Anyone Using Mastervolt AGM Batteries?

[DiploStrat]

An ammeter will do at the top end, ensure endAmps is reached at Absorb most cycles before dropping to Float.

> I actually worry a bit about my present setup as I have only 40A available from the alternator because of the size limitations of my B2B.

The high charge rate is good for longevity but not as critical as the SoC top and bottom.

Go direct off the alt for the first few hours of driving sometimes?

Or save your pennies and trade up to Sterling's 120A if you think it's worth it.

On my last truck I used an intelligent relay and a pair of 1/0 AWG (100mm2) cables. I could crack 150A charge, but, as you well know, only for about thirty minutes. My maximum overnight drain is around 125Ah, so I am only discharging about 20%. I have noted that, even with massive cables, the battery voltage rises so fast that the real world sustained charging is around 50A.

I have used Sterling products in the past but this time around, I went with REDARC as I got two mints in one - 24v to 12v step down and an extra MPPT solar controller. (Sterling does sell a 24v to 12v B2B, but it does not include a solar controller.)

If the 40A proves not to be enough, I can double up the REDARC. The REDARC has the advantage of being extremely compact and not needing a fan.

So far, the real world performance has been excellent and, as many campsites only offer full hookups, I can always run the Magnum if I am worried.

 

[Ducky's Dad]

I wonder if G31 is a particular issue with Odyssey.
31 seems to be a problem. My Odyssey 34s have been OK.

 

[john61ct]

No G31s are as superb as their others.

So many factors in the care cycle, so few actually go to the trouble, especially to be precise about reaching 100% Full via endAmps, can take over seven hours.

Alts rarely do even a mediocre job on their own, even if you are driving all day.

99.99% charge sources drop to float too early.

Need full user adjustability on the setpoints and Hold Absorb time, don't think Redarc offers that?

A free built-in solar controller isn't worth any sacrifice in the main functionality IMO.

And 40A is only optimal for ~100AH total.

 

[Ducky's Dad]

And 40A is only optimal for ~100AH total.
I think the Odyssey G31 (2150 Extreme) is 102ah, so my 40 amp 3-bank should work better than it does. When used on a single battery, the whole 40amps is available to that battery. When two or three batteries are connected to the extra cables, the charger basically time slices the charge so that each battery gets 40amps (or whatever that battery needs) but in short bursts. If all batteries are connected as a single bank, then the charger sees it as one battery and things just take longer. When I decided to "invest" in an Odyssey charger to try to eliminate my problems, they had already discontinued their 50amp charger.

 

[DiploStrat]

...

So many factors in the care cycle, so few actually go to the trouble, especially to be precise about reaching 100% Full via endAmps, can take over seven hours.

Alts rarely do even a mediocre job on their own, even if you are driving all day.

99.99% charge sources drop to float too early.

Need full user adjustability on the setpoints and Hold Absorb time, don't think Redarc offers that?

A free built-in solar controller isn't worth any sacrifice in the main functionality IMO.

And 40A is only optimal for ~100AH total.

I don't like to be snarky, but given the tone of your comments, not all of which are wrong, it is time for you to post wiring diagrams, product lists, and wiring diagrams of your truck. I'm traveling in mine, using its systems every day. We would all benefit from seeing how you have solved these problems - knowing the type and weight or vehicle, the size of the battery bank, the chargers you are using and the loads you are supporting.

That said:

-- The performance of an alternator alone is irrelevant; the issue here is the complete system. Got a modern Ford/Chevrolet/Ram? The odds are good that your temperature compensated, computer controlled charging system will be able to handle a large (say, 500Ah) lead acid battery bank with proper wiring and a switch/relay/intelligent relay. Got certain Toyotas, Mercedes Benz, regen braking vehicles (e.g. Ford 150) and you may need to do something else. In this case you may need to raise the system voltage or use some form of outboard regulator or charger. Adding another dedicated alternator/regulator may also be an option.

-- Alternators can be excellent for the boost/bulk stage. There performance in the absorb and float stages is less important for motor vehicles. (As opposed to motor boats.)

-- In an expedition vehicle, absorb and float stages are best handled by solar or shore power.

-- User adjustable set points are nice, but less important if the manufacturer gets them right in the first place. In my case, the REDARC goes to float when the charge rate drops to less than 4A for 30 seconds or more. My Magnum shore charger is completely adjustable. The weakest link in my current system is the Go Power PWM solar controller. Unlike the Blue Sky on my previous truck, it is not adjustable and the documentation is not very clear on how/when it transitions from bulk to absorb to float.

-- Sterling makes some interesting products, but I cannot find a 24v to 12v B2B with a 40A output.

Soooooo, what are YOU running? ;-)

 

[john61ct]

40 amp 3-bank should work better than it does.

Yes.

Bring a single isolated batt down to around 50% SoC, then document a full charge cycle with a DMM and ammeter, ideally logging every 30min or so over 8 hours or until it drops to Float.

Obviously trying to adjust it to Hold Absorb V as long as possible.

Or maybe set Float = Absorb and then manually halt when endAmps is reached.


> When two or three batteries are connected to the extra cables, the charger basically time slices the charge so that each battery gets 40amps (or whatever that battery needs) but in short bursts.

That sounds very odd, do you have a link to the tech details for that unit?

Many multiple-bank chargers require the unused outputs be jumpered together to get full output, some are even damaged if left disconnected.

IMO better to just have a single output, and use ACR / echo charger / DCDC, whatever to distribute from House to other batts.

And no I don't take requests for self-disclosure, choose that myself, thanks.

 

[Ducky's Dad]

That sounds very odd, do you have a link to the tech details for that unit?

Many multiple-bank chargers require the unused outputs be jumpered together to get full output, some are even damaged if left disconnected.
The time slice info came from Odyssey tech support in a phone call. Same call also confirmed that unused leads don't need to be jumpered or connected to get full output, and no damage if just left disconnected.

 

[lathamb]

I bit the bullet when my DHP31M (Odyssey) started dropping voltage at full charge at almost 3 years old. I had a NOCO genius charger that I used and it wasn't fully charging the battery. I was looking at replacing the battery with a Northstar or X2 31M, but I decided to spend that money on a better charger to see if it would help. I bought a promariner pronautic 40 amp 3 bank charger. I mounted it in my garage near where I park, rigged a plug out of the bumper of my 4Runner with an Anderson connector and 4 gauge welding cables. I can just pull up and plug it in when ever I need to. I have it set to bulk/absorb at 14.7V and float at 13.6. I conditioned the battery per odyssey's instructions a couple of times as well. Now the battery is holding voltage as it should again.

 

[john61ct]

I decided to spend that money on a better charger to see if it would help. I bought a promariner pronautic 40 amp 3 bank charger.

Great bit of kit.

Same as Sterling, shared design.

Setpoints well adjustable.

 

[Hillbilly Heaven]

I bit the bullet when my DHP31M (Odyssey) started dropping voltage at full charge at almost 3 years old. I had a NOCO genius charger that I used and it wasn't fully charging the battery. I was looking at replacing the battery with a Northstar or X2 31M, but I decided to spend that money on a better charger to see if it would help. I bought a promariner pronautic 40 amp 3 bank charger. I mounted it in my garage near where I park, rigged a plug out of the bumper of my 4Runner with an Anderson connector and 4 gauge welding cables. I can just pull up and plug it in when ever I need to. I have it set to bulk/absorb at 14.7V and float at 13.6. I conditioned the battery per odyssey's instructions a couple of times as well. Now the battery is holding voltage as it should again.

Like this one?
https://powerwerx.com/promariner-63150-pronautic-battery-charger-50a

 

[lathamb]

Yep the 40 amp version of that one. Bought off amazon though.

Like this one?
https://powerwerx.com/promariner-63150-pronautic-battery-charger-50a

 

[john61ct]

I believe Maine Sail sells them, support his fantastic work for the community!

 

[DiploStrat]

...

And no I don't take requests for self-disclosure, choose that myself, thanks.

I'm guessing that this comment is aimed at me. Got it. Your privilege, but it does hurt your credibility a bit. ;-)