Thread: Secondary Batteries

University of Hawii website... Batteries

scroll down the page and there is a set of formulae for calculating various parameters

e.g rule of thumb... Amp Hrs = (Reserve Capacity/2) +16
so Res Cap = 2(amp Hrs -16)

CCA = (approx) : Reserve Capacity x 5

so a 100AH has a RC of approx 2(100-16) = 168 Amps

so the CCA is approx 840 Amps... say 800

I've read other places never to deplete deep cell to less than 50%, so to get the full value in AMp Hrs you really do need 2 batteries in parallel... as you have proposed!

cheers


Edit:
ps: have you explored the Delco Marine deep cycle batteries which supposedly can support emergency starting as well as intended deep cycle functions?

I have a 105Ah deep cycle second battery that has 550 cca and starts my 6.5Ltr Chev, AC Delco.

Regards,
PeterW

Hi Hoges and garrycol, be very careful of any claimed calculation for converting CCA to Ah and reverse.

There is actually NO calculation and the only way to know what the potential CCA of a deep cycle battery is, is to get the info direct from that specific battery manufacturer’s data.

You can have two identical sized batteries from two different manufacturers and the CCA of the batteries can be hundreds and hundreds of amps apart.

The CCA of any battery is not just dependent on physical size but is more importantly, based on the type and way materials have been used in it’s construction.

Again, unless the manufacturer has listed the CCA on the battery, there is no effective way to calculate what it actually is.

As far as deep cycle batteries and using them for that occasional emergency jump start, you won’t do any harm, but if you were to try to use them as a replacement for a starting battery, then you may get as little as 6 months ( or even less ) out of them before they needed replacing.

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Originally Posted by drivesafe

Hi Hoges and garrycol, be very careful of any claimed calculation for converting CCA to Ah and reverse.

I bought a 105ah dual purpose wet cell deepcycle - the CCA from the manufacturer is 750cca. Being dual purpose - it doesn't quite have the CCA of a similar sized cranking battery, and as a deep cycle it doesn't quite go as "deep cycle" as a full on deep cycle battery of the same size.

This suits my usage fine - if rigged in parallel with one or two of my starting batteries will work my electric winch fine (will most likely work by itself) and is deep cycle enough to suit my needs.

As well, when at home it charges just fine off my 2600ma normal charger/trickle charger - just takes a day or so to bring back up if down a bit.

Price was a bonus.

Garry

Yep, I’m a fan of flooded wet cell batteries and marine dual purpose batteries.

These still seem to give the best value for dollars spent.

just bought 2 all rounder 105AH supercharge..great price
Well I might need to weld something with them on the track ...also have a NEX86 which refuses to die stashed in the back of the camper trailer to get a full 36Volts without touching the main cranker.

Would welcome recommendations on a suitable charger ...the All Rounders are of the expanded calcium grid variety so am under the impression they need a higher charge rate? like 16V for equalisation?

I've seen the RANOX advertised (has a temp. compensation facility) and also one called an Ozcharge (which goes to 16V and 16 amps) $179
any views?
cheers

BTW Drive Safe...am wiring the SC80 in this week now that the welding is complete !!

Hi Hoges, if you drive your lr regularly, you don’t need a special charger and even if you don’t drive all that often, there is no reason to get some special type charger for C/C batteries.

While they will not fully charge in a vehicle, it’s no where near the problem that many try to make out.

These batteries will charge to 95-97% using an alternator and not fully charging them at any time does not seem to have any form of adverse effects on the life span of these batteries.

Discovery 3s come standard with a C/C cranking battery and while most have never had a battery charger, of any form, connected to them, they are still giving 5 years of use.

For any type of cranking battery, 5 years is pretty good so don’t read too much into any claims that your have to do anything special to keep these batteries in good nic.