My solar and the chassis batteries

[mchero]

Outside of Quartzsite boondocking for the last month. Very happy with the solar but have one last question i thought id throw out to the group.
I can hear that Aux Start relay kicking in.
Im thinking about installing a switch next to the solenoid so that I can disable it. Is it necessary having the solar charging the chassis batteries? Not really sure how much parasite load i have on the chassis batteries. Not really sure if haveing them connected on a daily basis is good or not. I could flip the switch on once a week or so to keep them topped off. I was also thinking about setting it up so that the charge controller would dosconnect that solenoid when its harvesting solar. Driving down the road the panels are charging the house batteries. The alternator could just charge the chassis batteries.
Thoughts?

[CA_Traveler]

X3 Do a full bulk/absorb/float charge to 100 percent SOC.

Then check the SG to see if equalization is indicated. If so do it once then decide if the batteries are OK.

[mchero]

Thankyou both MrWizard and landyacht318

Will indeed make sure the house batteries are FULLY charged before the EQ. MrWizard.

Landyacht has it correct when he stated "last legs". They are indeed on the way out so I thought I'd slap them around to see what I can get out of them.

Clouds for the next couple of days so I'm going to give it a rest.

[landyacht318]

MrWizard wrote:


You don't start the equalize voltage from a partial SOC

You don't do it, unless the batteries are already fully charged

x2

I am surprised 40 or 50 xantrax amps can actually get the 2? GC-2 depleted batteries to 16 volts in what 'appears' to be within an hour or 2 time frame.

My single 90AH AGM battery when depleted can take 40 amps for 30 minutes before absorption voltage is hit. It then requires a minimum of 3.5 hours before amps taper to ~0.35a at 14.7v which is generally considered fully charged.

The battery needs to be held at absorption voltage for a period of time before pushing it to 16v for an EQ cycle.

Sounds like the batteries are really on their last legs, and new ones are in your future, but the new ones will not appreciate being pushed past 14.8v when less than fully charged either.

The hydrometer will reveal a lot, so would an ammeter. Voltage readings alone without knowing how many amps at that electrical pressure, are flowing, can be very confusing and not indicate much at all.

[MrWizard]

The problem I see now
Is your procedure
Iirc batteries are supposed to be fully charged normally (what ever number of hours it takes to get them there)

Then you check sg, then you equalize them , checking sg until they are as close to oem as possible

You don't start the equalize voltage from a partial SOC
Equalize is not a charge cycle
You don't do it, unless the batteries are already fully charged

[mchero]

WOW, I thought that I'd ask others for opinions. Not looking for any theatrics from Mex or winks and grins from red31.

Mex I'm running Interstate 6 volts that are most likely original to this coach. I don't know who Juanita Duran in the post princess bounder is and what it has to do with my question. Ever consider writing a book?

For the serious readers who want to lean.

I'm off grid.
Started the genset at 9:00 because I had to take the chill of so I decided to put the Xantrex into EQ
Was indeed watching the SC while I was cooking them at 16.1 volts. After about an hour I shut down the genny to let the Midnight Classic 150 take over but about 20 minutes later ran out of sun (the clouds rolled in) so I just shut down the EQ.
They are looking much better. Looks like a trip to Sams Club is in the near future. I will consider this thread done unless someone has something intelligent to add.

Midnight Classic default EQ set to 2 hours, Xantrex EQ will run for 8 hours. So, maybe I should have phrased the question differently.

Thanks all

[red31]

mchero wrote:
Red31
On my way out the door earlier when I saw your post;
Read this from Trojan, the name we all know & trust.

http://www.trojanbattery.com/BatteryMaintenance/Equalizing.aspx

so does that answer your question of How long to EQ? another wink 😉 and an added big grin :B

[MEXICOWANDERER]

Ain't life grand? The last I heard (2 years ago) Juanita Duran living in an RV in Campo, CA. was still using a Costco engine starting battery in her power post princess Bounder. Fewer waterings and when the power quit a few times for an hour or so the Johnson Controls group 27 did a fine job.

The Moral Is this: Analyze the scenario first before deciding a rote decision has to be an automatically correct conclusion. Some folks never boondock and from there a gradient exists all the way to 100% off-grid living. Imposing a one answer fits all is not the most intelligent response.

[mchero]

Red31
On my way out the door earlier when I saw your post;
Read this from Trojan, the name we all know & trust.

http://www.trojanbattery.com/BatteryMaintenance/Equalizing.aspx

[mchero]

red31 wrote:

mchero wrote:


How long should I Eq??

what is its purpose? 😉

Can someone provide a link to battery equalization? I'm not good at explaining it in plain english.

Thanks

[red31]

mchero wrote:


How long should I Eq??

what is its purpose? 😉

[jharrell]

I am fond of Blue Sea, its all marine grade and used quite a bit in Rv's for high amperage manual disconnect switches.

They have Automatic Charge Relays with some decent intelligence for auto connect based on charge voltage on either terminal with remote switch override and simple battery connect relays, both 500 Amps continuous. Pricy but you should never have to replace:

https://www.bluesea.com/products/7622/ML-ACR_Automatic_Charging_Relay_with_Manual_Control_-_12V_DC_5...

https://www.bluesea.com/products/7700/ML-RBS_Remote_Battery_Switch_with_Manual_Control_-_12V_DC_500A

[mchero]

1225 - 1240 SC at 75 deg on the batteries, Never seen it higher so I think I have squeezed most of the live out of these Interstates.

How long should I Eq??

[mchero]

Well, Since it was down to 40 deg. last night & I woke up this AM talking like Michael Jackson I decided to fire up the 7500 Quietdiesel. House batteries where sitting at 12.0 volts.

Was not getting much off the solar so I figured I would have the Xantrex EQ the house batteries while I had the generator running. House batteries slowly started ramping up to 16 volts so I kicked the Midnight Solar Classic 150 into EQ mode.
At 16.1 vdc I went out to check the house batteries with the hydrometer. I decided to check the voltage at the isolator solenoid and the BCC was sending it 14+ volts so I pulled the House Batteries disconnect solanois fuse that dropped the voltage to the isolator solenoid. Figured I'd rather pull a fuse than to break out the 10mm box end wrench and risk shorting one of the leads. No need to EQ the chassis batteries.

During my testing last couple of days it appears the BCC is NOT dropping the voltage to the isolator solenoid. Old Bounder thinks the BCC might be pulsing the isolator solenoid somewhere around 12 volts but during EQ I see it getting 14+ volts from the BCC. It would be nice if the BCC would drop the voltage to the isolator solenoid when EQ'ing the house batteries, e.g. drop the solenoid if the House batteries get up to something like 14.9 or 15 volts.

My next project will be a cutout relay. When the Classic is charging the house batteries or equalizing it will sent 12VDC to the relay that will open contacts and drop the voltage the BCC is sending to the isolator relay.

Any thoughts?

[MEXICOWANDERER]

I personally prefer ESSEX tower type relays over Trombetta. Mr Wizard sir, you definitely nailed it square-on