samsung tv/dvd inverter when dvd on

"Mismatched batteries should not be paralleled when not charging, however if the load is enough to drain (discharge) BOTH or all batteries it's fine." is the converse of not having enough charger/alternator capacity to lift battery terminal voltage above their OC (Open Circuit) terminal voltage. IOW one battery could be charging the other battery. EG - if a 12.7V battery and 12.2V or 10.2V battery are paralleled to a charging voltage of (say) 13V or higher, the 12.7V battery cannot discharge into the lower voltage battery(s). [Hence not allowing possibly huge battery-supplied currents into the lower battery(s) - something many argue is dangerous.] Discharging is similar but where the load drops the voltage of both batteries below the Open Circuit voltage of the lowest battery, hence even the lowest battery is discharging or NOT being charged by other batteries. Re voltage measurement, it's across each pair of monoblock terminals - a monoblock being each physically individual battery. [ 6 series 2V batteries is a battery. 6 series 2V cells is a battery. 2 series 12V batteries as a battery. 2x2 series/parallel 12V batteries is a battery. A 432V battery (36 series 12V monoblocks) is a battery and 2 or 10 of those in parallel is still a battery. ] Assuming "proper" interconnection & sizing, when paralleled the voltage across one battery must (or should) be same as all other paralleled batteries and loads. Measurement is a question of degree. You might chose to have a single monitoring voltmeter across the parallel interlink (or perhaps 2 series batteries...) to confirm the charge or system voltage or the overall SOC (state of charge) is acceptable - have you reached your minimum voltage yet, or is your charging voltage too high, etc? But to negate voltage drops along cables and across connections, full or manual testing is across each pair of monoblock terminals. So it's a case of how confident are you about interconnection integrity - being in parallel, is the terminal voltage of each battery the same? [ In series, under 28.8V charging one 12V battery might be gassing away at 15.2V whilst the other is undercharging at 13.6V, and that situation will self escalate hence the importance of matching series batteries for BOTH charging and discharging. ] From a monoblock condition or health POV, measure across its terminals, not from one -ve to another battery's +ve with whatever voltage drops in between. I doubt your motorhome has a brushless alternator, they are almost unheard of outside of marine & (some) motorbikes, RVs, scooters, competition vehicles, etc.     I'm not sure what you mean by your Watt meter readings. If between the panel controller and battery, then it will measure power from solar to battery and load. If no load, then it measures battery charging power - ie, close to zero (float power) if the battery is full, or zero if solar output voltage is less than battery OC terminal voltage. If between panel(s) & controller it will behave the same plus whatever power the controller consumes.

Great details and knowledge gain. I'm just comfortable with one area of Q&A Solar -> Cable -> Multimeter Read = 22v - 24v Solar -> Cable -> Multimeter Read = 12.v <=> 14v -> Controller (Controller attached) -> Battery Bank ie. When I isolate the controller and the battery - The readings are different pre-hitting the controller While we are on this Ac/Dc ---- Which is better for motorhome use on 12v irrespective of the TV Specs (Links below) 1) Axess TV running on AC/DC (TV1701-32) but they threw in a 12v cord $240    Just plug into a cigarette port ... 2) Axess TV made for AC ONLY (TVD1801-32) but they threw in the DVD.. which is nice but i don't care...$244    (Not sure of the AMPS draw.... Though i could connect to my inverter OR if the DC input is 12v (which they don't tell) after step-down transformer ... i could hook directly anyways using the right port connector A 19" of the same company pulls Operating=32w, Standby=1w Link.1 = http://www.amazon.com/gp/product/B00BEJSJRW/ref=ox_sc_act_title_4?ie=UTF8&psc=1&smid=ATVPDKIKX0DER#productDetails Link.2 = http://www.amazon.com/gp/product/B00BCS1XZ0/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A5W45QDYAHWB2#productDetailsalphabeta

Thanks for the knowledge gain. I do write too much but it mirrors a practical tuition class that may include alternate explanations or analogies, various dependencies, considerations and traps. The problem tho is not giving too much or worse - confusing the basics instead of emphasising them and showing how "simple" they are. [ More importantly to me is NOT having tunnel vision. IMO so many have arguments with me because they don't see past their rut nor understand other interactions - aka the big picture - and they confuse situations & theory, The Red dude is a classic as was a recent deleted thread hereon. In person verbals or classrooms rarely have such problems because if real time interaction & adaptation. (And for some reason, people seem to avoid getting personal in person. I often wonder if they would if remote writing?) ]     Anyhow, it was not my last reply that was epic I thought it was. Ok, I think the voltage drop with/without controller from the solar panels is easy - it's a typical "non ideal" power source. Jump to the diagram/graph below, or read the following if needed.     The ideal power source (battery, generator, solar panel, partner) has no resistance, ie a "zero-impedance power supply". That means no matter what load is placed on them, they retain constant voltage and no voltage says (brown outs etc). In the case of partners, it means that despite them gibing you the support or strength for real life, they exhibit zero resistance to your directions - ie, scratch back, find keys, do shopping, empty garbage, earn income. Alas it's not an ideal world. A battery is (modeled as) an ideal battery (eg always 12.67V with infinite current etc) and a series resistance (often referred to as ESR = Equivalent Series Resistance which increases in resistance as the battery discharges). Hence a fully charged 12.7V battery with ESR of 10mR supplying 100A with have a terminal voltage of 12.7 - (100A x 0.01 Ohm) = 12.7 - 1.0V = 11.7V. (FYI - The same battery if ~10% discharged (ie, 12.5V) might have ESR = 15mR hence 12.5V - (100A x 15mR) = 12.5 - 1.5V - 11.0V.) For solar panels, look at www.reuk.co.uk's Measuring the Power of A Solar Panel for the fllowing: So no-load or no controller connected panel output is the highers voltage - ie, the y-axis "Voltage" value when Current = 0A. Add a load and current increases. The panel voltage will be as read off the graph above - ie, the Voltage corresponding to the point on the curve with whatever current - aka the Operating point. If that voltage is close to zero, then that panel is undersized for that load at that light intensity - maybe it's night time or cloudy? Of course if the voltage is less than the battery terminal voltage, the panels won't be supplying any power. [ That's why MPPTs are used - apart from possibly including boost converters, they will sit at the maximum POWER point of the curve - which may be 17V for that light power and panel - and buck convert to 14.4V charging or a float of 13.4V at the battery terminals (else MPPT output). ] BTW - That VI curve is similar across many power sources and circuits - eg, batteries, zenor regulators, alternators.    TV-wise I'd buy neither since neither are FULL HD. (Even my 23" PC monitor is FULL HD if not better.) But otherwise - all things being equal, the unit with 12V connection especially since it comes with a cig-socket interface hence - unless that interface cord includes a regulator converter - meaning that its 12V DC input is indeed automotive 12V - eg up to 15V or 16V and lower than 12V without damage. The AC-only version requires an inverter (DC-AC) which adds cost and inefficiency (probably ~30% of the load), and usually quite a high standby current (often 10W or more). And similarly, an equivalent (automotive) DC DVD. Tho I no longer have to carry an inverter (and a spare) to run my stuff because I have gradually sourced dc versions or supplies (cheaply!), I still carry a small inverter (but no spare) as a fallback in case of dc adapter failures. AC/DC options are great for terrestrial travelers. (And for some, AC-DC is a good band, but I'll limit my pun/joke to that...) FYI - for some reason many think that (modern) dc dc converters have no AC and hence no electrical noise. Except for linear down converters, AC is involved in all dc dc conversion. In fact dc-ac inverters should be "quieter" than dc-dc converters because inverters are only dc-ac whereas (non-linear) dc-dc converters are dc-ac-dc. But their design means that the inverter AC output usually causes the noise. However, some dc-dc converters are known to be far noisier than almost any inverter - they can cause havoc to FM & TV and even GPS reception, and effect car audio, PCs, etc. (Dare I mention the M4 car PC supply?)