Lithium battery for caravan

RMD yes over $6K is way to much, I've been quoted $1700 for a 150A/H buy and drop in with existing electronics albeit the battery will not deliver the full power due to lower charging volts. A Lithium charger may arrive when funds permit.
thanks

Thanks Keith, most recent info is dated Oct 2017. But I guess it's relevant. The BMS included in battery that I'm looking at is to protect the battery from over charge and low discharge. My battery-mate cuts discharge at 11.5V. And yes charge to 14.4 is fine the battery just won't get to 100%
The $6K+ quote was virtually rewiring the van and supplying all new electronics which I had. Battery in the quote was for only 160A/H. I was quoted for 200A/H Lithium for around $2K, 150A/H is $1700.
Thank you to the other responses.
Geoff

You don't float Lithiums!

I have had a Lithium setup for around three ears now. I have 2X100Ah Lithiums in my setup, these have cell balancers on the cells but to date I have not needed them. I generally charge these with the A/C charger set to power supply mode which is 13.8V, there is no need to charge them any higher as they will charge to very close to 100% charge at this level. If I increase the charge voltage to 14.2V or higher once the Lithiums stop taking charge they will only resume charging for a few minutes them stop again.

Once charged I turn the charger off if not using the batteries. Off car charging is via DC/DC Lithium capable charger which I have set to max charge voltage of 14.2V (minimise recharge times) it them then turns off. It will resume charging when batteries drop to around the 90% SOC, or the car is restarted.

As far as I can see most suppliers who recommend higher charge voltages are also recommending you buy one of their cell balancing systems, or their batteries have integrated cell balancers/BMS. Generally these require around 14.6V or higher for them to allow them to function, if the cells aren't out of balance you don't need to cell balance. I have been using my system for around three years now, discharge the Lithiums generally to a max of 50% SOC but have gone to 20% at times, I have had no issues with cell balance and have not needed to raise charge voltage to 14.6V for the cell balance system.

Thanks for that info HKB

Thanks Phil, Perhaps you could share your knowledge on how to build up a Lithium? I have an electrical background and some 12V knowledge but the Lithium has been made to appear a very different beast requiring different attention.
Geoff

Geoff, have a look at EV Works or EV Power for the cells of the size you want. You need 4 for a 12v system. Then the braided connections, BMS, possibly a relay depending on how you want to control the BMS, and then the wiring is reasonably straightforward. You need to ascertain the best charge rate for the cells you use, and match the charging of your solar controller, BCDC charger, and 240v charger accordingly. The solar will depend on the size of your panels (I have used GSL), and I have used a Sterling BCDC charger as it has 9 settings built into it. I have a Tortech Inverter/Charger with multiple settings for the 240v side. I think the Enerdrive chargers can be custom programmed so that is worth looking at. Someone like EV Works can help you set the system up on the battery/BMS side. Obviously, size the cable to match the currents. I have used midi fuses as appropriate, as much better than the 2 pin fuses.
For my Winston cells I charge at 14.2v and float at 13.5v. The wiring is conventional. It is the BMS and charging that can be different to AGM/LA setups.
The BMS /relay is really an overlay over the 4 cells that are in series to cut the draw/charging off when thresholds are exceeded. I hope this makes sense. If not please call me on 0407976872.
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Thanks to PHILD.
That info is the first real usable info anyone has supplied or presented, even after reading the caravan forum reference in the next reply.
I guess much time and research has been done by Phil to arrive at a system which can be fitted by a skilled/competent person.

It is not that hard! I am an accountant, and can build a great system! You just need to know there is positive and negative, and current flows from its source to its destination, and how to size cables appropriately, crimp and solder properly, etc but practice makes perfect. If you fuse correctly, not much can go wrong.
Give it a go! If needed, I am happy to answer any questions.

.
No Phil, It is not like a cash flow, "flowing from its source to its destination".
Electric current flow is much better.... the electrons all come back to the source!

No wonder accountants and engineers never see eye-to-eye. lol

EDIT: Saturday, Oct 20. I'm uncertain of their sense of humour too!

I've just been reading on the caravaners forum, and I'm now concerned that perhaps I've made a rash decision that could come back and bite me;

Have a look at this video: https://www.facebook.com/enerdriverenewablepower/videos/254896411838752/?__tn__=%2CdkCH-R-R&eid=ARAzsAUDOZWvW8aMtj2mHZ5IJApevSPKogRw9g_fdtn2VCWsXr2N2qU_y6BLR4VMgYh5qar3j3qEhFfH&hc_ref=ARQwsDhkx4RxS-ynlrSymhfhKUmQMBm53D1nPEKWZRYglOb61_sa7mhdmb8N3AHadvI&fref=nf&hc_location=group

Roachie

Personally I avoided the drop in solutions for some of the reasons raised in the video. I went with built up batteries, 2X100Ah units that have cell balancers on each cell and the BMS that monitors all cells of both batteries. The isolation solenoid is rated 240A.

The video though is rather misleading, the BMS as pointed out will disconnect the batteries when they reach a critically low level, in my unit from memory is 10.5V, it is a last line of defence, if your running the batteries down to that level your asking for trouble, in a well designed system you will have a low voltage cut out installed that will isolate the batteries well before that level is reached.
Same applies for overvoltage, the BMS is a last line of defence, having another protection device would be a good idea.

Most good quality BMS's like the Victron units will also have overvoltage and under voltage alarms which can be used to trigger protection devices.

Thanks Roachie
Great info, makes sense , good on enerdrive for putting it out there.
Cheers
Robbo

My Zeva BMS cuts out at 11.4v, which is much more suited to my Winston cells.

To me the other issue here is the terminology used, most I believe if you mention BMS one thinks of something like a Victron or the Enerdrive Epro series of battery management systems that monitor current/voltage/wattage/SOC etc.

This not the case with Lithium BMS's, these systems as battery protection systems rather than battery management systems and are required to prevent catastrophic battery fail. They may also include cell balancing devices. These battery protection devices are the last line of defence to protect the battery and shouldn't be depended on for normal under and over voltage protection as they are not designed for this. All systems should have a separate under and over voltage protection devices that will operate before the batteries fail safes do.

The bottom line is if you intend to install a Lithium system yourself you need to do some research and find out what is actually required and how the systems operate. Don't take everything the suppliers say as gospel, do your own research. For instance one of the suppliers mentioned here insists that a cell balancing system must be installed to protect the battery, they also state that a charger set to GEL setting ie14.2V will be fine to charge the battery, funny thing is if you read up on their cell balancing system you'll find it requires a charge voltage of at least 14.6V from memory for it to be able to do its thing.

I have under and over voltage cut out using the Zeva board, and have monitoring of the voltage of the individual cells. They do not automatically rebalance, but in the past 4 years the cells have stayed perfectly balanced, so the extra electronics would be a wasted cost. This is with Winston cells.

Same here, three years no balance issues, the video from Enerdrive is rather vague, it implies they are having warranty issues due to the low voltage cutouts failing in their batteries, this appears to be caused by the cut outs operating at currents higher than the batteries rated current which they indicate rather vaguely was 100A for their 100Ah battery.

Now that's rather odd as if the battery is tripping due to low voltage and generally the low voltage cutout limit is very low way under what one would consider 0% SOC, how is the battery able to supply more than its rated current at such a low voltage?

They then allude to cell balance issues caused by the batteries being in parallel the cause of the problem. I and many others are running batteries in parallel and have no such issues?

It would therefore seem they have two issues:

1/ Cell balance issues in their batteries, maybe they need to look at the quality of their cells?

2/ Their low voltage cuts might not be up to the job. This would not surprise me, if you look at a built up 100Ah Lithium battery its physical size is around the same size as a equivalent AGM battery, the protection module on my batteries is rated at 240A and is around a third the size of one of the batteries, cramping suitable circuit into a drop in replacement type unit that can handle the currents involved would not be an easy thing to do.

They also imply other brands would have similar issue, do they? Personally I suspect that all similar looking units are probably made by the same company and branded as per the buyers requirements so maybe they are correct in that regard?

They then go on to say buy a bigger battery rather than two smaller ones, hmmm I wonder how much the bigger unit cost compared to the smaller ones and who's to say you won't get the same cell balance issues with the bigger battery? Also if you have two 100Ah batteries there is a reason for it as one 200Ah would cost less, you most likely have two batteries due to space constraints, at least that is why I have two batteries. Maybe they should have just been up front and advise customers buying two of their batteries that they don't work well together?

Also they then go on to say if you require higher capacity and load handling ability go for their larger battery or their system that uses built up batteries and separate control units. This again implies the BMS units in the smaller batteries and possibly cells aren't up to the job, but then as I have already written you shouldn't be relying on the batteries low voltage cutout for this function.

When I looked at the drop in solutions three years back I decided not to go that path though it would have been the more elegant and the simplest solution. My concerns were those now being raised by Enerdrive and I'm glad I went with built up battery packs and separate control units.

I'm also rather surprised that company that claims to have such a deep knowledge of Lithium batteries made no mention of not relying on the batteries protection device for normal day to day operation as that is not what it is intended for and most likely will fail if used as the only low voltage cutout. The company I purchased my batteries from made it very clear that the batteries protection system is the last line of defence and separate protection devices must be installed that operate prior to the batteries own device under normal conditions.

I had a quick look at an Enerdrive battery on Ebay and it doesn't appear to have any internal cell balancing system, if this is the case it is another good reason to steer clear of this type of battery as ceell balance issues will result in them being a rubbish bin job, though as I written above, my personal as yours is that good quality cells don't go out of balance.

Same here Allan, I will be looking to renew/replace in a couple of years as well.