18]

Originally Posted by tdw

pshaw .... first reply "ya batteries are stuffed" ... what more did you need ?

A second opinion!!