Charging Lithium Batteries Vs Charging AGM Batteries

[Ridge Runner]

Thanks for those useful demonstrations fellas.

Glad it was useful, :Y:

It's nice Towing a well set up Caravan/Trailer, Many of the American Caravans like the Alloy AirStreams have the Axles placed further back to stop some of the sway, Trouble is some of them can put 300 to 500Kg+ on ya Hitch and put you over the limit on the rear Alxe when the Tow vehicle is loaded and a few people on board, Aussie and Brit/EU Caravans are better set up,

 

[condor22]

Wasn't full disclosure lol, I also had a 24pk of 600mm water, some clothes etc. My aim was to reduce draw bar weight, I went too far lol.

30-40 kg at the back compared to putting it forward actually makes more than that in balance difference. Without measuring distances and load, it could be nearer to 50+kg overall and that can make a difference.

It's "funny" how the so called experts say "try to put heavy loads over the axles", when caravan designers in many instances don't give you any space to secure such loads in that area. In my van the fridge is on one side and the dinette seats on the other with the battery etc in that area.

Also, my van is a single axle and would behave like the video above as many will when loaded wrongly. Tandem axles are still affected but the load and wobble are less. pronounced.

 

[Tathradj]

The Avan I have is a single axle and yes, Critical to get
your balancing act correct.
if a bit front heavy I put some water in the main tank to balance it all out.
They are designed that way to allow for a full tank, 60ltres of water.
I always take it that if you have to go that far, You have something wrong.
Besides, That adds to your towing weight and on a long haul, Can impact
your fuel usage not to mention wear and tear plus safety in a bad situation.

The other Van a 18 footer Pop Top is a dual axle plus dual braked.
I m going to put a switch in to cancel the rear axle's brakes as that to me is
deadly on a wet road when you have to plant the anchors in a hurry.

In the dry, If you have the brakes turned up, It will nearly put you through
the windscreen on a bit more than gentle application of the brake pedal.

When I fitted my batteries, They are located pretty much square center between the axles.

And this thing tows like a dream. You hardly know it is there until you either plant the
throttle or come to a steep hill.

Like every thing else, Common sense goes a long way. :Y: :Y:

 

[Ridge Runner]

Wasn't full disclosure lol, I also had a 24pk of 600mm water, some clothes etc. My aim was to reduce draw bar weight, I went too far lol.

30-40 kg at the back compared to putting it forward actually makes more than that in balance difference. Without measuring distances and load, it could be nearer to 50+kg overall and that can make a difference.

It's "funny" how the so called experts say "try to put heavy loads over the axles", when caravan designers in many instances don't give you any space to secure such loads in that area. In my van the fridge is on one side and the dinette seats on the other with the battery etc in that area.

Also, my van is a single axle and would behave like the video above as many will when loaded wrongly. Tandem axles are still affected but the load and wobble are less. pronounced.

The UK and EU Caravans have all the heavy stuff near the Axle/s, It would be better if they allowed you to place the Batteries over the Axle one on each side of the Van and place the fridge and Cooker/Oven either side of the Axle and the Heater on the other side of the Van, They normally place the fresh water Tank in front of the Axle and the Waste water tank and the dunny behind the Axle.

One major mistake is Caravans with big fixed double beds in the rear because a lot of people load up the big storage area under the bed with heavy stuff instead of just using it for bedding etc and that is asking for trouble,

 

[Ridge Runner]

The Avan I have is a single axle and yes, Critical to get
your balancing act correct.
if a bit front heavy I put some water in the main tank to balance it all out.
They are designed that way to allow for a full tank, 60ltres of water.
I always take it that if you have to go that far, You have something wrong.
Besides, That adds to your towing weight and on a long haul, Can impact
your fuel usage not to mention wear and tear plus safety in a bad situation.

The other Van a 18 footer Pop Top is a dual axle plus dual braked.
I m going to put a switch in to cancel the rear axle's brakes as that to me is
deadly on a wet road when you have to plant the anchors in a hurry.

In the dry, If you have the brakes turned up, It will nearly put you through
the windscreen on a bit more than gentle application of the brake pedal.

When I fitted my batteries, They are located pretty much square center between the axles.

And this thing tows like a dream. You hardly know it is there until you either plant the
throttle or come to a steep hill.

Like every thing else, Common sense goes a long way. :Y: :Y:

I really like your "A" Van, :inlove: :inlove: :inlove:

 

[Tathradj]

Putting it up for sale shortly after I clean it out/Up and register it.

 

[condor22]

What gets me riled is, I've weighed both my van wheels individually. The 3 way fridge is on the driver side of the van. The dinette with battery & charger etc is on the other side.

The fridge side is 50kg heavier and there is no space to add more weight under the dinette. Then I put food in the fridge and in the pantry (also on the driver side) and I can easily see near 100kg more on the driver side.

However, I got fed up, turning the fridge on 240 V a couple of days before travelling, then to 12 V to travel, then to LPG when on my mates bush block.
Coupled with constantly checking the bloody temperature.

My last 2 trips, I've used the Engel for fridge food n drink and the Brass Monkey set to -12 for the frozos and they travel in the back of the 4x4. The 3 way gets switched on LPG when I get to camp and the food transferred when it's cold. I might add, the 3 way gets colder quicker on LPG than it does on 240 VAC. For me, that's much less stuffing round as I use the vehicle fridge/freezer when I do the shop for the trip and it saves moving the food from them until I get where I'm going.

 

[Nightjar]

Condor22,
Like you we have a 3way in our van and after initial problems we now have it sorted.
Like yours the fridge is on drivers side and batteries on passenger.
Our van is tandem axle and use load levelers.
We have 80l water tanks forward and aft of the axles.
We travel with the forward tank empty and approx 30litres in the aft tank to distribute weights.
We usually travel 1000k on the bitumen @ 100KMP, the last town usually Leonora we fill both water tanks in van and the two inbuilt 60l tanks under ute and an 80 litre on the back of the ute before travelling the last 70kms to destination.

After purchasing the van back in 2008 (5.5M Trailstar-Aquila fitted with shock absorber on each wheel) I made up a device for checking drawbar weight when loaded. (All good)
Ran heavy wiring + fuse from auxiliary battery to rear of ute + Anderson Plug then Anderson plug and wiring + fuse to the van batteries. (The original wiring did not keep up the charge to the van batteries during the heavy drainage from the fridge running on 12V while travelling.) All good.
Touch wood we have covered approx 50,000kms with out any drama other than tyre blow out on the van. (Fortunately was only travelling at low speed so the "wobbles" didn't cause too much drama.
Have an 80L + 39L Engels + 3kva Honda generator the back of ute which allows us about one month food storage while camping remote/off the grid.

 

[Ridge Runner]

Theres a couple of brands of Caravans over here that are made of fibre glass so "no" water leaks and they weigh from 580 to 850kgs but they have a load capacity of up to 4/500kgs depending on the model and layout, I would love to buy one because that would give me a load capacity of up to 1400kg's and they make a few Quirky models as well, being so light you can tow them with just about any car out there,

 

[condor22]

Jeez RR, I'm 6' tall would I fit. I used to collect Dinky toys in the UK as a kid, it looks like one lol.

 

[Ridge Runner]

Jeez RR, I'm 6' tall would I fit. I used to collect Dinky toys in the UK as a kid, it looks like one lol.

With the roof up they are about 6'6" and about 5'6" with it down, Those are the 3.10 and the 5.40 models they also make a 8.20 version that looks more spaceage, They are German made by the Hymar Group, Not cheap but they hold their secondhand price like nothing on the planet, A 20 year old one can still fetch 10 to $15k and they are light and about a 1/5th of the Cost of one of those American Aluminium Airsteams,

There is another company making fibreglass normal type caravans that wight 580kg's and can gross about 850/900kgs +/-. which would be a perfect addition to go with my Van

 

[Ridge Runner]

I have run the AGM test Vs Size of charger again only this time I used the 15A Noco Smart Charger and I ran the Battery even lower But I don't know if it was because of cycling the AGM again but it charged faster using the 15A charger compared to the 26A charger,

I used 37.9% or 30Ah from the 80Ah AGM and using the Noco G15000 it took 7 hrs 8 minutes to completely finish charging, Cutting the charge time in half, where as before I drain the AGM by 19% which is only half of what I did this time,

15A charge rate is 18.75% of the AGM's capacity and 26A is 32.5% of the AGM's capacity when compared to the charge times shows that a charge rate of 20% works a lot better/faster than a 30%+ charge rate. So I am guessing that 20% +/- is the best charge rate for AGM's, So for a 130Ah AGM 26A would be best. erfect:

 

[condor22]

One thing I found with quite a few people I chat to is their mistaken belief that, for example, (for AGM batteries)

1. A 30 A charger will charge 30 amps in one hour = rarely the case.
2. If, i.e a 120 AH battery is at 50% State of Charge (SOC) the same charger will take 2 hours to charge = It won't.

I'll use my chargers as examples - a. Voltech BC-1230 P 240 VAC mains smart charger and b. Redarc BCDC1220 DC-DC charger. The Voltech is set to 21 amps (it has increments of 10 to 100% charge rate) so set to 70%. I've monitored it's charge rate in Bulk mode on a number of occasions and never seen it exceed 18.2 amps and generally near 15 amps. This is because as a smart charger, like the Redarc, it is "very smart"/ It looks at the battery's condition, size, temperature etc etc. and adjusts accordingly to the best charge rate it determines for the battery.

However, this only occurs until the battery is approx. 80% SOC, then the charger goes into Absorption Mode. Here, the charger increases voltage to approx 14.4/14.5 V and the charge amps gradually reduce until the battery is nearly 100% full. This stage can take several hours to achieve and again can vary from battery to battery, charger to charger, install to install and temperature. So there is no definitive time anyone can quote.

What I do know is my 130 AH battery at 75% SOC (about 33 AH used) with the Voltech charger set to 21 amps charge rate takes about 2.5 to 3.0 hours to reach float mode.
That can vary as it also depends on if there is any load on the battery during charging.

Conversely, the Victron 15 A solar controller, on a moderate day in winter, reaches float mode around mid afternoon with the same use. Again impossible to quantify as solar is very weather dependent, I recently had 2 days of absolutely atrocious weather and needed to run the Voltech (genny powered to top up).

What Lithium allows is, in my opinion, 3 distinct advantages - 1. Much more rapid charging, whatever the source (VAC, DC-DC or Solar), 2. Extended time frame between charging as you can cycle deeper. and, 3. A more constant voltage through that cycling avoiding low voltage cutout on fridges and even some TVs.

 

[condor22]

Forgot to mention, never seen my 20 amp Redarc throw more than 14.8 amps at my 100 AH auxiliary in Bulk mode.

 

[Ridge Runner]

Forgot to mention, never seen my 20 amp Redarc throw more than 14.8 amps at my 100 AH auxiliary in Bulk mode.

Funny you should say that because I have a few chargers but I have noticed that I have never seen one of them put out their rated currant even on big batteries linked up , And ofcoarse when charging Lead Acid batteries the needle drops pretty quick after they are first turned on and then they stablize stuck in one place for a while. the big one is a 35A but the most I have ever seen is about 26.5A and that was only for a few seconds.

 

[condor22]

A good quality charger, in simple terms, interrogates the battery's SOC and in some its health. i.e. if I only use say 10 AH from my 100 AH AGM, when a charger is switched on the Voltech, or I start the car for the Redarc or even the Victron solar controller, they all start in Bulk mode.

Depending on the charger and the SOC of the battery, they all go through up to all 3 stages and at different rates. Usually ranging from some 10s of seconds to a few minutes, until they determine what the battery needs and therefore its stage of charge.

One of the biggest killers of a battery, are chargers that stay in Absorption mode when a load is applied. I won't name it, but one of my old chargers did that. So it was constantly gassing off at 14.5 V until the load reduced. That was around a 3 amp load < than floated, > than went into absorption.

I took note of the Voltech's voltage on my last trip, when I was at my mates place. He was away, so I tapped into his residential 240 VAC (solar powered) and turned my panels off. I have a remote head unit on the charger as well as a monitor on the battery. In the evening when watching TV on Satellite, running my laptop, the diesel heater and a light or 2, I showed a charger output of between 5 and 6.5 amps, but a net zero battery discharge/charge rate and both displays floating at around 13.2 volts.

This means the charger provided the power to the load through the battery, but as the battery was effectively under no load, it maintained Float mode over the several hours until I went to bed. After which the only load was the 0.8 to 1.0 amp heater load throughout the night. On the odd occasion I got up to "take the dog for a walk" the voltage was still 13.2 V. It was not in power supply mode, but AGM mode. Power supply mode gives a constant 13.8 V.

 

[condor22]

The Voltech has 2 LiFePo4 settings, one has an Absorption of 14.6 V the other at 14.4 V. Both float at 13.6. However, as and when I go Lithium, I'm going to use power supply mode at 13.8 V at the full 30 A setting, as it is a better voltage to charge and float for the battery I'll buy.

The battery's inbuilt BMS will regulate the current and the charger will only give what the battery wants.

FYI - I checked the specs of the Voltech, the current draw at its full 30 A charge capacity is 2.5 amps (600 W). So when run from a 2kVA genny at the same time as a microwave it's over the genny's constant power rating. So I switch it off on the remote head when in that scenario, keeping in mind it's set to 70% output and not necessarily in Bulk mode anyway.

I used my clamp ammeter on a test cable when on my mates system and when it was floating and providing 3 amps @ 12 V to the TV, the 240 VAC load hovered between 0.2 and 0.3 amps @ 240 VAC with the battery floating.

 

[Ridge Runner]

I also ran one of the fridges while I was charging 2X 115Ah batteries it was running off, when the fridge kicked in where the Amp Meter was reading 5 or 6 Amps it then when up to 8 or 9A so it was compensating for the fridge draw while still give the batteries the 5 to 6A they wanted,

It seems that these charger companies quote their chargers peak power not the constant power, because both yours and mine seem to be putting out a constant 25% less than the claimed rating. so based on that a person should buy a charger that is 25% bigger than what they need.

That works out fine for lead Acid but I am sure how that pans out for your smart chargers even though you are still lossing that 25%, The 80A AGM I charged with the 26A smart charge was not too impressive, I don't know if it was because the battery had been sitting for a week or so because it finished the Bulk charge in 3h 20m but it kept on clicking 14+ hours later yet whn I used more power from the AGM @ 39+Ah using the 15A smart charger it did its Bulk charge in roughlt the same time of 3h 20m+/- and then it stopped clicking after 7h 8m which is half the time of the bigger charger,

 

[Ridge Runner]

I went on another roadtrip on friday and just got back, I took one of the lithium packs and a foldout 120w solar panel and the biggest drop I saw was about 13% and within just over an hour hooked up to the PLB40 it was full again and stayed the way all day until about an hour after dark and in the following 14+ hours all the fridge used was 12% and again the panel charged it up in no time If I had left it hooked up over night then the fridge would of drawn less than 10% over night.

 

[Moneybox]

I'm told one of the advantages of the lithium battery is that it will accept a much higher charge rate than the equivalent AGM battery. My Redarc charger is not designed for lithium but my batteries have an inbuilt battery management system so I'm counting on that looking after the charge rate.