Keeping New Batteries in the best condition

[Dthomas9572]

Hello,

I want to keep my new AGM batteries in the best shape possible. Gil on a previous thread you have mentioned after a day of driving if dry camping to run the generator for a couple of hours. I am doing that now and when generator is turned off batteries are at 25.3 volts on my trace 4024 monitors.

What setting should I be putting my auto start to start up? I seems many on the thread do not recommend going below 24 volts...I know my auto start is set a a lot less then that?

Thanks

[Fratto]

Check with your battery manufacturer but 24 V is not a bad discharge point. Your manufacturer should be able to provide you with a rate of discharge chart

[Fratto]

http://forum.prevostownersgroup.com/blob:http://forum.prevostownersgroup.com/86a7567e-e7c7-428f-b097-5238eeadb9dc

[Joe Camper]

When my 24v bank is charged and rested it is at 26.2, 25.3 is a tic low unless u sill have some loads. The fridge?

[Gil_J]

That question doesn't have an easy answer with most autostart systems. There is no ideal voltage to trigger autostart if the batteries are in use. Load affects the voltage.

You can prove this by looking at your house battery voltage when the engine is off and the inverter is on. Note the DC voltage. Turn on a high current device, like an air conditioner. Now note the DC voltage. You will no doubt see a drop in voltage. Okay, you would expect the drop. Now turn the high load appliance off and note the DC voltage. You will no doubt see an increase in voltage. This simple exercise just goes to prove, voltage is not a great AGS trigger.

Older coaches have a single voltage trigger with a single timer. If the voltage drops below X voltages for X time the generator start is triggered. The timer is necessary so large short duration loads, like the microwave, don't trigger the generator start.

Many have Trace 4024 inverters. They have 3 voltage triggers assigned to 3 fixed timers. The default values are reasonable triggers.

New inverters almost all have the ability to trigger the AGS function based on the state of charge of the bank. SoC is the best trigger for both starting and turning off the generator. SoC is unaffected by load and voltage variables. Even though many have updated their inverters, few have added the SoC measuring capability.

[freds]

What is your energy budget that you feel need to auto start a generator for?

If it's just for maintenance while the couch is unused then I would suggest adding some solar, of course you could go serious solar and rarely use the generator.

Just went to major city RV show and solar was barely mentioned on the sales floor.

[BadFitter]

This works with my Magnum 4000/24 inverters

https://www.magnum-dimensions.com/battery-monitor-kit

I'll be adding it when I go to Lithium batteries. Should work well with the Magnum auto generator start function.

16206

[Dthomas9572]

Joe,

Yes fridge is always on, I also had misc tvs, some lights, ceiling fan, aqua hot running and misc chargers going. On the way home I had all these things on dry camping. After 15 hours on battery power, the meter red 25 volts left to go. This is so awesome to have brand new batteries.

Thanks

[truk4u]

Les, look at the Victron 712 (https://www.victronenergy.com/battery-monitors/bmv-712-smart), it has blue tooth.

[Gil_J]

Les, that will work for your inverters well. If you aren't using the Magnum router, you should add it as well. If you're not using it or the SoC unit, your AGS may not work correctly.

The Victron will do you no good, unless you just want to monitor SoC.

[BadFitter]

Thanks Tom and Gil. I've got another year to research and see where the technology goes.

[Anthem]

if you have the ability to set the generator auto start - i would set it at the 50% DOD point. AGM batteries are best cycled between 50-100 and not go lower. They also like to be "topped up" - as in they dont like to sit away from being charged all the way up. but I wouldnt set auto gen start at the first instance of a drop as you would cycle incessantly (the last little bit of AGM charge to top off takes a very long time in float). As someone else said - solar panels are a great match for AGM batteries.

as for battery monitor. the Victron BM712 is excellent, the balmar SG200 is excellent. Some of the ones that are paired with their units are also good. And as gil mentioned, these units are generally standalone unless paired or matched with their respective brand units (some have a relay that can fire off other relays though)

[Gil_J]

Anthem. DoD using battery voltage is impossible with a battery in use.

Les, what I said applies today, if you are using the Magnum networked AGS without the Magnum router or BMK.

[Dthomas9572]

Hello,

Currently my setting on my trace 4024 inverters is 23.8 when it drops to that or lower for 15 minutes....does that sound correct?

Thanks

[Anthem]

Anthem. DoD using battery voltage is impossible with a battery in use.

yes and no. It depends on your SOC method of calculation. The BMV712 after learning from your battery usage - uses SOC via discharge amp hours, peufkert efficiency and voltage, rather than straight voltage. But it correlates that with voltage as well.

But also this is dependent upon the ratio of discharge and how you are calculating it. If you are using your battery, and your rate of discharge is minimal (100w out of a 1000amp hour bank), the voltage drop corresponding with that fractional C discharge is so minimal to affect your SOC in a meaningful way - but you are still taking a batttery SOC while a battery is in use....

Basically saying that the battery is almost always being used (when not being charged with external sources like Gen, Shore, Solar, Wind) - but we are also taking SOC readings on those same battery banks all the time. While some might understand that the bank is under whatever load - that reading is still taking place as some sort of reference point. You dont always disable EVERY SINGLE draw off the battery(and in almost all cases, its impossible to remove all loads off the bank) - to get a SOC reading.

[Dthomas9572]

Hello,

Currently my setting on my trace 4024 inverters is 23.8 when it drops to that or lower for 15 minutes....does that sound correct?

Thanks

[Ck2hans]

Gil:
Forgive my ingnorance in matters of electricity, perhaps a dumb question.
I think my Featherlite (like most Featherlites) have four of the 8 4D batterys devoted (wired) for 12 volt and the other four are devoted (wired) for 24 volt. OR are all the battery's wired for 24 volt and 12 volts are tapped off of the 24 volt bus bar?
I ask this question because I am not sure how to determine total battery state after dry camping.

Chuck

[Gil_J]

Anthem, you've added a device to calculate SoC. Most don't have such and I bet the most of the few that do aren't using it signal generator operation. Even the older coach with the Link 2000 remotes didn't use it's ability to calculate SoC to trigger generator operation, even they could.

Because voltage alone us not a good indicator of SoC, most AGS systems use one or more triggers that require voltage to drop below a threshold and remain below the threshold for the time trigger.

[Dthomas9572]

Hello,

Currently my setting on my trace 4024 inverters is 23.8 when it drops to that or lower for 15 minutes....does that sound correct?

Thanks

[Gil_J]

Hello,

Currently my setting on my trace 4024 inverters is 23.8 when it drops to that or lower for 15 minutes....does that sound correct?

Thanks

That seems like a reasonable setting for when the coach is in use. The best way to tweak the settings is through use. If that setting has the generator starting too often or you could tolerate more frequent generator starts adjust the setting.

I like to preserve my batteries, so my settings are higher than the defaults. The Trace settings are very similar to settings prescribed by other manufacturers.

Here's the factory settings.
16211

[Gil_J]

Chuck,

You have a 24V house battery bank. Featherlight wired half of the batteries to their negative and 12V bussbars. The other half are wired to the same 12V bussbar and the 24V bussbar. An equalizer sits on all 3 bussbars. It's purpose is to pull current from the upper half of the bank's batteries and send it to lower half bank based on the 12V loads.

If you want to measure the banks SoC you'll likely have to add a negative bussbar. You'll install the SoC shunt between the negative bussbars. One negative bussbar will only be connected to the batteries. The other negative buss bar will connect to each inverter, chassis, and anything else on the current bussbar that's not a battery.