Wiring solar through Constant Power Solenoid

[Vogue75]

 I have a 75 vogue it has two batteries like most of these and I had installed a small solar setup to keep my house battery charged. Long story short the vehicle chassis battery has been a royal pain in my butt out on the road so I switched my house battery to it's position with the solar charger and inverter still attached. So far this has worked great as the deep cell spins the starter like a champ but my house 12v circuits are not functional so heres my question:


If I replace the chassis battery with another deep cell of the same kind (so my house and chassis battery are the same) can I wire the solar charger into the constant power solenoid in such a way that when I use my dash switch and put the battery booster on "sustained" the solar will charge both batteries? (With the key turned on).


Thanks in advance his website has already saved my butt at least 5 times. Cheers!

[DaveVA78Chieftain]

Chassis and deep cell batteries are designed differently for a reason.  Either your chassis battery is to small for your application or it is on it's last leg.  I do not recommend converting your chassis battery to a house battery type.


You can use a Trik-L-Start to accomplish what you are after (charging chassis battery from house side)

[Berlin-Tioga]

Or get a solar charger/regulator with two outs. One for the house bat -the main one- and one for smaller charging currents for the starter batt.

Like this one:


https://www.roadpro.co.uk/product/02h05a-mppt-solar-regulators/votronic-mpp165-12v-dual-regulator-c55871/C55871

[Vogue75]

Chassis and deep cell batteries are designed differently for a reason.  Either your chassis battery is to small for your application or it is on it's last leg.  I do not recommend converting your chassis battery to a house battery type.


You can use a Trik-L-Start to accomplish what you are after (charging chassis battery from house side)

Why can't I use this deep cell as the chassis battery, my understanding is using a truck battery as a house battery is bad, but I see no reason that the opposite would be a problem seeing as this deep cell is working fantastically in that capacity right now. I've even had an old pathfinder which used a deep cell and was great. If both batteries were the same deep cell it would seem logical that the system would work great, even when linked for solar charging. The dash switch solenoid was meant to carry alternator voltage so it should be able to handle 20amps of solar charge from the controller right?

Or get a solar charger/regulator with two outs. One for the house bat -the main one- and one for smaller charging currents for the starter batt.

Like this one:


https://www.roadpro.co.uk/product/02h05a-mppt-solar-regulators/votronic-mpp165-12v-dual-regulator-c55871/C55871

My solar charger has a switchable load circuit I haven't been using, perhaps I can run a lightweight trickle charger off that. For some reason I want to keep the dash switch in the mix I just think it's convenient and already cleverly wired for similar functionality.

[DaveVA78Chieftain]

Engine starting requires high current for short periods of time and fast recover of the battery after starting (alternator).  The chassis battery is designed with many thin electrode plates that allow that to happen efficiently.

House side requires much lower amp draw over an extended period of time.  House battery is designed with thicker plates that are more suited to that type of current draw.  They recharge at a slower rate than a chassis battery.

Simply put, using either battery type outside of it's intended designed purpose will result in shorter battery life and earlier replacement due to misuse.

[Vogue75]

Okay this makes sense somewhat. My main concern is with the trik l start it's $70+ and it's on all the time. If there's a parasitic draw because something shorts out it could easily kill both batteries and I'd be left with nothing. Surely there's a way to utilize the constant power solenoid and dash switch to link the charging only when I want it? Or I can drop the $70 and put the trik l start on the load circuit of my controller which I can easily turn on and off. Either way that's an expensive solution to a problem the rv is already seemingly wired to solve.

[DaveVA78Chieftain]

My main concern is with the trik l start itââ,¬â,,¢s $70+ and itââ,¬â,,¢s on all the time.

Not true.  Read the Trik-L-Start website.  Only connected when charging voltage is present on house side (converter, solar charger, generator 12VDC charging circuit, etc.).

to a problem the rv is already seemingly wired to solve.

Not true for the era your RV was built.  Connection between chassis and house battery was only intended to restore charge to house battery via the alternator when the engine was running.  That is why the constant duty relay coil is sourced from the ignition switch.   The converters of that era typically provided separate charging circuit to the house battery while concurrently disconnecting the house battery from the system.  They also have a bad habit of boiling the house battery dry because the output voltage is set to high.
Modern day converters (e.g. 3/4 stage) no longer need an isolation relay and are connected to the house 12VDC system in the same manner as a engine alternator is to the chassis system.

Can you connect up manually operated constant duty solenoid such that you control when the systems are cross-connected?  Sure you can however, if you forget it is ON when there is no charging source on either the chassis or house side then you will drain the charge down on the batteries on both sides.  The Trik-L-Start only connects the batteries when charging current is available on the house side.

[Rickf1985]

We used to use deep cycle batteries in out 4x4 trucks because they ran the electric winches better. Yes they did start the vehicle, BUT, They were NOT designed to take that 150 amp fast charge. Every person that used a deep cycle battery had to replace them in less than a year. We just considered t part of playing in the mud. The guys with pickup trucks would generally use two or three 8D truck batteries, These would last a long time. But there are HUGE batteries. If you can find Military 6TAGM batteries they are still large but if they fit they have massive reserve capacity and are designed for starting diesels. Putting your starting and house batteries together is never a good idea but there are a couple of ways you could pull it off if you have the room.
You could go with the old fashioned lead acid 6TL battery and still have massive starting AND reserve capacity.


https://www.remybattery.com/group-size-6tl-battery.html?gclid=CjwKCAjw3azoBRAXEiwA-_64Ohf_456Hafmw8QX_YG0UUPtwltWkqpuXNCEH-uryV_fWhzDoFA9AkBoCq0MQAvD_BwE

[Vogue75]

Excellent, so the trik l start won't charge the vehicle battery unless he solar is actively charging the house battery? I'll just go ahead and order one and consider this issue resolved. Thanks for the information everyone Iââ,¬â,,¢ll bump the thread later if anything new comes up.


I need to make a thread for the vehicle itself I'll probably have more to show and ask about and maybe get some tips on the greater restore I'm doing over time.

[Vogue75]

Just bumping this because the trik-l-start came in two days off amazon and the day after I put it on we had a good sunny day and both batteries got topped off even with my single 100w panel. Great product I should have never doubted!