DC to DC question

[AKTroy]

I've got a 24 V system consisting of 620 amp hour LIPO batteries, which is then connected to an MPP solar all-in-one inverter/charger.

I would like to be able to use my alternator to charge the batteries when in route. I was looking at the Victron 12/24 DC to DC 3 stage charger, but they are limited to 15 Amp/360 watt output. So it would get the job done--albeit very slowly.

I've heard some pretty horrible reviews about the sterling's DC to DC charger's, so have been steering clear of those.

I then got to thinking why can't you send an alternator (DC current) through an MPPT controller, assuming you don't violate the limits? Isn't solar also DC current?

I believe the MPP solar has a limit of about 2000 Watts, but have to double check that spec, but that's what sticks in my head. I realize here there would not be any regulation, so this might be more in tune to a relay system, and could potentially heat up wires quickly or possibly burn out the alternator if the LIPO batteries were very low on juice. Is the amps from the alternator too low for this to work? I would think it is the job of the MPPT controller to regulate though. Help me to understand this please.

I'm sure there's a reason this is not done, thus the reason I'm posting in the beginners forum. Could someone enlighten me?

And then on the same topic, what other DC to DC converters are available for 12-24 volt output that would be in the 60+ AMP output range? That's what I'm after.

Thanks,

Troy

 

[FilterGuy]

I've got a 24 V system consisting of 620 amp hour LIPO batteries, which is then connected to an MPP solar all-in-one inverter/charger.

I would like to be able to use my alternator to charge the batteries when in route. I was looking at the Victron 12/24 DC to DC 3 stage charger, but they are limited to 15 Amp/360 watt output. So it would get the job done--albeit very slowly.

I've heard some pretty horrible reviews about the sterling's DC to DC charger's, so have been steering clear of those.

I then got to thinking why can't you send an alternator (DC current) through an MPPT controller, assuming you don't violate the limits? Isn't solar also DC current?

I believe the MPP solar has a limit of about 2000 Watts, but have to double check that spec, but that's what sticks in my head. I realize here there would not be any regulation, so this might be more in tune to a relay system, and could potentially heat up wires quickly or possibly burn out the alternator if the LIPO batteries were very low on juice. Is the amps from the alternator too low for this to work? I would think it is the job of the MPPT controller to regulate though. Help me to understand this please.

I'm sure there's a reason this is not done, thus the reason I'm posting in the beginners forum. Could someone enlighten me?

And then on the same topic, what other DC to DC converters are available for 12-24 volt output that would be in the 60+ AMP output range? That's what I'm after.

Thanks,

Troy

Very few MPP controllers have a boost function. Therefore, before they start working the 'pv' voltage must be a few volts above the battery voltage.
The alternator voltage will never get high enough to turn on most (all?) controllers.

 

[mikefitz]

Sterling Power have a new range of high power DC to DC chargers

Battery to Battery Chargers

Market leaders in power distribution for off-grid purposes. Providing class leading AC/DC and DC/DC chargers, highly customisable charge options and high performance lithium batteries. Sterling aims to be an accessible performance brand.

sterling-power.com

Note that 60 amps output will take 120 amps or more from the alternator. For many vehicle systems this will be an excessive load on the vehicle electrical system.

Since you already have an AC charging system, using a stand alone 12v input inverter to generate AC from the vehicle 12v system and using this to power the inverter/ charger when mobile. Again the power limit of the vehicle 12v system needsto be considered.

The optimum solution is a dedicated 24v second alternator fitted to the engine with suitable charge control system.

Mike

 

[MisterSandals]

I've got a 24 V system consisting of 620 amp hour LIPO batteries,

Just out of curiosity, what do you use most of this power on? Heating?
And hopefully this is really LFP and not lithium polymer (LiPo the explody kind).

And then on the same topic, what other DC to DC converters are available for 12-24 volt output that would be in the 60+ AMP output range?

You could run more than one of these in parallel. These things are a bit spendy so i would imagine you want a one piece solution.

 

[AKTroy]

Thanks Mike! I just look yesterday at sterling's new DC to DC converters, but boy are they pricey. Someone else mentioned wiring up up two Orion's in parallel. I had not considered a 12 V inverter, so will check prices on that today. May be a cheaper option?

I've got a Chevy express Van, and I'll have to check on the stock alternator output, but I believe it's over 100+ amps. I know they have a 300 amp model available as well.

I can certainly see myself in a situation where it rained overnight, and there is no sun to speak of and the battery being almost dead. Being able to bring the batteries back to life quickly could be a lifesaver.

Grid power is generally NOT an option in van life where I camp. I'm in Alaska and get into some remote places.

And thank you filter guy! I kind of thought the voltage may be an issue, so that makes perfect sense! I'm learning.

 

[AKTroy]

Just out of curiosity, what do you use most of this power on? Heating?
And hopefully this is really LFP and not lithium polymer (LiPo the explody kind).



You could run more than one of these in parallel. These things are a bit spendy so i would imagine you want a one piece solution.

Ooops LiFePo?. I'm a newbie so cut me some slack! I'm learning here. Lithium iron phosphate not lithium polymer. I just mentioned in my other post about the parallel option. Definitely expensive but doable. Thanks for the reply.

 

[AKTroy]

Oh, and to answer your other question, the biggest consumers are cooking appliances, induction cooktop air fryer, etc. Using propane though for hot water, and and I have one of those cheap Chinese heaters for heat, similar to the wabasto/Espar.