steve hill Posted August 31, 2020 Share Posted August 31, 2020 Just walked into the parked up van ( no mains power) and found the B2B charger fan was running. When I checked the caravan side battery I found it at over 14.2v and the Fiat engine battery about 13v. It appeared the solar panels were charging the engine battery as they were high enough. Is this normal if there is loads of solar power and a good caravan side battery. I disconnected one of trhe 2 solar panel ouputs and the B2B went off. It may well have stopped anyway when the engine battery got higher and I would not have known? Link to comment Share on other sites More sharing options...
Steve928 Posted August 31, 2020 Share Posted August 31, 2020 Yes that's a normal scenario if your solar is also charging the cab/van battery. Once the voltage of the (host) battery is raised above 13.3V the B2B will activate, if it is in the default automatic mode. The solution, if either EHU or solar charge the cab battery, is to use the B2B's manual mode triggered either by the alternator's D+ signal or a switch. Link to comment Share on other sites More sharing options...
steve hill Posted August 31, 2020 Author Share Posted August 31, 2020 Hi Steve 928, no I don't think thats right, my solar panel that I put in is only connected to the caravan battery, the original cannot be connected to the engine battery as it shows no sign of charging that battery. It is only when the B2B is working(fan was on) was on that the engine battery registered a charge. The B2B host battery is surely meant to be the engine battery which passes current to the caravan battery when it is running the engine at about 14.7ish? I would be happy to be shown wrong please explain. Link to comment Share on other sites More sharing options...
Steve928 Posted August 31, 2020 Share Posted August 31, 2020 Having re-read everything I understand your question better Ithink; you think that the B2B, which is wired as usual to charge the hab battery from the cab battery, is actually doing the opposite and charging the cab battery from the hab battery once the hab battery is fully charged? If that is the question then, no, that isn't possible to my mind. Do you have any other devices installed such as a Battery Master, which could produce the results that you are seeing i.e the cab battery voltage being raised enough to activate the B2B? Link to comment Share on other sites More sharing options...
Deneb Posted August 31, 2020 Share Posted August 31, 2020 I'm not familiar with Sterling B2B chargers, but my Votronic B2B charger has a facility to divert a small charge to the vehicle battery. It sends a current of up to 1 amp to the starter battery whenever the habitation battery voltage exceeds 13.1 volts (13.5 volts if programmed for LifePO4) and switches off if the leisure battery voltage drops below 13.0 volts (13.4 volts LifePO4). The feature is automatically enabled if the B2B is connected to a D+ signal, following the first instance of receiving a signal on that connection, and disabled if the B2B is installed to operate via voltage sensing only. So effectively, whenever the leisure batteries are receiving current from the solar panels, since even the solar float voltage is above 13.1 volts, the vehicle battery charging branch of the B2B is enabled. Link to comment Share on other sites More sharing options...
steve hill Posted August 31, 2020 Author Share Posted August 31, 2020 Good to know, happier now I think thats happening. The B2b works fine normally, kicking in if required to charge the cab battery. I had a fully charged cab battery plus about 100 watts of midday sun when it was charging the engine battery from the cab battery. As I said the engine battery was at over 13v so was obviously getting a small charge as it should have read about 12.6 or less as it does normally when on a small gradual load from the alarm/radio etc. I will read all the paperwork again or ask Sterling to be sure. Thanks to all Link to comment Share on other sites More sharing options...
Steve928 Posted September 1, 2020 Share Posted September 1, 2020 Do let us know what you find out from your documentation or Sterling, please, as my Sterling B2B (BBW1220) certainly doesn't have this function. Link to comment Share on other sites More sharing options...
steve hill Posted September 1, 2020 Author Share Posted September 1, 2020 There is no mention of the charging of the engine battery in my sterling BB121250 paperwork. I think though the cabin electrics are feeding the power back to the engine battery when the cabin battery is really high to top it up. So it would be a Rollerteam thing, then the B2B starts up when the engine battery reaches 13Vish but should shut off when it sees the cabin battery is 14 (after the 20 minute boost cycle). Of course I cannot retest until I have the same big solar input..... Link to comment Share on other sites More sharing options...
Steve928 Posted September 1, 2020 Share Posted September 1, 2020 Perhaps you have something like a Battery Master fitted (if your van had a previous owner) which tops up the engine battery from the hab batteries. These are a common fitment when, for example, solar is connected only to the hab batteries. https://www.vanbitz.com/product/battery-master/ Either way, to me, your setup with what appears to be a loop between batteries doesn't sound ideal and if it were mine I'd be changing the B2B to D+ activation i.e. only when the engine is running. Link to comment Share on other sites More sharing options...
steve hill Posted September 1, 2020 Author Share Posted September 1, 2020 MMMM, as far as I am aware there is no switch on my option, the +cable is connected to the alternator/battery connection, the only switch is for battery type. A Battery Master would have to be well hidden, I think I would have seen it when I installed the Solar and B2B? I did not get this problem on my last van a Swift Royal that did 170,000 and had lots of sun but half the solar power. I am still thinking its the RollerTeam bit and am waiting for very sunny day to retrest it, as we all are.. Link to comment Share on other sites More sharing options...
Steve928 Posted September 1, 2020 Share Posted September 1, 2020 Yes, sorry, looks there isn't a manual/switched activation mode with yours - oh well. My Sterling B2B has these yellow+black cables pictured which can be used to over-ride the automatic voltage-related activation: with yellow/1 connected to the alternator D+ it is inactive unless the alternator is outputting charge. I'd assumed this would be a standard feature across the Sterling B2B range. Link to comment Share on other sites More sharing options...
arthur49 Posted September 1, 2020 Share Posted September 1, 2020 Just a thought ..... Has the existing split charge relay been disabled, assuming the B2B has its own D+ signal? If not, I wonder if this is confusing the B2B. Link to comment Share on other sites More sharing options...
steve hill Posted September 1, 2020 Author Share Posted September 1, 2020 No as the split charging worked prior to installation of the B2B. So far I have only been there once when this has happened.I will also try putting on mains supply to the cabin and turn on the cabin main switch, to help boost the cabin battery to see if it causes the same effect as the solar. Link to comment Share on other sites More sharing options...
arthur49 Posted September 1, 2020 Share Posted September 1, 2020 steve hill - 2020-09-01 4:02 PM No as the split charging worked prior to installation of the B2B. . Now I'm confused Steve! Are you saying that the split charge relay that existed prior to installation of B2B is still in place, it has not been disabled? Link to comment Share on other sites More sharing options...
steve hill Posted September 2, 2020 Author Share Posted September 2, 2020 The normal facility of the engine charging the cabin battery was functioning it is not necessary to disable this because you put in a B2B. Link to comment Share on other sites More sharing options...
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