Solar charging while driving

[Gus]

Hi. I've been thinking about this for a while and I'm sure someone out there can explain it to me.
I have a 2022 Boxer with stop/start (that I usually turn off), a battery "booster" and a Victron mppt solar charger. My question is when I am driving will both the solar or booster charger work together and both put in a combined charge, or, will one or the other shut down because one senses that the battery is at full charge due to the other supplying a charge voltage. In other words will both charging systems work together to fast charge the battery or, if the battery (wet acid) is at a charge voltage - say higher than 12.7 v. will one or both charging systems shut down?

 

[Jev88]

I would Guess the solar will sense full and back off charge. But depends what voltage it is set to and the measured voltage from the split relay?

 

[Lenny HB]

Usually the one outputting the highest voltage will be doing the charging.

 

[Gus]

I'm hoping that the answer is that the booster will have priority otherwise maybe the solar should be disconnected when driving?

 

[headlight]

I'm hoping that the answer is that the booster will have priority otherwise maybe the solar should be disconnected when driving?

No the solar does not need to be disconnected.

^{_{Subscribers  do not see these advertisements}}

 

[Hoovie]

The answer is .....
BOTH will work. It is that simple.

Top Chart is the current from my B2B kit. Bottom Chart is the output from my Victron 100/20 MPPT Controller.
Even though the B2B is sometimes putting out a pretty good current, it is not stopping the Solar from joining the party

 

[ChrisL]

I'm fairly sure that chargers look at a batteries internal resistance to decide what state of charge to deliver and Hoovie's post would seem to illustrate that.

 

[Gus]

That's what is puzzling me because if, say the solar, is charging into the battery, wouldn't the B2B limit it's charge thinking the battery was full? So having both charge systems running like this could mean the leisure battery was not getting maximum charge?

 

[Hoovie]

That's what is puzzling me because if, say the solar, is charging into the battery, wouldn't the B2B limit it's charge thinking the battery was full? So having both charge systems running like this could mean the leisure battery was not getting maximum charge?

It would mean the leisure battery would be able to accept a higher charge than is able to be provided.
Just because the charge voltage setting of an MPPT is say 14.4V, it doesn't mean it is outputing at 14.4V - the voltage depends on the batteries state of charge and that 14.4V is not an absolute, but a target.

Obviously it all depends on what chargers you have and what output they have, combined with what batteries you have and what charge they are at and what they can accept (which for Lead Acid, also dependant on the state of charge at the time).

The chart I posted was the output from Solar and B2B chargers. This chart for the same time period shows how much charge is going into the Lithium Bank and the Lead Acid Bank. The Batteries could accept more if it were available.

(the reason for the fluctation is the alternator output varying depending on the engine speed. My B2Bs are tuned to be active at certain voltages to try and optimise output whilst not overstressing it).

 

[Tombola]

My bluetooth battery reports 50 amps + going in from my 30 amp B2b and 550w solar when driving if batteries need it

^{_{Subscribers  do not see these advertisements}}

 

[ChrisL]

Here's an explanation of how it works for you.

What happens when I have multiple charge sources charging a single battery bank

 

[Ledzep]

The answer is .....
BOTH will work. It is that simple.

Top Chart is the current from my B2B kit. Bottom Chart is the output from my Victron 100/20 MPPT Controller.
Even though the B2B is sometimes putting out a pretty good current, it is not stopping the Solar from joining the party
View attachment 765367

Separate thread sorry. Does anyone know what size solar charger I need to keep my acid engine battery topped up when MH not in use. Also will it keep the leisure battery topped up via the engine battery?
Thank you. Peugeot boxer 2004.

 

[Lenny HB]

Separate thread sorry. Does anyone know what size solar charger I need to keep my acid engine battery topped up when MH not in use. Also will it keep the leisure battery topped up via the engine battery?
Thank you. Peugeot boxer 2004.

You need to do it the other way round, charge the leisure battery and keep the starter battery topped up.

Two ways of doing it fit a solar panel with a dual output controller. I use a Votronic which has a 1 amp output to the starter battery others do it by percentage normally 90/10% leisure/starter battery.

Other option is a single output controller to the leisure battery they use a battery maintainer like the Ablemail or Batterymaster to keep the starter battery topped up.

Size of the panel depends where you live, in the south 100 watts will be more than enough, in Scotland probably 200 watts or more.

 

[Coolcats]

It’s PFM

The Hymer has an upgraded alternator which charges both the vehicle and Lesuire. Battery it is capable of fully charging both as we drive along. We start with fully charged batteries and he’s in forbid use hook up when we arrive this also keeps both charged and whe. Standing idle and the suns out the solar charges both.

 

[G-RMPS]

I have two leisure batteries and the engine battery. I also had just one 100w solar panel fitted a couple of years ago. And I live in Scotland.

Never ended up (so far!) being unable to start the van, but 100w is marginal, especially if you have an alarm.

^{_{Subscribers  do not see these advertisements}}

 

[Ledzep]

You need to do it the other way round, charge the leisure battery and keep the starter battery topped up.

Two ways of doing it fit a solar panel with a dual output controller. I use a Votronic which has a 1 amp output to the starter battery others do it by percentage normally 90/10% leisure/starter battery.

Other option is a single output controller to the leisure battery they use a battery maintainer like the Ablemail or Batterymaster to keep the starter battery topped up.

Size of the panel depends where you live, in the south 100 watts will be more than enough, in Scotland probably 200 watts or more.

Thank you Lenny. Next ? When on EHU is the electricity charging the leisure battery at all. I presume it doesn’t put anything into the engine battery?

 

[headlight]

Thank you Lenny. Next ? When on EHU is the electricity charging the leisure battery at all. I presume it doesn’t put anything into the engine battery?

On EHU your on board mains charger will keep your leisure battery charged.
Given the age of your van if your set up is original I doubt it charges your starter battery.

 

[ChrisL]

Thank you Lenny. Next ? When on EHU is the electricity charging the leisure battery at all. I presume it doesn’t put anything into the engine battery?

The easy way to find out is when on EHU measure the voltage across the starter battery terminals using a multimeter set to 20 volts dc, if it's over 13.5 volts i'd say it is being charged.