Van/car batteries die after about 4 years - so that might be something to consider.

How old is you van battery?

You could try to recon it using a smart charger - but this does not save the battery in the end, may extend it for a year.

Rus

 

It depends on what type of split charge device you have. If you have a simple, standard split charge relay then typically as soon as the alternator generates output it connects the starter and leisure battery together. That's it - that's how it's designed to work.

If you have a VSR then it will connect the two together as soon as the starter battery + alternator together exceed the threshold voltage. Typically a modern alternator has such a high output that this will happen within seconds of engine start.

This also means that if one battery is low, you should always disconnect the split charge circuit before attempting engine start - if you don't, the split charge will connect the two together and the full battery will try to charge the low battery, which will typically blow the fuse on the split charge circuit (depending on wiring and fuse rating).

 

I’ve just got round to considering the EHU setup on my (new-to-me) T5.1 Caravelle. The previous, private owner was not very forthcoming on the setup, hence my interest in this thread.

I’m also having trouble with the starter battery discharging probably as a combination of repeatedly opening/closing the auto-sliding doors and not driving the van enough in the winter. I don’t think there is any significant drain on the leisure battery as I’ve disconnected the fridge.

I’m assuming both batteries charge up when the engine is running. However, I’m trying to understand if both batteries will be charged on mains hook-up.

All the terminology is new to me and I’m climbing the knowledge curve from a low base. I’ve found (next to the starter battery) a Samlex BSM140 dual input motion controlled battery separator. Is this the only ‘gizmo’ likely to be fitted and is it both the ‘split charge device’ and the ‘VSR’ (presumably, Voltage Sensitive Relay) you mentioned? I can’t help thinking there also must be something akin to a battery charger somewhere but don’t know where to look for it!

Any help (a ‘dummies’ guide!) would be gratefully received.

 

split charge relay could be stuck on - not unheard of. check voltage of both batts to see if theyre the same with engine running/ not running, isolate the leisure batt by pulling the fuse and repeat.

 

Wow! That's incredibly comprehensive and helpful. Thank you very much for taking the time to reply at such length.

I've identified all the 'odd' boxes I've come across but not yet found a charger. Are there places fitters would normally choose so I can narrow down my search (it is raining and cold out there at the moment after all!).

 

Under the seats is a popular place, especially if the space behind the cab area is still primarily a people carrier kind of setup.
If your hookup plug is under the bonnet, I would think under seat is most likely.
If your hookup plug in at the back somewhere, then maybe a charger could be within one of the moulded side panels on the Caravelle? there would be space to do so - pull up the cover on the left panel where the jack lives. or the cover on the right where the rear HVAC unit is and shine a torch around there and see if anything looks non-standard

 

well found

How to tell if it is charging the SB? some VSRs have a LED to show it is engaged. check for the presence of that it it has one and if it changes when mains charger is on. no light fitted? need a meter!
What is a very worthwhile thing to get is a Battery Monitor so you can keep an eye on the batteries. Lots of options around from a handheld multimeter to just put on to check occasionally to a fitted Battery SOC Monitor which will give you loads of info, but at a fairly high price.
A good well-priced option (IMO ) is the Battery Watch kit I make. You can connect it to both sides of the VSR you have, and just flick the switch to either read the Starter Battery or the Leisure Battery.
But end of the day, it is essential to have some way to monitor the Batteries to ensure as long a service life as possible.

 

How to tell if it is charging the SB? some VSRs have a LED to show it is engaged. check for the presence of that it it has one and if it changes when mains charger is on. no light fitted? need a meter!
What is a very worthwhile thing to get is a Battery Monitor so you can keep an eye on the batteries. Lots of options around from a handheld multimeter to just put on to check occasionally to a fitted Battery SOC Monitor which will give you loads of info, but at a fairly high price.
A good well-priced option (IMO ) is the Battery Watch kit I make. You can connect it to both sides of the VSR you have, and just flick the switch to either read the Starter Battery or the Leisure Battery.
But end of the day, it is essential to have some way to monitor the Batteries to ensure as long a service life as possible.

Well, after due reflection, I've made a move and fitted one of your Battery Watch Kits. (And, thank you for your helpful advice, too). I've also upgraded the on-board charger to a Victron Blue Smart IP67 12V/15A Charger. I've had fun watching the Bluetooth app go through the various charging modes and it has been comfortably ticking over on 'storage' mode for many hours now. The Leisure battery seems to be maintaining a constant 13.4V using 0.2A.

Ah, now .... you may recall I mentioned that the VSR is the only Split charge system that is bidirectional and switches on from either direction? That means that the mains charger will not do the starter battery as well with that setup (this is one of the few advantages the VSR has over the B2B).

Indeed, the Starter battery does not appear to be charging and has remained resolutely on 11.8V throughout the cycle.

So, I come to the next step in achieving my goal which brings me to my question. I like the idea of fitting a trickle charger such as the aforementioned Ablemail AMT-12 Battery Maintainer. Is it a simple matter of replacing my VSR with an AMT-12 or is it more complicated?

 

So this is your charger then - https://magnummotorhomes.co.uk/wp-content/uploads/2018/01/SUPERCHARGE-151-TECHNICAL.pdf

I'll be perfectly honest ... It is not a great charger it just puts out a constant 13.8V. It will not charge either Leisure OR Starter Battery completely. The typical Lead Acid Battery needs a voltage in the area of 14.4V to get to a full charge. The charger you have will never approach that level and you will never get close to the quoted capacity of your Leisure Battery.
The other unfortunate news is the Alternator will not be output much more than that either, so when the Leisure Battery is getting charged via Split Charge, you are in no better a situation
I would strongly recommend you get a Smart Charger of some kind in your Caravelle. You could swap out the VSR with a B2B (good idea if you drive a lot); You could swap out that Sargent Mains Charger with a decent Mains Charger (good idea if you stay on campsites a lot or plug in when at home); or if you are considering Solar, get a decent MPPT Controller (good idea if you camp off-grid a lot).

 

I would strongly recommend you get a Smart Charger of some kind in your Caravelle. You could swap out the VSR with a B2B (good idea if you drive a lot); You could swap out that Sargent Mains Charger with a decent Mains Charger (good idea if you stay on campsites a lot or plug in when at home); or if you are considering Solar, get a decent MPPT Controller (good idea if you camp off-grid a lot).

Thanks again. I'm probably not ready for solar just yet but the other stuff sounds very sensible. Are you able to recommend a good model smart charger and B2B module? Does the latter simply swap with the Samlex BSM140?

 

Many thanks. You've given me a lot to think about and moved me sharply up the learning curve! It's much appreciated.

I think it's now time for reflection.....:cheers

Andy

 

Interesting that - if I am reading your post correctly - that the Starter Battery is not charging when you have the Mains Charger charging the Leisure Battery.
A VSR will typically enagage at around 13.2V and disengage when the voltage is below around 12.8V (the exact values vary for different models). Now on a bi-directional VSR, it doesn't matter which side is at 13.2V, it will still engage and the two sides connected together. If you are not getting this happening, but the Leisure Battery is getting charged when the engine is running, the VSR is acting in a uni-directional way only. Your Samlex from what I researched looks like it should work bi-directionally though.
Have you confirmed that the VSR is actually working at all? It seems strange that it would partially work (though not impossible).
(I noticed I made a typo in an earlier post that could have been misleading? I typed "That means that the mains charger will not do the starter battery as well with that setup (this is one of the few advantages the VSR has over the B2B)." - I should have said "That means that the mains charger will NOW do the starter battery as well with that setup (this is one of the few advantages the VSR has over the B2B).")

Ref the Trickle Charger - with a 'normal' bi-directional VSR that will engage whenever a charger is fully active (either Mains or a Solar in decent light), the Trickle Charger will not be an advantage, but with a B2B or a uni-directional VSR (or a standard relay enabled by the Alternator D+ or Ignition signal, like many motorhome systems like a Sargent for example) a Trickle Charger becomes very worthwhile and can save a Starter Battery on a vehicle not used fairly frequently.

However .... a Trickle Charger CAN be useful even with a VSR as it (the trickle charger) will activate at a lower voltage so when the solar is providing maybe some charging but not enough for 'proper' charging due to limited light/time (typical in wintertime), the charging voltage may not be enough to turn on the VSR, but will be enough to send a small maintenance charge to the starter battery.
So in the wintertime if a camper has got solar but does not get plugged in, a Trickle Charger is useful even for a VSR-equipped campervan I should reiterate the Trickle Charger is not a replacement for a VSR or a B2B, but a complimentary device.

In terms of fitting a VSR in your van, the AMT-12 has three connections - +VE to Leisure, +VE to Starter and 0V/Ground. The VSR has the same, so it would literally be as easy as connecting the (supplied ring) connections to the same +VEs on the VSR, attaching the Ground to a suitable Chassis point and it is ready to work
The AMT-12 has encapsulated electronics as well so can be fitted under the bonnet without worrying about the weather aspects.

 

Thank you so much for your reply.

(I noticed I made a typo in an earlier post that could have been misleading? I typed "That means that the mains charger will not do the starter battery as well with that setup (this is one of the few advantages the VSR has over the B2B)." - I should have said "That means that the mains charger will NOW do the starter battery as well with that setup (this is one of the few advantages the VSR has over the B2B).")

Ah, yes, that did confuse me a bit but it doesn't take much! Part of the problem is the manuals and datasheets for this stuff tend to be written for people with a degree of advanced knowledge that I haven't yet acquired.

Your Samlex from what I researched looks like it should work bi-directionally though. Have you confirmed that the VSR is actually working at all?

The manual for my VSR states : "The BSM will only be switched on if a vibration is detected and the voltage on the primary side falls within specific values. The values are specified in the “Technical details” section. The relay will switch off when the BSM no longer detects vibrations or when the voltage limits are exceeded".

I've noticed before that the BSM has a small LED that lit up (flickered) when I tapped it. I've just tapped it several times (to mimic the engine running) and the LED came on fully, there was a discernible click and the voltage rose on the SB. This lasted for 30 seconds and the BSM switched off again. Presumably this means it won't allow bidirectional charging when the van is unused and static i.e. a safety feature to prevent discharge of the SB to the LB. It is possible to adjust the sensitivity of the vibration control but not switch it off. So, unless I stand there tapping it every 30 seconds, the SB won't get charged via the EHU.

As I don't have solar but mostly intend to use an EHU, should I replace the BSM with a bidirectional VSR that isn't motion-controlled (can you recommend one?) or should I just add an AMT-12 as you suggested earlier? My sense is the latter.

Would the charging power to the SB through a VSR be greater than the AMT-12? The AMT-12 data sheet states:
"The unit has a low current draw of less than 2mA on a 12V system & so presents a very small discharge load to the Vehicle & Leisure Battery. At 1 Ahr drain every 20 days the unit has negligible effect on the Battery Capacity & should will easily cover a winter storage period. When a charging source either a Mains Charger or a Solar Charger is connected to the Auxiliary / Leisure Battery the AMT1 2-2 Trickle Charger allows a maximum of 4A (Usually considerably less) to flow from the Leisure Battery to the Vehicle Battery thus ensuring the Leisure Battery is Charged first & the Vehicle Battery second."

 

I remember reading the "The BSM will only be switched on if a vibration is detected ....." and I think at the time thought it was an EITHER/OR type feature rather than a MUST feature (and a weird feature it is!)

I would think this motion-detection feature of the Samlex BSM is pretty unique (I've never come across it before anyway) and is really over-complex.
two options -
1) replace the Samlex with another VSR (just about any VSR will do. Certainly the ones I sell work bi-directionally and need no motion!)
2) fit a Trickle Chager such as the AMT-12.

The VSR has a higher charging current capability than an AMT in terms of maximum current, but in terms of battery maintenance (which is subtlety different to battery charging) the AMT is a better product for keeping your Starter Battery in a 'safe' state of charge.
The AMT-12 is the more expensive option of the two but for what you are talking about is the better one. One other aspect is that if you were in the future to fit a B2B (battery to battery) charger, that will stop any charging flow to the starter from the solar (if fitted) or mains charger - but the AMT-12 would keep that feature in place, so getting an AMT-12 instead of a replacement VSR would be the better technical option at an extra £30 or so over a new VSR.

HTH

 

Great, thanks. I've ordered an AMT-12 from your site.

kind regards
Andy

 

Cheers
Posted off to you 1st Class Royal Mail

 

I am guessing their website has not been updated since the AMT-12 was released which is why it is not mentioned and the installation document (SWI049) is not listed there? I didn't realise I didn't have the PDF on mine! I will correct that shortly. (PS. Ignore the 2nd file you were sent - it has typos on it regarding the technical info (it was also not produced in 2013!). The first one is the updated one to use).

 

(PS. Ignore the 2nd file you were sent - it has typos on it regarding the technical info (it was also not produced in 2013!). The first one is the updated one to use).

Thanks - good spot!. I've edited my post accordingly.

 

Excellent
Something which is a feature of this Battery Maintainer and is not in others, such as the Battery Master, is the way it is programmed to pulse on and off.
This method of operation can be critical when used with some B2B Chargers. If you had a basic trickle charger feeding the starter battery with a constant 1A or so, this could potentially trigger a B2B to turn on and off repeatedly as the battery hits its auto-on voltage threshold, and weirdly the result can be that adding a way to keep the starter battery charged actually results in the starter battery being discharged! (I had this effect myself with a Redarc 40A BCDC when charging the Starter Battery).
Because the designers of the AMT-12 are also designers of B2B Chargers, they understand what behaviour to check for.

 

Something which is a feature of this Battery Maintainer and is not in others, such as the Battery Master, is the way it is programmed to pulse on and off.
This method of operation can be critical when used with some B2B Chargers. If you had a basic trickle charger feeding the starter battery with a constant 1A or so, this could potentially trigger a B2B to turn on and off repeatedly as the battery hits its auto-on voltage threshold, and weirdly the result can be that adding a way to keep the starter battery charged actually results in the starter battery being discharged! (I had this effect myself with a Redarc 40A BCDC when charging the Starter Battery).
Because the designers of the AMT-12 are also designers of B2B Chargers, they understand what behaviour to check for.

That's really interesting and has got me thinking. I have been toying with replacing the VSR with a bidirectional one without the motion control on the current BSM140. Sort of belt and braces. Would there be any point? I.e. would I gain anything over the current AMT12 and, perhaps more importantly, could this damage the balance in the way you describe above?

 

Hoovie. You always have great advice. Thanks for all the hard work you put in. I’m still struggling with this website tbh and miss keeping ahead with all threads. Anyway if you have a van this forum is fantastic. Happy new year all!

 

Hmmm. Well basically you just would not use an "ordinary battery separator" in a vehicle with an 'intelligent generator' (or Smart Alternator as usually named).
Interesting idea that it shuts off when engine stops, but I would have thought that the same would be true of a non-motion VSR as the voltage will drop anyway, just not react as instantly.
Can't see this is a good solution TBH, just a cheaper one to promote than a B2B for a Smart-alternator fitted vehicle. You don't have one of those do you?

 

Can't see this is a good solution TBH, just a cheaper one to promote than a B2B for a Smart-alternator fitted vehicle. You don't have one of those do you?

My T5.1 has stop/start so I guess I have a smart alternator. I'll make sure to get a smart B2B if ever I replace the VSR.