Originally Posted by
drivesafe
Even when these isolators are left in SHARED Mode, they only stay on for 72 hours and would consume roughly 12 amperes of energy during that period.
The problem being shown here ( and in other related threads ) is that batteries are dropping in voltage levels far quicker than if they had discharged just 12 amperes of capacity.
...
Folks, you have to maintain your batteries to keep them in good condition, to reduce sulphration building up.
Hi Tim,
Thanks for your information and knowledge sharing. I'm just trying to get my head around this.
Part 1 question: Your post indicates 12Ah of drain over the 72 hrs of shared mode due to the SC80. In my case I see the shared voltage drop to around 12.4V or just above before disconnecting. This would generally be considered around 80% SoC for AGM as I understand it. I have a combined 150Ah (C20) of battery (95Ah main + 55Ah aux) so that lost 20% equates to around 30Ah which is nearly three times the SC80 drain. In the three days after disconnection I'll see much less than an additional 0.05V drop on the main (and nothing on the aux) which equates to less than 5% SoC or <5Ah. To be honest the voltage drop after isolating is negligible and hard to measure accurately. To me those numbers just don't align so I am looking to understand if there is something I've missed. Is there some sort of interaction that keeps the car awake more while the SC80 is linked? Why does the voltage of both batteries recover nearly 0.1V as soon as they are unlinked? Am I better off bypassing the SC80 at the moment and hard-connecting both batteries while still in infrequent semi-lockdown use?
In my Disco 1a I have two Optima 55Ah blue-tops. Either side of the engine bay. One is pretty old, the other is less-old. Hard connected via a simple rotary isolator switch, but I leave them connected. I can (and regularly do) leave that vehicle for two months and hop in it and fire it no worries. That's a very high compression large(ish) capacity V8. Granted lower parasitic losses but also less battery capacity and a much, much longer timeframe. If I leave my L320 for just a week it'll grind over slowly and not start with confidence at all (TDV8) whilst reporting a very low cranking voltage.
Part 2 question: What's your recommended recovery/maintenance cycle? Is it something cyclical like solar (charge, rest, charge, rest, charge, rest, etc)? Is it hook up to a reputable 5-7 stage smart charger and just leave plugged in all the time? Should both batteries be connected when charging or individual?
DiscoClax
'94 D1 3dr Aegean Blue - 300ci stroker RV8, 4HP24 & Compushift, usual bar-work, various APT gear, 235/85 M/Ts, 3deg arms, Detroit lockers, $$$$, etc.
'08 RRS TDV8 Rimini Red - 285/60R18 Falken AT3Ws, Rock slider-steps, APT full under-protection, Mitch Hitch, Tradesman rack, Traxide DBS, Gap IID
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