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DC-DC charger for lithium batteries

Jim McGarvie

By Jim McGarvie
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Jim McGarvie

Jim McGarvie

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I have installed three 12V 100AH LiFePO4 batteries. Initially I just disconnected the relay between the engine and house batteries to avoid the potential alternator issues of charging the lithium batteries while driving. I have solar, so depending upon available sunlight I might get by this way, but I am considering installing a DC-DC charger. What is everyone's favorite? I would just as soon not need to run a wire to the alternator if possible, simply replace the solenoid with the charger.

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1nolaguy

1nolaguy

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Not sure about your set up. I have 4-100 AHr LFP batteries and they are charged from my I/C ( Aims PICOGLF3K12050BY). I have had this set up for 3 years now with no real issues related to battery charging. Based on the settings I selected charge from the I/C cuts off at 95% SOC and cuts on at 10% SOC. I charge whenever connected to shore or on genny but you could easily add/substitute solar via a charge controller. A DC-DC charger would only be needed if you also wanted to charge from your alternator.  LFP batteries like to be cycled verses held at a full charge. I usually run the inverter while driving to discharge the batteries and help with teh cycling as we spend most time at CG with full hook ups. YMMV

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CAT Stephen

CAT Stephen

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Hello Jim,

The first consideration for selecting a DC to DC charger is your alternator capacity.  If you purchase a DC to DC converter which, in parallel with your other alternator loads, exceeds the capacity of your alternator, your alternator can be severely damaged or destroyed.  You can obtain the capacity of your alternator by using your engine model and engine serial number then contacting your engine manufacturer.

The second consideration for selecting a DC to DC charger is your shunt use and your other feature needs:

- If a shunt used to measure your LiPO4 bank state of charge is planned for your use either currently or in the future, then your ONLY DC to DC charger option is an isolated DC to DC charger.  To the best of my current knowledge, Victron Energy is the only company that manufactures isolated DC to DC chargers at a reasonable price: https://www.victronenergy.com/upload/documents/Datasheet-Orion-Tr-Smart-DC-DC-chargers-isolated-250-400W-EN.pdf

- If you are on a very constrained budget and never plan to use a shunt, Renogy DC to DC chargers provide the best value, but need to be manually switched on and off physically which is inconvenient: https://www.amazon.com/Renogy-Battery-Batteries-Multi-stage-Charging/dp/B07Q4SVX3M/ref=sr_1_1?crid=U04CR0YL3EJU&keywords=renogy%2Bdc%2Bto%2Bdc%2Bcharger&qid=1699890028&sprefix=renogy%2BDC%2Bto%2B%2Caps%2C92&sr=8-1&ufe=app_do%3Aamzn1.fos.f5122f16-c3e8-4386-bf32-63e904010ad0&th=1

- If you seek maximum flexibility and complete integration with your iOS or Android devices, The Victron Energy Orion Series Smart DC to DC isolated chargers are the flagship of the DC to DC charger industry, and are reasonably priced compared to other options except Renogy: https://www.victronenergy.com/upload/documents/Datasheet-Orion-Tr-Smart-DC-DC-chargers-isolated-250-400W-EN.pdf

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timaz996

timaz996

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Posted (edited)
2 hours ago, CAT Stephen said:

Hello Jim,

The first consideration for selecting a DC to DC charger is your alternator capacity.  If you purchase a DC to DC converter which, in parallel with your other alternator loads, exceeds the capacity of your alternator, your alternator can be severely damaged or destroyed.  You can obtain the capacity of your alternator by using your engine model and engine serial number then contacting your engine manufacturer.

The second consideration for selecting a DC to DC charger is your shunt use and your other feature needs:

- If a shunt used to measure your LiPO4 bank state of charge is planned for your use either currently or in the future, then your ONLY DC to DC charger option is an isolated DC to DC charger.  To the best of my current knowledge, Victron Energy is the only company that manufactures isolated DC to DC chargers at a reasonable price: https://www.victronenergy.com/upload/documents/Datasheet-Orion-Tr-Smart-DC-DC-chargers-isolated-250-400W-EN.pdf

- If you are on a very constrained budget and never plan to use a shunt, Renogy DC to DC chargers provide the best value, but need to be manually switched on and off physically which is inconvenient: https://www.amazon.com/Renogy-Battery-Batteries-Multi-stage-Charging/dp/B07Q4SVX3M/ref=sr_1_1?crid=U04CR0YL3EJU&keywords=renogy%2Bdc%2Bto%2Bdc%2Bcharger&qid=1699890028&sprefix=renogy%2BDC%2Bto%2B%2Caps%2C92&sr=8-1&ufe=app_do%3Aamzn1.fos.f5122f16-c3e8-4386-bf32-63e904010ad0&th=1

- If you seek maximum flexibility and complete integration with your iOS or Android devices, The Victron Energy Orion Series Smart DC to DC isolated chargers are the flagship of the DC to DC charger industry, and are reasonably priced compared to other options except Renogy: https://www.victronenergy.com/upload/documents/Datasheet-Orion-Tr-Smart-DC-DC-chargers-isolated-250-400W-EN.pdf

I use a shunt and a Renogy DC to DC charger (40 amp). The wiring for the Renogy charger pulls from your chassis battery when it's being charged and if you wire it and everything else through the shunt there is no difference. I went with the Renogy because they have a 40 and a 60 amp version. The 40 amp can pull as much as 60 amps when charging so keep that in mind when sizing for your alt. You can mount it laying flat because it has a cooling fan. The Victron is only 30amps and has to be mounted vertical because of the heat sink fins. I have used my 40amp for over two years and happy with it.

Edited by timaz996
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waterskier_1

waterskier_1

Posted
Posted (edited)
2 hours ago, CAT Stephen said:

Hello Jim,

The first consideration for selecting a DC to DC charger is your alternator capacity.  If you purchase a DC to DC converter which, in parallel with your other alternator loads, exceeds the capacity of your alternator, your alternator can be severely damaged or destroyed.  You can obtain the capacity of your alternator by using your engine model and engine serial number then contacting your engine manufacturer.

The second consideration for selecting a DC to DC charger is your shunt use and your other feature needs:

- If a shunt used to measure your LiPO4 bank state of charge is planned for your use either currently or in the future, then your ONLY DC to DC charger option is an isolated DC to DC charger.  To the best of my current knowledge, Victron Energy is the only company that manufactures isolated DC to DC chargers at a reasonable price: https://www.victronenergy.com/upload/documents/Datasheet-Orion-Tr-Smart-DC-DC-chargers-isolated-250-400W-EN.pdf

- If you are on a very constrained budget and never plan to use a shunt, Renogy DC to DC chargers provide the best value, but need to be manually switched on and off physically which is inconvenient: https://www.amazon.com/Renogy-Battery-Batteries-Multi-stage-Charging/dp/B07Q4SVX3M/ref=sr_1_1?crid=U04CR0YL3EJU&keywords=renogy%2Bdc%2Bto%2Bdc%2Bcharger&qid=1699890028&sprefix=renogy%2BDC%2Bto%2B%2Caps%2C92&sr=8-1&ufe=app_do%3Aamzn1.fos.f5122f16-c3e8-4386-bf32-63e904010ad0&th=1

- If you seek maximum flexibility and complete integration with your iOS or Android devices, The Victron Energy Orion Series Smart DC to DC isolated chargers are the flagship of the DC to DC charger industry, and are reasonably priced compared to other options except Renogy: https://www.victronenergy.com/upload/documents/Datasheet-Orion-Tr-Smart-DC-DC-chargers-isolated-250-400W-EN.pdf

Alternator capacity, while important, should not be an issue if it wasn't an issue with the original Isolator (IRD or BIRD, Big Boy or Trombetta).  The original Isolator did not limit charging, but just connected both batteries together at the same time.  Now it is true that LiFePO4 batteries have a much lower internal resistance, which means they can draw current much faster than Lead Acid batteries.  At that is the problem with connecting them together.  Other than the extreme charge current, the alternator should be able to supply the requirements of the 12 volt side and charge the batteries, as long as the current is limited (and, ideally, the voltage is controlled such that you don't charge at 14.2-14.4 volts the alternator puts out all day long (while driving).  

Can you elaborate on your statement that ONLY option is isolated DC to DC charger if using LiFePO4 batteries?  I can't see the logic.  Both systems already share the same ground.  I will grant you that the LiFePO4 bank may have a shunt between the battery bank negative terminal and the physical ground (chassis) but that only serves to measure the electron flow.  

I am not aware of any "integration with your iOS or Android devices" of the referenced Victron products.  They are only Bluetooth (BT) as far as I know.  I may not be aware of iOS or Android application that integrate inverters, MPPT controllers, batteries, and DC-DC converters, so please enlighten me (us).

If the OP already has Victron Products; Inverter-MultiPlus, MPPT Solar Controller and Victron Shunt along with a GX device (e.g. Cebro or CCGX) then and wishes to integrate all with a DC-DC controller, the only option I am aware of is the newly announced "Smart Buck-Boost 50A (700W) non-isolated DC-DC Charger 12/12-50".  This DC-DC Charger (Controller) has VE.direct buss that will integrate with other Victron products and will display the actual charger output on the GX device.  Otherwise, with other Victron products, you have to use BT to see this.  The net current (inflow from the DC-DC Charger and outflow to coach at the battery shut is the only value shown.  For most, this is sufficient.  

  -Rick N.

Edited by waterskier_1
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CAT Stephen

CAT Stephen

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Posted (edited)

@waterskier_1,

I'm replying to your question for my post.  You asked:

  • "Can you elaborate on your statement that ONLY option is isolated DC to DC charger if using LiFePO4 batteries?  I can't see the logic. "

Here is the electrical installation assumption:

  • Although the House and the Chassis share a common ground, the house shunt will be located between the house battery negative post and the chassis/house ground. 

Here is the electrical science :

  • An isolated DC to DC charger provides complete electrical galvanic isolation between the chassis input and house output circuits. This means that there is no direct electrical connection between the input and output sides of an isolated DC to DC charger.   Isolated DC to DC chargers utilize transformers to galvanically isolate the house from the chassis circuit.
  • Galvanic isolation separates two circuits electrically while allowing the circuits to transfer power. 

A non-isolated charger allows electricity to leak between the house and chassis electrical systems on the positive side because they become positively bonded during DC to DC charger operation.  This direct electrical bond between the house and chassis electrical systems impacts the accuracy of all shunts located on either the house or chassis systems.

I owned a Renogy 40amp DC to DC charger for some time, but I kept getting inaccurate state of charge readings on my shunt versus my LiPO4 battery bank SOC that is bluetooth enabled.  I contacted Renogy support.  Renogy support indicated that their DC to DC chargers which are not isolated result in impacting the accuracy of shunts as there is also a connection to the positive side of the 12V system (obviously).

I also confirmed with Victron Energy support that, if a shunt will be utilized anywhere in an electrical system, they indicate to use only their isolated DC to DC chargers.  Victron Energy also manufactures non-isolated DC to DC chargers.

Can you use a shunt with a non-isolated DC to DC charger?  Yes, but the shunt will not be accurate. 

  • I proved this through personally experiencing shunt readings that did not match my LiPO4 SOC via bluetooth. 
  • After I replaced my Non-isolated Renogy DC to DC charger with two isolated Victron Energy DC to DC chargers in parallel, my shunt SOC now matches my LiPO4 house battery BMS SOC. 
Edited by CAT Stephen
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CAT Stephen

CAT Stephen

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@waterskier_1,

I'm replying to your second question:

  • "I am not aware of any "integration with your iOS or Android devices" of the referenced Victron products.  They are only Bluetooth (BT) as far as I know.  I may not be aware of iOS or Android application that integrate inverters, MPPT controllers, batteries, and DC-DC converters, so please enlighten me (us)."

Yes you are correct.  The context is comparison between the Renogy DC to DC charger and the Victron Energy Orion Smart Isolated DC to DC chargers.

 

And your third question:

  • If the OP already has Victron Products; Inverter-MultiPlus, MPPT Solar Controller and Victron Shunt along with a GX device (e.g. Cebro or CCGX) then and wishes to integrate all with a DC-DC controller, the only option I am aware of is the newly announced "Smart Buck-Boost 50A (700W) non-isolated DC-DC Charger 12/12-50".  This DC-DC Charger (Controller) has VE.direct buss that will integrate with other Victron products and will display the actual charger output on the GX device. 

The Victron Energy Orion Smart Isolated DC to DC chargers utilize the charging profile that the end user configures to charge the target battery band as needed, thus there is no integration needed with the Cerbo GX.  

  • An additional shunt can be included between the Victron Energy Orion Smart Isolated DC to DC charger negative output and the out electrical system target to measure the energy transferred.
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waterskier_1

waterskier_1

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Posted
1 hour ago, CAT Stephen said:

@waterskier_1,

I'm replying to your question for my post.  You asked:

  • "Can you elaborate on your statement that ONLY option is isolated DC to DC charger if using LiFePO4 batteries?  I can't see the logic. "

Here is the electrical installation assumption:

  • Although the House and the Chassis share a common ground, the house shunt will be located between the house battery negative post and the chassis/house ground. 

Here is the electrical science :

  • An isolated DC to DC charger provides complete electrical galvanic isolation between the chassis input and house output circuits. This means that there is no direct electrical connection between the input and output sides of an isolated DC to DC charger.   Isolated DC to DC chargers utilize transformers to galvanically isolate the house from the chassis circuit.
  • Galvanic isolation separates two circuits electrically while allowing the circuits to transfer power. 

A non-isolated charger allows electricity to leak between the house and chassis electrical systems on the positive side because they become positively bonded during DC to DC charger operation.  This direct electrical bond between the house and chassis electrical systems impacts the accuracy of all shunts located on either the house or chassis systems.

I owned a Renogy 40amp DC to DC charger for some time, but I kept getting inaccurate state of charge readings on my shunt versus my LiPO4 battery bank SOC that is bluetooth enabled.  I contacted Renogy support.  Renogy support indicated that their DC to DC chargers which are not isolated result in impacting the accuracy of shunts as there is also a connection to the positive side of the 12V system (obviously).

I also confirmed with Victron Energy support that, if a shunt will be utilized anywhere in an electrical system, they indicate to use only their isolated DC to DC chargers.  Victron Energy also manufactures non-isolated DC to DC chargers.

Can you use a shunt with a non-isolated DC to DC charger?  Yes, but the shunt will not be accurate. 

  • I proved this through personally experiencing shunt readings that did not match my LiPO4 SOC via bluetooth. 
  • After I replaced my Non-isolated Renogy DC to DC charger with two isolated Victron Energy DC to DC chargers in parallel, my shunt SOC now matches my LiPO4 house battery BMS SOC. 

Your statements are are mostly correct.  But there is no reason to attempt to isolate the negative battery terminal from the chassis, because there is a huge direct short (called a shunt) between the two.  The purpose for Isolated chargers is for when you have isolated systems - that is the "grounds" of one system intentionally do not connect to the grounds of a second system.  In the Victron Class, they use the example of a towed vehicle where you don't want the two chassis to be electrically connected.  I personally don't understand why you would want that, I intentionally make sure all trailers and grounds are the same.  Be that as it may, in the case of our Monaco coaches, the Chassis Ground is intentionally electrically connected to the House Ground.  The grounds are the same.  Granted, for electron counting purposes to generate the SOC, a shunt which is just a piece of metal, shaved to have a specific know resistance, is connected between them.  But for galvanic isolation is a term I have only heard used with respect to marine environments (where Victron started and has it's main business).  Who did you contact at Victron?  I suspect they either misunderstood your were ill informed.  

Comparing your shunt SOC (which is a measure of current flowing (electrons) into and out of whatever the shunt is connected to then mathematically computed by some sort of device (like a Cebro GX) to display SOC.  The calibration of the shunt is important.  If the exact battery capacity (Amp-Hours) is not input correctly, then the SOC will be off.  It is quite possible that the internal battery BMS has a slightly different SOC programmed into it.  Also, if you start paralleling LiFePO4 batteries, the SOC of each battery will be different, since it is unlikely the cells are exactly the same.  These differences are quite small, but could be what you saw.  It is also possible that the Renogy (I deal Victron only so can't say) might have a different algorithm than Victron, or the battery capacity might have been slightly different.  In any case, the isolated vs non-isolated charges didn't likely cause any difference.  I have designed many of Victron systems, but only a few with DC-DC chargers, but never found a problem.

-Rick N.

1 hour ago, CAT Stephen said:

@waterskier_1,

I'm replying to your second question:

  • "I am not aware of any "integration with your iOS or Android devices" of the referenced Victron products.  They are only Bluetooth (BT) as far as I know.  I may not be aware of iOS or Android application that integrate inverters, MPPT controllers, batteries, and DC-DC converters, so please enlighten me (us)."

Yes you are correct.  The context is comparison between the Renogy DC to DC charger and the Victron Energy Orion Smart Isolated DC to DC chargers.

 

And your third question:

  • If the OP already has Victron Products; Inverter-MultiPlus, MPPT Solar Controller and Victron Shunt along with a GX device (e.g. Cebro or CCGX) then and wishes to integrate all with a DC-DC controller, the only option I am aware of is the newly announced "Smart Buck-Boost 50A (700W) non-isolated DC-DC Charger 12/12-50".  This DC-DC Charger (Controller) has VE.direct buss that will integrate with other Victron products and will display the actual charger output on the GX device. 

The Victron Energy Orion Smart Isolated DC to DC chargers utilize the charging profile that the end user configures to charge the target battery band as needed, thus there is no integration needed with the Cerbo GX.  

  • An additional shunt can be included between the Victron Energy Orion Smart Isolated DC to DC charger negative output and the out electrical system target to measure the energy transferred.

Second Question:  Okay.  I don't know anything about Renogy, so don't know what they display.  I was thinking of integration like Victron does where you can see on a single screen, the inputs and outputs of the Shore Power, Inverter, Battery Charger, Solar, AC Loads, and DC Loads.  All the Victron DC-DC chargers allow you to see via Bluetooth is data related to that charger only.  It doesn't send that data anywhere, nor can it be retrieved for use (other than display).

Third Question: 

    Part 1.  You are correct, I would think any ones DC-DC charger would be able to be configured to charge the target battery.  You are also correct that Integration is not needed.  Many are perfectly fine with a Magnum Inverter, with it's own display, doing it's own thing, without knowledge of solar MPPT controllers on the system, which you can view with an individual BT app, but do their thing without knowing what the inverter is doing.  And then having a separate Shunt and Display for SOC, which neither the inverter or the MPPT controllers (or the DC-DC Charger) knows anything about.  For example, you can't set your Auto Gen Start (AGS) on a Magnum inverter to start/stop on an SOC value because, even if you added a shunt to the system, the Magnum inverter can't see it.  

    Part 2.  I'm not sure what the response here.  My intention was to notify that just last week Victron has released a new DC-DC Charger which is the first in its line of DC-DC Charges to integrate (that is to connect to a Cebro or other GX device) such that you can now see it on the Main Victron screen, see it's performance, and potentially control it's operation in conjunction with connected MPPT controllers and shunt provided SOC.  Again, this is not needed for things to work, and if you didn't already have a fully integrated Victron system, might be of little value other than it's higher current rating.

I'm not posting this to criticize you, but instead to let others know some of the sometimes more subtle aspects of designing a complete electrical system and my experience designing around Victron components. 

  -Rick N.  

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CAT Stephen

CAT Stephen

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3 hours ago, timaz996 said:

I use a shunt and a Renogy DC to DC charger (40 amp). The wiring for the Renogy charger pulls from your chassis battery when it's being charged and if you wire it and everything else through the shunt there is no difference. I went with the Renogy because they have a 40 and a 60 amp version. The 40 amp can pull as much as 60 amps when charging so keep that in mind when sizing for your alt. You can mount it laying flat because it has a cooling fan. The Victron is only 30amps and has to be mounted vertical because of the heat sink fins. I have used my 40amp for over two years and happy with it.

@timaz996,

Victron Energy permits running multiple Victron Energy Orion Smart Isolated DC to DC chargers in parallel so multiple high DC to DC charging scenarios are possible.

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timaz996

timaz996

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Posted (edited)
13 minutes ago, CAT Stephen said:

@timaz996,

Victron Energy permits running multiple Victron Energy Orion Smart Isolated DC to DC chargers in parallel so multiple high DC to DC charging scenarios are possible.

Yep, I get it but how they should be mounted and their cost is why I went with Renogy. It works well. the Renogy doesn't display anything. I just look at my BMV-712.

Edited by timaz996
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Ivan K

Ivan K

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Posted
9 minutes ago, RoadTripper2084 said:

I use the Renogy 60A DC-DC and it's worked great the last two seasons. I have my house and chassis battery circuits isolated in my coach, so the DC-DC is the only bridge between the two (takes charge from chassis and uses it to charge house while driving).

 

How did you manage to totally isolate the house and chassis grounds? That would sound like a huge effort and why?

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saflyer

saflyer

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On 11/13/2023 at 9:00 AM, 1nolaguy said:

Not sure about your set up. I have 4-100 AHr LFP batteries and they are charged from my I/C ( Aims PICOGLF3K12050BY). I have had this set up for 3 years now with no real issues related to battery charging. Based on the settings I selected charge from the I/C cuts off at 95% SOC and cuts on at 10% SOC. I charge whenever connected to shore or on genny but you could easily add/substitute solar via a charge controller. A DC-DC charger would only be needed if you also wanted to charge from your alternator.  LFP batteries like to be cycled verses held at a full charge. I usually run the inverter while driving to discharge the batteries and help with teh cycling as we spend most time at CG with full hook ups. YMMV

What is an I/C?

Ed          
‘05 HR Ambassador 

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Tom Cherry

Tom Cherry

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Inverter/Charger.  We typically refer to them as the inverter as, with AGM & Flooded, they were dual purpose and every class A DP MH had the combo units. GELs or Lithium changed the playing field and some I/C did (do) not have the correct charging profiles.

That is a generic statement….AND some of the Gassers may not have had a charger and they had a “voltage converter”….usually low wattage and not an inverter.

So, for all practical purposes here, the term Inverter is synonymous with an I/C.

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saflyer

saflyer

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Posted (edited)
11 minutes ago, Tom Cherry said:

Inverter/Charger.  We typically refer to them as the inverter as, with AGM & Flooded, they were dual purpose and every class A DP MH had the combo units. GELs or Lithium changed the playing field and some I/C did (do) not have the correct charging profiles.

That is a generic statement….AND some of the Gassers may not have had a charger and they had a “voltage converter”….usually low wattage and not an inverter.

So, for all practical purposes here, the term Inverter is synonymous with an I/C.

Thanks. It helps to always spell out terms before using acronyms and abbreviations.

Edited by saflyer
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1nolaguy

1nolaguy

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1 hour ago, waterskier_1 said:

I think he is using that abbreviation for Inverter/Charger based on the Aims Model number.  I had to do a Google search to determine what he was talking about.

  -Rick N.

No need to Google. I/C= inverter/charger single unit.

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saflyer

saflyer

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Posted (edited)

This is a new solution from Renogy. I’ll be adding two more solar panels to my current 6 so will need a second charge controller. I’ve been thinking of a DCDC charger. Could this be a good solution. My eyes start to roll when I read all of thfeatures so if anyone can help please do.

Oops, left the link off originally:

https://www.renogy.com/renogy-12v-24v-ip67-50a-dc-dc-battery-charger-with-mppt-renogy-one-core-for-free/?utm_campaign=BU-50A DC-DC Battery Charger new launch (01HFNYHSWN2X7F4M9XWF6W4341)&utm_medium=email&utm_source=Highly Engaged - 120 day&_kx=bU3Dp1MbZ7wJpNcL7Jp9G_VKcgT7rc9HlWQNk3lVOzA%3D.HLdMzK

Ed                
‘05 HR Ambassador 

Edited by saflyer
Oops
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saflyer

saflyer

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Posted (edited)
4 minutes ago, Jim McGarvie said:

What is the new solution from Renogy? I don't see a link.

 

Oops:


https://www.renogy.com/renogy-12v-24v-ip67-50a-dc-dc-battery-charger-with-mppt-renogy-one-core-for-free/?utm_campaign=BU-50A DC-DC Battery Charger new launch (01HFNYHSWN2X7F4M9XWF6W4341)&utm_medium=email&utm_source=Highly Engaged - 120 day&_kx=bU3Dp1MbZ7wJpNcL7Jp9G_VKcgT7rc9HlWQNk3lVOzA%3D.HLdMzK

Edited by saflyer
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Capt. Tango

Capt. Tango

Posted
Posted

This little gizmo replaces your standard BIM and integrates charges for both AGM and Lithium battery banks.

Lithium Battery Isolation Manager | Precision Circuits Inc

 

The Lithium BIM (Li-BIM) isolates the two battery systems, chassis, and coach, in a motorhome. This prevents loads in one system from discharging both. It also connects the two battery systems together during charging. Both batteries are charged if either is being charged. The coach battery is charged while driving and the chassis battery is charged while plugged into Shore Power at a campground.

The Li-BIM monitors the voltage of both the Lead Acid Chassis and Lithium Coach batteries over long periods of time. If it senses a charging voltage, it connects the two batteries together. If the charging system is drastically overburdened, the batteries will be isolated, however, if the Li-BIM sees a long-term charging of both batteries it will allow the batteries to remain connected and allow the charging system to do its job. Once the batteries have charged for one hour, the Li-BIM will isolate the batteries to prevent overcharging, and will only reconnect the batteries for charging if one of the batteries drops to approximately 80% charge, and the other is being charged. This long-term monitoring of the batteries prevents the annoying relay clicking that exists in simpler isolation modules today. The Li-BIM does not guarantee 100% battery charge but prevents harmful charge levels.

Note:

The Battery Isolation Manager goes between the Chassis and Coach Batteries to maintain both batteries when either one is charging.

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