Dual battery maintainer with ‘smart’ isolator and daily driving.

[heinphoto]

Yeah, mains powered. Maybe not quite as large as those, which are intended as permanently mounted marine bank chargers so would be difficult to accommodate in @wADVr's Jeep. Not all of us are driving ex-Army FMTVs or large vans after all.

They both appear to offer several profiles with the ability to customize the voltage and current if you want. I'd like to know if there's any chargers that actually allow you to program in a profile, specifically giving you control over time or perhaps just what parameter triggers each step.

For example, neither of these (indeed none that I know of) appear to allow telling the charger to stay in absorption per Odyssey's recommendation, which is either 0.1% of the C10 rating (e.g. 4mA for a PC1200) or held to a maximum of 8 hours if that current isn't reached.

That's a frustration I have with the BatteryMINDer I use now. It uses fine voltages (14.7/13.6 @ 25°C) and a temperature compensation (25mV/°C over -20°C to +50°C) but seems to triggers the end of absorption at 100mA. So it kicks down to float a little early. Sure, it's probably marginal but at about 4 years old my Odysseys are starting to show more aging than I'd like and I can only wonder how much difference it's made not holding absorption fully.

There are some chargers that give you the ability via DIP switches to set absorption time, but I haven't seen any that allow tailoring any further than that.

FWIW, The Victron Blue Smart IP65 charger allows fairly detailed control of the charging program through the VictronConnect app. You have to enable Advanced Settings, User Defined battery preset, and "Expert Mode" to get to them (so they don't make it straightforward). The absorption duration can be set to either "Adaptive" or "Fixed". I use the IP65 12/15 to keep my truck battery charged and healthy since it will sometimes sit for several weeks. You can download the VictronConnect app even if you don't own one of their products and evaluate the settings available for most of their products using the "Demo Products" feature.

 

[wADVr]

In searching every which way I can on this issue/topic I found this thread that on post #16 shows a simple way to alter/increase the alternator charging voltage. I really didn’t want to mess with this for the same reasons @DaveInDenver stated but this may be the best step in solving my starter battery issue with less plugging in. I should purchase HP tuners anyway for multiple reasons so that cost isn’t terrible.

Taking a step back and looking at the situation it looks like I have two things to address:
1) improve daily charging to keep my starter battery up (80-100%) ideally 100%
a) increase alternator charge voltage, and/or:
b) on board charger plugged in daily/weekly/monthly?

2) charge aux battery after deep cycling or even keeping topped off during daily use (assuming the the alternator will not do it)
a) go the BTB route which means removing Genesis isolator as the BTB takes it place (I think) also I am unclear/concerned how this method works with the winch that I would prefer to run off both batteries when engine is running and only the aux when not running. I don’t think this is possible using the BTB charger/isolator.
b) utilize the on board charger to top off and provide bulk charging/top off when deep cycled and left discharged or unsatisfactorily supported by the alternator.

That said, it appears that the on board charger is still the preferred method to satisfy both batteries and the winch. BUT there are a couple issues that may need addressing:
1) the Genesis isolating relay connect the batteries above 13.2v. This will need to be disabled when being charged by the on board charger. No big deal, I can simply add a switch to open the ground lead. Slightly annoying but easy to do.I believe this needs to be done to isolate each battery so a charger can properly charge them considering there is a good chance they will be at different voltages and one may only need topped off and the other may need a full bulk charge. I could have this wrong.
2) I need to research the on board chargers further. I like the idea of the 2 bank chargers but can they charge each bank at different stages? Ie one may only need bulk 14.7 for a short time before switching to the lower float voltage while the other discharged battery will require much more time at 14.7. Again I could have this wrong and this may not be an issue to just throw them together and let it average them out and charge as a single battery. If that is the case a single bank charger would be fine and the isolator could be left alone. What say you all?

thanks all for the responses so far, all good info and definitely steering my in the right direction although I might not be fully understanding the way you’ve intended.

 

[wADVr]

FWIW, The Victron Blue Smart IP65 charger allows fairly detailed control of the charging program through the VictronConnect app. You have to enable Advanced Settings, User Defined battery preset, and "Expert Mode" to get to them (so they don't make it straightforward). The absorption duration can be set to either "Adaptive" or "Fixed". I use the IP65 12/15 to keep my truck battery charged and healthy since it will sometimes sit for several weeks. You can download the VictronConnect app even if you don't own one of their products and evaluate the settings available for most of their products using the "Demo Products" feature.

View attachment 693437

im still green on all this but that looks like a pretty nice option. Was looking at the IP67 version and still trying to figure out best size with my setup but the tune-ability of this looks like it should work well with the Odyssey batteries. too bad it’s not on the list of their approved chargers. Thanks for throwing this option into the mix.

 

[DiploStrat]

While it appears that the focus of this thread has shifted to the challenges of using Odyssey batteries, I would merely note that, based on years of personal use, an intelligent relay is a great way to charge two lead acid batteries of grossly the same forumulation. (In my case, Delco lead-calcium and Lifeline AGM.) The great advantage is that a charge (solar/shore/engine) at either end that is sufficient to raise the voltage over target (typically about 13.2v) will cause the relay to close and share the charge. In my case, the truck had a Magnum inverter/charger, so I did not need an outboard charger, all I had to do was plug in.

For dissimilar batteries, a B2B is generally the easiest solution. In this case, there are several options for starter battery maintenance, ranging from the overkill of a second B2B (and some relays) to this, which I have not actually tested, looks nice, especially now with lithium voltage settings.

AMP-L-START Starting Battery Charger/Maintainer - Overview Page

15 Amp Starting Battery Charger/Maintainer

www.lslproducts.net

 

[DaveInDenver]

2) charge aux battery after deep cycling or even keeping topped off during daily use (assuming the the alternator will not do it)
a) go the BTB route which means removing Genesis isolator as the BTB takes it place (I think) also I am unclear/concerned how this method works with the winch that I would prefer to run off both batteries when engine is running and only the aux when not running. I don’t think this is possible using the BTB charger/isolator.

A DC-DC or battery-battery charger will only run in one direction and the current limit is charging levels not winching or jump starting levels.

There's various options but there's no reason one would have to be on only when the engine is running. However most of them do sense based on ignition or voltage so you can limit charging of the aux battery to times when the alternator is generating power to prevent running the starting battery down inadvertently.

Using a DC-DC doesn't necessarily mean you can't still parallel the batteries for winching or jump starting yourself. But you'll have to do the connection some other way, like the Genesis you have would still work or even just jumper cables in a pinch.

You'd probably want to disable the DC-to-DC charger (it might or might not actually matter but no reason for the risk) if you parallel the batteries with the relay. And obviously when you are not winching you'd need to enable the DC-DC and open the isolating relay. Doable but complexity of the control logic and wiring starts to factor in.

Also, just because you have dual batteries doesn't automatically mean you can or even should connect them together for winching. If your dual battery setup has the two batteries some distance apart you might actually be better leaving them open and just using the starting one. It's difficult even with a tightly located bank to wire batteries to discharge equally into a load, much more so when the batteries are not co-located.

The philosophy I used in my dual batteries was for redundancy, so they are sitting right next to each other and wired to make sure they discharge (and indeed charge) equally when paralleled. The downside is that I couldn't maximize storage capacity with a very large house battery, although the combination of the two did give me a bump in total capacity it's more about having a backup. I don't even always force them to connect when I winch, preferring if the winching will be less demanding to just protect the aux instead.

 

[DiploStrat]

As Dave noted above, paralleling, for starting, or worse, winching, requires properly sized wires. If you used those wires with a B2B, then any form of bypass - jumper cable, manual or relay controlled circuit, will work. According to Sterling Power, at least, there is no need to remove the B2B from the circuit. (This is actually similar to what CETEK used to do with their "SmartPass", albeit for a different reason.)

If you are handy enough with enough relays, REDARC will show you how to use this circuit for maintenance charging of the starter battery. Personally, I would try the AMP-L-START.

 

[wADVr]

I got the ”opportunity“ to put 9 solid hours of alternator charging into the starter battery and about 3 with the aux in the loop. charging voltage broadcasted through the OB2 port was a constant 14.5-14.8 with the majority of it setting right in between. Will see tomorrow morning what they settle at and watch for a few days of normal driving.

Good suggestions here which gave me a lot more to think about for long term so I’m not throwing money at it. Gotta say the inverter/charger got my wheels turning. I’d really like to charge/keep topped off both batteries when not driving and on ‘shore power’. I really need to get some in the field experience with the current set up and see what the needs are, so many options and ways to do all of this and minimal experience with actually deep cycling the aux battery with fridge lights etc.

To address the winching setup I did find a wiring diagram on Redarc’s site than simply adds a relay to normally isolate the winch and starting battery from the aux battery So the aux battery can be charged by the B2B DCDC charger. This diagram shows the winch direct on the starter battery which does make sense for direct charging from the alternator. So long as I can run the winch off only one battery when the engine is off so that I can start the engine when mobile again I’m happy. Seems unlikely but have been in a few situations over the years that required the engine off..

 

[DiploStrat]

As noted, I can't help you with the Odyssey batteries - talk to Dave.

-- With a "smart" alternator, you may well need a B2B to keep the camper battery happy. Sterling, Victron, RECARC and others all give you options. Lots of electrons die horrible deaths debating which is best. Mixing lead acid and lithium, then a B2B is probably the most cost effective approach.
-- Typically shore and solar chargers attach to the camper battery as, typically, that is the larger bank, more likely to be deeply discharged, etc.
-- The trick is set things up so that it is easy to share charge sources. And, as noted, if you need an inverter/charger, then you can have the convenience of using something that is on your truck all the time.

Obviously, this is easier with a large camper and space is at a premium with a "Jeep" sized vehicle. (Of course, the battery in question is probably smaller, too.

Also, consider your usage power:

-- Both ways 'round the world, full time? Starter battery is simply not an issue.
-- Daily driver? Probably fine.
-- Parked for most of the time between trips? In cold climate? Then starter battery, and camper battery, for that matter, maintenance is probably a real issue.

 

[DaveInDenver]

Regards to the REDARC wiring diagram the relay is an "auto" sense so to speak to link both batteries when the winch is powered. You could use just a switch, which they show as presumably a manual override for jump starting or otherwise. I don't see any advantage to it happening automatically and would personally put a manual disable to prevent the winch auto connect should you want it *not* to happen. Which in my mind would mean just use a switch all the time.

Engine off winching is a tough situation no matter what and to be honest that is where I would think about forcing the aux battery to be isolated instead of connected, unless you're in an real serious pickle where you get one shot at the recovery working. Normally if your starting battery goes flat you can decide to try again with the second battery later.

I'd weigh figuring how to use your shovel, Hi-Lift, traction boards, axe (e.g. finding logs) instead of potentially having no batteries at all. You *might* fuss with a badly mired truck for a couple of hours or days but the health and safety risk of being unable to start your engine, power a radio or having food probably is worse.

But the overall priority does depend on the situation and what you have, like solar panels to charge back up.

 

[DiploStrat]

Yo! Dave! As a non-winch guy, what is the switching logic of the relay?

It appears to be on the ground/earth leg. Is it activated, to make a ground, when you turn on the winch? The other relay, the SBI212 is an intelligent relay - how is that being used? It appears that the ground is broken. So does turning on the winch (or pressing the manual switch) complete the ground and allow the relay to operate? So why an intelligent relay? To open the circuit if neither side has high enough voltage?

EDITED TO ADD: The SBI may simply be because REDARC do not sell a large, dumb relay.


Your thoze, please.

 

[wADVr]

@DaveInDenver the engine off winching absolutely is last resort and certainly not recommended but I have had to use this a few times over the years luckily always someone else and my rig was there to jumpstart it after the recovery. To be specific: operating the winch when the engine is at an angle that it cannot be ran (upside down or on its side or vertical - any angle that the oil pump cannot pressurize the system with constant oil) also have been in a situation that a poorly designed factory fuel pickup led to fuel delivery problems during extraction. While this sounds extreme(and is) it is a situation that I want to be prepared for in this particular Jeep as it does get a share of winter snow adventures as well as difficult trail usage.

The Redarc diagram complicates it a bit with the auto relay, I would just run a switch to simplify and also serve as an emergency jump start.

 

[DaveInDenver]

Yo! Dave! As a non-winch guy, what is the switching logic of the relay?

It appears to be on the ground/earth leg. Is it activated, to make a ground, when you turn on the winch? The other relay, the SBI212 is an intelligent relay - how is that being used? It appears that the ground is broken. So does turning on the winch (or pressing the manual switch) complete the ground and allow the relay to operate? So why an intelligent relay? To open the circuit if neither side has high enough voltage?

EDITED TO ADD: The SBI may simply be because REDARC do not sell a large, dumb relay.


Your thoze, please.

Assuming it's a literal schematic looks to me what they're trying to do is when the winch is energized, presumably when you activate it powered through the starting battery, the control relay pulls in the heavy solenoid to parallel the batteries.

This or the push button manually completes the ground for the heavy solenoid, low side switching is typical.

I'm not intimately familiar with the SBI212 but it looks like a one-way sensing solenoid, which would mean it *should* disconnect when voltage drops out (it appears open at 12.7 and reconnects at 13.2V).

Which in the engine not running scenario would be pretty much happen as soon as you hit the winch anyway.

There's no reason I'd think it has to be an intelligent solenoid other than as you suggest it's what REDARC has in their catalog. There is some benefit in that it would take additional steps to force the connection to sidestep the voltage sense, thus giving a "do you really mean to do this?" step.

But it's possible they are trying to imply something else, such as when you activate the winch relay it also connects the batteries, so one control relay is actually energizing two solenoids - the battery isolation and the one in the winch.

@wADVr, I'm not saying engine-off winching isn't important just that if one battery gives you 5 minutes of full power winching is it worth getting 10 minutes if that means you kill both? It might but I'd just prefer to make that decision instead of the solenoid. If you have a buddy with you for a jumpstart then the decision is different of course.

But I'd also think that if I have a buddy along I'd try using his winch with his engine running instead, if possible. There's not one solution so having options afield is good. I'm just questioning the need to add complexity by bothering to sense the winch state when in my mind it's a solution looking for a problem. Just having the push button to override the solenoid logic seems sufficient.

 

[DiploStrat]

Sometimes my REDARC bubbas are a bit too clever for me.

Sooooo.

Assuming standard layout, 86 left, 30 bottom, etc.

-- When the winch is activated by some switch, NOT shown in the diagram, current comes down the blue wire, seeking ground.
-- 86 completes the circuit to 85 and the relay closes, connecting 87 (purple wire) to 30. This completes the ground for the SBI. So the "load" for this relay is actually the ground of the SBI. (Which, as noted, could also simply be a big relay, eg., Blue Sea.)
-- At this point, the SBI (aka bypass relay) closes and the camper battery is connected to the starter battery.
-- The push button shown in the diagram will also ground the relay and put the batteries in parallel.

Sooooo,

-- I see no reason to bother with this relay and would simply vote for a dash switch, probably a toggle.
-- Similarly, I don't really see a reason for an intelligent relay. This based on the idea that when you a winching, it is such an exceptional event, that you will be monitoring everything - you don't really need a relay to act like a fuse.

Sound right to you?

 

[wADVr]

@DiploStrat I was originally going to use a PAC-500 to isolate my winch from the batteries. As the trigger I was going to run a dash mounted Contura switch that would also enable the dash mounted winch controls (Momentary on-off-on Contura style). The Contura winch override switch would have a red backlit indicator so it would be quickly identifiable (and probably annoying)
So changing this up to link the aux battery to the winch/starter battery would not be adding any complexity unless I still wanted to isolate the winch from the batteries which would could be just adding another PAC-500 run off the same switch (although might want to use a relay to power both these large relays)
I mainly was concerned this was not an option with a B2B DCDC charger supplying the aux battery.

 

[WSS]

These work very well.

https://www.hellroaring.com/bic95300B.php

I run dual Odyssey agm's and a 200amp alternator