Yet another AGM/battery bank question....

[hand_foot_maneuver]

Hi all, searched and searched but so many threads and tangents. Hard to tell if im getting the gist of what might be going on with my loss of power.

My deal:
-have an AT Bobcat, recently replaced the battery in it with Odyssey PF680, has not been able to keep power enough to make it through the night with the heater fan still having power. Also had to stop using power for lights and usb ports to preserve power forthe heater blower to be able to still have power in the cold mornings.
- havent had more than 3 hrs driving time on it at any one time, not sure ive ever reached full charge beyond the ‘full charge’ it came with.
-still learning this aspect of things, considering a solar rig as im wired for it, but thats for after winter.
-originally considering a second PF680 paralleled in to resolve my problem.
-the more i read here, the more my head spins but it seems that until my truck runs an AGM battery also, the charging wont be optimum on that camper battery. They charge at different rates right?
-no fridge, water pumps, etc. just LED lights, usb ports, and heater blower consuming power.

Can anyone verify if this is the case? Want to make sure im understanding ’starting battery’ correctly before i go about approaching this all wrong. My solution, if logical, is to go to Sears and get an AGM die hard for my truck, in hopes that having both batteries the same type will let them charge at the same rates.

Truck is 2016 Chevy Colorado diesel, 4wd. Comes with heavier alternator, just had the serp belt changed several months ago. Charging system should be in good shape. Never had an issue with the old deep cycle it came with, until it stopped holding charge on its warranty expiry month.

My truck could use a new battery, its the original 2016 AC Delco and isnt AGM type. Id put a nice AGM in the truck to make it all work.

 

[DaveInDenver]

It's likely you're under charging the truck battery, too, just that you don't notice since it's not being asked to work as hard. Installing an AGM in the truck won't change anything except make your wallet lighter.

You need to be more aware of how you're charging your batteries and in particular your house battery.

There's ample suggestions in the forum posts but the solutions are things like add a shore charger when parked, install solar with a controller/charger compatible with AGM, put in a DC-DC charger, watch and bump if necessary the charge voltage of the truck, etc.

Actually, if you fix the truck's alternator/charging system to make the house AGM happy the truck battery should be happier in any case. Conventional types are generally more tolerant of charge profiles and following one ideal for AGM is typically going to be plenty good for flooded and maintenance-free batteries, too. All lead acid batteries are generally OK to charge in parallel it's more that you have to match type and condition closely when you let them sit or actively discharge them wired together in a bank.

 

[hand_foot_maneuver]

So, its not necessary to have truck battery and the house battery be the same AGM or non- type?

With my storage situation and climate, a charger or solar aren't really in the cards. I have some annoying constraints between pounding snow and keeping it at a storage, outdoors. The truck is my daily till about new year, so i have to take it off between uses. It gets used about every two weeks, sometimes more, sometimes less.

might be able to remove battery and charge indoors while in storage. Really dont want to do that. My place is small.

Alternator? Ill see about having it tested, its got 90k on it after all.

Sorry for all the questions, keywords arent helping my search, lots of vaguely related results, still sifting away. Lots of new jargon to learn.

Any links to help with the rudimentary questions would be appreciated. No stickies or faq here for battery stuff.

I just want it to.... work. I dont want to ******** with it alot and deal with it failing while trying to go climb, i just want to sleep good and have heat in the morning. If it gets too complicated, im just going to eat the odyssey and get another deep cycle battery. Will make sure my alternator has good output. It should.

 

[dreadlocks]

if they are disconnected when not being charged, they can be any size or lead chemistry you want..

It takes ~6-8h to fully charge a depleted lead battery, you need a shore charger or to move further away from your job.. much further.. wire it up w/a engine warmer too and with that diesel you'll be motivated to keep it plugged in overnight.. Another battery is not gong to help if you cant even get the one you have now back to full before you go for an overnight outing.

Batteries will only take the charge current they want, and they they want to spend several hours absorbing at a very low charge rate.. so alternator size is really not going to help anything at this point.

I'd suggest some sort of house battery monitoring system, being able to reliably know your current state of charge makes it dramatically easier to manage/maintain it, not to mention knowing how much you need for your heater, and how much you have before you go to bed.. I'm really happy w/my Victron BMV-712, check it out.

 

[dwh]

A) buy a small generator and a good battery charger for charging. Do a full charge (8-10 hours) before you put it in storage and top it off when you take it out of storage. I use a 1500w/1800w Generator from Champion, but the 1200w/1500w also works fine for that.

And...

B) Get a heater that doesn't have a fan.

 

[hand_foot_maneuver]

Thanks, ill def look into the victron. For troubleshooting i left the camper on this week for commuting to work, 64 mi round trip. Three of those combined with 2 hrs to destination should get me there. also drove 3 hrs home on sunday, so that should all add up.

 

[dreadlocks]

i should have been a little more clear, it wants 6-8h uninterrupted to charge.. if you stop it mid absorb, then start it again the next day its going to take longer than that.. hence the need for a real overnight charge uninterrupted until the charger gets to a float state.

a bunch of commuting every day, is almost always a loosing proposition unless you have a fixed solar that finishes the absorb while parked.

also that AGM is not very tolerant to abuse, you need to get it back up to 100% SOC ASAP.. if you leave it sitting all the time at a partial charge, its gonna crap out on you much sooner than you'd expect.

 

[hand_foot_maneuver]

That sounds a lot like whats happening

 

[dreadlocks]

Here is a good illustration showing charging the same battery with both 42A and 21A.. your alternator is going to be more like the 42A profile.

source: https://marinehowto.com/how-fast-can-an-agm-battery-be-charged/

 

[luthj]

That is a good illustration. It assumes you have 14.4V at the battery terminals. The reality with most house/aux battery charging, is that you are always going to have some voltage drop. With poor charging circuits resulting in over 1V of drop at 20A or so.

 

[shade]

I just want it to.... work. I dont want to ******** with it alot and deal with it failing while trying to go climb, i just want to sleep good and have heat in the morning.

Makes perfect sense. Welcome to ExPo! ?

Here's a good 25A charger that will take care of your house battery.

Victron Blue Smart IP67 Charger 12/25 120V NEMA 5-15

You can download the VictronConnnect app for free and see the interface by using the Demo mode. For $140, that charger will work on whatever battery chemistry you're likely to encounter, and 25 amps is a respectable maximum output. You can mount it in your trailer, or leave it loose so you can also use it to charge your truck's start battery overnight to get that battery to 100% SOC (state of charge) occasionally.

You may decide to add solar charging or more battery capacity later, but having a reliable way to charge via shore power would be useful regardless.

 

[john61ct]

Sorry did not read all the responses

havent had more than 3 hrs driving time on it at any one time, not sure ive ever reached full charge beyond the ‘full charge’ it came with.

No you haven't, for sure.

It takes minimum 6 hours, often 8 to get back to 100% Full, no matter how many amps are available from a charge source.

You need regular access to shore power or solar panels to take proper care of the bank, ICE sources are just not enough unless you drive that long.

You really need to get to that 100% Full recharge at least once a week, or the battery gets murdered quickly. Doing so "most cycles" would really help with longevity.

Adding another lead battery won't help, nothing will get to Full much faster.

An LFP bank will, especially with a high-amp alternator and current-limiting voltage adjustable external VR.

But that costs thousands.

 

[john61ct]

buy a small generator and a good battery charger for charging. Do a full charge (8-10 hours) before you put it in storage and top it off when you take it out of storage.

Sure is a waste of fuel and wear & tear to run a little gennie for 7+ hours, when the battery is only accepting say avg 60W for the last 3/4 of the time.

ICE sources like a genset or alternator are best used early AM for an hour or two, getting the high-amps Bulk CC stage done, say to 85+% SoC

allowing a small solar setup to finish the 5+hr "long tail" rest of the day, silently and without using any fuel.

 

[john61ct]

OP, if you don't do solar then your only alternatives are shore power overnight,

or buying new batteries much more frequently.

If you can't run AC extension cord out to the batteries, then setup a quick-disconnect and bring them inside to charge.

Won't take up more than a cubic foot or so of your living space.

 

[dwh]

Sure is a waste of fuel and wear & tear to run a little gennie for 7+ hours, when the battery is only accepting say avg 60W for the last 3/4 of the time.

Yea, but not that much. After break-in my 1200w Champion would run 14 hours on 1.2g fuel. I'd just fill it up and let it run till it ran dry. Then no doubt the battery was fully absorbed.

ICE sources like a genset or alternator are best used early AM for an hour or two, getting the high-amps Bulk CC stage done, say to 85+% SoC

allowing a small solar setup to finish the 5+hr "long tail" rest of the day, silently and without using any fuel.

Sure, but the OP doesn't have that, doesn't drive enough to get the job done, and can't plug in while stored.

"Ya run what ya brung."