Charge Controller Gets 19.5V from Panels, but Sends 11.7V to the Batteries?

[eric@psmnv]

Total noob here.

When I connect a voltmeter to the panel side of the charge controller during direct sunlight, it reads 19.5V. But the battery side of the charge controller reads 11.7V. What's going on?

We used to start our generator with a pull, but we saw it has an electric starter, so we hooked the ignition to the battery bank. That seemed to work great, but recently we noticed that the genny was taking longer to start. It used to take about 1 second, but in the past couple of weeks it turns over for several seconds before starting. A few days ago there was a spark on the cable that leads from the starter to the negative battery terminal. It looks like the genny drew too many amps and melted the wire at the terminal end. We re-attached it and it started fine. Did we damage the batteries so they no longer take a charge from the controller?

[Mike90250]

If you measure the battery at 11.7v and come back 30 min later (while the solar is charging it) does the voltage go up any at all ?

11.7V is a pretty low battery

[SunEagle]

If you measure the battery at 11.7v and come back 30 min later (while the solar is charging it) does the voltage go up any at all ?

11.7V is a pretty low battery

Or in other words a dead battery.

[eric@psmnv]

If you measure the battery at 11.7v and come back 30 min later (while the solar is charging it) does the voltage go up any at all ?

11.7V is a pretty low battery

The sun had been strong on the panels for a couple hours when I took the measurement.

The battery bank accepts a charge from the generator, though. I run the generator for an hour or so and battery voltage goes up to 14.0 while charging. For a little while after I turn off the generator, voltage is at 12.8 (surface charge). Then settles down to 12.5, and then gradually decreases over the next several hours as I put load on it.

[eric@psmnv]

Or in other words a dead battery.

You sure? See my comment to Mike90250 above.

[GeorgeF]

Perhaps you can try this:
Disconnect all from the chargecontroller. Then connect the cables from the battery to the controller before connect to the panels.

[SunEagle]

You sure? See my comment to Mike90250 above.

Well they might not be "dead" but when a 12V battery is only 11.7V it usually means they are at the end of life and will probably not hold a true charge under load.

Through experience I found a battery that "quickly" charged up to 12.7V and then dropped quickly under load was no longer a viable storage system. Your's might still have a little life in them but I would not trust them to give you anywhere close to what they use to.

[eric@psmnv]

Well they might not be "dead" but when a 12V battery is only 11.7V it usually means they are at the end of life and will probably not hold a true charge under load.

Through experience I found a battery that "quickly" charged up to 12.7V and then dropped quickly under load was no longer a viable storage system. Your's might still have a little life in them but I would not trust them to give you anywhere close to what they use to.

It's a bank consisting of 8 x Trojan T105 batteries, purchased new in March.

[SunEagle]

It's a bank consisting of 8 x Trojan T105 batteries, purchased new in March.

I understand now. The batteries are relatively new but the CC may not be performing properly if it is only sending 11.7 while charging. Sorry for my confusion.

Although it sounds like you have a paralleled wire system (2S4P) which may be one of your issues.

[eric@psmnv]

I understand now. The batteries are relatively new but the CC may not be performing properly if it is only sending 11.7 while charging. Sorry for my confusion.

Although it sounds like you have a paralleled wire system (2S4P) which may be one of your issues.

That was our conclusion too. Thanks for adding some confirmation. We're ordering a new CC. Also, yes, we have a 2S4P bank. It was inherited from the previous owner. The whole thing will be replaced with a larger/newer/better system soon.

[mlsadler]

Hello am having an issue with my solar system, i have 18 panels of 290W each wired in 6 strings of 3 panels per string all connected through a combiner box, the combiner box outputs to a victron MPPT 150/85 charge controller, which is used to charge 24 2V 600AH batteries in series which makes a 48V 600AH battery bank, the Charge controller charges so fast and goes into float when the batteries are not fully charged then cuts down on the current, the color monitor will be showing SOC at 85%, but when i connect a load on the panels generate enough power to ran the load, but the batteries never charge to 100% with the charge controller yet when i charge the battery bank using a victron multiplus 48/5000/70-100 it fills upto 100% and the SOC of charge on the Color Control GX shows 100%, what could be the problem with my charge controller?

[Mike90250]

While charging and at the completion, have you measured your batteries specific gravity ? How often do you Equalize ? Add water ?

[mlsadler]

My solar system consists of the following setup

Victron Color Monitor GX firmware V2.42, Multiplus 48/5000/70-100 firmware 413, Battery Monitor BMV-712 smart firmware V4.03 charged voltage 55.4V, smartsolar charger MPPT 150/85 rev2 firmware v1.47 absorption voltage 55.7V float voltage 55.4V, a battery bank of 24 maintenance free batteries each 2V with the following specs Float 2.23-2.25V Boost 2.30-2.32V Current 60 to 120Amps, 18 Solarworld panels each 290W

The challenge am facing is over night the batteries discharge up to 75% and when the sun rises, the batteries charge up to 90% and the charge controller moves from bulk direct to float and skips absorption stage so the batteries don't get fully charged they only charge up to 95% with full 8 sun hours, what could be the problem with my solar solution

[Mike90250]

you have to read your manual and verify the configuration of the controller is correct. After correcting it, AT NIGHT, disconnect PV and then disonnect battery, Reconnect battery and then after controller boots up, connect the PV and see if the instructions took in the morning