Discussion:
Battery charge level error

Here's the thing...

After fully charging the batteries the BDI shows full charge and the actual battery voltage is 26,19 V.
I have load tested the batteries and three of them got 4.2 and one got 5,0 Volts.

After 10-20 mins of work BDI suddenly goes form full charge to full empty. The voltage is then 25,4 V and the battery icon flashes. Then I charge the batteries for 1 minute just to raise the voltage above the 26 V. After the key on the BDI goes to full charge again.

I've checked the power on the terminal 2 and the difference is 0,55 V. Also I've checked all the contacts on that line and all seems fine.

The batteries are weaker but it seems that they are not done yet. If it weren't for the BDI the machine would work much more.

Should I replace the batteries just to satisfy the BDI?
Is there some other way to take the most from them??
  • Posted 2 Jul 2014 02:05
  • By ivanlinaric
  • joined 16 Jan'11 - 110 messages
  • Zagreb, Croatia
Service technician.
Feel free to contact me at ivan.linaric@okretnimoment.hr
Showing items 1 - 6 of 6 results.
Those batteries are all stuffed. From full charge, raise from ground to full lift height and measure each battery while under load. Should be 6.2-6.3 no load and minimum of 5.8v under load. Even 5.8v is pushing it to be honest, i'd prefer higher but 4v is a no-no. Your voltage drop to the controller BDI input sounds acceptable if you're measuring it correctly. Compare BV at the battery plug to voltage measured at terminal 2 on the right hand terminal strip beside the charger. Ideally should be 0.5v difference max (can be hard to achieve, relay mod cures this). Any idea of battery age?
  • Posted 3 Jul 2014 20:06
  • By techno_nz
  • joined 9 Aug'13 - 138 messages
  • Canterbury, New Zealand
Thanks for your answers!
Regards!
  • Posted 2 Jul 2014 21:12
  • By ivanlinaric
  • joined 16 Jan'11 - 110 messages
  • Zagreb, Croatia
Service technician.
Feel free to contact me at ivan.linaric@okretnimoment.hr
this is just the nature of AGM batteries
when they go they go
if you look at the performance charts on lead acid v/s AGM batteries you will see that AGM batteries do out perform lead acid but the catch is the fall off rate. Lead Acid falloff rate is a progression where the AGM is more stable on the high end for a longer period but when an AGM battery gets to about 60 to 70 % discharged it drops off like a rock.
They react the same way when they get sulfated or go bad. The voltage may read ok but they don't maintain thier ability to hold a charge well and when loaded up they fail miserably.
Sort of like when your nicad or li ion batteries do in your phones.

Sounds to me like they just need to be replaced (all of them)
If you have 3 that are questionable then you might as well do all of them or you will be back in a short while with the same problem because of that ONE battery you leave in there.

:o)
  • Posted 2 Jul 2014 20:16
  • By swoop223
  • joined 23 Mar'12 - 3,691 messages
  • North Carolina, United States
You've been swooped!
swoop223@gmail.com
not really worth the effort ($) if you are paying someone by the hour, but I might try if I was stuck and could not leave until the machine moved, would be to pull the batteries and try about a 15 amp (not more) charger on each battery, separately, for an over night charge. really it is just time to bite the bullet and pay the money.
  • Posted 2 Jul 2014 20:01
  • Modified 2 Jul 2014 20:02 by poster
  • By edward_t
  • joined 5 Mar'08 - 2,334 messages
  • South Carolina, United States
"it's not rocket surgery"
Yes, these are sealed AGM batteries.
Is there anything I can try before I replace them?
  • Posted 2 Jul 2014 15:59
  • By ivanlinaric
  • joined 16 Jan'11 - 110 messages
  • Zagreb, Croatia
Service technician.
Feel free to contact me at ivan.linaric@okretnimoment.hr
my bet is these are sealed batteries?
any chance when you replace them, you change it over to a wet battery type?
sealed batteries drop out under load differently than wet batteries.
  • Posted 2 Jul 2014 11:25
  • By edward_t
  • joined 5 Mar'08 - 2,334 messages
  • South Carolina, United States
"it's not rocket surgery"

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