Victron mppt permanently connected to starting battery

MTM98290 · Mar 31, 2024

I would like to permanently install a Victron 75/10 mppt to our vehicles starting battery. This will give me a nice bluetooth battery monitor as well as the ability to keep the battery topped off with a small panel. It can also be used as a switch through the load connection.

My only concern is that the 12v vehicle system will have some unforseen adverse effects. I have no real theory as to why it wouldn't work, but it isn't a typical use for the device, and I don't want to damage one.

Is there a risk in doing this? Thank you for any insight or advice.

BlindBadger · Mar 31, 2024

Lots of folks use a small mppt as a trickle charger for their starting battery. I don’t think you’d have any problems there.

Just make sure your load output doesn’t exceed the 15A rating of the controller.

justinm001 · Mar 31, 2024

Using an mppt to charge a battery is absolutely its typical use. The battery type doesn't matter.

I thought of this but realized it's pretty pointless. You can easily get a 120v to 12v dc trickle charger and run it off your inverter and shore. I do this and it keeps my starter battery 100% all the time. You could do some Orion tr smart so it's DC to DC but a $20 charger beats out a 150. Also it's very nice to have a spare 120v charger just incase. I have some htrc on that's 12 or 24v and goes up to 20a and does lithium so I can just hit a button and connect it to my lithium setup if ever needed.

To monitor starter battery the Victron smartshunts have an aux voltage input for this reason. So you can use it on your house system then just run the aux voltage to your starter battery and it'll show both, plus with a Cerbogx it'll all be logged and alarms. It's saved us multiple times because wife likes to leave the key on.

MTM98290 · Mar 31, 2024

all

justinm001 said:
Using an mppt to charge a battery is absolutely its typical use. The battery type doesn't matter.

My concern is not about the mppt charging the battery, I know that it will. I have used a 100/20 in this way and it works well, but I haven't left it hooked to the battery all of the time. Having the starter/alternator in the circuit is my concern.

justinm001 said:
I thought of this but realized it's pretty pointless. You can easily get a 120v to 12v dc trickle charger and run it off your inverter and shore. I do this and it keeps my starter battery 100% all the time. You could do some Orion tr smart so it's DC to DC but a $20 charger beats out a 150. Also it's very nice to have a spare 120v charger just incase. I have some htrc on that's 12 or 24v and goes up to 20a and does lithium so I can just hit a button and connect it to my lithium setup if ever needed.

To monitor starter battery the Victron smartshunts have an aux voltage input for this reason. So you can use it on your house system then just run the aux voltage to your starter battery and it'll show both, plus with a Cerbogx it'll all be logged and alarms. It's saved us multiple times because wife likes to leave the key on.

The above makes a lot of sense in an RV,
but is for a Suburban with one starting battery. I have no house battery or inverter to charge the starting battery from. Hopefully one day I will add an auxiallry battery and an Orion DC/DC charger to maintain it.

I can plug it in to an AC/DC trickle charger and it works just fine while close to a 120v outlet.

Smartshunts are neat, but double the cost of a 75/10, and any additional information that would be gleaned from it would not be of much use to me. I have no cerbo to communicate and even if I did the vehicle isn't in bluetooth range of the house.

One can buy a smart battery sense for slightly less than an mppt, but it is a read only device and won't charge a battery or turn on a load the way the mppt will.

I am only concerned that the mppt will be damaged buy being in the circuit with the starter and alternator, although it doesn't seem much different than a system with a small battery and high amp draw in short bursts and fast charging in short bursts.

justinm001 · Mar 31, 2024

MTM98290 said:
all

My concern is not about the mppt charging the battery, I know that it will. I have used a 100/20 in this way and it works well, but I haven't left it hooked to the battery all of the time. Having the starter/alternator in the circuit is my concern.

The above makes a lot of sense in an RV,
but is for a Suburban with one starting battery. I have no house battery or inverter to charge the starting battery from. Hopefully one day I will add an auxiallry battery and an Orion DC/DC charger to maintain it.

I can plug it in to an AC/DC trickle charger and it works just fine while close to a 120v outlet.

Smartshunts are neat, but double the cost of a 75/10, and any additional information that would be gleaned from it would not be of much use to me. I have no cerbo to communicate and even if I did the vehicle isn't in bluetooth range of the house.

One can buy a smart battery sense for slightly less than an mppt, but it is a read only device and won't charge a battery or turn on a load the way the mppt will.

I am only concerned that the mppt will be damaged buy being in the circuit with the starter and alternator, although it doesn't seem much different than a system with a small battery and high amp draw in short bursts and fast charging in short bursts.

Ahh gotcha. I've never heard of any issues with any devices on the load side of the battery. On top of this lead acid starter batteries are very good at absorbing loads unlike lithium and such which isn't and even then it's normal for people to have generators off lithium house batteries and they have alternators and starters.

I really don't see any issues. When alternator is running likely solar won't. Also no issues with keeping a battery at float for long periods of time. I believe with lead acid you don't want it floating for years with no load but that isn't a concern for your application. Just thinking UPS have load test schedules but could be just to test life.

Thanks for the info on 75/10 I didn't know they made smartsolar mppts that low. Perfect size for 100w panel to charge my trailer battery

RV8R · Mar 31, 2024

MTM98290 said:
all

My concern is not about the mppt charging the battery, I know that it will. I have used a 100/20 in this way and it works well, but I haven't left it hooked to the battery all of the time. Having the starter/alternator in the circuit is my concern.

The above makes a lot of sense in an RV,
but is for a Suburban with one starting battery. I have no house battery or inverter to charge the starting battery from. Hopefully one day I will add an auxiallry battery and an Orion DC/DC charger to maintain it.

I can plug it in to an AC/DC trickle charger and it works just fine while close to a 120v outlet.

Smartshunts are neat, but double the cost of a 75/10, and any additional information that would be gleaned from it would not be of much use to me. I have no cerbo to communicate and even if I did the vehicle isn't in bluetooth range of the house.

One can buy a smart battery sense for slightly less than an mppt, but it is a read only device and won't charge a battery or turn on a load the way the mppt will.

I am only concerned that the mppt will be damaged buy being in the circuit with the starter and alternator, although it doesn't seem much different than a system with a small battery and high amp draw in short bursts and fast charging in short bursts.

Understand what you are trying to achieve ,,, solar maintenance charging / battery monitoring & recording of maintenance charge / permanently installed system

. This might interest you;

Thread 'Portable Solar Charger'
https://diysolarforum.com/threads/portable-solar-charger.79393/

The issue comes from the vehicle side ,,, modern vehicles’ alternators are controlled by regulators that are controlled by the vehicle computers “usually”.

To properly answer your question, you have to ask the vehicle manufacturer.

The work around ( as opposed to getting it sanctioned by your vehicle manufacturer) is to install a switch to turn the solar charger off while the engine/alternator is running.

justinm001 · Mar 31, 2024

RV8R said:
Understand what you are trying to achieve ,,, solar maintenance charging / battery monitoring & recording of maintenance charge / permanently installed system

The issue comes from the vehicle side ,,, modern vehicles’ alternators are controlled by regulators that are controlled by the vehicle computers “usually”.

To properly answer your question, you have to ask the vehicle manufacturer.

I don't think surburbans have smart alternators, usually only EU vehicles or ones sold in EU.

Even then I'm not sure it has any effect and even if somehow it did it would just not use as much alt if idling and there's sun. I thought smart alts are mainly to limit them charging while idling as a high load at low rpm is inneficient.

RV8R · Mar 31, 2024

justinm001 said:
I don't think surburbans have smart alternators, usually only EU vehicles or ones sold in EU.

Even then I'm not sure it has any effect and even if somehow it did it would just not use as much alt if idling and there's sun. I thought smart alts are mainly to limit them charging while idling as a high load at low rpm is inneficient.

I’m not talking “Smart” Alternators.

Regulators are deemed ( or last time I dove into the deep end years ago ) are “D / S / C”.

The “C” stands for “Computer”

The “S” stands for “Sensor”

The “D” stands for “Dummy”

“Lugs”

Over a decade ago & this off the top of my head ,, so take the info as to the best of my recollection.

justinm001 · Mar 31, 2024

RV8R said:
I’m not talking “Smart” Alternators.

Regulators are deemed ( or last time I dove into the deep end years ago ) are “D / S / C”.

The “C” stands for “Computer”

The “S” stands for “Sensor”

The “D” stands for “Dummy”

“Lugs”

Over a decade ago & this off the top of my head ,, so take the info as to the best of my recollection.

View attachment 206044

Ahh gotcha. I'm just thinking surburbans are very popular police/military vehicles and I'm assuming are on same truck chassis and engine as the 1500. It's very normal to add additional alternators, chargers and specialized electrical equipment.

RV8R · Mar 31, 2024

justinm001 said:
Ahh gotcha. I'm just thinking surburbans are very popular police/military vehicles and I'm assuming are on same truck chassis and engine as the 1500. It's very normal to add additional alternators, chargers and specialized electrical equipment.

I’m not saying there is an issue ,,, I’m saying get it sanctioned by the vehicle manufacturer.

Or don’t

I believe, most “modern” vehicles have computers, & those computers control the “C” style regulators.

Further, best practice would be to go to the vehicle manufacturer & get the okay dokay

I’m not saying there is an issue ,,, just best to “check it out”.

MTM98290 · Mar 31, 2024

Lots of good points and info here. It as a 2003 Chevrolet Suburban 1500 GMT800 platform. It uses a delphi alternator that is externally regulated alternator as most GM cars of the era have. It is pretty conventional. I think that the regulation is done in the ECM by varying the voltage input, but I haven't had to look to far into that system to say for sure.

GM doesn't have an answer. It is almost 8 times around the planet beyond in mileage. I don't have to be concerned with voiding my warranty.

MTM98290 · Mar 31, 2024

justinm001 said:
Ahh gotcha. I'm just thinking surburbans are very popular police/military vehicles and I'm assuming are on same truck chassis and engine as the 1500. It's very normal to add additional alternators, chargers and specialized electrical equipment.

Yes this is a good point. They are customized and modified in countless ways. I am not worried about hurting the vehicle as much as I am concerned that it will damage the Charge controller.

MTM98290 · Mar 31, 2024

RV8R said:
Understand what you are trying to achieve ,,, solar maintenance charging / battery monitoring & recording of maintenance charge / permanently installed system . This might interest you;

Yes exactly.

RV8R said:
Thread 'Portable Solar Charger'
https://diysolarforum.com/threads/portable-solar-charger.79393/

The issue comes from the vehicle side ,,, modern vehicles’ alternators are controlled by regulators that are controlled by the vehicle computers “usually”.

To properly answer your question, you have to ask the vehicle manufacturer.

RV8R said:
The work around ( as opposed to getting it sanctioned by your vehicle manufacturer) is to install a switch to turn the solar charger off while the engine/alternator is running.

I could add a relay that kicks it off when ACC circuit is energized, but that would give me grey bars of blank info in my dataloging.

Rocketman · Mar 31, 2024

I have done this on my MotorHome. The engine had a Lambert charger that took power from the house bank to charge the engine battery. However that charger was 22 years old and with the lithium bank it was on all the time.

So I took it out added another 100w panel to the roof and a mppt 100/20. It has worked great. But in looking at the data from Victron, I realized the 100w panel is not getting used much. So I will probably move the 100w panel to the house bank and get a 50w panel for the engine battery.

MTM98290 · Mar 31, 2024

RV8R said:
Understand what you are trying to achieve ,,, solar maintenance charging / battery monitoring & recording of maintenance charge / permanently installed system . This might interest you;

Thread 'Portable Solar Charger'
https://diysolarforum.com/threads/portable-solar-charger.79393/

The issue comes from the vehicle side ,,, modern vehicles’ alternators are controlled by regulators that are controlled by the vehicle computers “usually”.

To properly answer your question, you have to ask the vehicle manufacturer.

The work around ( as opposed to getting it sanctioned by your vehicle manufacturer) is to install a switch to turn the solar charger off while the engine/alternator is running.

I read that thread with interest. Great stuff, I never considering a healing shelf, haha. It usually falls under, 'partially functioning but possible useable" &" when I have the time, part, motivation" etc."

Now you just need to figure out how to bore through the potted sand to the fuse which should be accessable. This is a design flaw Victron!
The Victron should have reverse polarity protection like so many far inferior products do.

I put XT60 connectors on my Victron units so that screw it up. 5 male, 5 female sets cost $15.
They work well and should age well.
I didn't realize that reverse polarity would break a Victron unit. It kind of seems like a huge liability given the 5 year warranty period. I will be extra vigilant with my alligator clips.

I am collecting a nice assortment of adapters, splitters, plugs etc. It is very handy

MTM98290 · Mar 31, 2024

Rocketman said:
I have done this on my MotorHome. The engine had a Lambert charger that took power from the house bank to charge the engine battery. However that charger was 22 years old and with the lithium bank it was on all the time.

So I took it out added another 100w panel to the roof and a mppt 100/20. It has worked great. But in looking at the data from Victron, I realized the 100w panel is not getting used much. So I will probably move the 100w panel to the house bank and get a 50w panel for the engine battery.

i would guess that 25w-50w will be enough year round for me. Worst case I will see that it is low and take it for a drive in the dark winter months.

RV8R · Mar 31, 2024

MTM98290 said:
I read that thread with interest. Great stuff, I never considering a healing shelf, haha. It usually falls under, 'partially functioning but possible useable" &" when I have the time, part, motivation" etc."

Now you just need to figure out how to bore through the potted sand to the fuse which should be accessable. This is a design flaw Victron!
The Victron should have reverse polarity protection like so many far inferior products do.

I put XT60 connectors on my Victron units so that screw it up. 5 male, 5 female sets cost $15.
They work well and should age well.
I didn't realize that reverse polarity would break a Victron unit. It kind of seems like a huge liability given the 5 year warranty period. I will be extra vigilant with my alligator clips.

I am collecting a nice assortment of adapters, splitters, plugs etc. It is very handy

Yup, almost the moment I did it I was like ,,, “I didn’t just do that did I

”? ,,, yup you did. I finally donated “The Body” for Scientific Study

.

Yes “Victron” ,,, no battery reverse polarity protection.

I don’t think you are at risk of breaking anything with your proposal, but think at worse you might confuse the ECM if it tries to read the battery voltage & get solar charger reading ,,, or vice / versa.

Your datalogging might have grey outs or erroneous readings, regardless, as it will be for just the solar charger and not the battery (Victron Solar Charger will only log the solar energy / data that it provided to the battery ,,, not the alternator energy). If you wanted to log the battery, a shunt off the negative starter battery terminal, I suppose would be the instrument. Of course you have to size the shunt for the energy that goes through for starting the engine.

justinm001 · Mar 31, 2024

MTM98290 said:
i would guess that 25w-50w will be enough year round for me. Worst case I will see that it is low and take it for a drive in the dark winter months.

They make simple 20/40w 12v solar panels and they have a light that changes color when battery is charged. Perfect solution for leaving a vehicle outside but wanting to keep battery charged. I had this on my trailer until it flew off one day while driving

MTM98290 · Mar 31, 2024

justinm001 said:
They make simple 20/40w 12v solar panels and they have a light that changes color when battery is charged. Perfect solution for leaving a vehicle outside but wanting to keep battery charged. I had this on my trailer until it flew off one day while driving

I have a very small one that recently quit on me. It was too small but was no risk to the vehicles electrical system.

The history data will be interesting too.

MTM98290 · Mar 31, 2024

RV8R said:
Yup, almost the moment I did it I was like ,,, “I didn’t just do that did I ”? ,,, yup you did. I finally donated “The Body” for Scientific Study .

Yes “Victron” ,,, no battery reverse polarity protection.

I don’t think you are at risk of breaking anything with your proposal, but think at worse you might confuse the ECM if it tries to read the battery voltage & get solar charger reading ,,, or vice / versa.

Your datalogging might have grey outs or erroneous readings, regardless, as it will be for just the solar charger and not the battery (Victron Solar Charger will only log the solar energy / data that it provided to the battery ,,, not the alternator energy). If you wanted to log the battery, a shunt off the negative starter battery terminal, I suppose would be the instrument. Of course you have to size the shunt for the energy that goes through for starting the engine.

I am aware that it will only record voltage of the battery, PV, and load, if any. But if it stays energized 24/7 it should log constantly too.

It will get energy into the battery without being aware so this will skew some functionality of the connect app but that is fine.

Victron mppt permanently connected to starting battery

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