Ecotree Lithium Install

[Mrjenben]

Depends, theoretically can max out the bms. How much flow? Depends on wire resistance path. If resistance path is low, current will flow until bms or alternator maxed out. If wire will limit based on output voltage, ( no regen braking), a lower current will make it to the battery. What you don’t have, is a charger to call it quits when full. The alternator does not know when it’s full, it will trickle if voltage is held high.
LiFePo4 can fully charge even at 13,6v, it’s just a longer process. The 14,4-14-6v it’s just spending up the bulk rate pushing more amps in a shorter time span.

Yep I get the theory. My worry is the max charge current as my van has reasonably good and short cable runs:-(

Regarding the B2B recognising a full battery, surely the charge profile means they will go into absorption mode and will hold the battery at 14.2 for several hours anyway (Victron state 2 hrs for their B2B on lithium) ? So for most reasonable journeys it’s never going to do anything the alternator wouldn’t do on its own?

 

[Mrjenben]

You have a Hymer Exsis, the cables on the charge circuit are 16mm sq and it is a very short cable run between the starter and the leisure battery without a B2B you will easily exceed 55 amps, I've seen 45 amps into Gel batteries on an Exsis, the Lithium has a much lower internal resistance so is cabable of drawing much more current.

You also stand a high chance of burning out the wiring & relay in the EBL.

Lenny

Thats really useful info thanks. I already appreciated the excellence (!) of Hymers build quality but hadn’t got the real world experience of what charge rate that would result in.

You‘ve got me thinking now. Do I cave in and fit a B2B now or do I give it a go and stand by with the fire extinguisher

 

[Raul]

You could try and let us now if you like. Take note what Lenny posted as well. I’m not familiar with your van in particular, but Lenny knows.

 

[Mrjenben]

If it helps, I have the same model Motorhome and there is a thread in my signature about how I installed 2 Ecotree lithium.

I couldn’t be happier with them.

If you do decide to go a B2B, it was a very simple 30 minute job to put the Votronic 30amp one in.

Just don’t buy jump leads for cable.

Thanks. I saw your thread a while ago + it’s was very helpful. If I do cave in and go for a B2B I’ll probably get a higher capacity one and wire it in direct to the batteries rather than via the EBL though. Might as well make the most of it

 

[Raul]

I give you a clue to: I have a 30A dc-dc converter set as B2B with output at 13,55v dead. When the battery is partially discharged, 60-80% ish, with 4m run 10mm2, it pushes 28-29 amps into the leisure battery. The lithium is capable of absorbing good currents even on a small voltage difference, even 0,05v.

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[Mrjenben]

Install completed for now I’ve also switched the solar regulator to AGM/gel setting as advised by Ecotree.

Just need to do some testing now and see whether I need to open the safe and release some more funds for a B2B!

BTW Thanks to Lenny HB and Raul for their info. It’s made me do some more digging and realise it’s not as clear cut as I hoped!

 

[Jimbohorlicks]

Very nice and tidy and looking good so far.
Can't wait untill I recieve mine and install. All comments taken into account but the real truth will come out in the running of the batteries especially for a week off grid. Your install is also close to your heating conduit so should keep the battery in a warmer environment during colder weather.

 

[Mrjenben]

Been out to do some testing again. EBL charging fine and no issues with starter or hab batteries.

Also tried the engine alternator charger to get some comparison for when I put the B2B in tomorrow. It is a standard Hymer setup.

Initially chucked out 32 amps which then settled to 21 amps into the battery a few seconds later. Not bad for a standard setup. However, I then put the fridge on and was surprised to see it drop to 17 amps. This was consistent on idle or holding steady at 2500rpm.

Even with a 30 amp B2B you can nearly double the charge going in. Will be interesting to see the results once the B2B is wired in tomorrow.

Googlebot - just been going back over your thread and realised you’d already tried out the lithiums without a B2B and it worked ok! Fantastic info. Looks like I might be ok after all

Van currently sat with every 12v load I can find on. Might take a while to get to a low enough level to try out the alternator. Fire extinguisher at hand just in case

 

[Jimbohorlicks]

You just need to try it in sunshine now ,off your solar.

 

[Googlebot]

Googlebot - just been going back over your thread and realised you’d already tried out the lithiums without a B2B and it worked ok! Fantastic info. Looks like I might be ok after all

Van currently sat with every 12v load I can find on. Might take a while to get to a low enough level to try out the alternator. Fire extinguisher at hand just in case

I did try it briefly but it was literally, turn it on and see what happened, then turn it off.

I would make sure the shunt is fitted first so you can keep an eye on things.

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[Mrjenben]

Time to start playing

For this first trial the battery has been discharged to 80% (that took a while!)

The Smartshunt settings have been updated to the Ecotree advised values

So engine on, fire extinguisher handy..

Maximum charge current of 26.4 amps. No smoke. Phew!

Next let’s try the mains charger.

Max charge current 15.7 amps. Still no

Done for today. Next test will be a deeper discharge then full recharge. I’m not sure of the impact of a fuller discharge as I understand the resistance of lithium stays pretty constant?
Anyway it’s looking OK so far.

 

[Jimbohorlicks]

I assume the bottom axis is a timeline?

 

[Mrjenben]

I assume the bottom axis is a timeline?

Yep. it shows time of day.
For this first test I just let the current stabilise to establish a maximum and then turned off the charge. The graph was just an easy way to show the max current and voltage (near the left axis, just before the charge was halted. Ignore the rest of it).
Next I’ll discharge further and then do a full charge to ensure everything is ok.

 

[Raul]

Next test, see what the alternator does on a fairly full, or full battery. And note at what voltage the current stops flowing.

 

[Mrjenben]

Next test, see what the alternator does on a fairly full, or full battery. And note at what voltage the current stops flowing.

Will do

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[diddydave]

Yep I’ve seen that before. I don’t think it’s a fair example though. Their alternator is spinning quite slowly. The one on the van is effectively geared by the size of the pulleys so will be spinning faster than this even at tickover and therefore pulling more cooling air through. Also the van wiring adds to the resistance so I don’t think I’m ever going to see anything like 90 amps - and if I did the split charge relay in the EBL will go up first!

I haven’t see a real world example having these problems - and I have searched a bit However, I’m prepared to be wrong - we’ll soon see!

Victron have a video on YouTube bench testing two types of alternators and one goes up in smoke- can’t remember all the details of the test

 

[Tombola]

Victron have a video on YouTube bench testing two types of alternators and one goes up in smoke- can’t remember all the details of the test

see post 8 in this thread. but alos a good point made by a member about the pulley sizes

 

[jongood]

Interesting. I understand the standard lithium charge profile. You’re saying the issue is overcharging? Is that a theoretical or real problem. My 110Ah battery is good for 0.5c (55A). Do you think I will exceed that without a B2B?

Can I ask why you re resisting the B2B route?

Time to start playing

For this first trial the battery has been discharged to 80% (that took a while!)

The Smartshunt settings have been updated to the Ecotree advised values

View attachment 587822


So engine on, fire extinguisher handy..


View attachment 587823

Maximum charge current of 26.4 amps. No smoke. Phew!

Next let’s try the mains charger.

View attachment 587825

Max charge current 15.7 amps. Still no

Done for today. Next test will be a deeper discharge then full recharge. I’m not sure of the impact of a fuller discharge as I understand the resistance of lithium stays pretty constant?
Anyway it’s looking OK so far.

I'm not understanding the resistance to fitting a B2B, IMHO its £200 ish well spent for peace of mind.

You ve got charging potential from 3 sources all of which can vary through a fairly wide range, how can you hope to replicate any possible scenario? At least a B2B will make the dumbest one behave.

 

[Mrjenben]

Victron have a video on YouTube bench testing two types of alternators and one goes up in smoke- can’t remember all the details of the test

Thanks. That’s the example being discussed. As per my reply which you quoted - In real life, because of the size of the drive pulleys, the alternator will always be spinning much faster than in their example and will therefore be cooling itself.

 

[Mrjenben]

Can I ask why you re resisting the B2B route?

Im not really resistant to fitting one if I need it. But there are a couple of reasons I think it’s worth trying without—

1. I haven’t heard an good argument backed by real experience as to why I need one given the way I use my van. As far as I can see, unless you need ultra fast charging and have a smart alternator or poor wiring then a B2B seems to give very llittle benefit

2. I think there are a lot of people who will be interested in seeing a practical example of a simple install - most posts go the whole hog straight away.

Regarding the tests. I’m not trying to replicate all of the possible conditions. I fully understand the charge profile of all 3 sources when using lead acid but I want to do a safety check around the implications of the different resistance/impedance of the lithium. The smoke references are a bit tongue in cheek

BTW both Lenny HB and Raul have raised some very interesting practical points that I wanted to check.

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[Jimbohorlicks]

I suppose if you were moving daily and just stopping overnight and then moving on to your next stop ,then a b2b might be useful.We usually stay on a site for a few days and rely on the solar to top up our batteries.we have a couple of weeks off grid coming up after Easter so when we receive our lithium we can put that to the test for off grid with solar only

 

[Raul]

Also, is worth fittings swich to the B2B if you wish to go that route. If you have full battery and move off, it’s no point in having B2B active.
This a personal choice anyways.

 

[paddymcc]

Can I ask why you re resisting the B2B route?

I'm not understanding the resistance to fitting a B2B, IMHO its £200 ish well spent for peace of mind.

You ve got charging potential from 3 sources all of which can vary through a fairly wide range, how can you hope to replicate any possible scenario? At least a B2B will make the dumbest one behave.

I agree, especially for peace of mind when fitting a battery costing about£1000 it makes sense to look after it. We tend to move on every few days so it makes even more sense. If we stay longer it's likely to be in the summer when solar is hopefully available.

 

[paddymcc]

Also, is worth fittings swich to the B2B if you wish to go that route. If you have full battery and move off, it’s no point in having B2B active.
This a personal choice anyways.

I'm aware that sometimes when coming home I might want to disable the B2B when the battery is about 60% full - for example if I'm planning not to use the van for a while. Would a switch on the D+signal to the Votronic B2B do the trick or will I need it on the feed from the starter battery to the B2B?

 

[Mrjenben]

I'm aware that sometimes when coming home I might want to disable the B2B when the battery is about 60% full - for example if I'm planning not to use the van for a while. Would a switch on the D+signal to the Votronic B2B do the trick or will I need it on the feed from the starter battery to the B2B?

The D+ should work but you will need to check the setup as they can be used in voltage sensing mode too. A remote control is also available.

However I think you’re overthinking it. Yes theoretically to get max life you don't leave the battery fully charged. But if the battery is good for 5000 cycles then even losing 10% due to this means you still have 12 years of life if you cycle it every day!

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[stevewagner]

I got my Lifepos from Sterling and their 5 year warranty is only valid if you fit a B2B. I already had a B2B so it wasn’t a sales ploy.

 

[Mrjenben]

I got my Lifepos from Sterling and their 5 year warranty is only valid if you fit a B2B. I already had a B2B so it wasn’t a sales ploy.

Maybe not for you, but it’s a general warranty and they do make and sell B2Bs

Ecotree, KS and many others give 6 or 7year warranties without a B2B.

The whole market is moving very quickly, and the increasing experience and the improving functions of the onboard BMS’s are changing everyone’s views on what’s needed.

 

[Raul]

I'm aware that sometimes when coming home I might want to disable the B2B when the battery is about 60% full - for example if I'm planning not to use the van for a while. Would a switch on the D+signal to the Votronic B2B do the trick or will I need it on the feed from the starter battery to the B2B?

low power switch on signal. If no signal present, stays off.

 

[paddymcc]

The D+ should work but you will need to check the setup as they can be used in voltage sensing mode too. A remote control is also available.

However I think you’re overthinking it. Yes theoretically to get max life you don't leave the battery fully charged. But if the battery is good for 5000 cycles then even losing 10% due to this means you still have 12 years of life if you cycle it every day!

I've connected it using D+ with no wires going to the voltage sensing terminals on the B2B so I guess it should work. I may email Votronic to get their take on it.
I take your point regarding life cycles of the lithium - it will hopefully outlive me.

 

[jongood]

Im not really resistant to fitting one if I need it. But there are a couple of reasons I think it’s worth trying without—

1. I haven’t heard an good argument backed by real experience as to why I need one given the way I use my van. As far as I can see, unless you need ultra fast charging and have a smart alternator or poor wiring then a B2B seems to give very llittle benefit

2. I think there are a lot of people who will be interested in seeing a practical example of a simple install - most posts go the whole hog straight away.

Regarding the tests. I’m not trying to replicate all of the possible conditions. I fully understand the charge profile of all 3 sources when using lead acid but I want to do a safety check around the implications of the different resistance/impedance of the lithium. The smoke references are a bit tongue in cheek

BTW both Lenny HB and Raul have raised some very interesting practical points that I wanted to check.

Indeed and just for clarity, I'm not having a dig, just trying to understand the thought process, this being a route I may well go when I can source the batteries I want.

In my case I have two alternators, a 24v one for the vehicle and a separate 12v one just for the leisure side. My concern would be that if I was in a sunny place my PV setup could have totally charged the battery bank, then I start the engine and ive straight away got 50+ additional amps going into them until the alternator realises they re full?

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