Thread: Interesting battery information

The topic is of interest to me.

I am an electronics tech (by training but no longer by profession) but I am NOT a battery specialist. My background helps me understand what is being said.

My 2-year old AGM auxiliary battery has a cracked case and needs replacement.

My starting battery is dying and will need replacement soon.

Noting my second battery is under the rear floor in the wheel well with my LPG tank, do I buy:

• two identical starting batteries at the same time, or
• another AGM and a starting battery, or
• a sealed deep cycle and a starting battery, or
• some other combination?

Hi Ron, it’s simple, buy the batteries that best fit in the two locations.

It doesn’t matter what type and if their the same or not, just as long as they fit.

Originally Posted by longreach

good on you drivesafe,you have just hi-jacked MUNDY thread,to sell you own dual battery kit,MUNDY has only posted 43 times on this forum,give the man a go.

Longreach, as stuee pointed out, I used my experience, based on my gear, to show that the info that Mundy had posted, no matter how well intentioned and as also pointed out earlier, in no way aimed at mundy, but the information that the “EXPERT” had given to mundy was grossly incorrect, or are you of the opinion that I should just let this incorrect info be used by other, interested in setting up their own dual battery system and usually at unnecessary additional expense because of the incorrect info.

By the way, most people on here are already well aware of the equipment I sell so I don’t need to push my gear.

I might also point out that I deliberately did not mention my trading name or make specific reference by the name of my controllers, so try keeping your comments to the subject.

Originally Posted by drivesafe

Hi Lionel, as posted above, my dual battery controllers isolate at 12 volts. This means the cranking battery is left with a 50% SoC ( State of Charge ) and older vehicle can be started with batteries with 11.75 volts and most modern vehicles can be started from batteries with as little as 11 volts, so there is no problem with isolating the cranking battery at 12 volts.

Because my controllers share the load over both batteries, this means that neither battery is as low as would be the case with an ordinary dual battery set up with only the auxiliary battery providing all the power, so you will have fully charged batteries in a shorter time as both batteries are charged at the same time.

Again because my controllers share the load over both batteries, the operating time before you need to recharge the auxiliary battery is, on average, 50% longer than with ordinary dual battery set ups, so if you know how long your set up works, say it’s work for two days, then with my systems, your system will operate for at least 3 days, before needing to recharge.

My controllers have a number of other benefits, including the fact that because your auxiliary battery is not worked as hard as it would with any other dual battery controller, auxiliary batteries tend to last longer when used with my gear.

Good reply Mate, Thanks, make perfect sense to me.

I guess it is worthwhile having the debate but unfortunately I am not sure we have reached a collective agreement on the outcomes, meaning we may not have helped anyone. As I said before, it will be up to each to decide for themselves where reality lies.

I stand by my all my points except 6 and 9 for which I have been unable to find anything definitive or which are outside my experience. Still, I wouldn't use dissimilar batteries in circumstances where they were connected in parallel when discharging. And for me, allowing a starter battery to go to 50% discharge seems lunacy, unless its a hybrid battery. Even then, you'll impact the number of cycles you receive. Go and read manufacturers data on their batteries which describe impact of discharge depth on cycle life. So too, for point 4, go and look at discharge curves for various battery types and see for yourself.

Mundy

Hi Ron im not an expert, but I was looking at a high CCA agm as a starter and a deep cycle agm for the fridge, Optima,s seem to be popular but they are more expense. I like agm,s simply because there is less maint on them

Originally Posted by Mundy

I wouldn't use dissimilar batteries in circumstances where they were connected in parallel when discharging.

Hi Mundy, what do you base this on, because as posted, after 20+ years of parallel charging and discharging of dissimilar batteries, I have yet to find a problem but if you have an example of a reoccurring problem, then not only would I be interested, but I am sure those following this thread would be too.

Originally Posted by Hoodoo Brown

I have just put a pair of batteries in my Disco to run the fridge and inverter without much change from $1000.

I just gotta ask,,
any chance of a pic of these $500 batteries??