Concerns over starter battery if left for a month

[Ingwe]

Have two 110ah Ecotree lithium leisure batteries in our 2012 Bailey Approach. Also have a Van Bitz battery master fitted. We are going away for a month but not in the van. The van is kept in storage in a secure hanger so the solar panel (120 watts) is inoperative.
I’m concerned that, over a month, despite the battery master, the vehicle battery may lose enough power so as to make starting difficult when we return. The leisure batteries will be charged to 100% before we leave and I know that lithium batteries discharge much slower than the starter battery. With the alarm being the only significant draw on the starter battery, am I right to be concerned?
I could leave the van on hook up but prefer not to.
Thanks in advance.

 

[ontheroadagain]

Yes, you are right. We have an alarm and tracker and our battery would be flat in 2-3 weeks. We do have solar which also charges the starter battery so not usually a problem for us. I would leave it on hook up.
Edit. Sorry I missed the bit where you also have a battery master. That should be sufficient for one month.

 

[David and Sally]

I reckon the battery master will look after the starter battery. That’s what it is designed to do. The lithium will not discharge much and when the starter battery drops to a certain voltage difference the BM will top it up.

 

[TinaLes]

If its in secure "Cassoa rated" storage, can you not just disconnect the starter battery when fully charged it should be OK with no load on it, same with the Lithium's, they will be fine.
Check with your insurance company of course, tell them what you propose doing in turning off the alarm/tracker, although that may have its own supply battery to cover that period.
LES

 

[funflair]

If I leave ours for a month in a similar "no solar" shed to you I trip the power supply from the Lithium to van electrics as they are the ones using power even when switched off, then the Battery Master still takes power from the Lithium and will last for months that way.

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[Otter Spotter]

Your battery master should keep cab battery topped up and not drain your 2 Hab batteries. Just make sure you don’t have your invertor set to standby, switch it off completely and anything else that isn’t needed.

 

[Ingwe]

Your battery master should keep cab battery topped up and not drain your 2 Hab batteries. Just make sure you don’t have your invertor set to standby, switch it off completely and anything else that isn’t needed.

I have no invertor fitted. I turn off the master switch always.

 

[Ingwe]

….. I trip the power supply from the Lithium to van electrics as they are the ones using power even when switched off

Not sure how I’d trip the power supply from the lithiums to the van electrics.

 

[bigtwin]

It is not recommended to leave LiFePO4 batteries at 100% SOC; they should be stored at <80%.

I thought that I’d read somewhere that a Battery Master was only effective with a Lead Acid setup; have I got that wrong?

Ian

 

[funflair]

Not sure how I’d trip the power supply from the lithiums to the van electrics.

You could try just shutting down the habitation electrics but on ours it still uses a fair few amps, we have a trip switch which isolates everything including habitation door access and the radio, yours will be different though.

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[funflair]

It is not recommended to leave LiFePO4 batteries at 100% SOC; they should be stored at <80%.

I thought that I’d read somewhere that a Battery Master was only effective with a Lead Acid setup; have I got that wrong?

Ian

Vanbitz say that the Battery Master is OK with Lithium and we and others have had no problems, Votronic and a couple of other specifically say it's a "no no", if you have no other external power source like solar it tends to keep the starter battery a little low but still OK for starting, yes you are right about the 100% so I let it run down to 80% which takes a few days and then I flick the trip.

 

[bigtwin]

I thought that I’d read somewhere that a Battery Master was only effective with a Lead Acid setup; have I got that wrong?

Just had a quick look at the bumf on the Vanbitz website and it says that it charges the starter battery if the starter battery voltage is 0.5V below the leisure battery voltage. On a lead acid setup, that makes sense since both batteries should have the same resting voltage.

If leisure batteries are LiFePO4 then their resting voltage will be circa 13.6V (0.8 V above the 12.8V resting voltage of a lead acid). That being the case, with a voltage delta above 0.5V, the Battery Master will be triggered 100% of the time. Using the same trigger parameter (i.e. 0.5V below leisure battery voltage) used for the LA BM, ideally a LiFePO4 specific Battery Master should trigger at 1.3V (0.5 + 0.8) below the LiFePO4 leisure battery voltage. Thoughts AshVanBitz ?

However, I’m not sure that having the BM active 100% of the time is actually a problem as having the LiFePO4 feeding the lead acid battery 100% of the time is exactly what narrowboaters (myself included) are doing with their LeFePO4/LA hybrid systems.

Ian

 

[Kannon Fodda]

120Ah lithium and Vanbitz Battery Master. Over the least sunny winter months, even with the van in the open and unused the 100W solar can give very little contribution. With the strikeback set, and in numpty schoolboy mode that some of the hab electrics were not completely turned off so parasitic drain from stuff like the radio (which is fed from hab not cab), after 6 weeks leisure down to about 30% from 100% start, and cab battery still good at 12.6V.

As Lithium tends to have a fairly flat voltage profile through it's discharge range, unlike lead-acid that drops voltage as it discharges, and Lithium generally operates 13.6V ish, the Battery Master can work well to keep the cab lead-acid type battery maintained for some time, especially as discharge of the lithium is not a problem.

Oh and I've never worried about the 80% storage on lithium. Indeed it's not that practical to achieve unless I'm going to keep going out and pulling wires from the solar.

 

[bigtwin]

Vanbitz say that the Battery Master is OK with Lithium and we and others have had no problems, Votronic and a couple of other specifically say it's a "no no", if you have no other external power source like solar it tends to keep the starter battery a little low but still OK for starting, yes you are right about the 100% so I let it run down to 80% which takes a few days and then I flick the trip.

Our posts crossed in the ether!

Ian

 

[bigtwin]

Oh and I've never worried about the 80% storage on lithium. Indeed it's not that practical to achieve unless I'm going to keep going out and pulling wires from the solar.

I simply isolate the charge input via the BMS but appreciate that not all BMSs offer that feature.

Ian

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[Kannon Fodda]

I simply isolate the charge input via the BMS but appreciate that not all BMSs offer that feature.

Ian

I can't make the app work to bluetooth connect into my battery - I've a separate thread on that somewhere - so for the last 3 years battery just left to do it's thing and state of charge monitored simply via a Victron Smartshunt.

 

[funflair]

Just had a quick look at the bumf on the Vanbitz website and it says that it charges the starter battery if the starter battery voltage is 0.5V below the leisure battery voltage. On a lead acid setup, that makes sense since both batteries should have the same resting voltage.

If leisure batteries are LiFePO4 then their resting voltage will be circa 13.6V (0.8 V above the 12.8V resting voltage of a lead acid). That being the case, with a voltage delta above 0.5V, the Battery Master will be triggered 100% of the time. Using the same trigger parameter (i.e. 0.5V below leisure battery voltage) used for the LA BM, ideally a LiFePO4 specific Battery Master should trigger at 1.3V (0.5 + 0.8) below the LiFePO4 leisure battery voltage. Thoughts AshVanBitz ?

However, I’m not sure that having the BM active 100% of the time is actually a problem as having the LiFePO4 feeding the lead acid battery 100% of the time is exactly what narrowboaters (myself included) are doing with their LeFePO4/LA hybrid systems.

Ian

I think it's more like 0.65v differential leisure to starter, our Lithiums will sit 13.3v -13.4v with no charge on them so it holds the starter a bit below fully charged voltage, if there is sun on the solar it will obviously run the starter battery higher but never a problem.

 

[steve69]

During lockdown my van stood on the driveway for 6 months. When it was finally possible to travel it started first time. No alarm or trackers though.

 

[Otter Spotter]

Why don’t you ask Ashvanbitz on Monday he will know the answer

 

[Otter Spotter]

During lockdown my van stood on the driveway for 6 months. When it was finally possible to travel it started first time. No alarm or trackers though.

That’s great but what set up do you have ?

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[steve69]

That’s great but what set up do you have ?

Elddis 115. 2010 model

 

[bigtwin]

I think it's more like 0.65v differential leisure to starter, our Lithiums will sit 13.3v -13.4v with no charge on them so it holds the starter a bit below fully charged voltage, if there is sun on the solar it will obviously run the starter battery higher but never a problem.

Perhaps, but that would still give a required trigger level of 1.15V (0.65 + 0.5) below as opposed to the current 0.5V below. But, as noted above, I’m not sure that it’s critical.

Ian

 

[Otter Spotter]

Elddis 115. 2010 model

I meant electrics

 

[steve69]

I meant electrics

No idea. I just put the key in and it goes. lol.

 

[Ingwe]

No idea. I just put the key in and it goes. lol.

I was talking to someone when thinking about getting the lithium batteries. I said we’d opted for the Ecotree batteries to which he replied “batteries? Don’t you want electricity?” I said “it is electricity, what do think the power is from a battery” to which he replied “battery power”.

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[frenchie46]

Slightly off topic, but I would never dream of going anywhere, car or MH, or leaving the MH for some time, without having my NOCO boost power pack with me. Not only has it got me out of trouble on several occasions but I've used it often to help others with a flat battery. It's remarkably small and stowable for something so powerful that can start vehicles several times on one charge (I don't have any ties to the company!). That said, it is not good for the life of a battery to allow it to discharge too low, so prevention is better than cure.

 

[Ingwe]

Slightly off topic, but I would never dream of going anywhere, car or MH, or leaving the MH for some time, without having my NOCO boost power pack with me. Not only has it got me out of trouble on several occasions but I've used it often to help others with a flat battery. It's remarkably small and stowable for something so powerful that can start vehicles several times on one charge (I don't have any ties to the company!). That said, it is not good for the life of a battery to allow it to discharge too low, so prevention is better than cure.

I have a NOCO booster pack. Luckily, never had cause to use it for my van but did start a friends car where the battery was reading 10v. I connected the NOCO to the battery for 10 minutes before starting, to get some charge into the battery.

 

[Wee Bold Davy]

I've had a Battery Master for almost 3 years and have always believed that the only way the starter battery will receive a charge from the habitation battery is if the hab battery has excess charge from solar or Ehu which is why I connect the ehu for a day every 2 or 3 weeks during the winter when the solar panel contributes very little .

 

[funflair]

I've had a Battery Master for almost 3 years and have always believed that the only way the starter battery will receive a charge from the habitation battery is if the hab battery has excess charge from solar or Ehu which is why I connect the ehu for a day every 2 or 3 weeks during the winter when the solar panel contributes very little .

That would be true with the Votronic and CBE units and a few others that require 13.6v as the trigger voltage, but not the vanbitz that works on a differential in voltages.

 

[Scubagas]

I am going to fit a battery master after reading this thread. I have a 2015 bailey Approach 540. can anyone tell me where the split charge relay is located please? It appears to be the simplest place to install the battery master so as not to run long cables everywhere

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