Leisure Batt Just Exploded

Discussion in 'Mech Tech' started by AndyBcountry, Jul 30, 2020.

  1. scrooge95

    scrooge95 Moderator and piggy bank keeper

    Ah fair enough. I think mine maybe has the temp sensor stuffed in the plug hole as the temperature reading definitely changes (assume therefore it’s reading the temp inside the wardrobe as opposed to the battery temp!)
     
    Valveandy and Lasty like this.
  2. That's good news as mine is in the spring cover above the back door and I've not looked at the temp since fitting . I think Mike said they stop charging and dissipate the excess solar into the heat sink at about 40* ?

    Sent from my SM-G960F using Tapatalk
     
    scrooge95 likes this.
  3. mikedjames

    mikedjames Supporter

    Its probably fact the wardrobe is usually hotter than the engine bay that keeps it working safely .

    I have seen my epEver shut off in the heat as the sun shines on it.


    Big battery chargers will have temperature sensors because the current they put out can heat a fully charged battery noticeably. A 5 amp charger produces 50-80 watts of heat , which the battery can manage.


    Very few big chargers are simply bang-bang 0 or full output current.
    They control current to control the battery voltage, so a 10 amp charger only delivers that current into a battery below a certain voltage.

    Solar chargers are generally seen as "big" as they put 100 watts or 200 watts of energy , or more into the battery.

    Depending on sophistication smart chargere then target different voltages over time, maximising fast charge by increasing voltage to 14.4 volts or more for a while, then backing off in steps to end up at maybe 0.1 amps float charge.

    The problem is the high current/ high voltage phase is temperature dependent, and has to be reduced as the battery gets hotter or else...


    My maintainer type charger delivers 10 amps at 13 volts and basically 0 amps at about 14 volts unless it gets hot. Its just a straight line graph.

    The other problem is that some smart chargers like my car battery charger will go into 'safe' mode if there is more than about 0.2 amps drain from the battery while charging, resulting in the battery never reaching one of the higher voltage levels at low charge current after a few hours.
    Not useful for a camper van with domestic loads on the battery.

    An epEver temperature sensor in a silly place .
    20200731_105705.jpg
     
    jim mcglynn likes this.
  4. Zed

    Zed Gradually getting grumpier

    Left 24/7 in unrestricted Lancashire sunshine, my solar boiled the battery. I topped it up and it never did it again...because by that time the solar panel was on it's last legs.
    :mad:
    From now on it's split charger relay and hooked up 10A CTech for me.
     
    cunny44, snotty, 77 Westy and 2 others like this.
  5. That makes a lot of sense.

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  6. mikedjames

    mikedjames Supporter

    I have relocated my temperature sensor to under the quick release clamp on the leisure battery.

    By the way the epEver sensor is a Negative Temperature Coefficient (NTC) thermistor which is 40k ohms at 25C , conveniently thats how hot it was when I tried it.
    This means you can extend the wire to it using almost any size wire and its not polarity sensitive.
     
  7. scrooge95

    scrooge95 Moderator and piggy bank keeper

    Maybe I can look at yours at techenders?! (Snigger!)
     
    Lasty, F_Pantos, mikedjames and 2 others like this.

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