Lithium battery upgrade. Charging circuits

Ramland · 08-21-2021, 08:22 AM

I recently bought two Battle Born 100 Amp 12V house batteries as a first step to eventually going solar on my 2021 Greyhawk 29MVP. I was able to modify the Intellipower PD9100 converter/charger to provide the proper charge profile for the lithium’s with the simple addition of a plug in module from Progressive Dynamics for just $7.99.
I note that we’ve got a PD5100 automatic transfer switch to switch between shore power and the Onan generator so power is routed correctly through the converter/ charger.

My question is:what about the power coming from the truck alternator? Is it rooted through the PD9100 or do I need to address the charging profile coming from that for lithiums separately?

Anyone have access to an electrical schematic for the three way charging system?

Savage sea · 08-21-2021, 09:30 AM

Yes. You 100% need to address this. You will cook your alternator.

Two options.

A dc-dc charger like victron. You will wire that to your chassis battery and to the lithium’s. Probably reuse the factory wire with just removing the factory charging solenoid

This does a constant 30amps of charge

Option 2 is a lithium compatible replacement for the factory solenoid. Such has BMI. Battle born sells them as well as Amazon. This is a direct replacement. I moved my batteries to the rear of the coach (29v) so I did not feel comfortable with the 70 A plus of charging With smaller factory ga wire fro that long of a run so I replaced the whole run. If factory location should be ok. It’s only like a 30-40% duty cycle on this system.

ARoamer · 08-21-2021, 11:01 AM

""My question is:what about the power coming from the truck alternator? Is it rooted through the PD9100 or do I need to address the charging profile coming from that for lithiums separately?""

Depends on what you want your truck's charging to do. Since you are adding solar, and have a generator, I would not mess with it other than maybe a disconnect solenoid to stop lithiums higher voltage from back feeding truck battery when stopped. Or you could simply disconnect trailer when stopped. Original truck charge wires will only give so many amps, not enough to cook your alternator. I installed a relay that is triggered by my running lights so I only charge with headlights on. Usually my solar has batteries charged by 11am depending on remaining charge and clouds.

craigav · 08-21-2021, 11:19 AM

Quote:

Originally Posted by ARoamer

""My question is:what about the power coming from the truck alternator? Is it rooted through the PD9100 or do I need to address the charging profile coming from that for lithiums separately?""

Depends on what you want your truck's charging to do. Since you are adding solar, and have a generator, I would not mess with it other than maybe a disconnect solenoid to stop lithiums higher voltage from back feeding truck battery when stopped. Or you could simply disconnect trailer when stopped. Original truck charge wires will only give so many amps, not enough to cook your alternator. I installed a relay that is triggered by my running lights so I only charge with headlights on. Usually my solar has batteries charged by 11am depending on remaining charge and clouds.

While I agree with you if this was a trailer, but being a Class C changes things. There is a solenoid on the firewall under the hood almost directly in front of the steering wheel which will connect the chassis and coach batteries together when the key is on (or auxillary\emergency start switch is pressed). What is needed is to use a dc2dc charger, perhaps connecting the in and out of the charger to the solenoid but with disconnecting the direct connection that the solenoid provides.

In other words, disconnect the coach battery side of the solenoid, connect the coach side cable into the dc2dc charger output, and power the dc2dc charger from the solenoid where the coach battery cable was removed from. ~CA

ARoamer · 08-21-2021, 04:46 PM

My bad, I didn't realize this was a class c motorhome.

dvspl · 08-22-2021, 07:39 AM

Quote:

Originally Posted by Ramland

My question is:what about the power coming from the truck alternator? Is it rooted through the PD9100 or do I need to address the charging profile coming from that for lithiums separately?

Anyone have access to an electrical schematic for the three way charging system?

Alternator charges the coach batteries directly when ignition is on (converter/charger not in this circuit). Both Savage Sea and craigav have given good advice. You need to do something to prevent excessive load on your alternator. After you have solar installed, a third option would be to rely just on that and not charge from alternator.

If you email Jayco (motorizedsupport@jayco.com) they'll send you the 12V electrical system schematics.

Tgroves526 · 08-25-2021, 06:22 AM

Im tagging on to0, I understand that the alternator see's the lithium battery different and it will take as much amps as it will put out but my question is

Where can we install a dc2dc in a dry location? My 29 MV is packed , has anyone found a under chassis weatherproof box?

Thanks for reply's
Ted

dvspl · 08-25-2021, 06:43 AM

Quote:

Originally Posted by Tgroves526

Where can we install a dc2dc in a dry location? My 29 MV is packed , has anyone found a under chassis weatherproof box?

I installed mine on the forward wall inside the storage compartment directly behind the door. That's very close to the batteries (under the step) and it was easy to re-route the alternator charge line to it. It only takes up a small amount of storage space.

Ramland · 08-31-2021, 02:55 PM

May I ask if you were able to install the dual BB’s under the step without modification? Pix would be appreciated. Still debating on a BIM or the DC2DC charger route

robchampagne · 08-31-2021, 08:55 PM

I recently installed 2 Renogy Lithium 100aH batteries, and the fit right in under the step replacing the stock lead acid.
Like Ramland, I did the $7.99 module for when we are plugged into shore power, allowing the PD converter to charge Lithiums.
I installed a Renogy 40A DC-DC charger using the existing wiring from the alternator (4 ga as I recall). Renogy makes 20, 40 and 60 amp chargers. The stock alternator on my 2020 V10 is 155 amps, so I went with the 40A.
I also installed a Victron Smartshunt. This allows my to accurately monitor all power in and out of my batteries, including the PD converter, on my iPhone. Great for doing consumption audits. I occasionally throw out a 200W 'suitcase' solar unit, and the Smartshunt measures this as well.
I did sacrifice the storage compartment behind the steps for the charger, and found on hot travel days it gets up to 110F inside. So I added 2 vents and a small 12V fan, wired into the D+ ignition circuit the DC-DC charger requires. This ignition circuit ensures the charger is only live when the ignition is on, preventing the house batteries from draining back.
So far, I am very happy with the set up.
Also, a shout out to Renogy. What I purchased arrived as promised, on time. And questions to their tech dept were answered quickly.
One disadvantage from Battle Born is that Renogy can't be wired in series to create 24/48 V. I didn't care about this.

dvspl · 09-02-2021, 05:08 PM

Quote:

Originally Posted by Ramland

May I ask if you were able to install the dual BB’s under the step without modification? Pix would be appreciated. Still debating on a BIM or the DC2DC charger route

I don't think two BB's will fit under the step. It's been a year since I did the research for mine, but I was not able to find a way to fit BB's under the step. I used two Renogy 100AH SmartLithiums and they just fit. I had to do some modifications to the battery tray so that they length would fit, the width was the same as the battery tray and the height just fits beneath the step.

bluztoo · 09-03-2021, 10:42 AM

On my Melbourne I have roughly 20 workable inches under the step. If you moved wires and worked at it you could gain another inch.

aaurbane · 09-08-2021, 01:11 PM

I'm installing 3 battleborn, victron multiplus, DC to DC charger and solar mppt. In my 2021 30z there's 4 gauge wire from the eng bat to the emergency connect solenoid and then to the house battery. I removed the wires from the solenoid and connected them, which gives me 4 gauge back to the house battery. Just before the house battery I put an off/1/2 rotary switch. 1 goes to the victron 30 amp DC to DC charger. 2 goes to a breaker and then the house battery. 2 gives me the option to connect the house and engine batteries for emergency start but normally I'll use 1 so that the lithium batteries don't damage the alternator. Battleborn told me the li bim 225 won't limit the flow of amps. I've got a 60 amp breaker/switch at the eng bat and the same after the rotary switch. I also had to run a 10 gauge wire from the solenoid back to the eng bat to keep the step working.

kpeggleston · 09-11-2021, 03:07 PM

I am trying to do the same thing with my 2020 Jayco Greyhawk 27U class C. Where wold I mount the DC 2 DC charger and where would I find the selenoid you refer to? I am not RV electric savvy.

dvspl · 09-12-2021, 09:07 AM

Quote:

Originally Posted by kpeggleston

I am trying to do the same thing with my 2020 Jayco Greyhawk 27U class C. Where wold I mount the DC 2 DC charger and where would I find the selenoid you refer to? I am not RV electric savvy.

I'm not familiar with the specifics of the 27U, but you want to mount the DC-DC charger as close to the batteries as possible so the wiring runs are short and easy. My batteries are under the entry step, so I mounted the DC-DC charger in the outside storage compartment directly behind that. Easy to drill a small hole to route the wires and the wiring runs are about 1-2 feet. Very easy!

The solenoid that connects the alternator to the batteries is typically on the driver's side firewall under the hood, almost directly in front of the steering wheel.

kpeggleston · 09-12-2021, 09:22 AM

Thanks

kpeggleston · 09-12-2021, 09:51 AM

So is all the needed wiring already there? I would just need to identify which wires to connect?

bluztoo · 09-13-2021, 05:48 AM

Can’t know until you look. I had a little cover in the first bay behind the door. There were six wires there. Two to the roof (connected to outlet plugs already) two the coach battery and two to the chassis battery. The last two sets are not connected.

pconroy · 09-13-2021, 02:55 PM

Quote:

Originally Posted by dvspl

The solenoid that connects the alternator to the batteries is typically on the driver's side firewall under the hood, almost directly in front of the steering wheel.

We're in a non-solar prepp'd 2016 so it'll be different, but here's our solenoid.

bluztoo · 10-04-2021, 04:40 PM

aaurbane - Really helpful idea on the lithium to chassis battery connection with your breaker and switch. I am just now making the move to lithium and I am concerned about not being able to start the rig with the coach battery backup as it will hurt the lithium. I thought the dc-to-dc isolated charger would be enough to couple the two systems, but I guess not. Just seemed to me there should be a simple way to do it and I think you hit on it.

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