The 150 series Dual Battery Guide

[drivesafe]

Batteries are not complex

UNBELIEVABLE, that is the only way to explain your posts.

That one single line clarifies why you have posted up so many erroneous statements.

You have been LOOKING at battery info on the web for five minutes and your are now the worlds leading expert on the subject.

Talk about ignorance is bliss.

For example, you go on about how Optima batteries can be damaged from high current charging because they will heat up, then you rant on about 80 amp and 120 portable batteries chargers as if these would cook an Optima.

To cause an Optima the heat while charging you would need a charge current of 300 or 400 amps, not the low charge currents of those potable chargers or of any alternators.

I have an Optima Yellowtop D34 that, over the years, has been constantly charged with high currents, and was used because I needed something that would draw high currents while I tested new Isolators.

The battery has been in three different vehicles, being use and abused as an auxiliary/test battery, it on two separate occasions, sat around my workshop, untouched for many months and is now and has been my wife’s Toyota Seca’s cranking battery for the last 2 years and the battery is still going strong even though it’s now over 9 years old.

You have continually and erroneously rubbished products, based on nothing but your pure ignorance, and you have the hide to accuse manufacturers of posting up lies?????????

You are an overnight expert in a field you know nothing about!

[MelbournePark]

MelbournePark,
...
Relying on manufactures specs is fraught with danger, after doing acceptance testing for various companies for over 40 years I can tell you that seldom does equipment meet the manufactures own specifications...

I personally would not recommend any battery to another unless I had tested the battery in vehicle and had logged hard data to prove the battery performed as expected.

You keep saying the slower accepting marinepro to an AGM, I assume you have read somewhere that AGM's charge faster than flooded batteries, some do many others won't, if you took the solid separators out of a 720 and replaced them with glass mat would it now charge faster? There's a lot more to a batteries charge acceptance than glass mats.

....
You mentioned something along the lines will a 620 charge as fast as a 730 but can't find it again, they are basically the same battery just different plate count, therefore the 730 will have less surface area and peak recharge currents will be lower, however it is also a lower Ah capacity therefore one would expect it to be take similar or possibly less time to charge than the 730, only way to tell is by actual testing.

Charge discharge curves, discharge curves are readily available from most manufactures, Optima being the exception unless they have changed recently.

Charge curves, don't recall having ever seen one but then haven't gone looking for them as it pretty pointless from a dual battery perspective as the charge voltage, available current, wire dimensions, number and quality of connections are going to impact charging significantly anyway. Better to do some actually real time testing.

The problem with actual testing is that battery companies do it with statistical reliability. Some organisations also do bulk comparative tests. I put in production lines, very many and huge dollar amounts, and its not possable to test all the components. I have to rely on data, as do the manufacturer of machines in lines. When its built, final runs establish faults, and reputation for companies counts a lot in the reliability of their data and devices. Curiously Americans will buy Japanese lines and machinery, and will strip the Japanese electronics because they trust American electronics. Compared to all that a battery choice is pretty straightforward.

With the poster querying, no one assisted him. So I posted. I knew that if I was wrong, a fault would be pointed out.

But for experts to cherry pick and criticise via mis-quotes, yet when someone wants a confirmation on a system - and then no one posts - IMO I did the decent thing.

And I am not profiting from it. Unlike others here, I am not selling devices or installing systems. Which perhaps, makes some people biased in that it appears to me that when few brands are mentioned by people selling gear, I get the feeling that they are simply pushing a couple of brands.

As far as Optima and charging goes, they do publish lots of data. But to get it, you have to read page two. It's that easy.

As far as charging goes, I'll provide a bit of the data from Optima about charge times.

At 25 amps, the majority of their yellow tops charge at the same time - 140 minutes - from zero to 90% full charge:
D35 16.6 kg 48 AH 140 minutes
D75 17.2 kg 48 AH 140 minutes
D34 19.5 kg 55 AH 140 minutes
D34M 19.8 kg 55 AH 140 minutes
D27F 24.1 kg 66 AH 140 minutes

The D31 at 27kg 75 AH takes 210 minutes.

The D75 is actually the D75/25 ( the extra number made it difficult to read).

Give those 50 amps and they'll do it in 75 minutes, and 100 amps in 35 minutes.

That data is current, but the data comes from mostly 2008. I presume then that the battery electro mechanical reactions hasn't changed since then.

An issue with high charging, is the Christie chargers, made near Sydney I think. They have several 12V chargers, two Honda petrol ones cost around $1,400, and produce 80 and 120 amps. Since a fridge and lights use typically around lets say 50 amps a day, one of those things would only require a fairly short run, if the system could take advantage of it. With an Optima, I think temperature would be a big issue.

With more batteries though, the amps are distributed, and there's less stress on the batteries. But it costs more to install, the batteries cost more, and they weigh lots more. Darn ...

I've not talked to those Christie guys in Sydney, but I reckon they'd recommend the way to do it. Some time I'll ring them and post, but if someone else does, please post, I'd like to know what they say!

However - if over temp, batteries like the Optima are destroyed. Some US batteries have temperature limits built into their batteries! Its a shame Optima don't. I've read quite a few reports of temperature issues with Optimas in Queensland, from caravan site threads. Incidentally those charging stats are at 25 ambient too.

The interesting batteries are the ones I've left out. Namely the D51, and another which I'll mention.

The D51 only weighs 11.8 kg, yet has 41 AH. It recharges at 25 AH in 130 minutes. The attractive thing though, is that its so light. I'd like to weigh one. It also has more ohm resistance than other yellow or blue top batteries (I never inputted data for the red tops). So its design must be different in some way, but I don't know what.

Now, that 41 AH is equivalent to 51 AH in other deep cycling batteries. That's a good weight performance. Its a shame its close in cost to all the other yellow tops.

The other interesting battery is the marine - blue version of the one you have - the D27F. So, the 27M.

The marine blue 27M has the same AH capacity, less starting power, and it takes 24% longer to charge. My conclusion is that if I were to buy an Optima for under the bonnet and was willing to have 24.4kg, I'd put in that blue marine one, because I think its more deep cycle orientated. Optima seem to say that too. My guess is that the way the lead is wound or spooled is overall thicker, hence the lower starting power and also the slower charge time. I also think having an extra set of posts which the blue tops have is a benefit for many of us.

It would interest me too, to see the insides of the 27M compared to the D27F.

But for me, a more attractive AGM battery is an Exide, which seems tougher on a several grounds. But the tougher they take charge slower, due to their plate design.

As far as your own testing goes, one test may not reveal much. Especially the effects on the battery from high amperages. That a battery can take a high amperage may simply mean that its got a good CCA capacity ... but hitting it regularly with high amperages may be hurting it.

With respect Leigh - perhaps such tests may not establish reliability or certainty? I think the reason manufacturers are reticent to provide all their data, is due to the variances of loads etc, so much that they fear reliance on their data which as you say, rarely meets individual demands?

Anyhow ... I hope I haven't been rude or offended.

I'll be away for a while, so excuse me not replying for a couple of weeks perhaps. Cheers.

[MelbournePark]

MelbournePark,

I actual have a Optima D27 as a start battery and a Marine pro as the aux, the Optima depending on how you use the vehicle is not an ideal choice for a cranking battery but was put there for evaluation purposes. The Optima may provide higher CCA but in my observations this has not been the case, and due to its lower Ah capacity is not a good choice if your vehicle is garaged for long periods.

The fact that a battery has a maximum recommended charge rate of 20 - 30 amps doesn't mean that is the maximum charge rate the battery will accept, it is purely a warning that it shouldn't be charged at higher than that rate, all large capacity lead acid batteries will pull higher than 20 - 30 amps in a highly discharged state, the manufacture is simply advising the current should be limited to less than the max allowed.
...

I have one too. I don't like its recessed top and its poor packaging. Its worked pretty well though. I'd not buy another but for the promise of fast charging, but that comes down to available charge issues, I've not worked that out, I've haven't had time, been away, and am going away again tomorrow.

You say less capacity, but Optima say that their AH rating is a 100% usage rating. In other words, their 66 AH rating provides a full 66 AH until the battery cuts off (10.5 v I guess). Therefor, for your comparison, you need to rate the 27 Optima at 82.5 AH, rather than its labelled 66 AH.

Check their Australian website.

You'll screw your battery if its just left. The car's natural drain varies, but another real issue is that despite a VRLA battery self discharging monthly at typically 3% at 25 degrees, manufactures say that they should not be stored for more than six months without re-charge. Interestingly Optima say their shelf live is 15-18 months. But we can all be skeptical of that claim I guess!

[MelbournePark]

MelbournePark,

What an amazing transformation it has been, from someone who admitted knowing little about batteries a few days ago to now being a battery and dual battery system expert
...

Batteries are not complex, the problem is knowing the different electrochemical reactions. That - as you said - the manufacturers don't reveal much, its not straightforward comparing things.

As far as dual battery issues - that's pretty straightforward too except for the Prado's weight restrictions, and the variance in people's demands and camping habits. But add a camper trailer or a van (as I have now decided to buy) and then things get really complicated. Not because of battery issues though ... more because of demand and charging constraints.

For me, its basically a bottleneck analysis (something I've done in major manufacturing installations for many years), weight, cost issues and also available re-charge capacity.

I don't want to tow weight but I want to have the works behind me. I'm stuffed already, really.

Another thing that annoys me a touch, is that the capacity of a battery and its cost, is not linear. For instance, one pays little more for a similar brand's similar type of 75 AH battery, as their 100 AH battery. Very annoying IMO.

And also, differences in stats from manufacturers cannot always be explained, and also, can be simply wrong.

An example that I queried a few months ago, was the Marine Pro 620 and 730's weights. And no one told me their weights - which was disappointing. I eventually rang the company, and they agreed that their web site description was wrong. But ... they still have not changed it. So the 620 & 730 have different weights. Such things are quite frustrating.

Oh and by the way - when the battery tech issues were discussed (about Lithiums mostly), I knew about the CSIRO's new tech battery, but no one has mentioned it. It's going into production in the US soon I hope, its very clever yet a simple idea.

[mjrandom]

FWIW, I now have a Allrounder MRV70 as aux in a 2014 Prado GX sitting on a 305mm battery tray of ebay. Although the aircon pipe is gently shifted by about 18mm it is securely attached to the supplied new bracket and has a min of 8mm clear space on the full length of the pipe. Mat from online batteries came by with a set of 260mm and 305mm batteries to test fit (great service) but the MRV70 seemed to be the best match for the tray. No movement and perfect fit. A strong top bracket additionally secures it to the front guard. Now me and Prado can get cracking...

You don't want any cracking... Good work.

[foxpro]

FWIW, I now have a Allrounder MRV70 as aux in a 2014 Prado GX sitting on a 305mm battery tray of ebay. Although the aircon pipe is gently shifted by about 18mm it is securely attached to the supplied new bracket and has a min of 8mm clear space on the full length of the pipe. Mat from online batteries came by with a set of 260mm and 305mm batteries to test fit (great service) but the MRV70 seemed to be the best match for the tray. No movement and perfect fit. A strong top bracket additionally secures it to the front guard. Now me and Prado can get cracking...

[AJ120]

(Andrew, I agree can I have my gold star please? Maybe I forfeited it by this post though!)

Cheers
Prone

Its heavy, don't drop it




Cheers Andrew

[LeighW]

Leigh,

Being a bit pedantic and risking starting an argument I think that the first point in the above is incorrect. There will be a small power increase equal to the current by the voltage increase. At 50 amps the increase will be about 30 Watts for a 0.6V voltage increase.

(Andrew, I agree can I have my gold star please? Maybe I forfeited it by this post though!)

Cheers
Prone

Probably should have qualified the statement with maximum output power.

The alternator will have either output rating specified either in amps at a voltage or Watts,
ie it maybe 12V@100A or 1.2KW, the rating takes into account rectifier currents and therefore their temperatures, winding temperatures and the ability of the alternator to shed its heat load etc under ideal circumstances.

If you increase the charge voltage then the total current drawn must reduce to keep the alternator within its design specification, this really is a moot point though as most alternators will produce their maximum output current at quite a low voltage ie 12V, this voltage is well below the drop out voltage of the regulator, therefore a booster diode will not have any affect on the alternators maximum current output, it will only affect the alternators maximum voltage.

[foxpro]

Have a look for factory weld nuts/holes in the guard and make up a little bracket. Plenty to choose from in a Toyota.

That's it. Will do.

[BlakMoth]

When Andrew said Gold Star he actually meant a free rear bar and tyre carrier. What a nice bloke 😝


Sent from my iPhone using Tapatalk

[Prone]

MelbournePark,

Fitting a booster to the alternator does not increase it's output power ie x watts, only its charge voltage, if you start to add additional batteries then you need to consider the load on the alternator, be the aux charged directly through a VSR or DCDC charger. More batteries more load, once you reach three batteries then you should definitely consider the load on the alternator if three highly discharged batteries are suddenly dumped across it. If the alternator can't supply the amps then the only particle alternative is a bigger alternator. Putting in a DCDC charger to limit the current is generally pointless, if you have 400Ah of batteries your obviously using high Ah, and most are never going to drive long enough to put the charge back in.

Leigh,

Being a bit pedantic and risking starting an argument I think that the first point in the above is incorrect. There will be a small power increase equal to the current by the voltage increase. At 50 amps the increase will be about 30 Watts for a 0.6V voltage increase.

(Andrew, I agree can I have my gold star please? Maybe I forfeited it by this post though!)

Cheers
Prone

[AJ120]

LOL Leigh I've been reading this thread all the way through with that comment in the back of my mind.

You deserve a gold star if your reading it all I've just been skimming it for a while now. Like I said a while ago, I am amazed at how complicated you can make such a simple thing if you try hard enough

Cheers Andrew

[maulbeagle]

MelbournePark,

What an amazing transformation it has been, from someone who admitted knowing little about batteries a few days ago to now being a battery and dual battery system expert

LOL Leigh I've been reading this thread all the way through with that comment in the back of my mind.

[LeighW]

MelbournePark,

What an amazing transformation it has been, from someone who admitted knowing little about batteries a few days ago to now being a battery and dual battery system expert

I actual have a Optima D27 as a start battery and a Marine pro as the aux, the Optima depending on how you use the vehicle is not an ideal choice for a cranking battery but was put there for evaluation purposes. The Optima may provide higher CCA but in my observations this has not been the case, and due to its lower Ah capacity is not a good choice if your vehicle is garaged for long periods.

The fact that a battery has a maximum recommended charge rate of 20 - 30 amps doesn't mean that is the maximum charge rate the battery will accept, it is purely a warning that it shouldn't be charged at higher than that rate, all large capacity lead acid batteries will pull higher than 20 - 30 amps in a highly discharged state, the manufacture is simply advising the current should be limited to less than the max allowed.

Relying on manufactures specs is fraught with danger, after doing acceptance testing for various companies for over 40 years I can tell you that seldom does equipment meet the manufactures own specifications, most equipment needs massaging to meet the manufacturers specs, and in quite a few cases the purchaser has to down grade his requirement (usually the manufactures own specs) so that the supplied equipment can meet the customers specification. I remember many many, moons ago rejecting a batch of batteries due to low specific gravity and low Ah capacity. The manufacture asked how we were measuring the SG, we were using an electronic specific density lab instrument, the manufacturer was still using the old glass tube and rubber bulb type units!

I personally would not recommend any battery to another unless I had tested the battery in vehicle and had logged hard data to prove the battery performed as expected.

You keep saying the slower accepting marinepro to an AGM, I assume you have read somewhere that AGM's charge faster than flooded batteries, some do many others won't, if you took the solid separators out of a 720 and replaced them with glass mat would it now charge faster? There's a lot more to a batteries charge acceptance than glass mats.

Dual battery systems in cars can be quite complex, how many batteries need to be charged, what does the battery require, where are the batteries going to be located, what charge voltage is available, what size cable. It is no good putting two optimas in a trailer and then supply them via the cars aux for instance, unless huge cabling is installed little charging of the Optimas is going to occur until the cars aux gets to a reasonable state of charge, why do it this way then, main reason would be to limit the load on the alternator and isolator. The advantage of having a high charge acceptance battery in the car is the quicker it gets charged the quicker the trailer batteries will charge in this type of setup.

Fitting a booster to the alternator does not increase it's output power ie x watts, only its charge voltage, if you start to add additional batteries then you need to consider the load on the alternator, be the aux charged directly through a VSR or DCDC charger. More batteries more load, once you reach three batteries then you should definitely consider the load on the alternator if three highly discharged batteries are suddenly dumped across it. If the alternator can't supply the amps then the only particle alternative is a bigger alternator. Putting in a DCDC charger to limit the current is generally pointless, if you have 400Ah of batteries your obviously using high Ah, and most are never going to drive long enough to put the charge back in.

Interestingly though I have never came across an instance of an alternator failing due to overload, neither has drivesafe in many many years he has been installing dual battery systems. The manufactures will tell you its possible but IMO this is more from a thermal load perspective than actual amps drawn, if the mounting location of the alternator is poorly chosen and it can't shed its heat load then it will fail due to overheating issues. If the alternator is rated a 100% continuous output (many aren't) and it has sufficient airflow its very principal of operation provides some inherit overload protection. But that's a whole other story.

Better to be safe than sorry so all should ponder battery management when multiple batteries are involved.

You mentioned something along the lines will a 620 charge as fast as a 730 but can't find it again, they are basically the same battery just different plate count, therefore the 730 will have less surface area and peak recharge currents will be lower, however it is also a lower Ah capacity therefore one would expect it to be take similar or possibly less time to charge than the 730, only way to tell is by actual testing.

Charge discharge curves, discharge curves are readily available from most manufactures, Optima being the exception unless they have changed recently.

Charge curves, don't recall having ever seen one but then haven't gone looking for them as it pretty pointless from a dual battery perspective as the charge voltage, available current, wire dimensions, number and quality of connections are going to impact charging significantly anyway. Better to do some actually real time testing.

[mjrandom]

Have a look for factory weld nuts/holes in the guard and make up a little bracket. Plenty to choose from in a Toyota.