Thread: Lithium, again...

Another thing I'm curious about that I'm yet to research is charge time. I think DC-DC chargers by nature have a slower charge time. This is probably negated if doing lots of driving, and/or lots of sun, but interested to see what the difference is. My understanding is whilst DC-DC chargers might be able to charge batteries to a higher SOC, this comes at a cost of much slower charging. On the other hand, direct charging from the alternator (perhaps via a Traxide unit) might allow faster charging, but not to full SOC. Seems like an obvious trade off, but no idea which is better or worse (or either).

Originally Posted by Ranga

Another thing I'm curious about that I'm yet to research is charge time. I think DC-DC chargers by nature have a slower charge time. This is probably negated if doing lots of driving, and/or lots of sun, but interested to see what the difference is. My understanding is whilst DC-DC chargers might be able to charge batteries to a higher SOC, this comes at a cost of much slower charging. On the other hand, direct charging from the alternator (perhaps via a Traxide unit) might allow faster charging, but not to full SOC. Seems like an obvious trade off, but no idea which is better or worse (or either).

I thought that I could get away without a DC to DC & tried charging the Lithiums in the van off the end of the Traxide system. Well I couldn't. The Lithiums are at 13.4V ish most of the time & by the time you factor in the volt drop from the alternator to the van, the difference is minimal so little/no charging takes place. I have fitted an Enerdrive 50A DC DC in the van to solve the problem.

Hi,
June LWE, got the Lithium fully charged on 240V.
Left home and drove about 90 minutes, the dc2dc did not cut in.
Camped 3 days, 2 nights running fridge, heater and lights.
Driving home, the dc2dc cut in on startup and ran for 30 minutes till charged and then stayed off.

They are a different beast altogether. Completely different graphs to the old AGM.
Cheers

Originally Posted by austastar

Hi,
June LWE, got the Lithium fully charged on 240V.
Left home and drove about 90 minutes, the dc2dc did not cut in.
Camped 3 days, 2 nights running fridge, heater and lights.
Driving home, the dc2dc cut in on startup and ran for 30 minutes till charged and then stayed off.

They are a different beast altogether. Completely different graphs to the old AGM.
Cheers

Wow, that's a very quick charge time! Do you know what the voltage was before you left for home?

Hi,
below is a post I put up on Myswag, which will give you the details.
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Hi,
well I bit the bullet and up graded to a Lithium 200AH and managed to cobble it together for the LWE.
It behaves differently to the lead acid, and I'm not 100% sure of my graphs as I didn't log driving times, but below is my interpretation of what happened.

Got the battery connected, connected solar panel at first arrow, changed over to 240V charger at second arrow, achieved float at the third arrow.





I turned on the fridge about 2pm, at 3 pm I turned off the 240V charger (on power supply mode) and drove to the Lakes till 4pm, but there is no dramatic change on the graph. I am thinking that the DC2DC charger is taking the battery as charged and on float so has not applied any voltage to the battery on start up or during driving.





Camped at the Lakes, I attempted to connect the solar panel, but found out later that I had a faulty lead, so I am thinking there is no solar input at all.





I drove home about 3:30 till 5pm, yea, the charger has put some voltage into the battery after 2 days usage, but achieves float in about 30 minutes.
That is impressive, if my assumptions are correct.




So the next thing to do is tidy up the install and repair the faulty solar connection.

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Cheers

interesting all these restrictions for lithium.

i have lithium battery in my bike and they are drop in, no dc-dc charger, no changes. it just works.

OK folks and some operating explanations needed here.


First off, no conventional VSR isolators or my isolators will work in any vehicle, when sting to charge lithium batteries direct from the alternator.


With Land Rovers, and most European vehicles, the problem becomes worse, and I will explain later.


The reason my isolators do a far better and faster recharge of LEAD ACID batteries when used in Land Rovers, is because my isolators allow the cranking battery to supply some of it’s capacity to assist the auxiliary battery’s power supply demands while camping.


This means that when you start driving, because you have draw the cranking battery down from a fully charged state, the BMS will see the lower cranking battery voltage at startup, and will adjust the operating voltage to a higher level for a longer time.


Ordinary VSR isolators do not draw down the Cranking battery, so when you start your drive, the BMS will see the cranking battery is either full or nearly full and adjusts the operating voltage to a lower level soon after starting your motor.


With lithium batteries, the problem becomes more complex.


If you have fully charged or only slightly charged lithium batteries, their voltage remains the same, above 13.0v.


If you have them linked to the cranking battery, to allow them to be charged directly by the alternator, when you start your motor and the BMS monitors the cranking battery’s terminal voltage, the BMS is going to see a 13.0v, because the lithium batteries are keep the whole systems voltage at their normal operating voltage.


The result is that the BMS sees a voltage level that indicates the cranking battery is fully charged and no high voltage operation is needed. This lower voltage means the lithiums will never charge.


So the only way to charge lithium batteries properly while driving, is with a DC/DC device.


Even with the 60 amp Sterling Battery to Battery chargers I supply, the standard cranking battery + Optima auxiliary battery setup using one of my isolators, and charging say two 100Ah batteries in a caravan or camper trailer, will have the bulk of the used capacity of all of these batteries the charged in a much shorter time than the two 100Ah lithium batteries will be able to be charged using the 60 amp Sterling.


But if you are just using the two 100Ah lithiums in the van or camper trailer, then the DC/DC device, while taking longer during the bulk charge stage, will bring the two lithiums to a near fully charged state in a shorter drive time than you can bring the four lead acid batteries to a near fully charged state.


The above assumes all batteries are in a low state of charge at the beginning of the day’s drive.


Also note, my isolators work perfectly in vehicles with STOP/START function, and again, direct alternator to lithium recharging becomes an even bigger problem.


Where you have a vehicle where the alternator’s operating voltage can be maintained at a constant low 14V, such as a Ford Ranger, direct alternator to lithium battery charging will be the optimum way to charge lithiums but you have to use an IGNITION controlled isolator.

Thanks for the explanation drivesafe.

I’m not convinced converting to lithium is complex given the OP has a 300tdi so not a modern/late model car.

Costs aside the way I read your explanation is if the OP converted to lithium than it would be best change both the vehicle AUX-AGM and the camper AGM to lithium to maximize the function of the DC-DC rather than keep the vehicle aux-AGM and camper lithium.

Austatar seems to getting good performance from his setup with just a starter and lithium in the camper.

I’m considering the switch, space and weight is becoming an issue for planned overland trip.

I have a TD5 > basic redarc isolator > 110amp/hr AGM. I’m not interested in using the capacity in my starter hence why I didn’t consider a traxide isolator when I started the build and acknowledge that cost per amp it’s way I front of lithium.

To me this is a simple switch to gain more capacity. I also in a position not having to use a drop in replacement, I need to start researching sizes.

TD5 Starter > Enerdrive DC-DC > either a Revolution (or similar) drop in or a EV Powerpac all backed up with 2 x 125w panels on the roof and a 125w portable blanket.

How does that sound??