Best Charging Practices?

[ConcordCarlos]

Question for the group on best charging practices. I have a 2008 GX470, with a dual battery set up, the ACR is a Bluesea Systems ML-ACR. The starting battery is a Odyssey G34 and the house battery is a Bosch G35. My "shore power" charger is the CTEK Multi US 7002. I also have a Vicrton MPPT connected to the house battery for when I deploy my folding 100w Renogy panel. When I am charging at home with the CTEK, is it best to isolate the batteries and charge them separately or let the ACR close and treat both batteries as one bank? The CTEK plug is on the starting battery side, so it starts on that battery when I charge them at the same time. If I did leave them linked during charging, would it be better to charge from one side or the other?

Thanks,

Carlos

 

[Alloy]

When batteries are a different - brand - type - size or age it is better to charge them seperatley but better is only a small percentage of the lifecycle in this case as they are connect when the egine is charging.

If a charger does not have a storage mode my preference is to leave the batteries sit rather than keep them connect to a charger.

 

[john61ct]

Do not worry about the Starter batt much, hardly gets depleted, any old charger fine.

For House, nice Odyssey deep cycling want a **minimum** 0.2C current rate, really 0.4C is better.

Won't speed the cycle up much, 5-7 hours still needed to get back to 100% Full

but much better for AGM longevity.

Do not let the charge source drop to Float, until amps have trailed down at Absorb voltage to 0.005C, or current has dropped less than 0.1A over an hour.

 

[ConcordCarlos]

When it’s time to replace the house battery I’ll replace it with an Odyssey , but size and age of battery will still be different. The CTEK I have doesn’t have much as far as custom settings , just a few selections re battery type. I could run it in power supply mode and run it through the victron , which has more customization .

 

[john61ct]

Sorry reversed.

So forget "best practices" for now, non-adjustable chargers will nearly always be a compromise, unless you select the battery specifically so its profile specs match.

If you want to charge through the ACR, put the source on House, optimize any settings for that much as you can.

Starter hardly gets at all depleted, just top up occasionally if in storage - isolated!

Before you get your Odyssey House set up, buy a charger that lets you optimize for its profile specs as above.

 

[Martinjmpr]

Curious about why you would need to charge your house battery from a 120v AC source at all? I ran a dual battery system in my Suburban from 2016 to 2019 and never charged the house battery independently of the alternator. It never seemed to need it. Any time the engine was running the house battery was being charged by a 145a alternator.

Are you parking your GX and leaving some high-draw appliance in it all the time? But even that doesn't make sense because if you have a place to plug a 120vAC charger into your GX, you also have a place to plug in your high-draw appliance.

So what am I missing here?

 

[john61ct]

Once you get a House bank of expensive deep cycling units, you really want to keep them at 100% Full as per above spec for as much of their lifespan as possible.

That means utilizing every available power source, at least every couple weeks and that's if they are fully isolated from any loads.

Only people going for 6-7+ hour drives get there off an alternator, and even then, not all of them, even with a 200+ Ah alt.

If your House bank is cheap and you don't mind replacing it much more frequently than necessary, then never mind, good enough for your usage is good enough.

 

[ConcordCarlos]

Curious about why you would need to charge your house battery from a 120v AC source at all? I ran a dual battery system in my Suburban from 2016 to 2019 and never charged the house battery independently of the alternator. It never seemed to need it. Any time the engine was running the house battery was being charged by a 145a alternator.

Are you parking your GX and leaving some high-draw appliance in it all the time? But even that doesn't make sense because if you have a place to plug a 120vAC charger into your GX, you also have a place to plug in your high-draw appliance.

So what am I missing here?

I drive an average of 1 hour per day, mostly on the freeway. I plug in the charger every other week to keep the batteries fully charged more often. Nothing high draw in the rig. When we are camping in the same spot for a day or so I put out the solar panel , 50l ARB fridge is the biggest draw.

 

[Martinjmpr]

Once you get a House bank of expensive deep cycling units, you really want to keep them at 100% Full as per above spec for as much of their lifespan as possible.

That means utilizing every available power source, at least every couple weeks and that's if they are fully isolated from any loads.

Really? I only ask because wife and I just got E-bikes (Lectric XP) that run on Li-Ion batteries and the owners manual actually says to NOT keep them connected to power. In fact, it says keeping them hooked up to power after they've fully charged will shorten the lifespan of the battery pack.

The owner's manual recommends keeping the battery at 75% of charge for best longevity. Don't know if it's because it uses a battery pack made up of multiple small cells or whether that makes a difference from a larger LiFePo battery or not.

 

[Alloy]

Really? I only ask because wife and I just got E-bikes (Lectric XP) that run on Li-Ion batteries and the owners manual actually says to NOT keep them connected to power. In fact, it says keeping them hooked up to power after they've fully charged will shorten the lifespan of the battery pack.

The owner's manual recommends keeping the battery at 75% of charge for best longevity. Don't know if it's because it uses a battery pack made up of multiple small cells or whether that makes a difference from a larger LiFePo battery or not.

The OP has lead acid and those should be kept at 100%`

 

[john61ct]

keeping them hooked up to power after they've fully charged will shorten the lifespan of the battery pack.

Yes true for LI chemistries

but this thread is about lead batts only, no mention was made of getting involved with LI.

Endless Sphere forum is a good place to discuss optimal care of your LI ebike packs.

 

[ConcordCarlos]

Tried running the CTEK in “power supply” mode, into the Victron solar controller. It’s a no-go, the Victron needs 5vdc above battery voltage to turn the battery charger mode on.

 

[john61ct]

Run the CTEK direct for now

given the non-optimal system as a whole, good enough is good enough.

As components need replacing, work toward Best Practices over time