LiFePO4 Batteries, B2B Chargers, and Smart Alternators - is a Li specific B2B necessary?

Feb 2, 2009
256
259
North West
Funster No
5,535
MH
Concorde
Exp
Quite a while.....though not long enough
Hi,

Our current 12v setup is 2x 170ah AGM Batteries, 700w Solar (via Victron 100/50 MPPT Reg), 3000 Mastervolt Invertor / Charger, and also a Votronic B2B to deal with the "Smart" Alternator charge when driving.

I'm wanting to swap out the 2 x AGM for a single 320ah LiFePO4. I'm confident all should be fine, apart from the wizardry that is the "Smart" Alternator, as the current Votronic B2B doesn't have the Li setting (which I was surprised about as its a late 2016 Van).

The identical B2B but with Li setting is going to set me back nie on £400 on top of the battery cost, and is likely a bottleneck to getting the LiFePO batteries as I can't justify that extra expense for what is an identical bit of kit save for the Li at the end of the model number.

Has anybody else a similar setup, running via a Smart Alternator, and if so was a Li specific B2B necessary or was it OK under "other" settings (AGM1, AGM2, Gel, Lead)?

It would be the TN Power 320ah LiFePo. The current B2B is the Votronic VCC 1212-45 IUoU.

Daft thing is, I suspect 99% of the time, the Battery would be fully charged from Solar before moving off, but I don't want to have any weak spots or be susceptible to issues.

Thanks in advance for any info.
 
Last edited:
Sep 29, 2019
1,625
3,741
Funster No
64,846
MH
Hymer Exsis
Exp
20 years
I wouldn’t risk a lithium battery without a specific profile designed for them. They are too expensive.

I would sell the old one and get yourself the proper one. That way it won’t be as big a hit.

Poor really and penny pinching not to fit the lithium compatible model.
 
Apr 3, 2018
1,455
3,192
Funster No
53,151
MH
PVC
Exp
1995-2004 & 2017》
wouldn’t risk a lithium battery without a specific profile designed for them. They are too expensive.
The blurb for the battery OP is looking at states that it can be charged with most standard lead acid battery chargers... so why not a B2B with lead settings...
More and more lithium batteries are becoming less reliable on what used to be foreseen as a very specific charging protocol.

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OP
Ian-n-Suzy
Feb 2, 2009
256
259
North West
Funster No
5,535
MH
Concorde
Exp
Quite a while.....though not long enough
Hi,

Thanks for your replies.

My thoughts exactly re the penny pinching.

Votronic have just replied to my email this morning (I only sent it last night, very prompt of them).

Two options, the first being to check with the manufacturer of the battery if it is OK with using one of the other charging characteristics (as per the above post).

The other, is to send them the serial number of my unit to see if there is a Lithium update possible for it.

So fingers crossed that's a possibility, though accessing it to find the serial number may be easier said than done.
 
May 7, 2016
4,433
6,059
West Sussex
Funster No
42,951
MH
Carthago Compactline
Exp
Since 2003
I have a Votronic VCC1212-45 which is only a little newer than yours which does have LiFePO4 settings. I am surprised they did not change the model number with such a significant upgrade. My switches look like this.
3476C397-4311-4B0A-8EAC-3CAD810217E8.jpeg
 

eddievanbitz

Trader - Funster
Oct 4, 2007
6,991
29,255
Taunton Somerset
Funster No
540
MH
RV
Exp
since 1989
Hi,

Our current 12v setup is 2x 170ah AGM Batteries, 700w Solar (via Victron 100/50 MPPT Reg), 3000 Mastervolt Invertor / Charger, and also a Votronic B2B to deal with the "Smart" Alternator charge when driving.

I'm wanting to swap out the 2 x AGM for a single 320ah LiFePO4. I'm confident all should be fine, apart from the wizardry that is the "Smart" Alternator, as the current Votronic B2B doesn't have the Li setting (which I was surprised about as its a late 2016 Van).

The identical B2B but with Li setting is going to set me back nie on £400 on top of the battery cost, and is likely a bottleneck to getting the LiFePO batteries as I can't justify that extra expense for what is an identical bit of kit save for the Li at the end of the model number.

Has anybody else a similar setup, running via a Smart Alternator, and if so was a Li specific B2B necessary or was it OK under "other" settings (AGM1, AGM2, Gel, Lead)?

It would be the TN Power 320ah LiFePo. The current B2B is the Votronic VCC 1212-45 IUoU.

Daft thing is, I suspect 99% of the time, the Battery would be fully charged from Solar before moving off, but I don't want to have any weak spots or be susceptible to issues.

Thanks in advance for any info.
My Alternator is 225amp and the factory fitted B2B was 160 amp, my van was ordered and built in 2018

When we installed the 2 x 120 Amp lithium's I was happy that the factory fitted B2B would be OK, everything connected up and the app showed the batteries charging at 110 amps

However, the batteries are not fully charged when they are delivered to us, and the camper was in the workshop so no solar.

The first time we used it in anger, we hammered the batteries, and it was an overcast weekend so little solar input even with 3 x 175w panels, not worried we started the engine with a three hour drive ahead of us confident that the 160amp B2B would have them fully charged on arrival.

Twenty minutes down the road we hit a traffic jam, I checked the app and the batteries were still about 30% capacity, which didn't make sense, but the more I thought about it it did!

The factory fitted B2B didn't have a Lithium profile, but it had worked when the batteries were low IN the workshop, now were were driving the solar panels were doing a little, but the B2B was "seeing" a voltage that would seem OK if they were conventional batteries. To test the theory I nipped into the back of the camper and plugged Lyn's hair dryer in. As soon as the inverter required 200 amps the voltage in the system dropped, the on board B2B recognised this and started to work.

A little bit more internet digging and it seems that Intellitec the B2B manufactures launched a 225 BIM Li in 2020 a direct swap out for the 160 BIM factory fitted as Lithium batteries become the norm in the RV market in the States

Lithium is fantastic, but to get the most out of what is an expensive purchase, it is really important that the Holy Trinity of On road charging, mains charging and Solar charging are correct.
 

eddievanbitz

Trader - Funster
Oct 4, 2007
6,991
29,255
Taunton Somerset
Funster No
540
MH
RV
Exp
since 1989
I wouldn’t risk a lithium battery without a specific profile designed for them. They are too expensive.

I would sell the old one and get yourself the proper one. That way it won’t be as big a hit.

Poor really and penny pinching not to fit the lithium compatible model.
To be fair a 2016 registered van, was the finished conversion, the components were most probably manufactured 2015 and Lithium wasn't on any main stream converters radar then as way too expensive.

NEC 2017 we showcased the Dometic Lithium power pack (as they called it) £2200 and it needed the BMS on top of that !
 
OP
Ian-n-Suzy
Feb 2, 2009
256
259
North West
Funster No
5,535
MH
Concorde
Exp
Quite a while.....though not long enough
Thanks for your input Eddie, much appreciated.

When you start digging, to create a system to get the very best out of the LiFePO4 would cost a small fortune (I'm unsure as of yet, as I've not been to the Van to check), but the EHU Charging is done via the Mastervolt Inverter/Charger, itself a very expensive bit of kit and until I check this may or may not have a Lithium charging setting. Unsure if this will also go through the B2B/.

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eddievanbitz

Trader - Funster
Oct 4, 2007
6,991
29,255
Taunton Somerset
Funster No
540
MH
RV
Exp
since 1989
Thanks for your input Eddie, much appreciated.

When you start digging, to create a system to get the very best out of the LiFePO4 would cost a small fortune (I'm unsure as of yet, as I've not been to the Van to check), but the EHU Charging is done via the Mastervolt Inverter/Charger, itself a very expensive bit of kit and until I check this may or may not have a Lithium charging setting. Unsure if this will also go through the B2B/

I'd be amazed if the Mastervolt didn't have a suitable Lithium profile, or, couldn't be programmed to the correct parameters. I assume that it is a Mass Combi unit which is a first class piece of kit.

The advice I always give is if you can afford it, do it, but do it properly.

My Victron inverter/charger is rarely off the auto mode which means that we always have hook up
 
Jan 19, 2014
4,598
14,130
south shields
Funster No
29,767
MH
Chausson 620 welcoome
Exp
since 1990
I'm like most and would prefere a charging source that was specific to the battery chemistry... but at the end of the day the charging of batteries comes down to the applied voltages...and crucially with lithium the time those voltages are applied for..
I'd check the charging voltage profiles of the battery types available ... chances are that you will be able to select one that will do..
Are any of the parameters on your current battery to battery configurable?
On my Stirling you can pretty well set voltages ant times to suit whatever you want..but its quite an involved process of button pressing..
The default lithium profile on mine really only differs from some of the lead acid charging profiles in the time the peak absorption voltage is applied...
Andy
 
Dec 19, 2020
414
827
The salty bit of Hampshire
Funster No
78,519
MH
Carthago Compactline
Exp
Since 2017
I don't have a B2B in my Moho as I don't have a smart alternator. Checking with KS Energy, they suggested that the on-board mains charger be set to Gel. I have turned the mains charger off as I didn't want it trickle charging the lithium battery and the solar + alternator pushes in 30+amps when driving, so I'm happy with that.
 
Sep 17, 2017
1,920
3,232
Birmingham, UK
Funster No
50,575
MH
A-Class
Exp
2017
So you can drop-in a Lithium battery and it's safe. But the issue is that Lithium has a high voltage through most of it's charge range. So anything that's set to charge lead-acid/gel/AGM battery profiles will think the battery is full and decrease the charge current, even if the lithium battery is still only 20% full.

My van was registered in 2020. I'm pretty sure it doesn't have lithium settings either. I've got a Victron solar controller, so it would eventually charge a lithium battery. But the alternator charge and hookup charge would take forever.
 
Jan 19, 2014
4,598
14,130
south shields
Funster No
29,767
MH
Chausson 620 welcoome
Exp
since 1990
So anything that's set to charge lead-acid/gel/AGM battery profiles will think the battery is full and decrease the charge current, even if the lithium battery is still only 20% full
No ..I dont think so.. if the voltage applied is high enough from the charging source the lithium will take a charge..and on most lead acid profiles it will be high enough..
The chargers don't know what chemistry battery they are dealing with.. just the voltages they have been selected to run at and times and voltage thresholds to cut off at..
Like yesterday ..my mains charger was supplying 20 amps.. its max output..
But the batteries were getting just over 30 amps.. the balance was from the solar as it was a fairly bright day.. if the solar could have supplied more the lithium batteries would have taken it till there voltage rose to about 14.4 volts..

That would be my take on it ..
Andy..

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Apr 27, 2016
3,867
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Since the 80s
I have turned the mains charger off as I didn't want it trickle charging the lithium battery and the solar + alternator pushes in 30+amps when driving, so I'm happy with that.
The idea of a trickle charge or float charge is that the charger applies a voltage that is very slightly higher than the battery voltage, so that there is a very small current flowing into it, to exactly compensate for any internal discharge. It's done because a lead-acid battery should be kept at 100% charge when not being used, to avoid sulphation. If the voltage is too low, no charge will flow into the battery. But no charge will flow out, because of the diodes in the charger.

A lithium battery generally has a higher voltage than lead-acid, so the trickle charge voltage for a lead-acid battery is a bit too low to put any charge into a lithium battery. Lithium batteries don't need to be trickle-charged, and have no need to be kept at 100% charge. If the charger only gets them to 90 or 95%, that's a bonus.
 
May 19, 2020
182
204
Funster No
70,901
MH
Knaus Sun Ti 650 MEG
Exp
Since 2020
I was wondering if with your current B2B set up as a 'best fit' for Lithium, once at a decent charge level,it could then be turned off, obviously you need some way of measuring the state of charge i.e a shunt as voltage measurement is useless with Lithium, however depending how your D+ devices are wired would it not then lead to further drain of the Lithium if your running your fridge etc on 12v whilst driving and it's supplied by the leisure battery
 
Sep 17, 2017
1,920
3,232
Birmingham, UK
Funster No
50,575
MH
A-Class
Exp
2017
I was wondering if with your current B2B set up as a 'best fit' for Lithium, once at a decent charge level,it could then be turned off, obviously you need some way of measuring the state of charge i.e a shunt as voltage measurement is useless with Lithium, however depending how your D+ devices are wired would it not then lead to further drain of the Lithium if your running your fridge etc on 12v whilst driving and it's supplied by the leisure battery
Just a voltage measurement allows you to estimate how full a lead-acid battery is because voltage has a reasonable relationship with charge. But it's useless for Lithium because the voltage remains almost the same until they are pretty much dead. Shunts can measure the current that has flowed through, so can estimate charge levels over time.

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eddievanbitz

Trader - Funster
Oct 4, 2007
6,991
29,255
Taunton Somerset
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540
MH
RV
Exp
since 1989
The reality is that "Lithium" can be made to work with a number of different devices, and the suppliers that say (with Caveats) direct replacement, drop straight in, etc, are, I believe, no different to the satellite TV traders that we (Van Bitz) would be next to when we used to do shows.

All weekend we would hear the question "Will that work in Spain" and the trader would answer "Yes mate, no problem" Two people talking but having different conversations

The question that should have been asked is "Will we get BB1 & ITV on that dome in Spain" and the answer then would have been "No" but yes, it will "work" Turn it on on the Moon and it would "work"

One of the major advantages of Lithium is that it can soak up charge like a Sponge, so if you have solar, make sure you have a lithium profile or buy a new one, no point it "working" but not to its full potential!

On road charging, a couple of Lithiums will charge at 100amps if you let them, connect this to a conventional "cheap nasty split charge relay" (they all are) with a skinny bit of wire with and it will be grossly inefficient, with the potential to burn out the split charge relay and or the associated skinny wire or it the wiring is man enough (so few are) it will pull the guts out of the Alternator

Just because somethings can be done it doesn't mean that it should!
 
Jan 28, 2008
8,532
13,105
walthamstow east london
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1,353
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renault burstner delphin
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7 years campers before that
I have a lipo battery and oaktree assured us its just drop in neither solar controller or charger have a lipo setting
Weve had zero problems in a year battery always shows 13 v or more only time will tell if there are any long term effects
 
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