Dirtdaddy
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Re: Question on Coleman 100W Solar Panel "open circuit" voltage
CA Traveler wrote: Sounds like a short. A shorted bypass diode would not change the amps, assuming multiple diodes. I'm not sure what the bypass diode(s) function are. I assume they are in the panel, so i'm going to do some googling on the subject. Thanks for the tip to you and Jim.934Views0likes0CommentsRe: Question on Coleman 100W Solar Panel "open circuit" voltage
bigfootford wrote: Well I have never seen this phenomenon...hahahaaa. Spec ISC and low Voc.. Like a bypass diode shorted but why is the ISC at spec. Going to have to see if there is an answer from someone else or join the Northern Arizona solar elect forum... I am a member over there. If you get no answer and can not become a member when I get some free time next week I will ask over there. Jim https://forum.solar-electric.com/ Thanks for the help! Looks like an interesting forum, I went ahead and signed up934Views0likes0CommentsRe: Question on Coleman 100W Solar Panel "open circuit" voltage
bigfootford wrote: With most DVM's, set the meter to 10 amps and move the lead to the 10 amp position. If you do not you will blow the internal protection fuse for the lower amp readings. Jim. Thanks Jim, so I just checked the current using the 10 amp position on the DMM and I read close to 6 Amps (see picture). When I read the open circuit voltage it's 12.8VDC. This is with the panel disconnected from the controller. The current looks fine but the voltage is not high enough to get the controller to charge the battery more than a few milliamps even when the battery is under 12 volts. It's almost like this solar panel has a built-in regulator of its own. I can not see underneath it to read the specifications or brand, so i will have to remove it.931Views0likes0CommentsRe: Question on Coleman 100W Solar Panel "open circuit" voltage
So just one last question. I just want to confirm that the " Isc (short circuit) " test you put an AMP meter between the positive and negative leads of the panel while it's disconnected from the controller. I wanted to double check because this really is short circuiting the solar panel and i don't want to do a smoke test on it :-) Edit: while it's in full sun942Views0likes0CommentsRe: Question on Coleman 100W Solar Panel "open circuit" voltage
CA Traveler wrote: Are you using a digital meter with the panel in full sun? Voc (open circuit) and Isc (short circuit) are 2 basic checks for panel. A 100W 12V panel should have about Voc=18V+ and Isc=3A+. Thanks for the response! Yes, i'm using a digital meter (Fluke) and the panel was in full sun. I haven't tried to short it yet and read the current938Views0likes0CommentsQuestion on Coleman 100W Solar Panel "open circuit" voltage
I have what looks to be a Coleman 100W Solar Panel with a 30 amp Coleman controller in the trailer. It doesn't really charge my batteries, so I checked the open circuit voltage coming off the panel and it's under 13 Volts DC (This is when I remove the leads from the panel to the controller). I can not find a spec for the solar panel open voltage, but most other panels say it should be greater than 20 volts open circuit. Is it a fair guess the panel is shot? The controller rarely shows the indicator light it's charging, but does show the voltage of the battery.1.9KViews0likes11CommentsRe: Diodes between (-) terminals on parallel batteries. Why?
wa8yxm wrote: Dirtdaddy wrote: I think "Flapper's" response make the most sense. I think this was an attempt to balance the batteries when one was weaker and/or older and not well matched. I'm going to remove the diode circuit this weekend and replace with large AWG wire between the negative terminals. That would be my suggestion too. Also there are a lot of "Myths" about batteries in parallel Some of them are based on batteries in series. now when you take a pair of GC-2 and put 'em in series to make a big 12 volt they need to be twins. Same everything (Make, Model Age and so on) But when you put a pair of 12's in parallel.. That' not the case.. The myth is if you put say a Group 24 next to a Group 31 the 24 will "Charge faster" and convince the charger that it's full so it goes to float before the 31 is full.. NOT SO.. or that the 24 will run down faster.. again not so. What will happen.. For reference I'm going to use 70 AH for the 24 and 130 for the 31 for 200 AH total The smaller battery will take 35% of the charging current and the larger 65%.. They will hit full in perfect lock step (After the first discharge recharge cycle) And likewise when discharging they will share 35/65 and hit the cut off point precisely together..> The perfect power commune. Now in the case of older batteries that have developed a higher internal resistance.. Well then you may have something but they will work it out just not always in perfect lock step. I am the voice of experience on this. This is interesting stuff! It makes me think I could put a third battery in my trailer without too much fuss ( it would be a newer version of the same ones I bought at Costco). thank you for the help893Views0likes0CommentsRe: Diodes between (-) terminals on parallel batteries. Why?
I think "Flapper's" response make the most sense. I think this was an attempt to balance the batteries when one was weaker and/or older and not well matched. I'm going to remove the diode circuit this weekend and replace with large AWG wire between the negative terminals.895Views0likes0CommentsRe: Diodes between (-) terminals on parallel batteries. Why?
BB_TX wrote: Never seen or heard of anything like that. How many other wires are on those terminals? Honestly, it's hard to tell what was factory and what was added later. There are at least two sets of items I added (AC inverter & some accessory lighting) and a line to the Colman Solar charger/regulator that I believe was an aftermarket installation. Other than that the red wire that goes between the positive battery terminals of both batteries (no diodes) and the white wire with the opposing diodes between the two batteries on the negative terminals.893Views0likes0CommentsRe: Diodes between (-) terminals on parallel batteries. Why?
wa8yxm wrote: Not only would it prevent a stronger battery from charging a weaker battery It would prevent the converter from doing so as well.. No valid reason for doing that. The funny thing is it looks almost factory. No mention of it in the manual/schematics, so maybe someone added it.902Views0likes0Comments
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