BrianK Posted December 31, 2019 Author Share Posted December 31, 2019 Thanks Keith, I think I'm going to do another sketch adding what I have learnt from all of you, because I'm a sucker for a diagram. Brian Link to comment Share on other sites More sharing options...
Keithl Posted December 31, 2019 Share Posted December 31, 2019 AND... you need to move the main ground from the RH battery to the load. Otherwise the LH battery is connected to ground via both black wires and the RH via neither. Link to comment Share on other sites More sharing options...
BrianK Posted December 31, 2019 Author Share Posted December 31, 2019 Hello All, Please see my new sketch below. Not 100% happy with the quality but happier than I was with the last one. Amongst other things I have dropped the busbars, I can’t be sure I can do the positive side without one but should be able to get all of the negatives onto the load side of the shunt. Happy New Year to everyone Brian Link to comment Share on other sites More sharing options...
BrianK Posted January 1, 2020 Author Share Posted January 1, 2020 Thanks plwsm2000 plwsm2000 - 2019-12-31 2:39 PM I would probably use a spare midi fuse to connect the charger input (even though the charger has a built in fuse) just to protect the cable from the "bus bar" to the charger. You should be very careful to properly insulate the busbar, particulary in a PVC with a metal chassis, to avoid the risk of a fire. Would this go as close as possible to the charger or battery and what rating would you suggest? Fairly sure the one in the charger is 25A plwsm2000 - 2019-12-31 2:39 PM I also see in your diagram that you are using a "ign Live" to control the Redarc B2B. Is this live only when the engine is running (not just with the ignition switched on)? If not (and your hab. batteries are low), your starter battery will have another significant load and may struggle to start the engine. I think it is normal practise to use the D+ (or equivalent) that only goes live with the engine running. This is usually a fairly low current so you need to check the load on the B2B control signal. Are you sure this is the case with the Redarc? Extracts from operating instructions below. Link to comment Share on other sites More sharing options...
BrianK Posted January 1, 2020 Author Share Posted January 1, 2020 I have had confirmation from the supplier of the Redarc that the unit does work as described in the operating instructions and switches according to the voltage it reads. Link to comment Share on other sites More sharing options...
Alanb Posted January 1, 2020 Share Posted January 1, 2020 I am increasingly concerned that this discussion, by concentrating on battery balancing rather than safety, is pushing Brian towards an unsafe installation When cables with increased csa have been fitted, I am tempted to wonder whether differences in battery emf and internal resisance have a greater effect than small differences in cable length/resistance. The installation of a battery fuse, as close as practicable to the battery terminal, is sound engineering practice. Balancing battery cable lengths and fitting a dedicated battery fuse is relatively simple when the batteries a in a dedicatad locker or compartment, and interconnecting cables may be as short as 300mm. The situation in a PVC, where batteries commonly installed under the front seats, is quite different. The available cable route my be considerably longer than a direct line between the batteries. In Brian's latest sketch, the positive battery interconnector, and anything connected directly to it, is entirely unprotected. Should this cable suffer an earth fault, the fault current based on battery CCA, could be as high as, 1300A, or 1600A. The resulting fireworks could be to say the least "interesting", and could possibly result in vehicle loss. Insurance companies could use the lack of fusing as a reason not to pay out. On my PVC I have 20A maxi blade fuses close to the batteries, and have found busbars or connection points essential for cable management The fuses provide simple battery disconnection points, and the busbars avoid battery spaghetti. A possible solution to the problem would be to use 2 x 50A battery cube fuses, but at about £17 per battery, they seem expensive. Perhaps the ease of installation would compensate? Alan One solution to the problem would be to install 50A battery cube fuses Link to comment Share on other sites More sharing options...
plwsm2000 Posted January 2, 2020 Share Posted January 2, 2020 BrianK - 2020-01-01 1:10 AM Thanks plwsm2000 plwsm2000 - 2019-12-31 2:39 PM I would probably use a spare midi fuse to connect the charger input (even though the charger has a built in fuse) just to protect the cable from the "bus bar" to the charger. You should be very careful to properly insulate the busbar, particulary in a PVC with a metal chassis, to avoid the risk of a fire. Would this go as close as possible to the charger or battery and what rating would you suggest? Fairly sure the one in the charger is 25A Brian, As this was intended to protect the cable and not the charger, the fuse should be placed as close as possible to the battery terminal (the fuse box that I linked to has some spare fuses). Ideally, the fuse rating should be less than the rating of the cable but greater than the 25A fuse on the charger. Something like a 30A midi fuse might be ok.. As Alan has said, you need to pay particular attention to the safety of your setup - a short circuit anywhere on the battery connections (before the fusing) is likely to be castastrophic. That is why I suggested something like that fuse box (you might even find something that bolts directly onto the positive battery stud if you have the space for it). BrianK - 2020-01-01 1:10 AM plwsm2000 - 2019-12-31 2:39 PM I also see in your diagram that you are using a "ign Live" to control the Redarc B2B. Is this live only when the engine is running (not just with the ignition switched on)? If not (and your hab. batteries are low), your starter battery will have another significant load and may struggle to start the engine. I think it is normal practise to use the D+ (or equivalent) that only goes live with the engine running. This is usually a fairly low current so you need to check the load on the B2B control signal. Are you sure this is the case with the Redarc? Extracts from operating instructions below. After looking at the Redarc manual, I realised that I had misinterpreted the function of the "blue" Ign. live wire - I assumed it enabled/disabled the B2B but it seems it is used to set the switch-on voltage threshold to 12V for smart alternators or 13.2V for "standard" ones. There seems to be a delay timer (20s max.) that allows the ignition to be switched on and the engine started before the B2B kicks in. If correct, it doesn't allow you to leave the ignition on for long. Link to comment Share on other sites More sharing options...
BrianK Posted January 2, 2020 Author Share Posted January 2, 2020 plwsm2000, I decided I couldn't really go wrong with Alan's idea of fitting a couple of cube fuses on the actual terminals so have ordered a two of these in 50A. Just have to decide which other fuses are still valid and their position now. Thanks for points about the 30A fuse between battery and charger. I'm not overly concerned about battery draw on leaving a key in the ignition because having had vans such as transits that have been known to lock out their owners I have conditioned myself just not to do it at all. However id be interested in anyones advice on how I can monitor this once the Redarc is installed just out of interest and wishing to know the system as much as possible. Brian Link to comment Share on other sites More sharing options...
BrianK Posted January 19, 2020 Author Share Posted January 19, 2020 Hello All, Trying to get back into this after having man flu so bad it ended up in a chest infection and bronchitis for three weeks *-) Not sure if anyone will be able to help but my van has one of the diesel heaters linked below and I find it rather strange that both the positive and negatives are fused (both 25A). I did read somewhere that this is only required when the heater is connected to both terminals of the habitation batteries directly but if this is the case I have no idea why. https://planarheaters.co.uk/shop?olsPage=products%2Ft5t6-vw-diesel-heater-kit-2kw-planar Brian Link to comment Share on other sites More sharing options...
BrianK Posted January 19, 2020 Author Share Posted January 19, 2020 I should have said above that this heater came with these two fuses in a ready made loom from the manufacturer. Having thought about this some more I wonder if there is a possibility this is done to cater for boats where a negative charge is used.Any thoughts anyone as my instal would be easier if could get rid of it. Link to comment Share on other sites More sharing options...
Alanb Posted January 20, 2020 Share Posted January 20, 2020 Brian I am sorry to learn that you have been ill. I think that you have answered your own question. I had not previously encounterd the term "negative charge" in relation to +ve earthed systems, with which I am familiar, but in motor vehicles these have largely been phased out. A fuse is used to protect wiring, or apparatus, from excess current in the event of an overload or fault. Like you, I cannot see how a fuse in the negative connection to a negative earthed system, is going to offer any additional protection to that given by the fuse in the positive supply wire. Alan Link to comment Share on other sites More sharing options...
BrianK Posted January 20, 2020 Author Share Posted January 20, 2020 Alan, Many thanks for the input much appreciated. I have emailed the maker with the hope they can confirm but do tend to find not many usually reply if there is no chance of a reply. Brian Link to comment Share on other sites More sharing options...
BrianK Posted February 1, 2020 Author Share Posted February 1, 2020 Hello, I'm getting there with my installation. Could anyone with a CBE 516 charger tell me if their fan runs continuously? Mine doesn't since connecting in a test set up with my new two habitation batteries but the reason for asking the question is that I'm fairly sure my fan ran all the time the charger was switched on before. `Does anyone know which one is correct? Link to comment Share on other sites More sharing options...
Robinhood Posted February 1, 2020 Share Posted February 1, 2020 I'm pretty sure the CBE chargers I've had in the past only had the fan running when required. It was very noticeable with the one installed under the front seats that the fan speed increased ( obvious from the fan noise) when the 12V system was under heavy load. It is quite possible, I suppose, that the fan was running much slower off-load, but in retrospect, I'm pretty sure that under such conditions it was inactive. Link to comment Share on other sites More sharing options...
Alanb Posted February 1, 2020 Share Posted February 1, 2020 Brian, Simple answer is NO. Fan runs briefly for a few seconds on start up, then presumably is controlled from the charger temperature. I can only remember mine operating once in this fashion, when my first set of batteries were old, and had been heavily used. Alan Link to comment Share on other sites More sharing options...
Derek Uzzell Posted February 1, 2020 Share Posted February 1, 2020 BrianK There have been occasional reports here saying that a battery-charger’s ventilation-fan was running continuously (including the odd scenario discussed here) https://forums.outandaboutlive.co.uk/forums/Motorhomes/Hints-and-Tips/Battery-Charger-PC-100HB-T/37601/ My 2005 Hobby motorhome had a CBE-516 battery-charger, as does my current 2015 Rapido. In neither case did the charger’s fan run continuously, and I would not have expected it to do so. Where the Rapido is concerned, the only time I’ve ever heard the charger’s fan run is (as Alannb has said) when the motorhome is initially connected to a 230V EHU and the charger begins to operate. The fan then runs very briefly (a couple of seconds), stops running and does not restart (or at least I have never noticed it restart...) Exactly the same thing happened with the Hobby. As the fan is there to prevent the charger overheating, it would be logical to expect the fan to only run when the charger became hot enough to require this. Otherwise the fan should not need to run. There could be occasions when the charger is working ‘hard’ and the fan cuts in and out, but continuous ‘flat out’ fan-running suggests that the charger has been installed where there is little ventilation and/or the location itself gets warm. If the charger has some age and the fan runs a lot, it would be worth taking off the charger’s outer cover and cleaning out any dust that has accumulated inside. There are on-line comments about battery-chargers’ fans running a lot of the time https://tinyurl.com/ukeybt5 but I don’t think this applies generally (or normally) to CBE 5-Series chargers. Link to comment Share on other sites More sharing options...
BrianK Posted February 1, 2020 Author Share Posted February 1, 2020 Thank you so much everyone. My gut feeling was that being off most ion the time was most likely correct and I'm now guessing it was only on continuously in the past due to the weak/old/inadequate habitation battery the last owner installed. Brian Link to comment Share on other sites More sharing options...
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