Voltage inconsistency

[woodwardable]

I have four 12V 170 AH BigBattery batteries connected together in parallel, that are then being split into two outputs with a reversed parallel cable. One output runs directly into my RV while the other leads to a 100 amp Renogy solar charge controller (1200 watts of solar panels are connected), a 1,000 watt renogy inverter, and a battery monitor.

The inverter and charge controller continuously screech low voltage alarms, while the battery monitor and the batteries themselves (the batteries have a voltage monitor screen) say everything is fine. I turned off the solar charge controller alarm because I feel like the batteries are more accurate. I’m wondering why the charge controller and the inverter are inaccurate? Does it have to do with the fact that I split the batteries into two connections from the source? I also just installed the fourth battery recently. Maybe this could have something to do with it? Everything has been fine for the two months leading up to the fourth battery installation.

 

[snoobler]

Your wiring and/or connections are producing an excessive voltage drop between the battery bank and the inverter.

 

[HRTKD]

How much cable distance is involved here?

 

[woodwardable]

How much cable distance is involved here?

Not much - less than 10 ft in all but there are four different parallel connections happening

 

[woodwardable]

Your wiring and/or connections are producing an excessive voltage drop between the battery bank and the inverter.

I figured, thanks for the feedback!

 

[HRTKD]

Not much - less than 10 ft in all but there are four different parallel connections happening

What gauge wire?

 

[woodwardable]

It’s 10 awg for all battery connections. 8 for the SCC and 6 for the inverter.

 

[snoobler]

1000W/12V = 83A for inverter, 6awg is good for about 75A @ 90°C insulation
1200W/14V = 86A for SCC, 8awg is good for about 55A @ 90°C insulation

10awg for all battery connections? Huh?

Could we get a pic?

 

[HRTKD]

In the above post, Snoobler did the math, similar to to what I did. Depending on how you have this wired up, there is at least a 4% voltage drop, potentially a lot more than that.

As asked in the above post, we need to see what you're doing. A picture or a diagram would really help.

 

[snoobler]

Yep. Using 10' and 80A, I was seeing 0.6V drop.

 

[woodwardable]

Sorry for the late reply- hell of a week. I made a mistake here. 6 awg wire for all battery connections, 1/0 awg for the inverter and 4 awg for the 100 amp charge controller (110 amp circuit breaker connected).

it’s hard to get a clear picture in the crawl space so I drew some diagrams.

the battery cables are 5’ a piece, while the inverter wires are 6”, and the charge controller wires are 5’. I don’t think the battery charger wires matter in this setup?

additionally, my battery charger keeps giving me a “low output voltage” message and I’m not sure if it’s related?

 

[woodwardable]

Having some issues uploading photos - this is an attempt

 

[time2roll]

OK now you need to measure the voltage at the inverter when the alarm is heard. Then measure at the primary bus, secondary bus and then the battery. Post the voltage at these four points should indicate where the issue is created.

 

[woodwardable]

Alright here’s a dropbox link with some photos - I can’t seem to upload them to this forum for some reason?

Mobile Uploads

Shared with Dropbox

www.dropbox.com

 

[woodwardable]

Ok will do - I’ll leave the inverter running and try to run down the battery the week after next when I have access to a voltometer - thanks!

OK now you need to measure the voltage at the inverter when the alarm is heard. Then measure at the primary bus, secondary bus and then the battery. Post the voltage at these four points should indicate where the issue is created.

 

[woodwardable]

Well everyone I thank you for your help - the issue is resolved!

a battery monitor I’d installed had been losing power due to wiring inefficiency and a loose connection. Fixed that and everything else fell into place.

Again thanks for all of your help-it’s a huge relief to have this issue fixed!!