andrew.halls2309gma Posted November 16, 2020 Share Posted November 16, 2020 Hi all Setting up my solar trickle charger for winter storage and I noticed that my van battery was only at 12.2V. When the engine is running I'm getting 13.8-14V, so charging okay and when I switch off it drops to 12.7V and stays at that for a couple of minutes but over about a 5 minute period it steady drops to 12.2V and then stays there. The van starts quite easily and it is a new battery (only about 4 months old), I just don't understand why it drops down to what I believe is about 50% charge. I have basic knowledge of van electrics but not the technical stuff, am i missing something? Any advise gratefully received As always thanks in advance Andy Link to comment Share on other sites More sharing options...
Keithl Posted November 16, 2020 Share Posted November 16, 2020 "Van Battery at 12.2v" Time to charge it! Keith. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted November 16, 2020 Share Posted November 16, 2020 Andrew's motorhome is 2008-vintage and based on a Renault Master chassis. The vehicle was discussed here about a month ago. https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Replacement-Lunar-Champ-over-cab-skylight/56548/ Although a 12.2V reading would suggest a 50% state of charge, that diagnosis would only be reliable if the reading had been taken when the battery was disconnected from the vehicle and had been allowed to ‘rest’ for several hours without receiving any charge. Mt wife’s Skoda car exhibits similar behaviour. If I fully charge its newish starter-battery with my CTEK charger, let the battery rest for (say) 4 hours and then take a reading (with an known-to-be-accurate multimeter) at the battery’s terminals, the readout suggests that the battery is heavily discharged. As it’s plain from the immediacy and vigour of the car’s starting that the battery is actually well charged, I’ve learned to accept this phenomenon. There must be something about the Skoda’s electrical system that skews the voltage reading, but I don’t know what it is and - as there’s no obvious negative symptoms or effect relating to the low voltage reading - I don’t care. Link to comment Share on other sites More sharing options...
colin Posted November 16, 2020 Share Posted November 16, 2020 Are you using the trickle charger on the van battery, and what output is it. Link to comment Share on other sites More sharing options...
Keithl Posted November 16, 2020 Share Posted November 16, 2020 Running the engine for a few minutes will artificially raise the voltage at the batteries terminals. As has already been stated you need to let the battery rest for several hours to get a true reading. I would still recommend a minimum 24 hours charge with a quality charger before allowing to stand and measuring again. Keith. Link to comment Share on other sites More sharing options...
andrew.halls2309gma Posted November 16, 2020 Author Share Posted November 16, 2020 colin - 2020-11-16 2:27 PM Are you using the trickle charger on the van battery, and what output is it. Yes it's charging the van battery Simple system 20W, 12V panel through a charge controller (with overcharge protection) to keep the battery charged over winter, worked fine last year Link to comment Share on other sites More sharing options...
andrew.halls2309gma Posted November 16, 2020 Author Share Posted November 16, 2020 Keithl - 2020-11-16 2:36 PM Running the engine for a few minutes will artificially raise the voltage at the batteries terminals. As has already been stated you need to let the battery rest for several hours to get a true reading. I would still recommend a minimum 24 hours charge with a quality charger before allowing to stand and measuring again. Keith. The readings came after a 40 minute drive which I would have thought would be enough to charge the battery up to a decent charge Think I will put it on charge and re-test Link to comment Share on other sites More sharing options...
andrew.halls2309gma Posted November 16, 2020 Author Share Posted November 16, 2020 Sorry new to this think I should have used the "quote" instead of "reply" to reference the answers to the questions Link to comment Share on other sites More sharing options...
Keithl Posted November 16, 2020 Share Posted November 16, 2020 andrew.halls2309@gma - 2020-11-16 4:10 PM Sorry new to this think I should have used the "quote" instead of "reply" to reference the answers to the questions Corrected for you :D Link to comment Share on other sites More sharing options...
Brian Kirby Posted November 16, 2020 Share Posted November 16, 2020 andrew.halls2309@gma - 2020-11-16 1:01 PM Hi all Setting up my solar trickle charger for winter storage and I noticed that my van battery was only at 12.2V. When the engine is running I'm getting 13.8-14V, so charging okay and when I switch off it drops to 12.7V and stays at that for a couple of minutes but over about a 5 minute period it steady drops to 12.2V and then stays there. The van starts quite easily and it is a new battery (only about 4 months old), I just don't understand why it drops down to what I believe is about 50% charge. I have basic knowledge of van electrics but not the technical stuff, am i missing something? Any advise gratefully received As always thanks in advance Andy What are you using to measure the battery voltage - a stand alone multimeter, the van control panel, or other? But, as the battery is only 4 months old, it should still be under warranty. It would be useful to know when the van was last used, or on EHU, to the extent that the battery could be assumed to have been fully charged. That might indicate whether the battery had, in fact, run flat while standing, so that what you are seeing is only the transient consequence of having 14V put through it for insufficient time to do any beneficial charging, which then rapidly subsides back to its true state of charge. You'll need a decent multimeter for the next bit. To start, can you remove the solar charge and get the van on EHU for 24 hours or so, and then disconnect the EHU it and leave the battery to rest (as suggested above) for a few hours, and then take a voltage reading? If the Voltage then looks healthy, and is not visibly declining, disconnect the + lead from the + battery terminal, and monitor it's Voltage at the terminals hourly for several hours, noting the Voltages and times. If this shows the battery Voltage continuing to fall over, say, 12 hours (or less), either something was draining it, or it is a dud battery. To know which, you'll need to use an Ammeter (the multimeter should have this function, but read the manual carefully on using the Amps function before connecting it) between the + lead and the + battery terminal, and look for current flow. If you see one, start pulling the 12V fuses one at a time to see which stops the drain. When you find the right fuse, you'll then need to check everything fed via that fuse to identify the actual source. If, however, when the ammeter is connected, you see no (or very, very, little) current flowing, it is most probable that the battery has a high rate of self-discharge and is, in effect, a dud. Link to comment Share on other sites More sharing options...
colin Posted November 16, 2020 Share Posted November 16, 2020 As your system worked ok last year, then have you changed anything, even something seemingly small? Maybe added a B2B, or Alarm, or USB outlet, is the panel shaded more than before? Link to comment Share on other sites More sharing options...
witzend Posted November 17, 2020 Share Posted November 17, 2020 Here's the setup I've been using successfully for several years to keep my engine battery charged from leisure battery's which are charged by solar http://www.motts.org/BRIDGING%20FUSE.htm Link to comment Share on other sites More sharing options...
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