question on cranking amps
Discussion
Can someone answer the following?
I know my Chimaera needs something in the region of 540-640 cranking amps. (this is through experience of replacing the battery several times)
My question is this. If I wanted to use two smaller batteries do the cranking amps add together? ie. could I use two batteries with 300 cranking amps. (its been a long time since my btec in electrical engineering)
The reason I ask is that if I were to move the battery to the boot, which I am hoping to do, could I use two smaller ones with less cranking amps to do the same job. They would fit a lot better in the boot, perhaps just above the petrol tank.
Kwacker
I know my Chimaera needs something in the region of 540-640 cranking amps. (this is through experience of replacing the battery several times)
My question is this. If I wanted to use two smaller batteries do the cranking amps add together? ie. could I use two batteries with 300 cranking amps. (its been a long time since my btec in electrical engineering)
The reason I ask is that if I were to move the battery to the boot, which I am hoping to do, could I use two smaller ones with less cranking amps to do the same job. They would fit a lot better in the boot, perhaps just above the petrol tank.
Kwacker
Kwacker said:
my btec in electrical engineering
A random person off the street can be forgiven for questins like that, but if you've got qualifications related to electrical engineering then you should be ashamed of yourself!If you want to double the output current, put the batteries in parallel.
eff eff said:
ok got that, but here's the question I can't get an answer for, will a regular alternator and wiring charge them both
If they're wired in parallel then they will charge and discharge in parallel. Whether the alternator will cope with that would depend on the rating of the alternator and batteries, but in principle it's just a matter of connecting the two +ve terminals together and the two -ve terminals together and treat it like a bigger (higher capacity) battery.
GreenV8S said:
If they're wired in parallel then they will charge and discharge in parallel. Whether the alternator will cope with that would depend on the rating of the alternator and batteries, but in principle it's just a matter of connecting the two +ve terminals together and the two -ve terminals together and treat it like a bigger (higher capacity) battery.
GreenV8S said:
eff eff said:
So am I right in thinking a standard 100amp Griff alternator wouldn't be powerful enough?
For what? Unless you're an alter ego of the original poster, you haven't said what you're trying to do.eff eff said:
GreenV8S said:
If they're wired in parallel then they will charge and discharge in parallel. Whether the alternator will cope with that would depend on the rating of the alternator and batteries, but in principle it's just a matter of connecting the two +ve terminals together and the two -ve terminals together and treat it like a bigger (higher capacity) battery.
err yeah I did,
The OP asked
My question is this. If I wanted to use two smaller batteries do the cranking amps add together? ie. could I use two batteries with 300 cranking amps. (its been a long time since my btec in electrical engineering)
my first question was,
but here's the question I can't get an answer for, will a regular alternator and wiring charge them both
to which you replied
If they're wired in parallel then they will charge and discharge in parallel. Whether the alternator will cope with that would depend on the rating of the alternator and batteries, but in principle it's just a matter of connecting the two +ve terminals together and the two -ve terminals together and treat it like a bigger (higher capacity) battery.Then i asked another question
So am I right in thinking a standard 100amp Griff alternator wouldn't be powerful enough? Anybody know if there is a formula for battery amps and alternator charging output?So I'll see what Google has to offer on the subject
The OP asked
My question is this. If I wanted to use two smaller batteries do the cranking amps add together? ie. could I use two batteries with 300 cranking amps. (its been a long time since my btec in electrical engineering)
my first question was,
but here's the question I can't get an answer for, will a regular alternator and wiring charge them both
to which you replied
eff eff said:
GreenV8S said:
If they're wired in parallel then they will charge and discharge in parallel. Whether the alternator will cope with that would depend on the rating of the alternator and batteries, but in principle it's just a matter of connecting the two +ve terminals together and the two -ve terminals together and treat it like a bigger (higher capacity) battery.
So am I right in thinking a standard 100amp Griff alternator wouldn't be powerful enough? Anybody know if there is a formula for battery amps and alternator charging output?
eff eff said:
err yeah I did
If you say so.You can treat the pair of small batteries in parallel just as if they were a single big battery with the total CCA and capacity. Since the original battery is around 100 Ah and 500 CCA, this would be equivalent to two smaller batteries with 50 Ah and 250 CCA in parallel. The CCA gives an indication of charging current and as long as the total CCA is roughly the same then the alternator will charge it OK.
What you're proposing isn't quite the same, because you're proposing to double the total CCA (two 500 CCA batteries in parallel). This means the batteries would charge faster. Would the extra current cause trouble? There's a chance it would, and it would be most likely when both batteries are flat and drawing the maximum charging current. Most likely you would get away with it though - I think the alternator would just current limit.
One way for this to go horribly wrong is to use gel style racing batteries as your small batteries.
These are physically nice and small, have a good charge capacity and excellent CCA rating. But you wouldn't want to use them on a road car; they're no good at deep discharge cycles and would soon be wrecked.
These are physically nice and small, have a good charge capacity and excellent CCA rating. But you wouldn't want to use them on a road car; they're no good at deep discharge cycles and would soon be wrecked.
Two six volt batteries could also be used.
Less wiring.
Early Porsches used two 6 volt cells, although this was actually for weight distribution, not to increase CCA.
Before embarking on this.....do a proper battery test on your existing battery.
Fully charge it, let sit for an hour to let surface chage disipate. Then use load tester. If your battery passes then Mega your ground it should be less than .5 ohm.
Then a DC clamp on to your charging.
Those CCAs will start a diesel in a cool climate
You could just be masking a prob that will re occur.
Less wiring.
Early Porsches used two 6 volt cells, although this was actually for weight distribution, not to increase CCA.
Before embarking on this.....do a proper battery test on your existing battery.
Fully charge it, let sit for an hour to let surface chage disipate. Then use load tester. If your battery passes then Mega your ground it should be less than .5 ohm.
Then a DC clamp on to your charging.
Those CCAs will start a diesel in a cool climate
You could just be masking a prob that will re occur.
Edited by jeff m on Tuesday 17th February 17:26
Kwacker, this is from the Odyssey site "The Odyssey battery ingeniously uses absorbed glass mat (AGM) technology to offer, in one box, the characteristics of two separate batteries. It can deep cycle as well as provide enormous cranking power. They are also dry cell I guess that means that they are not gell type.
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