Stop it now!
Leisure Battery Charging
- Thread starter Beata
- Start date
There is one important element missing from this discussion. It is also the first question that I ask a prospective customer, "how do you plan to use your van"? This has a huge bearing on what equipment I would recommend. There are two very different camps at the moment. There are the died in the wool "caravan mentality" (converters and end users) and there are the "new wave". The former is most likely to be parking up on a camp site for a week and plugging into the mains so proper split charging isn't really a requirement here as the onboard charger looks after the battery. The new wave however is a very different proposition. These are people that use their vans very differently. Wild camping, one nighting, extreme sports etc. These people depend very heavily on full charging of their battery from the vehicle as they very rarely encounter a hook up facility. There are also many people that don't have this facility at home either. They may live on a street of terraced housing or have allocated parking away from their house. Mains charging is not really an option for here. If these conversions were done with just a relay based split charging system then their aux battery would never truly achieve absorption and subsequently the battery gives poor performance and ultimately is damaged. I have always made it clear to anyone buying a battery from me that it must be charged properly, otherwise I cannot support the manufacturers warranty.
I don't see a fully charged aux battery as a "holy grail", I see it as an absolute prerequisite to a properly functioning system with dependability. Judging by our customers feedback this exactly what we achieve.
The Sargent/PIS/CBE all in one options may be acceptable for the old guard and the "caravan mentality end users" but just don't cut it for the new wave.
I don't see a fully charged aux battery as a "holy grail", I see it as an absolute prerequisite to a properly functioning system with dependability. Judging by our customers feedback this exactly what we achieve.
The Sargent/PIS/CBE all in one options may be acceptable for the old guard and the "caravan mentality end users" but just don't cut it for the new wave.
P
Phil_G
Guest
Good points Martin.
If I can add to that, another consideration is that there can be up to 3 sources of charge - alternator (or B2B), MHU and Solar.
Whilst there are integrated solutions, most often each source has its own discrete charger, and each charger is unaware
of the others existence. They dont talk to each other, theres no syncronisation.
The only thing each charger can base a decision on is the battery terminal voltage, which varies according to the state each charger is in,
so its very easy for any of these chargers to make a wrong decision about the state of the battery.
For example:
Whilst you were taking all day to pack the van, the solar charger could have done a bulk charge, spent some time in absorbtion,
then settled at its maintenance or float voltage.
You start the engine, and at this point your aux battery is most likely higher than the starter battery, so if its a VSR it could briefly direct
quite a heavy current in the 'wrong' direction (see Loz's pic). If its a B2B rather than a VSR, it will probably begin a bulk charge,
even though the solar has already done that. This charge cycle continues through your journey.
You arrive on site and plug in your MHU, and the mains charger charger immediately begins another bulk charge, even though the
solar and B2B have each already done that. Before it can complete, you unplug and nip down to the chip shop. Again, as you
start the engine, the aux battery is most likely higher than the starter battery, so a VSR could direct quite a heavy current in the
'wrong' direction, or a B2B might begin yet another bulk charge.
Its not an ideal string of events for the poor old battery, ultimately if all the charge sources were integrated or talked to each other,
the battery would have an easier life, but few installations do - some B2Bs partially achieve sync by integrating B2B and solar,
but share via a switch the solar input and MHU. Its all very much a huge compromise
Cheers
Phil
If I can add to that, another consideration is that there can be up to 3 sources of charge - alternator (or B2B), MHU and Solar.
Whilst there are integrated solutions, most often each source has its own discrete charger, and each charger is unaware
of the others existence. They dont talk to each other, theres no syncronisation.
The only thing each charger can base a decision on is the battery terminal voltage, which varies according to the state each charger is in,
so its very easy for any of these chargers to make a wrong decision about the state of the battery.
For example:
Whilst you were taking all day to pack the van, the solar charger could have done a bulk charge, spent some time in absorbtion,
then settled at its maintenance or float voltage.
You start the engine, and at this point your aux battery is most likely higher than the starter battery, so if its a VSR it could briefly direct
quite a heavy current in the 'wrong' direction (see Loz's pic). If its a B2B rather than a VSR, it will probably begin a bulk charge,
even though the solar has already done that. This charge cycle continues through your journey.
You arrive on site and plug in your MHU, and the mains charger charger immediately begins another bulk charge, even though the
solar and B2B have each already done that. Before it can complete, you unplug and nip down to the chip shop. Again, as you
start the engine, the aux battery is most likely higher than the starter battery, so a VSR could direct quite a heavy current in the
'wrong' direction, or a B2B might begin yet another bulk charge.
Its not an ideal string of events for the poor old battery, ultimately if all the charge sources were integrated or talked to each other,
the battery would have an easier life, but few installations do - some B2Bs partially achieve sync by integrating B2B and solar,
but share via a switch the solar input and MHU. Its all very much a huge compromise
Cheers
Phil
All good points and also if you have any sort of regenerative braking/smart alternator then VSR, intelligent relay or ECU controlled relay systems are just no longer appropriate.
Roll on the holy grail of B2B/Solar/mains charger all in one nice unit. Or better still a modular system with a common control bus.
If you did then combine such a unit it would be able to charge both sides of the B2B on mains and keep both batteries charged up nicely when on hook up.
Roll on the holy grail of B2B/Solar/mains charger all in one nice unit. Or better still a modular system with a common control bus.
If you did then combine such a unit it would be able to charge both sides of the B2B on mains and keep both batteries charged up nicely when on hook up.
Yes, all very valid points. However, what I find in practice is that all of the various source units that I have fitted will very quickly revert to the batteries previous charge status after about 20 seconds of bulk charging. Presumably they know the true state of charge from the internal resistance of the battery. For example, I always fit the solar panel first to allow any bonding to have the rest of the day to cure. This usually means that the battery (brand new and usually fully charged anyway) will have several hours of solar before the rest of the kit is initialised. So, battery floating at 13.8. Start engine and begin set up of DC-DC charger. Charger does go into bulk but very quickly cycles through eq and back into float. Same with the Victron mains charger. Not sure what you class as very high current but I can't see a battery at 13.8 flowing much above 20 amps into a partially depleted battery as the 13.8 will very quickly fall to a level too low to cause any forward current.
Not really, it's a bit behind the curve in terms of performance.
wow. what a discussion here.
travelvolts can I pick up your brain on with one more question: what is your view on multidevices like charger/inventer? I was given an advice to buy Victron Energy Multi 12/500/20-16 230V instead of the inverter I originally mentioned. What is your view on that?
Thanks, Beata
travelvolts can I pick up your brain on with one more question: what is your view on multidevices like charger/inventer? I was given an advice to buy Victron Energy Multi 12/500/20-16 230V instead of the inverter I originally mentioned. What is your view on that?
Thanks, Beata
Is the the bees knees of split chargers then? I'm about to buy one for my T6. I plan to install two leisure batteries, ideally under the passenger seat. However unsure which charger to go for? Plus where will it all fit? ha!
I'd like the option of the split charging (or bluemotion dc to dc equivalent) but I'd also quite like to be able to plug into 240v in the rare occasion but would like to have it anyhow.
They are excellent items but I always find it difficult to locate combined items because of their size. It is always easier to locate two smaller items in the available spaces under the seats. As with all engineering, it's a compromise! If you have the room then go for it.
For a two battery set up I recommend the Redarc BCDC40-LV. You can fit the batteries, one under each seat and the Redarc alongside one of them. I will post some pics later of a similar set up.
@travelvolts Okay thanks! How would you then get 240 input to it? Via a ctek charger or similar and then have separate plugs some to an inverter off the lesuire batts and some to 240v mains in only via consumer unit perhaps. Best way of doing that?
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my ring b2b has given up the ghost after a couple of years of iffy service,not sure if the discharge has damaged my two 110ah batteries and we are going away in the van for a week at the weekend aaaaarrrrrrgggghhhh.would the redarc 1240lv with wiring kit be ok with two batteries and a 100amp solar panel? thanks
It's probably the "100 Amp" solar panel wot killed it
Would a 100w solar panel have the same affect? Thanks a lot Travelvolts.
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Yes, perfect!
Consumer unit will fit in front of one of the batteries. For more info on routing cables visit our website and download the fitting PDFs from the product pages.
Thanks @travelvolts I am planning on fitting an underslug heater with pipe come up via drivers seat. So might have to put consumer unit in rear?
Is there a way of using the same plugs but switching a switch between batts and consumer unit? Or better to do it separately?
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