MichaelT
LIFE MEMBER
Just for clarity the B2B charger goes between the normal engine battery and the Lithium(s) and the normal charging from the alternator is somehow disconnected?
Lithium vs Lead Acid. Some Facts !
- Thread starter PhilandMena
- Start date
If you buy a B2B with a profile to match your Li battery you may not need to worry about the mains charger. I haven’t. You will always arrive on site with a full battery and if you are on a hook up it only needs to supply a maintenance voltage. Unlike lead acid, Li batteries come to no harm from a little under charging. I know nothing of Nordelettronica chargers but if it has an AGM or Gel setting it should be ok.
I have a Votronic VCC1212-45 B2B which has 3 different LiFePO4 charging profiles to suit most makes of Li including Victron(14.2V), Exide(14.4V) and Relion(14.6V).
SteveJulesMontycame2
Free Member
That’s a good point; in theory the batteries should be/would be charged on arrival, unless a really short drive. But what about when/if they’re still only half charged and the Nordelettronica is powered up on mains? I don’t understand the science enough - will the charger that has a max output of 18A only pump out 18 A until it senses the batteries are full then change to maintenance charge, or will it overheat and think it’s been short circuited if the batteries are asking for more? Also, I would be worried that the Nordelettronica unit will overheat anyway after prolonged duration charging at full chat, because it will be putting more in than it would be with AGMs.
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Jim
Ringleader
The 14.4V Gel setting should be fine. This is the advice Relion give:
RELiON LiFePO4 Battery Frequently Asked Questions | RELiON
Do you have questions about RELiON LiFePO4 batteries? Let us help you get the right answers.
relionbattery.com
As I understand it the charger will deliver 18A at 14.4V until the Li reaches 14.4V by which time the flow of current will have dropped to next to nothing. At some stage thereafter it should drop back to the 13.8V maintenance charge. All pretty much the same as with lead acid. The Li does not suck the power from the charger, it just takes whatever it is sent.
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DBK
LIFE MEMBER
Yes, any split charging system, which effectively joins the vehicle and leisure batteries together to the alternator must be disconnected as the B2B runs with the two sets of batteries running at different voltages. This won't be possible if a split charger connects them together.
- Feb 8, 2014
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Surely this video test was a total waste of time. It only shows how to totally destroy any non lithium battery discharged to 10.5 Volts that has no BMS protecting devices that we all have by not allowing any discharge below 11.7 volts? However I am seriously impressed with lithiums performance and the claim that a single 100amp lithium battery could possibly equal the output of 2 x 100amp lead acid batteries.
If my 2 x 100 lead acid leasure bats were to pack up and if claims are to believed I would consider one lithium 100amp at a quarter of the weight and go for eddievanbitz 's 10% off
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my 2 x 110ah lead acids packed up in Spain recently so i replaced with a LiFePO4 100ah with Bluetooth realtime SOC, Volts and Amps. Also with beefed up cabling alternator to split on Euro 4. Very happy with enhanced charging.
This article was very useful against large scale propaganda and misinformation. (and vested interest and prejudice)
R
This article was very useful against large scale propaganda and misinformation. (and vested interest and prejudice)
B2B, Battery to Battery chargers : Fast, Safe Motorhome Alternator charging
Euro 6 compliant Battery to Battery chargers for modern Motorhomes. Faster Habitation Battery charging that works in harmony with the existing wiring. Does not degrade the battery. Finally a solution to that can make a Hymer fully optimised for AGM batteries.
www.aandncaravanservices.co.uk
R
eddie
LIFE MEMBER
Equally the author was known for spouting off about things then admitting he knew nothing about the subject matter when Jim called him on it, Also was known to post as a woman to start arguments and when called out and proven wrong would dismiss it as a simple mistake
Talking nonsense about the Van Bitz Battery Master that i designed for example
Whilst I don’t doubt that putting in some decent sized cables would improve charging in some motorhomes I don’t think it resolves all the issues.
My previous motorhome was a Hymer with good wiring but it did have a smart alternator. The engine battery was quickly recharged so the alternator voltage dropped off to a trickle level, leaving the leisure battery undercharged and that is how it stayed. My B2B cured it.
There are recognised disadvantages in mixing different battery types in one bank but if the engine and leisure battery are of different types this is what happens when a simple relay links them for charging. A B2B makes sure the leisure battery gets the voltage and charge that suits it and the ECU looks after the engine battery. The matter is probably even more of an issue with a LiFePO4 leisure battery where the B2B protects the battery and the alternator from each other.
For me undercharging a LiFePO4 is only an issue when I am going off grid because I want to arrive at my camping spot with it fully charged. If I am using an ehu a bit of undercharging doesn’t inconvenience me or damage the battery.
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DBK
LIFE MEMBER
The phrase "snake oil" springs to mind when I read that. As has already been said, but is worth repeating, if the cab and vehicle batteries are exposed to the same voltage the only way to quickly charge depleted leisure batteries is to expose the vehicle battery, which is likely to be more or less fully charged, to an excessive voltage, risking frying it. This is what a B2B avoids.
This guy, although no doubt well-intentioned, seems to have strong views without much solid facts to back it up. He makes the point that the alternator to starter battery wire is often inadequately thick, and even a very small voltage drop along it will affect the charging effectiveness. Beefed-up cables and a heavy-duty relay will often make a huge difference, so sometimes a B2B is not needed at all.
However it seems to me that the Schaudt B2B is practically identical in function to a Victron or Sterling B2B, yet he puts the Schaudt forward as the solution to all the problems and disparages all the others.
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SteveJulesMontycame2
Free Member
That article makes interesting reading and andncaravanservices seem to know there stuff on lead acid batteries. But they’re certainly not singing along from the same hymn sheet as the motorhome fun crew on this topic.
This is a matter of science, not emotion, where I’m looking for facts and data on which to base a decision. Science debunked the witch doctors. There is nothing wrong with a challenge when data can speak for itself. Just it seems there is not much data out there on the effects of deep discharge on Lithiums. Where is the data challenging the aandncaravan DOD graphs?
I get the benefit of B2B; we set off this morning with the AGMs down to 65% and it’s taken 5 hours driving to get them back up to 100%, whatever factory kit the Adria is fitted with, putting a maximum 15 amps into them (according to the battery computer).
We need to know what effect on the life of a Lithium deep discharging has? Apart from the weight saving, isn’t the strength of Lithium based on the premise that it can be taken down to 80% DOD regularly? But now we see charts suggesting their lives are shortened significantly if they are worked like this, from 3 x 10 to the power 4 down to 0.5 x 10 to the power 4 number of cycles. I was expecting to see a doubling in my battery capacity, rapid recharging plus a payload reduction and long life. Utopia! But it looks like I’ll be spending up to £2000 to save 30kg without any real increase in useable storage capacity.
Where is the data?
Jim
Ringleader
Bless him, he's no longer with us. Often held up as an authority on many topics. He really knew his way around Schaudt Elektroblocs, and repaired hundreds. However, he would rant about items he didn't like, for example. Inverters, Battery Masters, B2B systems, these rants would have outrageous claims and dire warnings, often showing glaringly obvious misunderstandings on his part. As people questioned or sometimes ridiculed his assertions he would change the articles somewhat to make them a little less wrong. I'm not saying anything I didn't say to him personally in our many conversations.
He was a nice guy who often meant well. He had a couple of kids and died far too young.
Lenny HB
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Alan died a few months ago so not sure if his partner who has carried on the business will update the technical side of the website.
He was probably biased towards Schaudt because he had strong links with them and repaired their equipment. Most of what he has said is good but I think we all have our own bias when it comes to batteries & charging.
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funflair
LIFE MEMBER
This is a good article on Lithium but you will need to run in in Chrome or something to translate it, https://www.amumot.de/lipo-lithium-batterie-wohnmobil/
Martin
Martin
SteveJulesMontycame2
Free Member
Having said the above, I’ve just seen this
Even Relion accept an approx 50% reduction in number of cycles between taking them down to 50% DOD and 80% DOD, but even though reduced by almost half, the number of cycles are still high! (From 13000 to 7000).
StephDeLux
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It is my understanding that using a B2B is a must with Euro 6 engines. For lithium batteries, a B2B has benefits with older engines too, like limiting the charge current to values that are reasonable for the alternator. A Lithium has very little internal resistance and can take high charge current. Drawing, say 80A from an alternator at idle can actually destroy the alternator because of under-ventilation. Not sure if that applies to a 200A alternator or not, but better safe than sorry.
From what I gather, one cannot go much wrong with electronics from Schaudt, Votronic and Sterling Power.
From what I gather, one cannot go much wrong with electronics from Schaudt, Votronic and Sterling Power.
Lenny HB
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Mercs yes but Fiat's pre Euro 6d were not fitted with smart alternators for the Motorhome converter market. I'm not sure about the Fiat Euro 6D.
StephDeLux
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True, forgot that. I saw a Schaudt B2B in the new simplified Exsis. Doesn't mean it is indispensable, though.
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If you directly connect a fully charged battery to a nearly flat battery that is twice as big, then the first battery sends a big charge boost to the second battery, and they very quickly settle down to the same charge level, maybe about 50% or less. The alternator then has to charge starter and hab batteries back up to the 100% level. They'll be charged as if they were one large lead-acid battery. Which may or may not be what you want. As you say, a B2B avoids all that.
DBK
LIFE MEMBER
That sounds simple but it's not what I've experienced. Before I fitted the B2B if we had the leisure batteries discharged down to say 60% the alternator would put a heavy charge in, say 20 amps or more for a while with the voltage at 14.4 but after half an hour or so the voltage would reduce significantly and it could take another four hours of driving to fully recharge them with a charging current of only around 5 amps. I don't think the split charge circuit was to blame as it had heavy cables and a 100 amp fuse. The B2B holds the voltage at 14.4 for an extended period, pushing in the amps.
I think what happens is if the split charge relay was closed, connecting the two sets of batteries, the cab battery would indeed start charging the depleted leisure batteries if the alternator wasn't doing anything, but that's not what happens. Once the alternator is running the leisure batteries start to draw from it and the voltage climbs up as the alternator starts charging. At 14.4 volts current will be flowing both into the cab and leisure batteries. I can't see the cab battery discharging against that sort of voltage so it remains fully charged and risks being over-charged.
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