DEBATE: Can LB be charged using 240v charger working off SB

[mikeonb4c]

My understanding is that most split charging systems do not supply 14.5ish V to the Leisure Battery - they have a voltage regulator which keeps the charging voltage at somewhere around 13.5V. Mine certainly does this - tested using a Voltmeter. This is because leisure batteries have different characteristics to starting batteries and could potentially be damaged if charged for a long period at 14.5 (I can't remember the reason given for this). The net result is that the LB cannot ever be fully charged using the split charger. I have had problems starting our Diesel heater due to the LB not being fully charged - a session on the conditioner fixed that. There are "battery to battery" chargers available which do what the OP wants but they are expensive (£300 ish). I suspect that the cobbled solution suggested will need a long period of time to charge the LB so unless they drive for many hours at a time will not be successful.

A really intelligent post and thanks. It makes sense to me. My concern then is whether simply shoving 14.5v over to the LB (which these simple split charging systems seem to do - with engine running, the voltage at my LB is 14.5v approx) without any cutout/control, is going to have a shortening effect on the lifespan of the LB. Then again, I thought most onboard charging systems worked in this way, so...........

Suppose the C-Tek type charger was used, and you didn't drive for many hours. Would it not just give what charge it can. And if it ever does get to the point where it has fully charged the LB, then its design ensures no over-charging. It's as though what is needed is an inexpensive C-Tek type device running off the starter battery and connecting to the LB via the voltage sensing relay?

[scanner]

My understanding is that most split charging systems do not supply 14.5ish V to the Leisure Battery - they have a voltage regulator which keeps the charging voltage at somewhere around 13.5V.

My Willinton system charges at well over 13.5v when the alternator voltage is above that - there is no sign of any form of regulator in the circuit.

[Shaun_E]

Sorry, looks like I have confused split chargers and electric hookup chargers. It is actually the EHU charger which is regulated to 13.85V and therefore cannot ever charge the leisure battery to it's full capacity.
I need to think about this some more and re-read the stuff I read over the last few days about charging circuits.

[scanner]

Sorry, looks like I have confused split chargers and electric hookup chargers. It is actually the EHU charger which is regulated to 13.85V and therefore cannot ever charge the leisure battery to it's full capacity.
I need to think about this some more and re-read the stuff I read over the last few days about charging circuits.

13.85v should fully charge a 12v battery shouldn't it? I pretty sure that used to be about the regulated voltage of dynamos and early alternators.

[mikeonb4c]

Sorry, looks like I have confused split chargers and electric hookup chargers. It is actually the EHU charger which is regulated to 13.85V and therefore cannot ever charge the leisure battery to it's full capacity.
I need to think about this some more and re-read the stuff I read over the last few days about charging circuits.

I'll be interested to get your thoughts (and yes, I suspected that was where the confusion might lie i.e. EHU vs. onboard 12v charging systems - easily done).

This VW thread on overcharging leisure batteries shows that confusion persists out there:

http://www.vwt4forum.co.uk/showthread.php?t=51067

In one ear it seems, we are being told we must give LBs a charge from a mains charger at regular intervals. In the other, that LBs get all the charge they need from the alternator, which will back off sending current to them once fully charged (though quite how it does that, while at the same time producing 14+v at the LB, is not made clear).

[mikeonb4c]

Sorry, looks like I have confused split chargers and electric hookup chargers. It is actually the EHU charger which is regulated to 13.85V and therefore cannot ever charge the leisure battery to it's full capacity.
I need to think about this some more and re-read the stuff I read over the last few days about charging circuits.

13.85v should fully charge a 12v battery shouldn't it? I pretty sure that used to be about the regulated voltage of dynamos and early alternators.

According to Elecsol at:

http://www.electricfence-online.co.uk/s ... faq-s.html

....they don't. Neither it seems, do alternators risk (seriously) overcharging them. It's as though putting up to 14.4v or so into an LB is fine and won't especially harm it. You would thank then that the average Bongo LB should get sufficient charge without any special 3 monthly treatment. I note the Elecsol stuff likes solar panels (fitted with a charge regulator) as a way of charging LBs. I notice also that they like to see LBs left to discharge to about 70% capacity before they are charged up again, as regular tiny top-ups aren't so good for them. That would seem to be a point against our simple split charge relay systems. It's as though we could do with something that says 'don't supply any charge to this battery until it is down to 70% capacity' (though how you measure that is not clear to me).

I think another good investment might be the device Julian (321Away) pointed us to: a low voltage cutout protector that sits between the LB and anything that it delivers power too. This would protect it from accidental full discharge (easily done) as well causing false triggering when such a device is fitted to an appliance working at some distance (in terms of electrical wiring) from the LB.
Complex beasts, batteries, thats for sure.

Maybe we should do as Kirsty says I say: Shut up and drive (but then of course that's more expensive than waffling away on here )

But I do love chasing the Holy Grail that is the completely self-contained wild camping Bongo beast. Now, how do we capture drinking water and recycle organic waste (for engine fuel) while on the move

[g8dhe]

Not had a chance to comment due to being mobile the last week so lets see;

LBs like to have a full charge from a 240v device every 3 months or so, and it occurs to me that those who cannot park up somewhere where they can run an extension lead out to the car, may have a problem with this. Taking an LB out and dragging it indoors every 3 months is a pain.

Not heard this before! The battery doesn't know the source of energy flowing into it so it could come from anything you like, another battery, the Mains or a Flash of lightning!!! As to 3 months again you shouldn't leave a battery uncharged for more than 3 months as in storing it in the garage, but provided it is stored charged and that charge is manaintanied the it should be OK so yes give a stored away battery a boost every three months to keep it at its best.

What I am wondering is whether a 240V charger (I have the Aldi bargain offer version of the C-Tek type charger) could be used to give my LB the full charge it likes to have at intervals, but that (I understand) it can’t get from the 12v charging system.

If its not being charged from the alternator then yes it won't do any harm.

It seems to me that this idea won’t work if the inverter is working off the battery it is trying to charge, so it would need to be running off the starter battery. Also, I don’t like the idea of the LB taking charge through the onboard 12v charging facility (I’ve just fitted the wonderful Willinton charging kit at the same time as fitting the Energy Bull) whilst also attempting to receive charge from the 240v charger (I’m not sure what unpredictable effects might result).

So, what if the 240v inverter ran off the starter battery (in reality it will effectively be running off the alternator and not draining the SB once the engine is running). And what if a breaker switch was fitting into the +ve to +ve connection from SB to LB so the LB could be isolated when it is receiving a charge from the 240v charger. You might then use time when you are running around in the Bongo, but not camping, to charge the LB.

You could do that but then how will you charge the S/B ?

You could argue then: why bother with a 12v charging setup at all. I guess the answer is that an inverter wastes power running itself before it even delivers power to the 240v charger, so it is inefficient and not a good idea for normal charging.

As regards the switching arrangements, I can think of al kind of fancy things that could be made to work by the flick of a switch: swapping 240v charge and inverter powering around so either LB or SB could receive a conditioning charge; switching on the inverter at the same time, and hard wiring the charger from inverter to battery(s) etc. etc.

But is all this nuts? I’d be interested to get the thoughts of anyone knowledgeable about this kind of electrical stuff.

You have the floor

As above the battery doesn't have a clue as to the source of the energy so it can be Alternator, other battery, Mains or lightning it makes no difference to it. The only criteria is don't pass more current thru it than its rated for charging with typically 8-12 Amps for L/B, don't exceed the Max. charging voltage typically 14.4 volts (this varies with temperature and precise battery type) but above 14.4volts most Lead Acids will start to release gas from the water H2 and O, this for a sealed battery is very bad as you can't replace the water! After that things can be improved further but it takes a lot of work to be precise about the improvement possible and for any Lead Acid battery designed for the rough and tumble of life the improvements will be small and difficult to prove.

Right I need to get back to our campsite catch you later.

[mikeonb4c]

Not had a chance to comment due to being mobile the last week so lets see;

LBs like to have a full charge from a 240v device every 3 months or so, and it occurs to me that those who cannot park up somewhere where they can run an extension lead out to the car, may have a problem with this. Taking an LB out and dragging it indoors every 3 months is a pain.

Not heard this before! The battery doesn't know the source of energy flowing into it so it could come from anything you like, another battery, the Mains or a Flash of lightning!!! As to 3 months again you shouldn't leave a battery uncharged for more than 3 months as in storing it in the garage, but provided it is stored charged and that charge is manaintanied the it should be OK so yes give a stored away battery a boost every three months to keep it at its best.

What I am wondering is whether a 240V charger (I have the Aldi bargain offer version of the C-Tek type charger) could be used to give my LB the full charge it likes to have at intervals, but that (I understand) it can’t get from the 12v charging system.

If its not being charged from the alternator then yes it won't do any harm.

It seems to me that this idea won’t work if the inverter is working off the battery it is trying to charge, so it would need to be running off the starter battery. Also, I don’t like the idea of the LB taking charge through the onboard 12v charging facility (I’ve just fitted the wonderful Willinton charging kit at the same time as fitting the Energy Bull) whilst also attempting to receive charge from the 240v charger (I’m not sure what unpredictable effects might result).

So, what if the 240v inverter ran off the starter battery (in reality it will effectively be running off the alternator and not draining the SB once the engine is running). And what if a breaker switch was fitting into the +ve to +ve connection from SB to LB so the LB could be isolated when it is receiving a charge from the 240v charger. You might then use time when you are running around in the Bongo, but not camping, to charge the LB.

You could do that but then how will you charge the S/B ?

You could argue then: why bother with a 12v charging setup at all. I guess the answer is that an inverter wastes power running itself before it even delivers power to the 240v charger, so it is inefficient and not a good idea for normal charging.

As regards the switching arrangements, I can think of al kind of fancy things that could be made to work by the flick of a switch: swapping 240v charge and inverter powering around so either LB or SB could receive a conditioning charge; switching on the inverter at the same time, and hard wiring the charger from inverter to battery(s) etc. etc.

But is all this nuts? I’d be interested to get the thoughts of anyone knowledgeable about this kind of electrical stuff.

You have the floor

As above the battery doesn't have a clue as to the source of the energy so it can be Alternator, other battery, Mains or lightning it makes no difference to it. The only criteria is don't pass more current thru it than its rated for charging with typically 8-12 Amps for L/B, don't exceed the Max. charging voltage typically 14.4 volts (this varies with temperature and precise battery type) but above 14.4volts most Lead Acids will start to release gas from the water H2 and O, this for a sealed battery is very bad as you can't replace the water! After that things can be improved further but it takes a lot of work to be precise about the improvement possible and for any Lead Acid battery designed for the rough and tumble of life the improvements will be small and difficult to prove.

Right I need to get back to our campsite catch you later.

At last - the beak has speaked. Thank you so much Geoff - this is an excellent bit of guidance. It seems then that as long as the LB is not being allowed to get into and/or remain in a heavily discharged state, there is no special need for a mains charge every 3 months (though if it is easy to do, then might as well do it for peace of mind).

So, it seems our owner with no access to 240v charging has nothing to worry about. Which means that if and when circumstances cause me to be in such a dwelling, I need not fear for the health of my Bongos leisure battery. Yippee

Here endeth etc. (I hope )

[maxi_77]

Agree that your batteries have no idea where the charging power comes from. The main problem is car alternators have very crude controllers and will never put 100% back into a battery. This is not really a problem for starter batteries because you usually only need a few percent of capacity to start even on bad days. LBs are a different kettle of fish especially when you consider that only 50% is really useable on a regular basis. Then you do beed to get as much back in as possible. Smart chargers do this fastest, and better because they adjust the charging routine to suit the state of charged and will close down to a float charge when they have squeezed the maximum in. The can also be set to charge at optimal patterns for different battery technologies such as normal flooded acid or gel types etc. Yes some of the smart chargers are pricey but but many of them are overkill for a bongo LB. The one on my boat gives out 30A, but I have 300 AH worth of battery and I need it as near 100% capacity as I can get. You should not have to pay more than £100 for a smart charget for a bongo, and I just use a Lidl one which is nothing like as smart as the cetrek, but does. Using and invertor whilst the engine isn't going to do that much good because the alternator output will confuse the smart charger output. There are smart alternator chargers where the normal alternator controler is bypassed and allows the alternator to mimic a smart charger. Now the bongo needs a voltage sensitive split charge relay because tampering with the alternator charge light circuit can cause problems so I am not sure if one of these alternator controllers can be used as they do alter the alternator wiring. If you really want to monitor the state of yout LB look at the NASA BM1

[mikeonb4c]

Agree that your batteries have no idea where the charging power comes from. The main problem is car alternators have very crude controllers and will never put 100% back into a battery. This is not really a problem for starter batteries because you usually only need a few percent of capacity to start even on bad days. LBs are a different kettle of fish especially when you consider that only 50% is really useable on a regular basis. Then you do beed to get as much back in as possible. Smart chargers do this fastest, and better because they adjust the charging routine to suit the state of charged and will close down to a float charge when they have squeezed the maximum in. The can also be set to charge at optimal patterns for different battery technologies such as normal flooded acid or gel types etc. Yes some of the smart chargers are pricey but but many of them are overkill for a bongo LB. The one on my boat gives out 30A, but I have 300 AH worth of battery and I need it as near 100% capacity as I can get. You should not have to pay more than £100 for a smart charget for a bongo, and I just use a Lidl one which is nothing like as smart as the cetrek, but does. Using and invertor whilst the engine isn't going to do that much good because the alternator output will confuse the smart charger output. There are smart alternator chargers where the normal alternator controler is bypassed and allows the alternator to mimic a smart charger. Now the bongo needs a voltage sensitive split charge relay because tampering with the alternator charge light circuit can cause problems so I am not sure if one of these alternator controllers can be used as they do alter the alternator wiring. If you really want to monitor the state of yout LB look at the NASA BM1

Good post. I had imagined running the Aldli/c-tek type charger off an inverter driven by the starter battery. The leisure battery would be isolated from the VSR/alternator charging circuit whilst smart chargin was in progress. Might this work? Then again, as many have said, I'd have to be driving all day and night for the smart charger to have half a chance of doing it's thing (unless of course it is able to do it bit by bit in whatever small chunks of driving/charging it is given to do it in).

[maxi_77]

Agree that your batteries have no idea where the charging power comes from. The main problem is car alternators have very crude controllers and will never put 100% back into a battery. This is not really a problem for starter batteries because you usually only need a few percent of capacity to start even on bad days. LBs are a different kettle of fish especially when you consider that only 50% is really useable on a regular basis. Then you do beed to get as much back in as possible. Smart chargers do this fastest, and better because they adjust the charging routine to suit the state of charged and will close down to a float charge when they have squeezed the maximum in. The can also be set to charge at optimal patterns for different battery technologies such as normal flooded acid or gel types etc. Yes some of the smart chargers are pricey but but many of them are overkill for a bongo LB. The one on my boat gives out 30A, but I have 300 AH worth of battery and I need it as near 100% capacity as I can get. You should not have to pay more than £100 for a smart charget for a bongo, and I just use a Lidl one which is nothing like as smart as the cetrek, but does. Using and invertor whilst the engine isn't going to do that much good because the alternator output will confuse the smart charger output. There are smart alternator chargers where the normal alternator controler is bypassed and allows the alternator to mimic a smart charger. Now the bongo needs a voltage sensitive split charge relay because tampering with the alternator charge light circuit can cause problems so I am not sure if one of these alternator controllers can be used as they do alter the alternator wiring. If you really want to monitor the state of yout LB look at the NASA BM1

Good post. I had imagined running the Aldli/c-tek type charger off an inverter driven by the starter battery. The leisure battery would be isolated from the VSR/alternator charging circuit whilst smart chargin was in progress. Might this work? Then again, as many have said, I'd have to be driving all day and night for the smart charger to have half a chance of doing it's thing (unless of course it is able to do it bit by bit in whatever small chunks of driving/charging it is given to do it in).

As you are really looking at 12-24 hours to properly do the job driving around is perhaps not the way to go, it is well worth the effort taking the battery out. Small chunks will not really achieve anything as you will slip back to where you started before you start again. I used to have to bring the battery ashore in a dinghy to get it charged up. Rather than call the Aldi a 'smart charger' I would rate it as not so dumb. Rather than the c-tek, look at the Ring smart chargers, you do not need a mortgage to buy one, and they came out very well in a recent yachtie test.

[maxi_77]

Agree that your batteries have no idea where the charging power comes from. The main problem is car alternators have very crude controllers and will never put 100% back into a battery. This is not really a problem for starter batteries because you usually only need a few percent of capacity to start even on bad days. LBs are a different kettle of fish especially when you consider that only 50% is really useable on a regular basis. Then you do beed to get as much back in as possible. Smart chargers do this fastest, and better because they adjust the charging routine to suit the state of charged and will close down to a float charge when they have squeezed the maximum in. The can also be set to charge at optimal patterns for different battery technologies such as normal flooded acid or gel types etc. Yes some of the smart chargers are pricey but but many of them are overkill for a bongo LB. The one on my boat gives out 30A, but I have 300 AH worth of battery and I need it as near 100% capacity as I can get. You should not have to pay more than £100 for a smart charget for a bongo, and I just use a Lidl one which is nothing like as smart as the cetrek, but does. Using and invertor whilst the engine isn't going to do that much good because the alternator output will confuse the smart charger output. There are smart alternator chargers where the normal alternator controler is bypassed and allows the alternator to mimic a smart charger. Now the bongo needs a voltage sensitive split charge relay because tampering with the alternator charge light circuit can cause problems so I am not sure if one of these alternator controllers can be used as they do alter the alternator wiring. If you really want to monitor the state of yout LB look at the NASA BM1

Good post. I had imagined running the Aldli/c-tek type charger off an inverter driven by the starter battery. The leisure battery would be isolated from the VSR/alternator charging circuit whilst smart chargin was in progress. Might this work? Then again, as many have said, I'd have to be driving all day and night for the smart charger to have half a chance of doing it's thing (unless of course it is able to do it bit by bit in whatever small chunks of driving/charging it is given to do it in).

As you are really looking at 12-24 hours to properly do the job driving around is perhaps not the way to go, it is well worth the effort taking the battery out. Small chunks will not really achieve anything as you will slip back to where you started before you start again. I used to have to bring the battery ashore in a dinghy to get it charged up. Rather than call the Aldi a 'smart charger' I would rate it as not so dumb. Rather than the c-tek, look at the Ring smart chargers, you do not need a mortgage to buy one, and they came out very well in a recent yachtie test.

[Shaun_E]

After another weekend away where the heater failed to start, I have returned to this topic. When I got home, I measured the voltage at the LB After 2 nights away running a Waeco compressor fridge and occasional lighting, the battery voltage was 12.2V which is somewhere between 25% and 50% capacity remaining - i.e. almost flat! No wonder the heater wouldn't start. I then measured the voltage at the LB with the engine running and it was ~13.8V so my split charging circuit is voltage regulated and will never charge the LB fully.
I read some stuff on the Sterling Power website, which explains why 13.8V will never charge the battery completely (it will but it will take so long to do it that in practice that means never).
I think the way forward for us is to ensure the LB is completely charged using an intelligent charger before we go away.
We could replace our EHU on board charger with an intelligent one - not sure if this will work whilst using things like the fridge. I have used intelligent chargers on cars with an immobiliser which is small load and it's not been a problem.
The ultimate would be to use one of the Sterling Power products, either a battery to battery charger or an alternator to battery charger - not sure which is best but at £360 they would seem to be overkill.
The search continues for the perfect solution!

[g8dhe]

it was ~13.8V so my split charging circuit is voltage regulated and will never charge the LB fully.

Do you know that you have a regulated system ? There not that common, and its very easy to get a voltage drop between all the connections and fuses such that you won't see the full charging voltage. Another point is where exactly are you measuring the battery voltage and what sort of meter is it that your measuring it with ?

I would suggest that if its a reasonable meter, that you measure the voltage drop starting from the S/B +ve terminal down thru the first fuse and to the split charge relay/module, then again on the otherside of the relay and down to the second fuse next to the L/B. Its also a good idea to check that you have a good earth connection and that there is minimal voltage drop (less than 0.1 volts) when drawing a load (say 2-4 amps) between the -ve of each battery and the chassis of the vehicle.

[maxi_77]

After another weekend away where the heater failed to start, I have returned to this topic. When I got home, I measured the voltage at the LB After 2 nights away running a Waeco compressor fridge and occasional lighting, the battery voltage was 12.2V which is somewhere between 25% and 50% capacity remaining - i.e. almost flat! No wonder the heater wouldn't start. I then measured the voltage at the LB with the engine running and it was ~13.8V so my split charging circuit is voltage regulated and will never charge the LB fully.
I read some stuff on the Sterling Power website, which explains why 13.8V will never charge the battery completely (it will but it will take so long to do it that in practice that means never).
I think the way forward for us is to ensure the LB is completely charged using an intelligent charger before we go away.
We could replace our EHU on board charger with an intelligent one - not sure if this will work whilst using things like the fridge. I have used intelligent chargers on cars with an immobiliser which is small load and it's not been a problem.
The ultimate would be to use one of the Sterling Power products, either a battery to battery charger or an alternator to battery charger - not sure which is best but at £360 they would seem to be overkill.
The search continues for the perfect solution!

There is no basic problem using power whilst your smart charger is running. I have a 30A sterling on my boat and it acts as a power supply much of the time because the batteries are floating whilst I am alongside. See my comments above about Ring smart chargers they do an 8 amp one which is affordable and big enough for an LB charger and also 8A should cover a peltier fridge and a TV or at least cut the drain down to a manageable level. Remember when using battery voltage to estimate capacity it should have stood for 12 hours to settle, after a discharge it will rise, and of course after charging it will fall.