Forum Discussion
40 Replies
- ByrogieExplorer
bcbigfoot wrote:
BC_Explorer wrote:
Getting back on topic of the MotoMaster 1000 Watt pure sine wave Inverter.
I have been testing the inverter but noticed that the voltmeter on it seems to reading the battery (which is slightly discharged) a bit low. It shows the voltage at 12.3 volts whereas the voltmeter in the trailer and a handheld voltmeter both read 12.5 volts.
I am not too worried about it, but wondering if others have experienced the same.
The meter on my inverter is similar except shows a little over 1 volt to low and the watt meter is out 25 watts, I can't remember which way. All in all not bad.
My observations when I bother to look:
Battery: 12.5
Inverter: 12.4 (always shows .1 less than battery, load or no load)
Inverter beeps (no screaming) any time volts <11.5. My coffee maker draws voltage down to 11.4 - 11.6.
I have 2x6 volt Trojans, #4 AWG to inverter - SoundGuyExplorer
BFL13 wrote:
It is the OP's job to start a thread, but our job to talk about anything we like! :)
In this case, maybe you should start yet another thread on why is it a bad idea to buy 12v 31s, but a good idea to buy T-1275s?
But first--read the "Screwy 31" thread by LY. OTOH I have no info on how that might apply to AGM 31s vs Wet 31s.
Why would I start a different thread when my posts are right on topic? :h I run my CT 1000 watt inverter with a single, 9 yr old G27 Interstate and with a fresh charge it will easily run my 550 watt coffee maker without protest but does start to squeal after a minute or so when I run my 650 watt toaster because voltage sag (which is exactly the subject of this discussion) is too great unless I load support with my truck, in which case sag is minimal and the inverter doesn't come anywhere near close to alarm. brulaz powers his own CT 1000 watt inverter with four GC-2s which clearly offer FAR more battery AH reserve yet with just a 950 watt load his inverter is also suffering sufficient voltage drop that it alarms as well. Obviously a significantly different power source with the same inverter yet with the same result - excessive voltage drop and the resulting low voltage alarm. Knowing that 12 volt batteries typically suffer less voltage drop under heavy inverter load than do similarly rated 6 volts should be part of discussions like this. :R - bcbigfootExplorer
BC_Explorer wrote:
Getting back on topic of the MotoMaster 1000 Watt pure sine wave Inverter.
I have been testing the inverter but noticed that the voltmeter on it seems to reading the battery (which is slightly discharged) a bit low. It shows the voltage at 12.3 volts whereas the voltmeter in the trailer and a handheld voltmeter both read 12.5 volts.
I am not too worried about it, but wondering if others have experienced the same.
The meter on my inverter is similar except shows a little over .1 volt to low and the watt meter is out 25 watts, I can't remember which way. All in all not bad.
( edited: should of read .1 volt not 1 volt ) - BFL13Explorer IIIt is the OP's job to start a thread, but our job to talk about anything we like! :)
In this case, maybe you should start yet another thread on why is it a bad idea to buy 12v 31s, but a good idea to buy T-1275s?
But first--read the "Screwy 31" thread by LY. OTOH I have no info on how that might apply to AGM 31s vs Wet 31s. - SoundGuyExplorer
BC_Explorer wrote:
Getting back on topic of the MotoMaster 1000 Watt pure sine wave Inverter.
6 volt vs 12 volt IS on topic as the characteristics of any battery bank directly determines how well any inverter will operate, including how much voltage drop is suffered with the inverter under heavy load. Good grief, that was the whole point of my post. :R - BFL13Explorer IIIs that with a load on the inverter? Anyway, if the inverter's idea of the voltage is less than the battery's voltage, that will make for an "early" low voltage alarm. Otherwise it is fairly harmless if it is not accurate.
- BC_ExplorerExplorerGetting back on topic of the MotoMaster 1000 Watt pure sine wave Inverter.
I have been testing the inverter but noticed that the voltmeter on it seems to reading the battery (which is slightly discharged) a bit low. It shows the voltage at 12.3 volts whereas the voltmeter in the trailer and a handheld voltmeter both read 12.5 volts.
I am not too worried about it, but wondering if others have experienced the same. - SoundGuyExplorer
brulaz wrote:
SoundGuy: AFAIK a pair of Marine G27s or G31s in parallel should have less V drop than a pair of GC2s under high loads. Their design specs include motor starting, so I guess they have more surface area or whatever that deals with that issue. But they usually have less Ah and can't do as many cycles as GC2s.
My understanding is that 12 volt "deep cycle" batteries typically have less internal resistance than similarly rated 6 volt batteries and that's the reason they suffer less voltage drop under heavy load. It seems to me this would be directly related to plate surface and thickness but in examining specs for various battery combinations I found AH rating isn't necessarily always in favour of GC-2s. For example, because "I know a guy" I can get a deal on RV Care Batteries distributed here in Canada by East Penn but which in reality are Deka batteries manufactured in Pennsylvania. The G31 flooded is 20hr rated @ 105 AH, or ~ 210 for a pair, compared to 215 - 230 AH for a pair of flooded 6 volts in series. However, the reverse is true when looking at their AGM offerings - 105 AH (~210 AH for a pair of G31s) vs just 190 AH for a set of 6 volt AGMs in series.
It's become my view that a pair of 6 volt GC-2s aren't necessarily always a better choice than a pair of similarly rated 12 volt G31s, a recommendation all too often presented here on the forums. :R For those who always dry camp and for whom maximizing battery life despite repeated deep discharge is important, sure ... but I suspect many more of us than not are only dreamers when it comes to dry camping and in fact very often only camp without shore power because we either can't get an electric site or because power to the electric site we did get has failed for one reason or another. For me that typically means I might find myself without shore power 3, 4, 5 times a season, so if I do the math there's no way that battery cycle life will ever be an issue ... the darned battery will die of old age long before it ever comes close to exceeding it's maximum number of rated cycles. :R
Secondly, although a few here are acutely aware that no battery is going to offer maximum capability if it's not treated to a proper recharge regimen the reality is that the vast majority of RV owners have no idea whether that converter / charger is handling the task correctly or not ... they simply plug their rig into shore power the next chance they get, or a genset, and just let happen whatever will happen, regardless of whether it's good or bad for the battery, and as a result my bet is FAR more batteries than not never come anywhere near close to their maximum rated life expectancy anyway. :(
Third, as prices of decent quality pure sine wave inverters continue to drop and more & more RV owners become increasingly aware of the advantages of having one in their rig for those times they may not have campsite power, it seems to me that a pair of 12 volt G31s, because they do typically suffer less voltage drop under heavy inverter load, would in fact be the better choice for many than a pair of 6 volt GC-2s, a view which unfortunately is often overlooked by the populist clamour over 6 volt GC-2s.
JMO, but I suspect many more than would care to admit would in fact be better served with a pair of 12 volt G31s than a pair of 6 volt GC-2s, for the reasons detailed. After all, why invest in maximum cycle life offered by GC-2s if you're only cycling a a few times each season while at the same time suffer excessive voltage drop under heavy load when using an inverter? Doesn't make a lot of sense to me. :R - pianotunaNomad IIIHi brulaz,
The main reason for lower voltage drop is there are twice as many cells in paralleled 12 volts vs series 6 volts. That means each cell in the 12 volt configuration provides 1/2 the amps that the 6 volts has to, provided that balanced wiring is used.brulaz wrote:
SoundGuy: AFAIK a pair of Marine G27s or G31s in parallel should have less V drop than a pair of GC2s under high loads. Their design specs include motor starting, so I guess they have more surface area or whatever that deals with that issue. But they usually have less Ah and can't do as many cycles as GC2s. - brulazExplorerSoundGuy: AFAIK a pair of Marine G27s or G31s in parallel should have less V drop than a pair of GC2s under high loads. Their design specs include motor starting, so I guess they have more surface area or whatever that deals with that issue. But they usually have less Ah and can't do as many cycles as GC2s.
BFL: 11.2v low cutoff is closer to where the warning should be I think. Mine seems wonky. It doesn't cut-out at 11.6-7V, just starts screaming. Have always backed off then as I don't want to destroy it (ahem!), so I don't know what V it actually cuts off at. Have checked my battery and inverter voltages, and there's little detectable cable (1/0) loss and the lugs are soldered and cool (unlike my previous hammer crimped lugs and #4 cables).
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