BM1 Battery Meter

Discussion in 'Tech/Mech General' started by hilldweller, Dec 28, 2013.

  1. hilldweller

    hilldweller Funster Life Member

    Joined:
    Dec 5, 2008
    Messages:
    26,432
    Likes Received:
    25,110
    Location:
    Macclesfield
    "I don't need a BM1" I've been saying for years, and I guess I didn't but now I've added a solar panel and could not get the controller in view, plus the recent thread on the BM1 I weakened.

    First, they go for £99+ on Ebay but I just bought one off Amazon for £89 delivered.

    Fitting was easy and now I'm a convert.

    I now think every whinging FUNster endlessly whining about batteries, hair dryers, inverters would benefit from one.

    The reason is simple, a great big AMPs display. It doesn't half focus the mind on where those amps are going when you can see the result of flicking that switch. The volts and remaining capacity display also give advanced warning when it's time to turn the TV off or risk a dark night.

    It also shows the other side of the coin, charging, though I've not seen this yet since it's dark, but come daybreak I'll be hoping to see the opposite of discharge.

    A good investment for the price of a tank of fuel.
     
    • Like Like x 2
  2. pappajohn

    pappajohn Funster Life Member

    Joined:
    Aug 26, 2007
    Messages:
    29,466
    Likes Received:
    16,914
    Location:
    YO11 2BD
    Huh !!! Turncoat. :Wink:
     
  3. pappajohn

    pappajohn Funster Life Member

    Joined:
    Aug 26, 2007
    Messages:
    29,466
    Likes Received:
    16,914
    Location:
    YO11 2BD
    you can save a few more amps now Brian....flog the television cos yer eyes will never be off the BM1 :Laughing:
     
  4. hilldweller

    hilldweller Funster Life Member

    Joined:
    Dec 5, 2008
    Messages:
    26,432
    Likes Received:
    25,110
    Location:
    Macclesfield
    Sorry.

    I resisted for years :Sad:

    I resisted solar for years too.

    Solar got the green light at Chester this year, so cold the battery did not last the meet. So that was a choice of second battery ( bit of room problem ) or solar which is not brilliant early in the year but might just have been enough. I went for solar as being a better all round solution on the basis some sun gives endless off hook camping but a second battery would just extend life to maybe 8 days.

    There is a fine line in all these decisions. No clear cut right-wrong.
     
    • Like Like x 1
  5. hilldweller

    hilldweller Funster Life Member

    Joined:
    Dec 5, 2008
    Messages:
    26,432
    Likes Received:
    25,110
    Location:
    Macclesfield
    Nice try, no lollipop :Laughing:
     

    Attached Files:

  6. pappajohn

    pappajohn Funster Life Member

    Joined:
    Aug 26, 2007
    Messages:
    29,466
    Likes Received:
    16,914
    Location:
    YO11 2BD
    you'll certainy need to increase the brightness on the TV Brian.....jeez, thats bright.
     
  7. Wildman

    Wildman Read Only Funster

    Joined:
    May 30, 2008
    Messages:
    15,458
    Likes Received:
    8,598
    Location:
    Ilfracombe, Devon
    with the sun this low in the sky don't expect to see much over .7 of an amp tomorrow apart from maybe at midday if the sun is shining, hee hee
    how much power is the bm1 consuming.
     
  8. jonandshell

    jonandshell Funster

    Joined:
    Dec 12, 2010
    Messages:
    5,261
    Likes Received:
    7,881
    Location:
    West Norfolk
    That £89 could have bought something useful like another battery Brian!:Laughing:
     
    • Like Like x 1
  9. jonandshell

    jonandshell Funster

    Joined:
    Dec 12, 2010
    Messages:
    5,261
    Likes Received:
    7,881
    Location:
    West Norfolk
    Of course, I am really envious because even the BM-2 isn't man enough for our 12v system!:Doh:
     
  10. dougallen237

    dougallen237

    Joined:
    Dec 28, 2013
    Messages:
    2
    Likes Received:
    0
    Location:
    littlehampton
    newbie response

    as a newbie to motorhomes this subject interests me as I am having battery problems.
    I had a second leisure battery fitted by the dealer when I brought my 3 year old Nuevo last month but they don't seem to hold any charge for long, even when empty.
    on hook up they charge quickly to 13v but drop to 3v within days, even when nothing on.
    Dealer fitted 2 new batteries but this has not helped.
    does anyone think a BM would at least help me identify the battery usage and amperage?

    thanks All. :Eek!:
     
  11. Wildman

    Wildman Read Only Funster

    Joined:
    May 30, 2008
    Messages:
    15,458
    Likes Received:
    8,598
    Location:
    Ilfracombe, Devon
    Dropping to 3v within day suggests a drain of around 8-9amps/hour someplace. If they are removed from the van and charged do they hold the charge with nothing connected
    I wonder if the fridge is on 12v and the relay gone short circuit. Or is there an inverter switched on.

    It sounds to me like a problem that the dealer should sort out under warrenty.
     
  12. hilldweller

    hilldweller Funster Life Member

    Joined:
    Dec 5, 2008
    Messages:
    26,432
    Likes Received:
    25,110
    Location:
    Macclesfield
    WHAT ?

    200*12= 2.4kW.

    That's some hair dryer.
     
  13. jonandshell

    jonandshell Funster

    Joined:
    Dec 12, 2010
    Messages:
    5,261
    Likes Received:
    7,881
    Location:
    West Norfolk
    2100 watt inverter, 4100 watt peak @ 90% efficiency = up to 339 amps at 12 volts.

    That will fry a 200 amp shunt!

    We do have occasions when that load might be placed on the inverter, for instance I might be inflating the canoe with the compressor and shell might put on the kettle!:BigGrin:
     
  14. pappajohn

    pappajohn Funster Life Member

    Joined:
    Aug 26, 2007
    Messages:
    29,466
    Likes Received:
    16,914
    Location:
    YO11 2BD
    yes, it will show current drain....but it wont stop it.

    if your batteries are dropping to 3 volts there are completely dead and will never recover.
    the 13v you are seeing is a residual/floating voltage and doesnt mean the batteries are fully charged as the voltage hasnt been absorbed by the electrolyte.

    batteries should never be discharged below around 12.1v which is 50% discharged and recharged as possible to prevent oxidisation.

    a pair of 110ah battery discharged to 50% should take at least 10 hours to charge at 15amp charge current.

    voltage shown on a meter or control panel will show 13.6 within minutes but that is showing the charger voltage, not the battery voltage.
     
    Last edited: Dec 29, 2013
  15. hilldweller

    hilldweller Funster Life Member

    Joined:
    Dec 5, 2008
    Messages:
    26,432
    Likes Received:
    25,110
    Location:
    Macclesfield
    I wonder ! What fails first the shunt or inverter. For the cost of a shunt a BM2 should be worth a punt or just ask Clipper.

    The shunt is two brass blocks with a ( guess ) copper tube soldered between them, so the solder is the weak spot.
     
    • Like Like x 1
  16. hilldweller

    hilldweller Funster Life Member

    Joined:
    Dec 5, 2008
    Messages:
    26,432
    Likes Received:
    25,110
    Location:
    Macclesfield
    Yes it will show you exactly what is going in and out of your battery, but so would a much cheaper ammeter if you just want to find your problem and cure it as a one off task.

    If you're not into electric DIY then the cost to install a BM1 is about the same as an ammeter so you might as well go BM1 and have a permanent feature.

    It looks like you've left something switch on for that kind of drain.
     
  17. haganap

    haganap Funster Life Member

    Joined:
    Dec 5, 2007
    Messages:
    11,069
    Likes Received:
    13,677
    Location:
    Heavan
    Ha ha brian..... next you will be joining us b 2b addicts
     
    • Like Like x 1
  18. Wildman

    Wildman Read Only Funster

    Joined:
    May 30, 2008
    Messages:
    15,458
    Likes Received:
    8,598
    Location:
    Ilfracombe, Devon
    Well its 19mins past 12 and still waiting for Brian to post the charge current reading from the new solar panel??????????
     
  19. hilldweller

    hilldweller Funster Life Member

    Joined:
    Dec 5, 2008
    Messages:
    26,432
    Likes Received:
    25,110
    Location:
    Macclesfield
    The sun shone and a bike needed exercise.

    At 09:30 I saw 200mA. The sun was not over the hills at that point. Even that would keep the battery from self discharge.
     
Loading...

Share This Page