Replace PV panel input with Lifepo4 battery

[GoneDiving]

Would someone please check my logic.

I have a 48v Lifepo4 house bank, 24v start battery, and occasional 15a @ 24vdc autopilot. I removed a generator with a 24v alternator so now have no start battery (re)charging.

Can I use a Victron 100/20 Charge Controller with Start battery as Batt, 48v house as PV input and, and the Radar as Load? PV input can be throttled by setting the appropriate charge and output limits? This seems a neat package and avoids multiple chargers, converters etc.

Will this work or will the Lifepo4 over curent the input and destroy the converter?

Other suggestions?

Many thanks

 

[socalrider]

Would someone please check my logic.

I have a 48v Lifepo4 house bank, 24v start battery, and occasional 15a @ 24vdc autopilot. I removed a generator with a 24v alternator so now have no start battery (re)charging.

Can I use a Victron 100/20 Charge Controller with Start battery as Batt, 48v house as PV input and, and the Radar as Load? PV input can be throttled by setting the appropriate charge and output limits? This seems a neat package and avoids multiple chargers, converters etc.

Will this work or will the Lifepo4 over curent the input and destroy the converter?

Other suggestions?

Many thanks

What you need I think is a 24V battery charger that runs on 48V

Here's one for $67 by Victron that might work.

It's possible that a 100/20 mppt controller could do the job but it's not really built for it, and more expensive than the option I outlined above.

 

[SteveK]

What you need I think is a 24V battery charger that runs on 48V

Here's one for $67 by Victron that might work.

It's possible that a 100/20 mppt controller could do the job but it's not really built for it, and more expensive than the option I outlined above.

Grab it quick, must be loss leader as if you type "Victron DC/DC charger" in their search engine, does not show up and the more common ones are3-4 times cost

 

[twistedtree]

I think it would probably work, but agree with others that it’s much better to use a DC/DC charger designed for the purpose rather than hoping the solar charger behaves in an acceptable way. It will also be much less confusing to the next person who comes along and tries to figure out how the system works and what the heck that solar charger is doing …..

 

[GoneDiving]

Grab it quick, must be loss leader as if you type "Victron DC/DC charger" in their search engine, does not show up and the more common ones are3-4 times cost

Socal's link is to the 5A trickle charger. Yes, other models are several times as expensive but they are 12 or 16A. I'd agree that these are a better option than jury rigging a charge controller.

Prices in Aussie Pesos (typically 2x US prices):

 

[socalrider]

Socal's link is to the 5A trickle charger. Yes, other models are several times as expensive but they are 12 or 16A. I'd agree that these are a better option than jury rigging a charge controller.

Prices in Aussie Pesos (typically 2x US prices):

Yeah the 5A (at 24V) is probably enough from your description, but I'd be a little concerned about the autopilot draw discharging your start batteries over time. If you truly only use it occasionally no big deal, but you might consider a higher power unit to put that worry out of mind (and for the next owner).

I usually end up regretting trying to save a few $$ on a lower spec piece of kit. Especially when it's only $50 or $100.

Pete