Which battery, what's new?

I have had great success with lithium iron phosphate (LiFePo4, commonly called LiFe) batteries in my Karavan. See my blog here. When camped I run a 130 litre compressor fridge and a 55 litre car fridge as a -10 deg freezer and can do that for at least 5 days with average to poor sun.

I have 360Ah of lithium which is equivalent to about 720Ah of lead acid.

You won't have the luxury of those amp-hours, but if you could get a lithium battery of about the same Ah capacity as you already have to fit your battery space you would have about double the useable battery capacity. ie, if you currently have 105 Ah of AGM or whatever, if you could get 105Ah of lithium in the same space you would have the equivalent of about 210Ah of AGMs in useable capacity. To put it simply, on an amp-hour for amp-hour basis, you get about 1.5 times the useable capacity from LiFe, even double if you want to push it.

If I were in your position and given your pretty high loads, I would investigate as to whether LiFe batteries can tolerate the high temperatures found in the rear of an engine bay. Sorry, I don't know that info off hand, my Karavan batteries are in a benign environment. BUT, my supplier has a small LiFe battery as a direct replacement for his car battery in his Falcon and it has been going for years, so that may be an indication.

Though the initial outlay is expensive, cost of ownership of LiFe batteries may be cheaper than lead-acid because they typically outlast 3 sets of lead acid batteries.

If you're interested, just check how they go in a hot under-bonnet environment.

Cheers

I've never had less then 10 years service from an optima which makes them the cheapest battery I have bought when compared with all the middle of the road stuff I played with for years. The biggest optima is 'only' 75 ah but thats not the whole story. Internal resistance is very low so they recharge much quicker and accept charge off solar panels more easily than others. They are by no means cutting edge, just well manufactured with quality componentry which is half the battle. Definitely my number one choice of deep cycle battery. Mine runs off a ctec 250 as well, but in the ute well. The ctec 250 is temperature compensated and has a history of not liking being under bonnets - I'd confirm this isn't an issue?

gbc, what are you driving off your battery? The OP is running both a fridge and a freezer of his battery. I suggest he would require a battery for each to have sufficient capacity.

I run a 60 evakool 24/7. It doesn't get turned off.
The op would need a couple at least. The issue I've always found with running two fridges is that they eventually sync and the computers will trip them as the startup current is quite high, meaning you end up with hot beer and enough current to run the fridges which is a heartbreaking and unacceptable situation. I'd go three batteries .... ;)

Thanks HKB. The current battery is a Turbo brand battery and is rated 105Ah. My car is a 2006 Nissan Patrol TD42ti and I'm using a CTec 250 battery manager that is mounted under the passenger's seat. There is also a digital voltmeter. The Engel is a 60L and run as a fridge. The Waeco is 20L and run as a freezer and there is a 150mm cooling fan running. Typically we go away 3 to 4 times a year camping, Sometimes we'll stay in the same place for a few days whereby we run the fridges on the generator. Other times, we're on the move every day so the battery powers the 2 devices from about 3 pm till 8 am. For all the other weeks of the year (about 40 of them) the battery just sits under the bonnet and has no discharge imposed upon it.
The problem arises when we decide to stay at a campsite a second night. We've already run the fridges off the battery on the first night so it is depleted. During the second day we use the generator but then we have to switch it off when we go to bed and that's when we run into trouble. I have been using the generator to charge the battery while it is also powering the fridges during the day. I'm not sure if this is a smart thing to do or not. Thanks for your interest and advice. Deejay.

You appear to have tow issues, not enough battery capacity and insufficient charge from your generator. I would suggest that you need to connect at least a 25A charger to your generator, this would allow you to recharge your battery from around a 50% SOC in around 3 to 4 hours.

Ulimatley more battery power and solar to suplement wood be good but that would depend on wether you think the investment is worth it for the amopunt of camping you do.

Charging off the generators battery charge terminals is going to take much longer.

Thanks Allan. The current battery is a Turbo brand battery and is rated 105Ah. My car is a 2006 Nissan Patrol TD42ti and I'm using a CTec 250 battery manager that is mounted under the passenger's seat. The Engel is a 60L and run as a fridge. The Waeco is 20L and run as a freezer and there is a 150mm cooling fan running. Typically we go away 3 to 4 times a year camping, Sometimes we'll stay in the same place for a few days whereby we run the fridges on the generator. Other times, we're on the move every day so the battery powers the 2 devices from about 3 pm till 8 am. For all the other weeks of the year (about 40 of them) the battery just sits under the bonnet and has no discharge imposed upon it.
The problem arises when we decide to stay at a campsite a second night. We've already run the fridges off the battery on the first night so it is depleted. During the second day we use the generator but then we have to switch it off when we go to bed and that's when we run into trouble. I have been using the generator to charge the battery while it is also powering the fridges during the day. I'm not sure if this is a smart thing to do or not. Thanks for your interest and advice. Deejay.

Deejay, from what you said there it indicates to me that you have insufficient battery capacity. I was getting 2 to 3 days use out of a 110 Ah battery driving one Waeco fridge. I was also using lights and a car radio in the van. The batteries were not charged during that time.

Hi Deejay,

looking at your travelling/charging pattern, no clear conclusions can be drawn about battery charging status.

Easiest thing to do is buy a $10 voltmeter and mount it in a highly visible spot.
When connected to the auxiliary battery it'll give you a good indication of state of charge.
Not accurate SOC but good enough anyway.

During regular use of your aux battery i.e. when touring/camping the voltmeter should read 14.4V for a consecutive 3 hours or longer, at least twice a week, or better every time after the voltage has dropped to below 12V.
Excursion below 11.8V are to be avoided if at all possible.
If you frequently see low voltage it could be one or a combination of the following:

battery on its way out
battery chronically under-charged
not enough installed battery capacity
hot ambient

Is this battery of yours a flooded type?
If yes, I'd replace it with an AGM or gel which will last at least twice as long in your application provided it gets charged thoroughly.
If at all possible, mount the battery away from the heat.
And do not leave it under the bonnet for the rest of the year when not travelling since heat will affect its life even when sitting idle.

Cheers

Deejay, summarising what you have said:
Battery: 'Turbo' 105ah (presumably AGM deep-cycle)
Load: 60 ltr fridge and 20 ltr freezer
Charge: Ctek 250s (= 25 amp maximum)

So from that can be assessed that you have 50ah of available battery capacity as you should only draw down no more than 50% of rated. Your fridge load will be at least 5ah per hour so will consume about 60ah overnight and that is more than the allowed drawdown. Recharging from your car alternator via the Ctek would require at least 4 hours driving. These figures do not allow for higher ambient temperatures or a less-than-new battery so it is probably much worse. So it can be seen that your installed system is not up to the task even when the battery is new.

The demands on your battery are contributing to its short life and it is probable that high engine bay temperatures are also damaging it. The main contributors to short battery life are over-discharging, high temperatures and severe vibration. The location of your battery in the engine bay exposes it to high temperature and as it is close to being directly over the front axle it will also receive maximum vibration shock from road conditions. Relocating the battery to inside the cabin would ease both of these conditions.

For the fridge demand of 60ah overnight you really need more battery capacity. A second battery is advisable. Even then, the existing Ctek 250 may not replace the consumed energy within the driving time and a second charger may be needed.

A couple of useful links are "Electricity for Camping" and "Auxiliary Battery Systems Wiring".

If you wish to reduce battery heat, a photo of my arrangement is below and two forum threads on this are Thread 91116 and Thread 106611.

PS, Your wife is a wise woman - thinks the same as my wife.....unfortunately :-)

Further to what Ross said Read this article.

Thanks Ross. It's a 1kva Honda with the built-in battery charger.

What id the output current of that "built-in battery charger?" Is it just the standard low power 12 V OP from those generators. If it is then read the article I gave the link to @ Tuesday, Oct 06, 2015 at 16:53 above.

Those 12 V outputs are just for powering 12 V appliances and incidental battery charging. They are useless when it comes to charging deep cycle batteries.

Thanks Robin for your reply.
1. I've not heard of calcium batteries - are they more durable/better than wet cell or AGM?
2. Am I understanding your comment correctly that they are $175 each?
3. And lastly, you suggest charging the auxiliary battery straight off the alternator yet other people have told me that an alternator only puts 70 to 80% charge into a battery. What do you think?
The current battery is a Turbo brand wet cell, deep cycle battery and is rated at 105Ah. My car is a 2006 Nissan Patrol TD42ti and I'm using a CTec 250 battery manager that is mounted under the passenger's seat. The Engel is a 60L and run as a fridge. The Waeco is 20L and run as a freezer and there is a 150mm cooling fan running. Typically we go away 3 to 4 times a year camping, Sometimes we'll stay in the same place for a few days whereby we run the fridges on the generator. Other times, we're on the move every day so the battery powers the 2 devices from about 3 pm till 8 am. For all the other weeks of the year (about 40 of them) the battery just sits under the bonnet and has no discharge imposed upon it.
The problem arises when we decide to stay at a campsite a second night. We've already run the fridges off the battery on the first night so it is depleted. During the second day we use the generator but then we have to switch it off when we go to bed and that's when we run into trouble. I have been using the generator to charge the battery while it is also powering the fridges during the day. I'm not sure if this is a smart thing to do or not. Thanks for your interest and advice. Deejay.

Deejay, you are not listening. The majority of replies are advising that you need 2 batteries at least. As Robin Miller advised, you are using the wrong charging method. I am a believer in using DC-DC charging. However you need the appropriate equipment, a 20 A charger is not sufficient for your use. When you get your second battery you will need at least a 50 A DC-DC charger, it's no good using a boy to do a man's job.

You are doing the same with the Honda generator. The 12 V output is useless when it comes to charging deep cycling batteries. Did you not read the link I presented to you in a folllowup in the previous reply. You are not using heavy enough equipment to charge your batteries, that's why you are killing them. If you are going to use a generator you should be using it to drive a 50 A battery charger to charge your batteries (and you will probably find that your generator will not drive that large size charger.)

The battery and charging regime is barely sufficient to run only one fridge/freezer.

Hi Deejay

As above I don't disagree with most of this threads comments , I am just coming at your problem from a different angle.

I agree with your friends comments about standard alternator not always fully charging battery and also agree with Peters comment that, if done right a DC-DC charger can do better.

The GU patrol as sold in many areas has provision for 2 battereis and sufficent power to charge at over 100 amps (for a few minutes till regulator reduces volts when hot).
So for most of the year your car will automatically take care of those batts.

You don't need to do anything to make it all work except run car for a few minutes at a time .
Mines a petrol gu so its very quiet and on worst of days it might need 1/2 hour total.

But its important to know when it needs a charge so as batteries are not frequently run down to far,
and to use stratergies that minimze power needed from batts.

As for actual batteries slight variations in models and specs are occurring constantly so I checked at local Bayswater place when getting my morning coffee today.

The current equivalent to my 18 month old Exide N70zzlmf is called the Endurance and retail today was $187. It is a sealed Maintenance free Calcium/Calcium type capable of many discharges , but not as many as a full deep cycle. I prefer this version as I change them regularly even though they ok still.

It also comes in straight lead acid (cheaper) and a higher spec extreme AGM version $235 with over 800cca.

Note the attached reference list about a dozen variations of N70's

http://www.exidebatteries.com.au/Downloads/Brochure/N2046F%20Exide%20Product%20Category%20Brochure%20SUV-4WD-LC.pdf

P.S. My CF25 Waeco fits between the patrols front seats with some slight mods, and hence never suffers from extremes.

P.S.2 I think I said that N70 will fit the Patrols N50 cradles with some slight trimmings

Well thank you very much Geriatric Navara - your care and understanding is duly noted. It's not a case of me not listening, idiot, but rather struggling to understand a field in which I have very little knowledge and being bombarded with information which sometimes appears to be contradictory. I thought the whole purpose of this forum was to help other people, not berate them with sarcastic admonishments. Just as well you took up engineering for a career - coz you'd make one lousy teacher! Deejay.