Solar panel readouts (1 Viewer)

Mellers42

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Apr 15, 2023
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My solar panel readouts show : solar panel voltage and current, in amps and battery voltage and current, also in amps and bulk!!
What do these readings mean, is the ampage under battery going into or out of the battery and what does bulk mean?
 
Apr 26, 2015
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The solar panel outputs voltages that are to high for battery charging so the solar controller reduces the voltage to that suitable for the battery, for lead acid battery variants there are three stages of charge routine, bulk, absorption and float, in the bulk stage the controller depending on output from the panels and the batteries internal resistance inputs as many amps as it can until the battery is around 96% charged, it will then move to the absorption phase where the controller will apply a fixed voltage depending on battery type for a set period of time, once the battery is fully charged the controller will go to the float phase where it will apply a reduced voltage intended to just keep the battery topped up against nominal discharge, as you use the battery the controller will cycle through these phases as and when required. The amps from the solar are what the panels are putting out, the amps for the battery are what the controller is putting into the battery, you would need a shunt on the battery to see the difference between what is going into the battery and what is going out, for instance the solar controller may be putting 10 amps in but the shunt might only show 8 if you also had a 2 amp drain at the same time.
 
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funflair

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Just to add to the excellent explanation above, if you are seeing solar panel Volts and Amps and battery in Volts and Amps you will notice that the Volts into the battery are lower that the solar volts but the amps to the battery are higher, this is because the power is measured in Watts which is a product of Volts x Amps.
 
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Mellers42

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Apr 15, 2023
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Autotrail cheyenne
The solar panel outputs voltages that are to high for battery charging so the solar controller reduces the voltage to that suitable for the battery, for lead acid battery variants there are three stages of charge routine, bulk, absorption and float, in the bulk stage the controller depending on output from the panels and the batteries internal resistance inputs as many amps as it can until the battery is around 96% charged, it will then move to the absorption phase where the controller will apply a fixed voltage depending on battery type for a set period of time, once the battery is fully charged the controller will go to the float phase where it will apply a reduced voltage intended to just keep the battery topped up against nominal discharge, as you use the battery the controller will cycle through these phases as and when required. The amps from the solar are what the panels are putting out, the amps for the battery are what the controller is putting into the battery, you would need a shunt on the battery to see the difference between what is going into the battery and what is going out, for instance the solar controller may be putting 10 amps in but the shunt might only show 8 if you also had a 2 amp drain at the same time.
Thanks for that, I have a 1600 inverter and I have put my wifes mobility scooter on charge. Battery was at 12.5v and I was watching the amps from the solar and the amps into the battery and the battery was steadily going down, when it got to 11v I turned it off. I have two 120 leisure batteries linked together, which I thought was a good idea, but I'm beginning to wonder, as I've since been told that if one starts to fail it drags the voltage down for both of them. Do you think I'm doing the right thing in turning off the charge until yhe voltage goes up again.
 
Apr 26, 2015
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Thanks for that, I have a 1600 inverter and I have put my wifes mobility scooter on charge. Battery was at 12.5v and I was watching the amps from the solar and the amps into the battery and the battery was steadily going down, when it got to 11v I turned it off. I have two 120 leisure batteries linked together, which I thought was a good idea, but I'm beginning to wonder, as I've since been told that if one starts to fail it drags the voltage down for both of them. Do you think I'm doing the right thing in turning off the charge until yhe voltage goes up again.
Yes you were right to stop charging as going any lower may permanently damage your batteries, with regard to linking batteries there is nothing wrong with that provided the batteries are of the same type, size and preferably fitted as a pair from new, however it is also true that if one was defective it would pull the other one down. I am not familiar with the charging requirements of mobility scooters unfortunately, but I'm sure there are members on here that do have experience with these and could better advise you on what you're best options might be. One thing to be aware of is that the voltage you are seeing at the battery during daylight is the voltage output from the panels, this doesn't mean your batteries are fully charged, the best thing to do is cover the panels with a towel or blanket let the batteries settle for 30 minutes then take a reading. Don't forget to remove the towels/blankets after.

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Mellers42

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Apr 15, 2023
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Yes you were right to stop charging as going any lower may permanently damage your batteries, with regard to linking batteries there is nothing wrong with that provided the batteries are of the same type, size and preferably fitted as a pair from new, however it is also true that if one was defective it would pull the other one down. I am not familiar with the charging requirements of mobility scooters unfortunately, but I'm sure there are members on here that do have experience with these and could better advise you on what you're best options might be. One thing to be aware of is that the voltage you are seeing at the battery during daylight is the voltage output from the panels, this doesn't mean your batteries are fully charged, the best thing to do is cover the panels with a towel or blanket let the batteries settle for 30 minutes then take a reading. Don't forget to remove the towels/blankets after.
Hahaha my Wife played merry hell with me for going on the roof to do a clean, ably supported by my two daughters, I suppose at 80 years young they have a point. Perhaps I should wait until it's dark. Thank you so much for your advice it is much appreciated.
 
Dec 16, 2017
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As regards battery voltage this is worth downloading and keeping:

battery_status.JPG
 
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Mellers42

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Apr 15, 2023
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As regards battery voltage this is worth downloading and keeping:

View attachment 739407
Wow thanks for that info., I had a glitch at the end of December when, for no reason that I know of, having not being using the van, I checked the victron battery read outs which showed a four day drop to around 4.5volts and then a slow recovery to 12.5. We went away for the New Year, left the van for a party, came back to no lights or anything. Steward at rally linked me up to mains and then we took van to local motorsave who checked batteries out with specialist pad and said they were ok, which was pretty good as I was ready to pay for new ones and make a claim as batteries are only two years old. He could have just sold me new ones but he showed me the read outs.
I now put van on mains for a couple of days before I set off. They seem to be ok now but it makes me nervous.
 
Apr 26, 2015
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Wow thanks for that info., I had a glitch at the end of December when, for no reason that I know of, having not being using the van, I checked the victron battery read outs which showed a four day drop to around 4.5volts and then a slow recovery to 12.5. We went away for the New Year, left the van for a party, came back to no lights or anything. Steward at rally linked me up to mains and then we took van to local motorsave who checked batteries out with specialist pad and said they were ok, which was pretty good as I was ready to pay for new ones and make a claim as batteries are only two years old. He could have just sold me new ones but he showed me the read outs.
I now put van on mains for a couple of days before I set off. They seem to be ok now but it makes me nervous.
I think that your motorsave guy might have given you misleading information, most places do a test that is designed for starter batteries, ie can the battery deliver the designed number of cold cranking amps for the few seconds needed to start an engine, this is not a measure of battery capacity, once a battery gets sulphated it is effectively reducing the area of the lead plates available for the chemical reaction to occur thereby reducing the batteries capacity, so a 100 ah battery discharged to 50% (a safe depth of discharge) would be able to supply a 1 amp load for 50 hrs, a sulphated battery might be reduced to 70 ah so would only be able to supply 1 amp load for 35 hours this may be the reason that you're not getting the duration of battery that you would hope for, personally I would think that if your batteries have been down to 4.5 volts they have had it.
 

pappajohn

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Agree with above, the batteries need replacing after constantly being discharged to a low voltage.
Putting them in charge will eventually give you a voltage of around 13.6v when removed from charger and soon down to 12.6v.
But.....as soon as you put a load on the batteries the voltage will drop a lot.
It isn't the voltage so much as the battery capacity....the lower the capacity the less time it can provide useful power.
Even a good battery will show lower volts under load.
Consider a starter battery showing full charge, then crank the engine......I've seen a healthy battery show 9v while cranking

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Mellers42

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Apr 15, 2023
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Autotrail cheyenne
Agree with above, the batteries need replacing after constantly being discharged to a low voltage.
Putting them in charge will eventually give you a voltage of around 13.6v when removed from charger and soon down to 12.6v.
But.....as soon as you put a load on the batteries the voltage will drop a lot.
It isn't the voltage so much as the battery capacity....the lower the capacity the less time it can provide useful power.
Even a good battery will show lower volts under load.
Consider a starter battery showing full charge, then crank the engine......I've seen a healthy battery show 9v while cranking
So is there a test you can do to test capacity, my caravan service guy did a test as well and he said they were fine but after the New Year fiasco I thought I'd better try someone else.
 
Apr 26, 2015
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So is there a test you can do to test capacity, my caravan service guy did a test as well and he said they were fine but after the New Year fiasco I thought I'd better try someone else.
There is but it takes time, this post from Lenny HB should help, he has given the voltage charts for different battery types so you can match that against your battery type.

Post in thread 'Battery' https://www.motorhomefun.co.uk/forum/threads/battery.278570/post-5482160

Edit: in Lenny's example he suggests a 5 amp load, you could provide that by wiring a 60 w 12 volt bulb across the battery terminals.
 
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