Replacing my Hymer camper van’s lithium batteries. Plug and play?

[Wtavern]

I have a question I hope someone can help me with answering.

I have a 2019 Hymer Aktiv Loft edition with two 200ah Ecotrek lithium batteries. The battery bank is charged via a second 280 amp Nations alternator with a MC614 Balmer regulator. The system also has a proprietary Voltstart automatic start system that switches the engine on automatically when the battery voltage falls to a certain threshold to recharge them. There is no solar on the loft editions of this van as there’s a pop top on the roof for additional sleeping quarters. The lithium’s are wired in parallel with an AGM battery to avoid having to have a dc-dc charger. I attached a wiring diagram below.

The Ecotrek battery banks are notoriously unreliable and have documented failures all over the internet.

I recently purchased 16 280 ah cells from Amy in the hope of creating my own battery bank to replace the Ecotrek system. I have a few reasons to replace them as I (a) want something more reliable than the Ecotrek lithium battery banks, (b) need more power to hopefully power a 12v dc air conditioner overnight without hookups (system yet to be sourced and the current AC system is an undermount system that does not cool effectively), and (c) I want to be able to use the vehicle in freezing temperatures (current Ecotreks are mounted under the vehicle chasis and have heaters, but can‘t be used in freezing temperatures), which means I may have to move the batteries in the cabin or purchase better heaters if I choose to keep them under the vehicle.

By the diagram, will this endeavor be plug and play after I choose my battery configuration, BMS, custom enclosure? Will it work off the bat with my second alternator and Balmer, which is already programmed to charge lithium’s? Will it work with the voltstart system to automatically start the vehicle when the voltage is low enough to start charging from the alternator?

Thank you in advance!

 

[grizzzman]

Will it work? It does now doesn’t it?. I would suggest that you look at a separate port BMS. However this would require a bit of a system upgrade. And likely a better understanding of how it would be beneficial to you to upgrade.

 

[GSXR1000]

I would think that directly connecting LIFEPO to AGM might be why your batteries are not lasting

 

[John Frum]

I would think that directly connecting LIFEPO to AGM might be why your batteries are not lasting

Looks to me like the only integration between the house and starter battery is via the iDataStart component.

Is the house battery lifepo4 400 amp hours@12.8 volts nominal?

I am embarrassed to ask but what does a balmer regulator actually regulate?
Is it voltage or current or both?
Is it configurable?
Does it do anything else?
Your minimum charge current for the new batter{y,ies} is ~224 amps or .2c.
The maximum continuous charge current for same is 672 amps or .5c.

 

[HRTKD]

Your diagram is overly complicated. A simplified diagram that focuses on just the components that are critical would help. Do you have an on-board generator, or is the vehicle's engine represented on the diagram twice?

I would want a DC-DC charger in between the LiFePO4 battery bank and the alternator. But if there is a component in there that allows power to flow back to the starter battery, that would require a new set of wires because the DC-DC charger is going to flow power one way, to the LiFePO4 bank.

With regard to your Voltstart automatic start system, a concern there would be that the voltage for LiFePO4 is flat all the way until it's pretty much dead. If you can adjust the voltage of the auto start for LiFePO4 that would help. Otherwise, the system could be starting when the LiFePO4 battery bank is at 5% state of charge. I don't have an auto start system in my RV (it could have that feature with a new panel), so my concern may be invalid.

 

[GSXR1000]

Your diagram is overly complicated. A simplified diagram that focuses on just the components that are critical would help. Do you have an on-board generator, or is the vehicle's engine represented on the diagram twice?

I would want a DC-DC charger in between the LiFePO4 battery bank and the alternator. But if there is a component in there that allows power to flow back to the starter battery, that would require a new set of wires because the DC-DC charger is going to flow power one way, to the LiFePO4 bank.

With regard to your Voltstart automatic start system, a concern there would be that the voltage for LiFePO4 is flat all the way until it's pretty much dead. If you can adjust the voltage of the auto start for LiFePO4 that would help. Otherwise, the system could be starting when the LiFePO4 battery bank is at 5% state of charge. I don't have an auto start system in my RV (it could have that feature with a new panel), so my concern may be invalid.

 

[HRTKD]

The charge profile you get from the alternator isn't quite what LiFePO4 wants to see. He can avoid a DC-DC charger all he wants, but his LiFePO4 will not be happy.

 

[John Frum]

View attachment 43878

What was your interpretation of the diagram?

 

[GSXR1000]

AGM strait to BMS.. so direct connected

 

[John Frum]

AGM strait to BMS.. so direct connected View attachment 43911

Does that mean that both alternators feed both battery banks?

 

[GSXR1000]

per drawing alt 1 only for radio and power step..
I wonder if starter batteries and coach are 24v?
makes little to none sense to have 2 separate 12v systems for the chassis.

tie those 2 systems together and use 2nd alt for coach batteries. looks like a fancy regulator (balmar) that might could be configured for lifepo

 

[GSXR1000]

looks like it

 

[John Frum]

looks like itView attachment 43946View attachment 43947

I'm too tired to dig into this.
The part you hi-lighted is not ringing my clue bell.
Seems weird to me to have the starter alternator and house alternator charging the house battery.
Although I can think of reasons to do it.

 

[John Frum]

I have some vague memory that "AGM“Starter” Battery11.0v min to trigger Balmar" is a workaround for a component level or system level issue.
I know I've looked at this or similar stuff before but can't really recall.

My gut says that 11.0 volts is the lowest possible setting and they chose it to mitigate some issue.

 

[GSXR1000]

I'm too tired to dig into this.
The part you hi-lighted is not ringing my clue bell.
Seems weird to me to have the starter alternator and house alternator charging the house battery.
Although I can think of reasons to do it.

I bet... it was built as a work van.. and no matter what lights or radios where left on you could always start the truck...

now it seems the lifepo should replace the top battery but then would auto start work?

 

[John Frum]

I bet... it was built as a work van.. and no matter what lights or radios where left on you could always start the truck...

now it seems the lifepo should replace the top battery but then would auto start work?

Hymer makes purpose built recreational vehicles.
I'm not aware of them making work vans.
I did some research on the company a few years ago because I was considering investing.
Luckily I gave it a pass.

But your suggestion is what I was thinking as a justification for the tied systems.

 

[GSXR1000]

Hymer makes purpose built recreational vehicles.
I'm not aware of them making work vans.
I did some research on the company a few years ago because I was considering investing.
Luckily I gave it a pass.

But your suggestion is what I was thinking as a justification for the tied systems.

I know nothing about the brand... I was being a technician and looking at info presented.
I just don't see how you can use 2 types of battery in parallel

at least lifepo is pretty happy with lead acid battery charge voltage...
it does seem like upon start it would trip lifepo battery BMS since lower internal resistance and lack of voltage drop it would pull all current from lifepo..

maybe remove agm start battery and a 4 280ah batteries with 4 daily 200A BMS

 

[John Frum]

I know nothing about the brand... I was being a technician and looking at info presented.
I just don't see how you can use 2 types of battery in parallel

at least lifepo is pretty happy with lead acid battery charge voltage...
it does seem like upon start it would trip lifepo battery BMS since lower internal resistance and lack of voltage drop it would pull all current from lifepo..

maybe remove agm start battery and a 4 280ah batteries with 4 daily 200A BMS

Would a starter battery at 11 volts even be able to crank a reasonable displacement engine for the van that weighs ~9000lbs?
Just saying it seems very low.

 

[GSXR1000]

that's why I said lifepo also.. 11v would be 2.75v so all have about 4% left with a absolute min of 10v (2.5v)

 

[Rampromaster]

I have a question I hope someone can help me with answering.

I have a 2019 Hymer Aktiv Loft edition with two 200ah Ecotrek lithium batteries. The battery bank is charged via a second 280 amp Nations alternator with a MC614 Balmer regulator. The system also has a proprietary Voltstart automatic start system that switches the engine on automatically when the battery voltage falls to a certain threshold to recharge them. There is no solar on the loft editions of this van as there’s a pop top on the roof for additional sleeping quarters. The lithium’s are wired in parallel with an AGM battery to avoid having to have a dc-dc charger. I attached a wiring diagram below.

The Ecotrek battery banks are notoriously unreliable and have documented failures all over the internet.

I recently purchased 16 280 ah cells from Amy in the hope of creating my own battery bank to replace the Ecotrek system. I have a few reasons to replace them as I (a) want something more reliable than the Ecotrek lithium battery banks, (b) need more power to hopefully power a 12v dc air conditioner overnight without hookups (system yet to be sourced and the current AC system is an undermount system that does not cool effectively), and (c) I want to be able to use the vehicle in freezing temperatures (current Ecotreks are mounted under the vehicle chasis and have heaters, but can‘t be used in freezing temperatures), which means I may have to move the batteries in the cabin or purchase better heaters if I choose to keep them under the vehicle.

By the diagram, will this endeavor be plug and play after I choose my battery configuration, BMS, custom enclosure? Will it work off the bat with my second alternator and Balmer, which is already programmed to charge lithium’s? Will it work with the voltstart system to automatically start the vehicle when the voltage is low enough to start charging from the alternator?

Thank you in advance!

I'm looking to achieve the same set up with 600-700 ah of lithium. Have you gotten any confirmation of this being the correct/ safe setup?