Long Term Storage of Lithium Batteries (1 Viewer)

Oct 26, 2013
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In the past few days I have been on a steep learning curve as I investigate the new kit needed for a planned Roamer seatbase 230Ah install. When chatting with Roamer they recommend charging between 30% and 80% of capacity and then isolating from loads and chargers completely when not using the MH for longer periods. I plan on upgrading my Schaudt solar regulator to a Votronic 1715 Solar-Regulator MPP 250 Duo Dig since this has a specific LiFePO main charge setting at 14.2v and will connect via the EBL using the same cable set which I used for the Schaudt. This regulator also trickle charges the starter battery which is great in the winter months.

Can someone recommend the best way to isolate the leisure lithium battery from the solar regulator (to avoid charging the battery over 80%) whilst still being able to trickle charge the starter battery? For example, is there a fuse on the EBL or Solar regulator that I can remove?
 

bigtwin

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Can’t you isolate the charge source using the internal BMS (via blue tooth)?
You can with those from Life batteries.

Ian
 

MisterB

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enough to know i shouldnt touch things i know nothing about ....
I thought all lithiums had a BMS so you can set them as you wanted, to prevent under and over charging?
 

gerry mcg

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With A Victron MPPT, one can deactivate the MPPT via the victron app and switch off the solar charging

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Hoovie

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I thought all lithiums had a BMS so you can set them as you wanted, to prevent under and over charging?
It would be very unusual to buy an off-the-shelf Lithium Battery with a user configurable BMS that you can 'set as you want'. Just picture the discussions between seller and customer when anyone could set a battery as they think best!
 

Hoovie

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With A Victron MPPT, one can deactivate the MPPT via the victron app and switch off the solar charging
That will stop the trickle charger working though.

Or you could put one of these between the +ive MPPT output and the leisure battery
It is unlikely he can fit that and have the trickle charger still working . It is possible but would need the wiring already in a fairly unusual way and have a controller that doesn't need a connected battery to work (quite a few stop working when they don't detect a connected battery.
 
Apr 3, 2018
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Pebble99 .. that is exactly the set up I have, with an isolator to isolate solar from battery's (unfortunately starter battery as well), however why not fit a Battery Master to keep your starter battery topped up from your lithium battery, then if required turn solar back on when lithium needs a boost,
Just a thought.!

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Dec 17, 2016
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I have a Roamer and a Votronic duo. I have a fuse on the positive from the solar panel that I can pull to stop the lithium charging above 80% but as mentioned above it also means that the SB doesn't get a charge. Periodically I put the fuse back in to give both a top up. It's easy for me to do as it sits on the drive. I generally don't have the B2B on when I return home from a trip so the lithium is only partly charged. To to be honest I don't think that it matters that much as I use the van regularly so the lithium is always active even if it's only small loads being applied.
 

gerry mcg

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But he does not have a Vlctron.. He has a Votronic!
No the OP Doesn't.
In the OP, he says
I plan on upgrading my Schaudt solar regulator to a Votronic 1715 Solar-Regulator MPP 250 Duo
The statement on how the victron MPPT works was for information only in case this influenced his purchase decision.
Pebble99 .. however why not fit a Battery Master to keep your starter battery topped up from your lithium battery,
I have previously suggested this as any option to the OP
 
Apr 3, 2018
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Ok gerry mcg point taken.. However still does not help him... his question was how to disconnect solar to hab battery and maintain trickle charge to starter battery... reading your reply even a victron cannot do that.
Please indicate where you suggested a Battery Master to OP.?
 
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Pebble99
Oct 26, 2013
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Thanks all. I wanted to try and avoid buying more kit and making the installation more complicated but it looks like a battery master is the way to go so I will look into this. I have actually ordered the Votronic regulator from Gridtec in Germany along with a Votronic 50A B2B but stupidly forgot about the import duty and tax so may (no one sells the Votronic MPP 250 duo in the UK at the moment). I will try and cancel the order today and rethink things.

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MisterB

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Thanks all. I wanted to try and avoid buying more kit and making the installation more complicated but it looks like a battery master is the way to go so I will look into this. I have actually ordered the Votronic regulator from Gridtec in Germany along with a Votronic 50A B2B but stupidly forgot about the import duty and tax so may (no one sells the Votronic MPP 250 duo in the UK at the moment). I will try and cancel the order today and rethink things.
I am also looking to buy a 250 duo, but will now wait until next year and buy one when we go over to mainland Europe. I asked Votronic for details of their 'sellers' in France, so I will try to place an order before I travel.
You are allowed to import goods up to a certain value PLUS claim back the VAT paid in France - though you only get back around 12% I understand.
 

funflair

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When our van is not being used it goes in a shed without power or sun, I isolate the batteries to prevent over discharge but the solar is still connected so yes if it was outside the batteries would still get charged, as I have a Victron solar regulator I imagine it would be possible to set up a charge profile on the Victron connect app that would hold the LiFePO4's at say 70% charge, I then also have a battery master to trickle charge the starter battery.
 
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Pebble99
Oct 26, 2013
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One thing that might work is removing the EBL99 15A Solar fuse at the front panel which will stop the leisure battery being charged, since I intend to connect the Votronic MPP 250 via the EBL using a dedicated cable set. The starter batter is trickle charged directly from the Votronic MPP and does not go through the EBL.
 

gerry mcg

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The battery Master works very well with lead acid starter and leisure batteries as the voltage between the two is similar.
Many of us had battery Master fitted as part of a typical lead starter / leisure setup. And we have successfully carried it over to a lead starter / lithium leisure setup.

The theoretical problem with the battery Master is the starter trickle charge is initiated when there is a small difference between the voltage of the starter and leisure batteries.

The issue with lithium battery is the standing voltage of something like 13.4v is >> than standing voltage of the lead acid starter battery 12.4-12.7v, therefore there is an outside risk the leisure battery could be fully depleted over an extended time by the 1a parasitic draw of the starter battery.

That said, I've not experienced any issues

There is another product on my market (I can't remember it's name) that works in a similar fashion to the vanbitz battery Master but is configurable for lithium voltages
 

Hoovie

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Ok gerry mcg point taken.. However still does not help him... his question was how to disconnect solar to hab battery and maintain trickle charge to starter battery... reading your reply even a victron cannot do that.
Please indicate where you suggested a Battery Master to OP.?
On this point, and to expand further ....

It IS actually very possible (and quite simple) to use a Victron MPPT controller with a Load output to trickle-charge a Starter Battery even when the Leisure Battery is disconnected. :)
What you do is get your battery maintainer of choice (I use the superior Ablemail AMT12-2 for this purpose although I know there is a Battery Master obsession on this forum) and instead of connecting between the Leisure and Starter batteries, you connect it between the Solar LOAD and Starter battery.
You then set the LOAD output of the Victron MPPT to be "always on".
What will happen then is that when in normal operation with the Leisure battery connected, the battery maintainer will work just like it was connected in the conventional manner, but if the Leisure battery was disconnected for any reason the battery maintainer would operate only whilst the solar was getting power from the panels.
A Victron MPPT does not need a battery connection to actually operate - without a battery connected it works essentially and automatically as a power supply, which actually makes it emminantly suitable for the kind of purpose the OP is looking for ... Low current starter battery maintenance when in storage and only in daylight hours.
If you desire to stop the trickle to the Starter battery you can just turn off the LOAD output.

The reason why you don't connect the LOAD directly to the Starter battery is it is not current regulated and if the Starter is low and the Leisure is connected you could easily exceed the permitted current and shut the controller output down. It won't damage it but it is better to design a setup that prevents a fault IMO which is why I use an AMT12-2 Battery Maintainer between the MPPT and Starter.

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gerry mcg

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(I use the superior Ablemail AMT12-2 for this purpose although I know there is a Battery Master obsession on this forum)

Thanks, that was the one I was thinking of.
As I said above, I think many of us (myself included) have VanBitz Battery Master fitted as a legacy from lead acid starter and leisure batteries.
It works well enough with lithium to not bother replacing it, but I might have considered the Ablemail AMT12-2 if starting from scratch now with lithium leisure
 
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Pebble99
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I believe roadpro are uk Votronic distributers
https://www.roadpro.co.uk/product/0...ery-charger-vcc-1212-50-marin-c85066m/C85066M
and
Thanks. They have been out of stock for months and funny enough just checked this morning and they are back in stock. Just now need to decide whether I change plan and go with the Victron and Ablemail approach.
 
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Pebble99
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Thanks, that was the one I was thinking of.
As I said above, I think many of us (myself included) have VanBitz Battery Master fitted as a legacy from lead acid starter and leisure batteries.
It works well enough with lithium to not bother replacing it, but I might have considered the Ablemail AMT12-2 if starting from scratch now with lithium leisure
I have just reviewed the Ablemail AMT12-2 specs and looks a good product. If I went with the Votronic MPP 250 with the Ablemail I wouldn't connect the starter connection from the Votronic and rely only on the Ablemail to trickle charge the starter battery. When parked up for long term, I could pull the solar fuse on the EBL (or install a switch on the +ve to leisure battery) and as the current draw from the leisure to starter is only 1Ah drain every 20 days, I also don't need to worry about the additional "cycles" on the lithium. Is my understanding correct.
 

bigtwin

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I have a fuse on the positive from the solar panel that I can pull to stop the lithium charging above 80% but as mentioned above it also means that the SB doesn't get a charge.

Can you not just adjust the BMS setting to isolate the charge source at 80%? Then there is no manual intervention required.

Ian

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gerry mcg

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FYI, I've a Ks-energy 205Ah underseat battery and told the best of my knowledge I can't adjust the SOC cutoff
 

RedFrame

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It would be very unusual to buy an off-the-shelf Lithium Battery with a user configurable BMS that you can 'set as you want'. Just picture the discussions between seller and customer when anyone could set a battery as they think best!
Screenshot_20221024-104537_SMART BMS.jpg

Screenshot_20221024-104524_SMART BMS.jpg


Not that I'd want to mess around with them !

Cheers
Red
 

Hoovie

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Not that I'd want to mess around with them !

Cheers
Red
And THAT is why is is very unusual to allow a customer access to the settings! They'll be watching Youtube Andy from the Off-grid Garage and start ****ing around with the settings, end up with a setup that doesn't work properly anymore and of course it will be the fault of the battery supplier naturally ;)

Retail Battery makers actually put effort into STOPPING customers changing parameters, not just shipping out a battery with an open BMS!
 

Hoovie

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I have just reviewed the Ablemail AMT12-2 specs and looks a good product. If I went with the Votronic MPP 250 with the Ablemail I wouldn't connect the starter connection from the Votronic and rely only on the Ablemail to trickle charge the starter battery. When parked up for long term, I could pull the solar fuse on the EBL (or install a switch on the +ve to leisure battery) and as the current draw from the leisure to starter is only 1Ah drain every 20 days, I also don't need to worry about the additional "cycles" on the lithium. Is my understanding correct.
The advantage of devices like the Battery Master or Ablemail (more suitable for Lithium) is they will work with any charge source, unlike the Dual Battery Solar Controllers which if there is no solar provide no starter trickle.
As an aside, I fitted an AMT12-2 alongside a Victron 75/15 last month, replacing a Truma Duo Solar Controller. The owner of the van was into monitoring the voltages and found the Starter Battery was actually being maintained at too high a level by the Truma!
The AMT12 is not just a dumb trickle charger, but it actually monitors the voltages of both Leisure and Starter Batteries and will stop and start its operation depending on what they are (as one example of this monitoring, it will stop trickle when Starter is at 12.8V - or 12.4V if a Smart Alternator vehicle)
 
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Pebble99
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The advantage of devices like the Battery Master or Ablemail (more suitable for Lithium) is they will work with any charge source, unlike the Dual Battery Solar Controllers which if there is no solar provide no starter trickle.
As an aside, I fitted an AMT12-2 alongside a Victron 75/15 last month, replacing a Truma Duo Solar Controller. The owner of the van was into monitoring the voltages and found the Starter Battery was actually being maintained at too high a level by the Truma!
The AMT12 is not just a dumb trickle charger, but it actually monitors the voltages of both Leisure and Starter Batteries and will stop and start its operation depending on what they are (as one example of this monitoring, it will stop trickle when Starter is at 12.8V - or 12.4V if a Smart Alternator vehicle)
The Ablemail does look a decent bit of kit. My EBL99 also trickle charges the starter battery when on EHU. I probably won't buy a new mains charger even though the EBL doesn't have a lithium setting since I won't be using EHU that much. If I end up installing the Ablemail trickle charger, I will need to whether I need to disable the EHU trickle charge from the EBL and also from the Votronic B2B.

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