Battery Type for Dual-Battery 1HDT?

[swamprunner]

One of the old Diehard AGMs in my 81 has finally crapped out after 8 years. These were the good ones back when odyssey made them

Currently looking replacement options. Is there anything worth while that is not $500 per battery?

 

[jellis]

@swamprunner This is hilarious timing, I JUST dug into this over the weekend. My post melted on the LH battery and about stranded me way out in the Maze District of Canyonlands NP. Here's what I figured out, hopefully this saves someone a few hours of research:

I run a fridge/freezer and other crap when camping for a week or two at a time and my normal lead-acid starters have sucked for this. So I definitely need to switch to deep cycle AGM, but most deep cycle AGMs don't put out proper CCA's for diesels which, based on another thread and some research, should be at least 650 CCA for each battery (that's what came stock in our rigs). I live in a cold climate and visit Wyoming in the winter so high CCAs are a real concern for me....but it seems like all deep cycle AGMs are either 550CCA and $300 or 900+CCA and $500.
I ended up going with Odyssey Performance because I didn't want to go with less than stock CCA. NAPA currently has a 20% off online purchases (with in-store pickup) sale thru April! Regardless, the trick right now is finding any single supplier with two batteries that will fit properly, in stock. I ended up going with, for $675 total (the sale only applies if you buy 3 things so two high-end batteries and a $3 bubble level, haha):

• RH side: ODP-AGM27M for $325 after discount. This is the marine version with posts, should drop right in, but ODP-AGM27 will also work. I can't use a larger battery here because I installed a York so my AC unit is SUPER close to the battery box.
• LH side: ODP-AGM31A for $350 after discount. This is slightly larger than the 27 but should work with very minor modifications to the battery tray and yields 15% more AH (it's also way heavier so beware). The ODP-AGM27F is our specified battery (terminals reversed) but I couldn't find a place that had both 27/27F in stock at a reasonable price. Note that the ODP-AGM31A actually has the terminals reversed (same as RH battery) BUT the terminals are in the middle across the depth of the battery so it doesn't matter which way its installed. I'm just going to install it "backwards" and the cords should reach an extra inch or so no problem. EDIT AFTER INSTALL: No mods required to tray but holder isn't big enough and cords do require modification, see my install post below for details.

I went with the Pros instead of Extremes because of price. Performance specs (900 cycles at 50% DoD/400 @ 80% DoD) are the same, primary differences are lead vs. tin-coated brass terminals and polypro vs. polycarb case material.

Note that the terminal configs get complicated very quickly and have no rhyme or reason. The ODP-AGM31 has only threaded studs, 31A has normal SAE terminals, but 31M has reversed terminals from the other two--and the 31M Extreme version (ODX-AGM31M) has them reversed from the Pro (which means it will work great in LH position, but it's the Extreme version and they say not to mix and match for some reason....probably BS). At any rate, their EU website has MUCH better spec sheets with terminal configs and dimensions to posts/terminals so go here instead if you're trying to put a system together:

Battery Range - Odyssey Battery

eu.odysseybattery.com

 

[jellis]

@veiloctane Thanks for that DC-DC PDF you posted earlier. But it's geared entirely towards separate starting and domestic batteries which isn't how our rigs are setup. Are you somehow using this to top-up charge both batteries from the alternator? If so, how?!? Figuring this out for AGMs is obviously next on my list!

 

[Dilspec]

@jellis did you have to pay shipping on the batteries? My local Napa was asking for shipping since it’s special order.

I went after work and tried to fight the shipping cost but had no luck,

 

[Dusten]

@jellis did you have to pay shipping on the batteries? My local Napa was asking for shipping since it’s special order.

I went after work and tried to fight the shipping cost but had no luck,

Do you have a pacific power or batteries plus? I bought mine locally

 

[Dilspec]

I went to Napa because they have a 20% deal going on when 3 items are purchased.

Everything went well until the clerk said $150 for shipping, which basically offset the 20% savings. Combine that with Chicago tax and it’s basically the same price as if I ordered direct.

Maybe I’ll try a different Napa.

 

[Dusten]

I went to Napa because they have a 20% deal going on when 3 items are purchased.

Everything went well until the clerk said $150 for shipping, which basically offset the 20% savings. Combine that with Chicago tax and it’s basically the same price as if I ordered direct.

Maybe I’ll try a different Napa.

Or literally go get them from batteries plus. They're in stock.

 

[Dilspec]

I think you’re missing the point of the discount @Dusten. Even at 10% off the Northstar AGM are more.

 

[Dusten]

@jellis did you have to pay shipping on the batteries? My local Napa was asking for shipping since it’s special order.

I went after work and tried to fight the shipping cost but had no luck,

Northstar also has an AGM that isn't deep cycle. Which will never charge correctly with the 1hdt alternator.

As you said, is it really a discount if you're paying shipping?

$300 for a group 27 AGM from Northstar is a great deal.

 

[veiloctane]

@veiloctane Thanks for that DC-DC PDF you posted earlier. But it's geared entirely towards separate starting and domestic batteries which isn't how our rigs are setup. Are you somehow using this to top-up charge both batteries from the alternator? If so, how?!? Figuring this out for AGMs is obviously next on my list!

Explain how your rig is setup?

Mine is exactly as per diagram.

More details in the ctek manual

https://www.ctek.com/storage/2CEC8E11E857CA508C9B6675D033DF1F2060CB21F0B5A017F6446579F55ABD4B/f5c63e52af444f8ab164c80cf59a816b/pdf/media/d2fca6de95b7475ca48ec447e8e99ed4/D250S_DUAL-manual-low-UK-EN.pdf

I’m on 12v start conversion with one starting battery and the other is the aux battery. The Cteck automatically switches to where the charge needs to go. When parked I can charge over solar or external battery charger.

On the aux battery you can add additional batteries if you need more capacity.

Simply put you can run a convential starting battery along side with the aux battery bank.

I have no issues running both deep cycles and alternator is fine. When aux battery is dead the alternator is capable of charging up to 800Ah thru the ctek d250s + smartpass

So help me understand what I’m missing if this is a wrong setup as per use. I would like to hear your input.

 

[Dilspec]

Northstar also has an AGM that isn't deep cycle. Which will never charge correctly with the 1hdt alternator.

As you said, is it really a discount if you're paying shipping?

$300 for a group 27 AGM from Northstar is a great deal.

I was just wondering if the other member paid for shipping when he purchased his batteries from Napa. Nothing else.

 

[IanB]

@swamprunner

• RH side: ODP-AGM27M for $325 after discount. This is the marine version with posts, should drop right in, but ODP-AGM27 will also work. I can't use a larger battery here because I installed a York so my AC unit is SUPER close to the battery box.
• LH side: ODP-AGM31A for $350 after discount. This is slightly larger than the 27 but should work with very minor modifications to the battery tray and yields 15% more AH (it's also way heavier so beware). The ODP-AGM27F is our specified battery (terminals reversed) but I couldn't find a place that had both 27/27F in stock at a reasonable price. Note that the ODP-AGM31A actually has the terminals reversed (same as RH battery) BUT the terminals are in the middle across the depth of the battery so it doesn't matter which way its installed. I'm just going to install it "backwards" and the cords should reach an extra inch or so no problem.

You might have already considered this, but how will charging work with 2 different sized batteries? I've always been under the impression that you want the 2 batteries to be matched in capacity or they'd eat each other during charging, lol.

 

[swamprunner]

@jellis Man I feel your pain. I researched battery options yesterday till my eyes crossed. It's truly a pain in the ass and pocket to find proper agm batteries for the stock 81 configuration.
Group 27 is the best fit and 27F has the terminals flipped but.....they both don't seem exist in an AGM that is in stock. Terminal configuration is the kicker. I found a few possible options you could just install one backwards and I think the cables will reach.

My local Napa is a joke so I'm not even going to attempt ordering from them.

FWIW right now at Costco you can get lead acid 27 and 27f for $99. I may go this route for now and hope they last a few years and maybe by then supply chain might be a bit better and you can find things again

 

[swamprunner]

Anyone have any experience with these AC Delco AGM. From the dimensions I found they will fit in the 81 stock configuration. One will just have to be reversed to address the terminal config.

ACDelco 88864542 ACDelco Gold Automotive AGM Batteries | Summit Racing

Free Shipping - ACDelco Gold Automotive AGM Batteries with qualifying orders of $109. Shop Batteries at Summit Racing.

www.summitracing.com

 

[jellis]

@Dilspec I did it all online and simple chose a store for pickup. It says not all stores are participating in the 20% off thing but it seemed like I could pick any store for pickup--definitely no shipping charges, "Free ship to store". I ordered on Saturday PM and was just notified that the order is ready for pickup!

@veiloctane Since you have 12V start your system mirrors the PDF perfectly so it makes sense how this works. I was curious how it would work with the two batteries connected in parallel/series for 24V start....and I don't think it can.

@IanB The 15% difference in capacity should be mostly irrelevant to charging these batteries. They will be supplied a voltage and current and will simply charge at slightly different rates....not sure how this could be a noteworthy problem? At the end of the day I'm going to ruin these batteries no doubt about it and it's not like this is a $30k off-grid bank in a temp-controlled room--if I can get 4 years instead of 2 at twice the price AND not run my truck for a few days while camping with my fridge, that's a plenty big win to me. They are simply incredibly expensive disposable items, unfortunately.

@Dusten Deep Cycle vs. Starting makes no difference, AGMs all require a different voltage than FLA batteries. The difference is cycle life: The Odyssey tech manual states that alternators should output 14.7V to maintain battery cycle life in deep cycle applications with 14.2V vs. 14.7V charging causing cycle life to be cut in half. It also states that 14.2V is the bare minimum and 15V is the absolute maximum, 14.7 is ideal:

The manual specs 14.0-15.0V as standard. I put in a Terrain Tamer 120A a few years ago, so I'll have to see where I'm actually at (per FSM method of measuring alternator output, NOT using my multigauge readout which can be considerably lower). If I need to adjust I will simply add a diode to the 7.5A charge circuit fuse to up the voltage output slightly. This can be accomplished with a simple fuse diode, lots of versions out there but they're all mini fuses instead of our standard size.

The small differences in voltage do matter, not only for battery life (as shown above) but also for performance. So does wiring! This is from another post about the alternator voltage adjustment....fridge went from 8-10hrs to nearly 60hrs of runtime:

In my opinion the best option is to get the alternator to do the job as it has more amps to play with.

If I may give you a real world case to backup my post. My mate Andrew driving a 02 Hilux installed a reputable dual battery management system with an Optima D31A (13" Yellowtop, 75Ah Cycling Capacity) located in the tray of the vehicle. His issue was his Engel Eclipse fridge would last only for 8-10 hours once the vehicle stopped.

Grabbed my multimeter and measured voltage at the starting battery (14.04 volts) then checked at the Optima (13.77 volts). Why the voltage drop? Optima grounded to the chassis however the starting battery was not. Bolted in an earth between motor and chassis, we now had a voltage of 14.02. A drop of .02 (very acceptable). I explained the voltage issue with him and the use of a diode to bring the voltage up but he decided to run with the improved voltage.

He was now achieving around 15-18 hours run time on the Engel Eclipse. Expecting more from that battery he returned and I convinced him to use the diode. He is now achieving 14.61 volts on the starting battery and 14.59 on the optima. On a test run before his fraser island trip, his engel lasted for 58 hours without starting the car. The battery voltage was down to 11.9 volts so it still had some capacity left.

The only change made was the voltage. It might seam over thinking or not important but it makes a difference to how long your fridge runs between running the car.

 

[Dusten]

@Dilspec I did it all online and simple chose a store for pickup. It says not all stores are participating in the 20% off thing but it seemed like I could pick any store for pickup--definitely no shipping charges, "Free ship to store". I ordered on Saturday PM and was just notified that the order is ready for pickup!

@veiloctane Since you have 12V start your system mirrors the PDF perfectly so it makes sense how this works. I was curious how it would work with the two batteries connected in parallel/series for 24V start....and I don't think it can.

@IanB The 15% difference in capacity should be mostly irrelevant to charging these batteries. They will be supplied a voltage and current and will simply charge at slightly different rates....not sure how this could be a noteworthy problem? At the end of the day I'm going to ruin these batteries no doubt about it and it's not like this is a $30k off-grid bank in a temp-controlled room--if I can get 4 years instead of 2 at twice the price AND not run my truck for a few days while camping with my fridge, that's a plenty big win to me. They are simply incredibly expensive disposable items, unfortunately.

@Dusten Deep Cycle vs. Starting makes no difference, AGMs all require a different voltage than FLA batteries. The difference is cycle life: The Odyssey tech manual states that alternators should output 14.7V to maintain battery cycle life in deep cycle applications with 14.2V vs. 14.7V charging causing cycle life to be cut in half. It also states that 14.2V is the bare minimum and 15V is the absolute maximum, 14.7 is ideal:

View attachment 2986213


The manual specs 14.0-15.0V as standard. I put in a Terrain Tamer 120A a few years ago, so I'll have to see where I'm actually at (per FSM method of measuring alternator output, NOT using my multigauge readout which can be considerably lower). If I need to adjust I will simply add a diode to the 7.5A charge circuit fuse to up the voltage output slightly. This can be accomplished with a simple fuse diode, lots of versions out there but they're all mini fuses instead of our standard size.

The small differences in voltage do matter, not only for battery life (as shown above) but also for performance. So does wiring! This is from another post about the alternator voltage adjustment....fridge went from 8-10hrs to nearly 60hrs of runtime:

I would be surprised if your alternator puts out more than 14.4 in any situation. But this is from my experience with electrical systems.
.

 

[swamprunner]

I have old die hard deep cycle AGM in my hj61 as well. They are from 2014. They are still kicking. Not a daily driver. Gone dead after being parked for months. They still take a charge and hold charge to this day. They don't build them like they used to.
Sure I just jinxed myself

 

[jellis]

I finally got a chance to install my new batteries yesterday, here are my notes.

RH: ODP-AGM27M. This thing dropped right in and was an easy install. A bonus I didn't realize with the Marine version is that the terminals appear to be upgraded to the Extreme version (tin-coated brass vs. lead on Pro).

LH: ODP-AGM31A. This isn't a direct drop-in replacement. It does fit just fine in the battery tray without any modifications to the tray which is nice, however the OEM holder isn't wide enough for it. I already have one of these holders on the RH side so I just ordered another for the left (simple to install but the bolts aren't long enough to attach the front side at the bottom of the tray dip like you'd want, this requires paying attention to that detail when installing). A bigger issue is that the + lead going to that big terminal block which connects the 12/24 switchover relay to the starter and the battery isn't quite long enough because the terminals on the 31A are in the middle of the battery body. I was in a hurry to pickup my kids so I stretched it and made it work but there's a huge strain there so that wire will want to be replaced with something an inch or so longer. Also, on my rig the fusible link on that side wasn't long enough either so I had to make up a new one. Simple enough but I don't know the specific wire gauge spec there so I'll need to look into that, I should make up some extras all around anyway. If anyone has the info at hand for the fusible links on our rigs please post it up here.

I received my GM diode to replace the 7.5A charging fuse to up the alternator output but I haven't had a chance to play with the voltages yet, I will report back here when I get that lined out, hopefully this weekend.

 

[Dilspec]

Nice - @jellis - any more info on the GM diode?

 

[jellis]

I finally got a chance to check voltages, and it's weird.

With everything disconnected on the LH battery including the alternator, my alternator will output 14.8V. If I reconnect the fusible link on that side and disconnect the alternator (so now all electronic circuits are connected between both batteries, but no charge input from the alternator), the alternator now outputs 14.35-14.4V. This does NOT change, ever, regardless of what's happening with the 7.5A Charge fuse even if no fuse is in there at all.

The fuse does not seem to control alternator output voltage but instead seems to control nominal ambient voltage to the rest of the truck. With no fuse in there (open circuit), I get 13.45V on the + terminal and 12.9V on the - terminal of the fuse. With a normal fuse in there, both sides drop to 12.93V. With my GM diode, + 13.25V and - 12.9V. With a huge 22MOhm resistor or 3 1N914 diodes in series, it acts as if there's an open circuit and goes up to + 13.45V and - 12.9V. So as resistance goes up across the terminals the voltage does go up, but it has no affect on my alternator output voltage whatsoever.

So, I'm not sure what to think. Basically the option which yields the greatest voltage increase is simply to leave the fuse empty. Is something wrong with the regulator on my alternator or what?!?