The 150 series Dual Battery Guide

[InnerCityBoy]

OK sounds like a non-starter ... thanks for the guidance Leigh.

[LeighW]

I'm assuming the second 12v battery would be unlikely to pull a current that the standard trailer wiring couldn't handle.

Thanks - Sim

A heavily discharged lead acid battery will pull 60 amps plus, it is quite possible it will
blow the fuse protecting the trailer wiring assuming it is around 15A and not designed
for battery charging.

Cheers
Leigh

[Prone]

It scared Toyota with their hybrid cars, which had lead acid. Evidently the latest ones now get - Lithium (the latest Lexus SUV built on the RAV platform) is said to have Lithium recovery architecture. but the petrol starter is still lead acid - because Toyota can't don't want owners to have over warranty starter batteries, they'd rather save the money.

The Toyota Hybrids (Prius at least) have used nickel metal hydride (NiMH) batteries for the traction supply to date. 200+ 6.5AH cells in series to make 200+ volts, the final voltage and cell count depending on the model. The original Japanese model was reputed to have used NiMH "D" cells to make up the battery! The small 12 Volt auxiliary battery has been lead acid.

The computer control is very aggressive in not letting the capacity drop too low. (But it can be a fun task driving to see how low you can get it.) Later models are even more aggressive at protecting the battery. This is my opinion based on 3 vehicles in the fleet where I used to work.

I note that the possibility of Lithium Ion types in up coming variants and some European models, in particular the "plug in" models.

Cheers
Prone

[InnerCityBoy]

Hi - first post from a new Prado owner. This thread seems pretty hard-core, but I couldn't find another thread for newbie questions so apologies if this is the wrong place.

Am planning to install a second battery in the future (into my camper trailer, not actually in the Prado) but am not yet ready to take the plunge with isolater switches, Anderson plugs and pulling the trim apart just yet.

For the time being, and for the sake of having something in place for some camping over Christmas, is there any reason I can't just hook up a second battery (which is in a battery box) to the 12v power running in to the trailer via the tow connection? I get this probably won't deliver rapid charge, but it would seem to be a relatively fool-proof option. After all, it can't drain the starter battery (as long as I don't have acc on) and I'm assuming the second 12v battery would be unlikely to pull a current that the standard trailer wiring couldn't handle. The trailer already has a cigarette lighter socket installed so I think in can handle putting together a simple cable with a fuse for good measure.

BTW although this thread is hard going for non-auto electricians like me , I've picked up a lot of great advice and have a good sense already as to what my eventual solution will be.

Thanks - Sim

[LeighW]

I picked two batteries that are designed for car applications and readily available: Optima maximum charge current = No current limit as long as battery temperature remains below 52C approx, 30 minutes to charge to 90% SOC at 100A charge current. Fusion max recharge 40A, normal recharge 20A. Optima operating temperature say 52C for above reason. Fusion 60C. Max discharge 830 amps Fusion used to state 100 amps from memory but now they don't seem to list it, not much good for winching. A quote from someone in the industry regarding Lithium: I notice the 3 warranty period for the Fusion, this seems very low to me when the battery has qualities that far exceed normal wet/agm type batts and many of them have 3 year warranties. As for Kimberly, their customers want 12V air conditioning, judging from the chassis failures they are having I not surprised they are opting for light weight batteries. Will Lithium take over, if the price comes down and reliability is proven maybe, but then again their already talking about different chemistries that will supposedly make Lithium obsolete.

[MelbournePark]

I think you made some good points drivesafe, the main one being that we all need to analyse our bottlenecks and also our requirements. That why batteries can be confusing - we can all have different set ups and as long as we are aware of the issues that effect us, they'll all work OK, with the odd lesson along the way. Whatever battery setup we have IMO our bottom line should be to ensure that we can always start our Prado's motor.

Its ironic drivesafe that you have a go about not putting up points, when you leave things out yourself! I guess that is the fun of this great site! For instance the heat and ampage limitations that for Optima specifically apply to their batteries. You know - their "if over 10 amps them monitor the temperature".

And while you criticise Lithium for 95% charge issues, you neglected to point out that 95% state of charge with a lithium doesn't hurt them, and that 95% still still allows much greater capacity. And not to mention that Lithium's almost flat power curve compared to lead acid's constant drop off. Something that further pushes Lithium's usable power advantage.

And with a lead acid, when you don't fully charge them, they loose their capacity because sulphication effects the non re-charged areas. Not fully charging Lithium doesn't damage them nearly as much - only due to more cycling from a 95% level rather than 100%.

Notice to those of us with costly batteries like my Ultimas: don't think that the battery will get fully charged from short drives. It is best for such battery owners to invest in a 240v smart charger - they provide much longer battery life, because they get the battery fully charged. Drivesafe - IMO you don't agree with that, but its accepted by most IMO including LeighW.

I do agree with your overall point though drivesafe - I interpreted that for the casual 4WD'er you'd go for a lead acid. For me if prices continue to drop, one day I'll go Lithium. I wish they came standard from the factory. And if not, then why not at least a deep cycling capable battery in our brand new Prado's? Or at least the option of one?

Applying your argument about battery life and the 300 cycles - for the front weight sensitive Prado: Save the weight, avoid heavier per Amp hour AGMs, and go for a flooded marine style deep cycle capable battery. Or a rugged flooded. They are cheaper than AGM, more heat tolerant, provide more amps per kg and their main downside is that they recharge slower. That last point is the confusing one IMO. And if marine, check its warranty - as some are not warrantied if under the bonnet. Check the length and weight if its in the Prado's front spare spot - over 260mm and their length effects the air conditioning pipe which is in close proximity.

As far as campers who travel a lot and want lots of power, weight becomes a real issue, especially to us Prado users, either towing or just doing it all out of our Prados. Kit out a Prado with a few people and its easy to go over our weight restrictions (and we can only pull 2.5 tonne in most Prados but a GXL or GX can be upgraded to 3 tonne for $3k). So if we have a big electric power requirement the game changes - light weight becomes increasingly important. That's why more and more off road setups like Kimberley's ones are appearing with air con, then Lithium wins there, despite the cost, which is a big reason why most Kimberly non canvas pop ups now ship with Lithium.

[drivesafe]

Hi MP and again, you are making it up half of your post as you go along.

CCA and Ah are totally unrelated and if your theory was correct, then Optima batteries would be the worst battery on the market, instead of being what they are, one of the best.

Next, sulfation is only a problem if someone discharges a battery and leaves it that way.

If you discharge a battery over a weekend away and then charge either on the way home or when you get home, there will so little sulfation take place in that short time that the charging will completely reverse the sulfation.

And if a battery is at 75% SoC or higher, no sulfation occurs in the first place.

Now back to the use of Lithium batteries in the RV field.

While many makes of lithium batteries can be charged by an alternator while driving, while this is ideal for lead acid batteries, this is anything but idea ideal for lithium batteries.

For instance, 14.7v is the optimum charging voltage for most new Standby type AGMs, but you can fully charge AGMs with as little as 13.0v. In fact Fullriver have a graph on their web site that shows the time required to fully charge one of their batteries, using different voltage levels.

And while it would take 30 hours to fully charge a low AGM battery, it would still be fully charged.

The same applies to wet cell batteries and the reality is that most will be charged with at least 13.8v ( and better with one of LeighW’s fuses ).

The difference is that the closer you get to a lead acid battery’s OPTIMUM charge voltage the short the time required to fully charge them.

This is not so with a Lithium battery. The OPTIMUM charge voltage is 14.6v. But just lower the charge voltage to 14.4v and no matter how long you keep that voltage applied, a lithium battery being charged with 14.4v will only reach a 95% charged capacity.

The lower the charge voltage applied to a lithium battery, the lower the capacity you get.

So you are not only up for the higher cost of lithium batteries but you have to add the cost of the special charger needed to get the maximum out of lithium batteries. Something not needed to get the maximum out of lead acid batteries.

Now to another bit of misinformation.

That is the reduced life span caused by discharging a lead acid battery down to 20% SoC.

This one is used regularly to try to “scare” people into thinking there lead acid battery is going to have a short life span if you cycle it down to 20% like you can safely do with a lithium battery.

The theory is correct but people using this argument, always neglect to give the full story.

Fullriver state that their batteries will only get 750 cycles down to 20% SoC but will get 1,250 cycles to 50% SoC.

The reality is that Fullriver are one of the better quality batteries, but I’ll halve their cycle rates so as to better represent a larger cross section of batteries being used by RVers.

So lets say we only get 300 cycles down to 20% SoC when we use battery Brand X.

So if we go out every weekend, and every weekend, we cycle the battery down to 20% SoC. This would only give us an expected life span of 6 years, as long as we look after the battery in all other aspects.

I don’t know about the rest of you, but 6 years from a battery being used like that is pretty good.

Now lets look at a more realistic use and say the battery is used one weekend a month, but is still cycled down to 20% SoC and you now have a “SHORTENED” life expectancy of 24 years.

As we all know, a battery is going to die of natural causes way, WAY before that and way before the 20% cycle rate has any effect of the battery’s real life span.

MP, try putting up all the details, and not just the bits that best suit your argument.

[MelbournePark]

Pointing to various technologies in not succeeding in the Auto world, is not a satisfactory. Its an Ostrich's argument.

The fact is that Lithium is cheaper over the long term that AGM. The main downside of Lithium is that if it fails before its financial break even point with AGM, then you've done your money. Although you have saved weight and been able to discharge and re-charge quicker. But its the financial risk that scares most.

It scared Toyota with their hybrid cars, which had lead acid. Evidently the latest ones now get - Lithium (the latest Lexus SUV built on the RAV platform) is said to have Lithium recovery architecture. but the petrol starter is still lead acid - because Toyota can't don't want owners to have over warranty starter batteries, they'd rather save the money.

All the lead acid manufacturers provide data that shows their products have much less re-charge lives if you go below 50%. And the higher the CCA v AH levels, the worse such batteries are effected.

Lead acid also has major sulphation issues.

The thickness of their lead results in them charging slower and having less CCA amounts. But such batteries - with thicker plates - last much longer.

I have two Optima yellows and they have high CCAs and take charge quickly. This means they have a high percentage of thinner lead. it may be wound but physics is physics.

Lead Acid is also more sensitive to heat.

Lithium is a much better metal to use than lead. Its a super light metal, while lead is a very heavy metal. So its great for transport.

Lithium does not suffer from sulphating issues.

Balancing of charge was an issue - but its now a known technology, and all the time, balancing tech is getting cheaper. Many Lithiums have it standard. And people can buy lithium cells, and put on their own purchased balancing systems. That's what Kimberly would be doing. By doing so, they sell heaps of Lithiums, that are quite cheap to buy direct from China. They add the technology and they make a good profit. Plu

Lithium is standard on but one Karavan and all the Kruisers now (yes three single axle Kruisers have been announced), and an option on the flip tops canvas trailers. Kimberly say that the future need of off road power, will be over 800 AH capacity, as their customers lust for more luxury.

A lead acid at 30Kg for 80 AH (much better than an Optima can achieve) means that for 800 AH you'd need 300 kg. But you'd in fact, due to the depth of cycle issue, you need more like 500 kg of lead acid. Imagine that in severe off road conditions.

If you want lots of power and mobility - the choice is really Lithium, supplemented by solar and importantly a generator.

[drivesafe]

Hi again Craig and thanks for the link.

It just demonstrates the lengths “sellers” will go to, to get sales.


Hi Derek and the “Don’t discharge beyond 50%” would be for a use specific requirement and to be honest, I have no idea as to what field that would be a requirement.

If you were living permanently off-grid and using your batteries as your main power supply, then depending on the brand, they should not be cycled below 65%

The 50% does NOT apply to RV use and it is quite safe to cycle RV batteries to 20% and still get a very good life span from the batteries.

BTW Fullriver is one of the better AGM batteries and their web site is a wealth of info.

[derekclapham]

All new lead acid batteries, including all forms of AGMs will now safely tolerate being discharged down to 11.58v or 20% and a number can be discharged down to 10.5v or 0%

@drivesafe are you saying that the "Don't discharge beyond 50%" (or 12.2v) is no longer applicable with new AGMs? If so, what kind of specs would one look for when buying a new AGM? I typically buy Fullriver.

[craigm]

http://www.allpurposebatteries.com.a...roducts_id=333

[drivesafe]

Hi Craig and sorry mate but that comparison list is so erroneous that it is not a realistic comparison at all.

First off, by lead acid, do you mean WET CELL, because AGMs and GELs are all lead acid batteries.

Next, there are two groups of AGMs.

The first and most common is Standby types, like Fullriver, and these batteries have a constant charge current of 35% or in your comparison, 35 amps, not 10 amps.

The second type are genuine automotive grade AGMs, like OPTIMA and they have NO CHARGE CURRENT LIMIT. Thats a lot different to 10 amps, and I have personally charged 55Ah Optima Yellowtops with as much as 63 amps on numerous occasions and that equates to way higher than Lithium’s 100 amps.

As to age, well my oldest Optima Yellowtop is now 9 years old and has had a very hard life, yet still working fine.

The list also neglected to mention voltage tolerances.

Lithium have a maximum voltage tolerance of 14.6v and this should be lowered to under 13.8v once the battery is fully charged. Something that is not easily achieved when charging straight from an alternator.

Where as Standby type AGMs tolerate between 14.4v and 14.7, while automotive grade AGMs, again, like Optimas, will tolerate 15.1v

Wet Cell batteries will tolerate 15.5v during boost/equalisation charge cycles and 14.7v continuos voltages.

All new lead acid batteries, including all forms of AGMs will now safely tolerate being discharged down to 11.58v or 20% and a number can be discharged down to 10.5v or 0% but Lithiums can only be discharged down to 20% and you can not use voltage measurements to try to determine capacity with lithiums, making monitoring their capacity somewhat more complex and expensive.

While some Lithium batteries can be charged straight off the alternator, as long as the alternator voltage does not rise over their safe limit, but once the motor is turned off, the lithium batteries MUST BE separated from any lead acid batteries.

As above, not a very realistic comparison. Where did you get that info from

[LeighW]

Not saying the aren't but they were pretty impressive specs for the others
that have now faded into the back ground too.

Problems have also started to rear their heads with the newest new brutes, ask
Kimberly owners, and have a look a cell balancing issues.

[craigm]

Pretty impressive spec's on the LifePo4 batteries Leigh. Just the price still hurts at the moment...

Not sure what the Battery equivalent the below chart refers to but whoa!

TECHNOLOGY COMPARISON CHART
TYPE	LITHIUM ION	AGM	LEAD ACID	GEL
Cycle Life	3000-5000	500 - 1000	300 - 500	500
Life Years	10+ YEARS	3 -5	2 - 4	2 - 4
Efficiency	98%	60 - 90%	40 - 60%	50- 70%
Continuous Amp Draw	200AMPS	25 amps (cont)	20 amps (cont)	25 amps (cont)
MAX Charge Rating	100AMPS	10 amps	5 amps	5 amps
Average Weight	15KG	30kg.	28kg	31kg
ROHS Compliant	YES	No	No	No

[LeighW]

As I have written before, quite a few years ago Nickel Cadmium batteries were the
bees knees and everything else was going to be obsolete.

Then along came LIPO and everything else was going to become obsolete.

Now along comes LifePo4 and everything else is going to become obsolete.......