Battery maintainer between Lithium and starter batteries

[Ian_H]

Hi All
I'm hoping to have a solar panels and a lithium leisure battery fitted in a month or so. The solar charger and new mains charger will be Victron. To keep the starter battery topped up while the van is not being used I thought a battery maintainer would be the way to go eg Vanbitz, Sterling or Ablemail. But I'm not sure which if any will do what I expect, or whether I am expecting the right thing?
I'm basing this on my understanding (which may well be wrong!) that the standing voltage of the lithium battery when pretty full is around 13.3-13.6V and the standing voltage of the starter with a smart alternator is around 12.4V.
My expectation was that while the lithium battery is being charged by solar (or mains), the maintainer would detect the lithium voltage being higher than normal standing voltage (above say 13.7ish?) and top up the starter battery if needed. It's a smart alternator so I guess something less than 12.4V on the starter would be the right value to start charging? Then stop charging if the starter battery is over a value (around 12.8V?) or the leisure battery is under another value (around 13V?)
I've got the impression that the Vanbitz works on a 0.5V difference so would be charging with no solar input?
The Sterling seems to work on the leisure battery being over 13.3V so again would be charging without any solar input until the starter is within 0.2V of the leisure battery.
The Ablemail at least has lithium and smart alternator settings although the leisure battery start charging voltage seems a bit low at 13.5V. I need to email them but it looks like it turns off when the starter is over 12.4V, so that seems closer to my thinking.
If this is all twaddle please can someone explain things correctly, but be gentle!

 

[funflair]

We use the Vanbitz battery master between our LiFePO4 and standard starter battery, with no solar input in the shed it maintains the starter at around 12.5volts, higher with solar of course

EDIT I should also add that it was only after adding said BM that I realised that our Buttner B2B would also maintain the starter battery, but possibly not when I have isolated the batteries

 

[GMLS]

Might be of interest

 

[AdrianChen]

We have an Ablemail AMT12 for our Lithium and Flooded starter battery (non smart alternator) and use setting 6 which maintains the start battery to around 12.6v with solar at this time of the year - the AMT12 uses the leisure and starter battery parameters as you have described but also charges when there is a differential between the two of 1V (0.3v non lithium) if the start battery drops below 12.1v.

My Lithium batteries standing voltage when not fully charged during winter storage would be around 13.2-13.4, and will only hit more than 13.5 when there is some solar (Our Victron kit and MIFI are permanently on line and draw around 0.5 amps). It's possible to set whatever parameters you want (when buying through a dealer or Ablemail, or buying the bluetooth add on), however the standard options seem to work well for us.

I went with it because we can override the Ablemail's programme remotely using a relay on our Victron kit, if there has been little sun/solar for a while (think December Jan and Feb) and I want to give the starter battery a good charge, the AMT12 can be set to charge the starter battery at up to 3amps though limited by whatever voltage the Lithium's are at. (The van is stored without EHU and although only 1yr old I think the start battery was poorly maintained and drops quite quickly).

Doubt you would notice much difference between VB and Ablemail in practice

 

[treblid]

I should also add that it was only after adding said BM that I realised that our Buttner B2B would also maintain the starter battery, but possibly not when I have isolated the batteries

Your Burstner (assuming you meant Burstner) most likely uses an EBL to control all the 12V electrics. These provide a starter battery maintenance charge but only when on electric hook up.

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[Ian_H]

Might be of interest

That certainly was useful, using a lithium as leisure battery. Although I think it showed that the starter was being charged above what the vehicle system would normally charge to with a smart alternator, since at 12.8V the starter battery didn't need charging at all. I assume the vehicle manufacturers have good reasons for not charging to higher voltages (economy, battery life)? Having said that the guy is obviously happy with the battery master.

 

[treblid]

Smart alternators provide higher charge voltages and therefore current when decelerating, going down hill, etc. That's where the efficiency comes in.

To allow for this, AGM batteries are typically used and a voltage headroom is reserved for the eco charging at the higher voltage.

 

[Lenny HB]

I would go for the Ablemail not only does it have a couple of Lithium profiles it is also user programmable as AdrianChen mentioned.

 

[funflair]

Your Burstner (assuming you meant Burstner) most likely uses an EBL to control all the 12V electrics. These provide a starter battery maintenance charge but only when on electric hook up.

Buttner as in https://www.buettner-elektronik.de/produkte/lade-booster.html we have the lade-booster 90A I was checking some dip switches a couple of weeks ago to drop the charge level from 90A to 60A and I noticed in the instructions that it had the battery maintain feature but I didn't flick the switch to see what level it maintained at and as I said it wouldn't work if I isolated the main batteries anyway.

 

[Ian_H]

I would go for the Ablemail not only does it have a couple of Lithium profiles it is also user programmable as AdrianChen mentioned.

Yep I think you are right. Slightly surprised that of 2 professionals, one proposed to fit a vanbitz and the other a sterling.

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[Dolmen]

Yep I think you are right. Slightly surprised that of 2 professionals, one proposed to fit a vanbitz and the other a sterling.

I am not that surprised that that is what they recommended, I am surprised they didn't understand your wishes to have your own user profile, you are looking to add user profile to what the vanbitz and others have simplified to 'fit and forget'. I have a smart alternator and have a votronic battery master and no solar. The Lithium battery maintains the cab battery at 12.9 when in storage. The drain on the Lithium battery is minimum and I calculated would last many months if I ever needed to leave it in the storage compound. Its a simple fit and with a Lithium battery that's what your 'professionals' thought was needed. You however, want to have the flexibility of inputting your own user profile and hence the Ablemail is the right choice for you.

 

[Ian_H]

Hi Dolmen
Actually, I'm not particularly looking to enter my own parameters, it's more that I don't understand how the parameters especially in the vanbitz and Sterling maintainers work with the Lithium, lead acid and smart alternator combination, bearing in mind that the vehicle manufacturers seem to aim to keep the starter battery at about 12.4V as mentioned by treblid in post #7.

 

[Dolmen]

Although I have a smart alternator I had not heard of the 12.4 figure before, I think mine sat at 12.7/12.8 before fitting the battery master, although it dropped in storage due to alarm and tracker which is why I had a battery master fitted, it now sits at 12.9 consistently. Do you happen to know where the recommended 12.4 came from?

 

[treblid]

vehicle manufacturers seem to aim to keep the starter battery at about 12.4V as mentioned by treblid in post #7.

It wasn't me!

12.7V is more typical with a good AGM battery at rest after a journey.

During travel, a smart alternator charging voltage can go as high as 15V during the eco boost phases.

 

[Ian_H]

Sorry teblid for misquoting! You mentioned the voltage headroom. Elsewhere I have seen manufacturers aim to charge to 80% and for an agm I think that is about 12.5V. Eg here https://www.redarcelectronics.com/u...ators-faqs/smart-alternator-fixed-alternator/
It might only apply where regenerative braking is used? In the first post I did ask to be told if I was talking twaddle!

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[treblid]

This is a graph of our engine/starter battery during a trip. You can see the voltage swings and the start and finish rest voltages.

 

[Speve]

it's more that I don't understand how the parameters especially in the vanbitz and Sterling maintainers work with the Lithium, lead acid and smart alternator combination, bearing in mind that the vehicle manufacturers seem to aim to keep the starter battery at about 12.4V as mentioned by treblid in post #

I thought the video GMLS posted explained it pretty well