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In Reply to: RE: An 18 amp battery isn't much power. posted by thump on January 14, 2017 at 15:13:39
It is the bass that consumes the power. Good chargers use SOC, inexpensive ones use voltage, that can easily be misleading.
Same recommendation, get your hands on a voltmeter. I was at a hamfest today, they were selling the ones they give away as a promotion at Harbour Freight for a dollar. If that's all you can do now, it is better than nothing, I think. That is if it has .1 volt resolution that is sufficient to tell you what is going on. Or ask around, maybe a friend has a voltmeter you can borrow.
The fading power light, I disregarded, assumed it was if you switch remote or power or both. You could experiment and find out.
Follow Ups:
i ALMOST went to sears to buy a power meter as that's about the only place i think i could get a digital meter seeing both the auto & battery stores i called didn't have them, but they start at $12 for ones i could get for half that on amazon, and i REALLY wanted to get one of these $16 meters instead.when i checked to see if harbor freight had volt meters online, the only results i found were for mutimeters that start at $5. i've seen coupons for those that are free with purchase, but in maybe 1 out of 10 ads.
as it stands, i've been charging the battery for about 10 hours or more by now, and it's STILL in charging mode (under 80% charge) when the charger was saying it was at at least 80% the entire time i last charged it before hooking the new speakers up.
i'll try to see if i can find a coupon for a free multimeter. i already have 2 flashlights too many and don't need the scissors in the latest ad i saw, but i planned to go there to get a drill, some bits, solder & an iron anyways to build the system. $5 isn't a lot for a multimeter that might be useful for other things like maybe measuring amp output once i learn how to use it.
if i DID get the multimeter, it would help me test if a really nice battery tender "jump starting" charger i saw at a thrift shop works, but my experience has been electronics at goodwill NEVER work and they refuse to do "thanks for your money SUCKER!" refunds.
Edits: 01/15/17 01/15/17 01/15/17
The power meter you included the picture of is a nice one. Would be a good addition to the DC audio system you are building, but a general purpose DVM would serve you better for this problem and other uses.
Goodwill's let you plug things in, try them. When you get a meter you could bring it along to test things like battery chargers.
well, the "fancy meter" will be better as this will be a bicycle trailer system, so i'll need a permanent display. that, plus it will look nice and hopefully tell me more than just my batteries' voltages. it's programmable too so i can set a low charge threshold warning to start flashing, even if it's behind me.i'm really wondering if the charger is working right as sometimes i have to jiggle it to get the indicator lights to turn on, and i'm still not convinced they're telling me the correct status to begin with.
it seems to change its mind about the percentage or status of charge in between doing nothing more than disconnecting it and reconnecting it the next day.
if memory serves me right, isn't 13.7v a full charge and 11.2v the lowest one should go?
i just hooked the charger up, and no lights came on. i shook the charger, and it indicated 75% then charging for a second and then the lights went out again. apparently, it only charges to 13.15v.
i'm using a harbor freight meter. my coupon for a freebie was expired, so i used a 20% off coupon. NOT a fan of the needle probes instead of alligator clips. they're a pain to deal with one handed, especially with curious cats knocking them loose from "wedged in". it's too bad i can just bolt them in to my distribution blocks for semi-permanent use until i get the programmable one, but a scan of the directions mentioned turning the unit on before completing circuits.
Edits: 01/18/17 01/18/17 01/18/17
the terminals are no longer corroded. i swapped the screw & nut for new ones and dropped the washers. the only thing corroded now is the charger's negative alligator clip."testing" things is hardly ever possible at goodwill unless you bring your own interconnects & cables and if the have an amp, there's no speakers and if the have speakers, no sources or amps etc. i just don't like buying from them after having to toss a heavy $15 door-stop, i mean receiver stuck in fault mode, because it was too heavy to carry a 2nd time, but everything lit up nice on it until i made the "mistake" of connecting speakers at home. i'd rather buy used gear at a place that properly tests it and guarantees it. i think the charger was just $12, and LOOKED to be in new condition with a box. i doubt it's still there though.
everything worked fine for over an hour last night after the charger indicated a 75%, i believe, charge, until my media player's battery went dead. i do think you were right about the amp undervolting. i gave the battery around a full day's charge after that, and haven't had any issues since. i might have been drawing a lot more power than i thought when the sub was still hooked up.
there's ANOTHER issue i have to resolve as the cone made a plastic buzzing noise on a couple tracks with really deep bass when i turned the mains up to something approaching a normal listening level with the sub bridged and its input maxed plus 50% bass boost too i think. i'm thinking it MIGHT be overexcursion related as it could be an impact related buzz, but my 1st guess was a loose dustcap.
i just powered the amp back up with a low volume load, and the voltage dropped to 12.87v quickly and got down to 12.82v within a few more minutes.
Edits: 01/18/17 01/18/17
in looking up how to measure watts, i got the multimeter version of V x A = W, so i decided to give it a go and right away got a very weird result. measuring the speaker out allen screws, i get -.09v (polarity correct) on the left channel and +.03v to +.04v on the right @20v meter setting. as i suspected, the left channel IS lower in volume, but the right channel is wired out of phase too.i got -.22a on the left and +.09a on the right at the 10 amp setting on the meter.
BTW, if i'm doing the math right, that = -3.98w on the left channel and +.72w on the left channel, right?
if the front mains left channel is wired out of phase, then maybe the rear channel's left is too so that would mean i MIGHT have been bridging the sub L positive to R positive. instead of L- to R+. now i wonder if MAYBE the buzzing was related to the sub bottoming out. THAT would cause a buzz i bet.
i reversed the inputs in case it had anything to do with the media player or the cables and got the same readings.
Edits: 01/18/17 01/18/17
The small DC voltages don't mean anything, just slight leakage at the output stage of the amplifier. If you see bass deflected (pushed in or out) with no sound, then you have a problem. Follow your wires to be sure amplifier + to speaker (or crossover) + and the phase will be correct. Don't know what kind of speaker wire you are using, but most have some indicator so you can determine one lead from the other at both ends. On lamp cord, one has small ridges.
Over 13+ volts is battery float voltage. After a few minutes of playing it will drop to 12 something, that is normal. To see if the problem you are having is battery drain, play it until you hear the problem and check the DC voltage at the amplifier.
If you continue to have problems and want to talk about it, I accept e-mails, send me phone number and I will call you.
Prolly not helpfull :-)
In My dabblings with D amps I will only say these are too often Junk.
Buy Cheap = Buy twice or if Obtuse; repeatedly
You could try a Car Battery yup yank your cars' battery and see what happens when it's thge power source.
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