50Ah LiFePo4 Battery Installed

alexandruast · May 27, 2024

Hi,
This is what I've worked on the past 3 days:

I used the DS250SE to manage the LiFePo4 battery, and left the initial vehicle configuration intact (the two batteries managed only by the smartpass 120):

This is the battery that I used:

LiTime 12V 50Ah Lithium Battery- 640Wh Energy, Marine, RV, Fish Finder

LiTime 12V 50Ah lithium battery is engineered with grade-A cells offering superior performance and high reliability for RV, fish finder, trolling motor...

www.litime.com

I manufactured two aluminum rectangle supports to clear the bottom chassis screws, 10-minute job using a rectangle aluminum profile and a drill.

The black wire of the DS250SE has to be connected to +12V for the management to switch to lithium.
I use the lithium battery to power a Garmin PowerSwitch (Autotherm heater, fridge) and the all the vehicle AUX (direct feed via relay).

nuclearmonkey · May 27, 2024

Can you walk me through the charging process of using the D250 for the lithium? I’ve been trying to wrap my head around how I’m going to wire up my system… I was thinking of adding the D250 for the standard dual battery system, then add another dc charger to handle the lithium. This has me rethinking my strategy.

alexandruast · May 28, 2024

nuclearmonkey said:
Can you walk me through the charging process of using the D250 for the lithium? I’ve been trying to wrap my head around how I’m going to wire up my system… I was thinking of adding the D250 for the standard dual battery system, then add another dc charger to handle the lithium. This has me rethinking my strategy.

The two CTEK devices (Smartpass 120 and 250SE) do not seem to communicate in any way with each other, and there is no logical reason for them to do so - it's basically parallel charging. So the behavior of Smartpass 120 and 250SE is the same, no matter the configuration - single CTEK120, dual CTEK120, CTEK120+250SE, dual CTEK250SE, you get the idea.

In the standard dual battery system, adding the CTEK250SE means you split the alternator feed into two parts (120+250) and join them together after, with more charging capacity.

If you want to charge lithium as a third battery, you keep the alternator plate connection betweeen the terminals of the 120 and 250 (A) and remove the (B) plate between terminals, so the outputs from the devices do not combine after. Then, you take the (B) output of the 250SE and feed it into the lithium battery positive terminal. You also need to apply +12V on the black wire of the 250SE to tell the device you are charging lithium. I connected this thin wire to the alternator feed terminal of the 250SE (A).

nuclearmonkey · May 28, 2024

I have been trying to figure out the role of the 250 (other than solar), with some people saying it was the only way to get the second factory battery fully charged. Your logic certainly makes sense in using it for the lithium and letting the 120 take care of the factory setup. Are you able to monitor the charging parameters of your factory auxiliary battery, and Is the 120 able to top it off sufficiently on its own?

alexandruast · May 29, 2024

nuclearmonkey said:
I have been trying to figure out the role of the 250 (other than solar), with some people saying it was the only way to get the second factory battery fully charged. Your logic certainly makes sense in using it for the lithium and letting the 120 take care of the factory setup. Are you able to monitor the charging parameters of your factory auxiliary battery, and Is the 120 able to top it off sufficiently on its own?

In normal use, the secondary battery is charging with up to 120A by the Smartpass 120, according to the manual:

If the battery doesn't take charge, it could be a lot of reasons but not the Smartpass. As a rule of thumb, a charger can provide amps, but it's in the battery chemistry and state to accept those amps. What you see on the screen in the offroad menu is the SoC of the primary battery. Also, the charging amps tells only 1/3 of the story. Charging amps only shows current that is flowing in or out the primary battery. It does not account for any current flowing in or out the secondary battery or in or out into the car electronics. Your alternator could be pushing 180A, but if 50A is going to the vehicle consumers and 100A to the secondary battery you will only see 30A charging on the screen.

A lot of the issues arise from the pesky SoC monitor. In a normal car, you don't have such thing and you ignore it for good. Lead batteries tend to accept less and less charge flow very quickly. That's the reason everyone should put their car batteries on smart chargers at home at least once a month. Aflter only a month, on a normal vehicle, there is an 80% drop in accepted rate of charge for a new battery. After reconditioning for 48h, the accepted rate of charge is back to normal. You don't feel this drop in capacity on a normal car, but it is there.

Yes, the 120 should be more than enough to charge the factory aux battery, if the aux battery is in good condition. If not, it doesn't matter which charger you use. Remember, chargers only provide available charging capacity, they cannot "force" current into the battery.

I don't have any monitoring available, but the car stays on a Victron charger 24/7 when in the garage, so the batteries are always at 100% and happily take 80A of charging when a bit low, measured with a clamp meter at 85% SoC reported by the car.

nuclearmonkey · May 30, 2024

Great breakdown - really appreciate it!

Asnes · May 31, 2024

alexandruast said:
In normal use, the secondary battery is charging with up to 120A by the Smartpass 120, according to the manual:
View attachment 7858335
If the battery doesn't take charge, it could be a lot of reasons but not the Smartpass. As a rule of thumb, a charger can provide amps, but it's in the battery chemistry and state to accept those amps. What you see on the screen in the offroad menu is the SoC of the primary battery. Also, the charging amps tells only 1/3 of the story. Charging amps only shows current that is flowing in or out the primary battery. It does not account for any current flowing in or out the secondary battery or in or out into the car electronics. Your alternator could be pushing 180A, but if 50A is going to the vehicle consumers and 100A to the secondary battery you will only see 30A charging on the screen.

A lot of the issues arise from the pesky SoC monitor. In a normal car, you don't have such thing and you ignore it for good. Lead batteries tend to accept less and less charge flow very quickly. That's the reason everyone should put their car batteries on smart chargers at home at least once a month. Aflter only a month, on a normal vehicle, there is an 80% drop in accepted rate of charge for a new battery. After reconditioning for 48h, the accepted rate of charge is back to normal. You don't feel this drop in capacity on a normal car, but it is there.

Yes, the 120 should be more than enough to charge the factory aux battery, if the aux battery is in good condition. If not, it doesn't matter which charger you use. Remember, chargers only provide available charging capacity, they cannot "force" current into the battery.

I don't have any monitoring available, but the car stays on a Victron charger 24/7 when in the garage, so the batteries are always at 100% and happily take 80A of charging when a bit low, measured with a clamp meter at 85% SoC reported by the car.

Alex - thanks for this. I too will put a victron on my starter battery when in the garage. Do you use the Blue Smart charger? What amperage do you have to cover both starter and secondary battery? I was thinking 15A would be fine for both.

I assume you just connected the viltron charger to the starter battery and then the smartpass will let additional current flow to the secondary as needed so bot are always charged?

Logsplitter · May 31, 2024

Asnes said:
Alex - thanks for this. I too will put a victron on my starter battery when in the garage. Do you use the Blue Smart charger? What amperage do you have to cover both starter and secondary battery? I was thinking 15A would be fine for both.

I assume you just connected the viltron charger to the starter battery and then the smartpass will let additional current flow to the secondary as needed so bot are always charged?

Here’s mine permanently installed. Just plug a mains lead in at the back of the vehicle.

Asnes · May 31, 2024

This is great logsplitter. Did you wire directly to the starter battery?

alexandruast · May 31, 2024

My charger is wired to the primary loop via the compressor aux wire which is permanently powered. I use a 30A charger because when camping it's the only power supply, so I need enough for charging plus keeping all the electronics working and not worry about sucking more than putting in.

Logsplitter · May 31, 2024

Asnes said:
This is great logsplitter. Did you wire directly to the starter battery?

Yes directly to starter battery

Asnes · Jun 1, 2024

Thanks to both of you for this.

Asnes · Jun 2, 2024

Installed my Victron IP22 today. Thanks again for your recommendations.

This is to keep the batteries floating whilst I am traveling. I am going to figure out where to install a an exterior outlet so I don’t need to keep the window down whilst whilst charging.

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50Ah LiFePo4 Battery Installed

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