Hi, I have just read the article in June’s Caravan World regarding extra solar panel connections. I have two 170-watt panels on the roof of my van, 28 amps connected to a BMPRO BatteryPlus35-II-HA allowing a total of 35 amps input. I have purchased an iTechWorld 100-watt solar blanket, therefore an additional 8.3 amps.
I have an Anderson plug connecting to the additional solar connection terminals on the BMPRO. I have the solar blanket connected directly without using the MPPT regulator, thinking that the extra solar connectors on the BatteryPlus35-II-HA does the same thing. Is this the case? If not, how do I connect the extra solar?
Cheers,
Mal
Forster NSW
Thanks for your question Mal, as this highlights a common scenario faced by many RV owners looking to boost their off-grid power capacity: how to correctly connect a portable solar blanket to an existing BMPRO BatteryPlus35-II-HA system.
Effectively there are two options – the first is as you rightly point out. Utilise the two fixed 170-watt solar panels on the roof of the van, producing a combined 28 amps on a good day. As your total solar input is less than 350 watts, you can then wire an Anderson connector to the unused positive and negative solar connections for a solar blanket, which can add around 8.3 amps again, under ideal sunlight conditions.
If you install more solar panels on the roof of your van to go over the 350 watts, you would need to wire it differently. This is the second option, where you would parallel up the solar positive and negative to spread the load, but this is not required for your scenario.
The BMPRO BatteryPlus35-II-HA includes a built-in MPPT solar regulator capable of accepting a total solar input of up to 35 amps, so adding a solar blanket that contributes 8.3 amps is perfectly within the system’s capacity.
A very important warning: the solar panel negative output (0V) is not a common ground and cannot be grounded if connected to the BatteryPlus35-II. Grounding the negative output can result in damage to the BatteryPlus35-II and batteries. Both positive and negative must be wiring directly from the Anderson connector to the BatteryPlus35-II without grounding on the negative.
Another key to successful integration is connecting the blanket directly to the BMPRO’s unregulated solar input, not directly to a battery or with a separate external solar regulator. This is because the BatteryPlus35 already has a high-quality MPPT regulator onboard. Feeding it pre-regulated solar power can confuse the system, reduce efficiency, and potentially limit charging performance.
There’s no need for a manual selector or switching between the two — as long as both are unregulated inputs, the BMPRO will take care of the rest.
Using an Anderson-style connector is a great choice. These are reliable, robust, and well-suited for caravan environments where vibration, dust, and weather are common.
When wiring the system, ensure:
While solar blankets typically aren’t as efficient per watt as fixed rooftop panels, they do have a major advantage: portability.
With a solar blanket, you can position it wherever the sun is shining best. This is especially useful in shaded campsites or during early morning and late afternoon when the angle of the sun is less optimal for roof panels. You can even move the blanket throughout the day to track the sun and maximise exposure, something roof panels simply can’t do.
Additionally, when parked under trees or awnings, a solar blanket allows you to make use of that clear patch of sunlight a few metres away, keeping your battery topped up while enjoying a cooler campsite.
Your approach is spot-on. Connect the solar blanket via an Anderson plug directly to the BMPRO’s additional solar input terminals, without using a separate MPPT controller. It’s a straightforward upgrade that offers flexibility, redundancy, and peace of mind when travelling off-grid.
Safe travels and sunny skies Mal.
Cheers,
12V Guru
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8 thoughts on “12V Guru – How to Connect a Solar Blanket to Your BMPRO System – the Right Way”
Hi team,
I have a Jayco Lark 2022 with a BM PRO set up.
100AH lithium battery.
The fridge we have is a manual 3way set up.
I hear mixed feedback about if this set up will maintain the fridge temp utilising the battery when off grid.
Have a solar set up wired to BM PRO to maintain battery level.
Hope you can help
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Please reach out to them to see if they can help further.
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hi Jason
recently I bought a camper trailer with bmpro system with 100hr battery, the issue is recharging the battery
wont charge off 240 v mains with 15 amp lead
wont charge off solar 350 watt
wont charge off car via anderson plug
very frustrated
can you help with this issue
regards Shane Hill newbie to van life
Hi Team
Can I plug in a unregulated portable solar blanket to the Anderson plug that connects to the car on a BatteryPlus35-II
and will it show up on the monitor if charging the battery in the caravan cheers .
Hi. A few years ago, I had my BMPRO BatteryPlus35 upgraded to BMPRO BatteryPlus35-II-HA and changed the battery over from AGM 100Ah to a Zeal Lithium LiFePo4 100Ah. (In retrospect I should have put in a min. of 200Ah). I have 2 x 300W Flexible Solar Panels (to save on weight) installed on the roof in Parallel and connected to the Solar Input of the BMS using the already available connection point in the cupboard next to the BMS. I have fused both positive Inputs and another Fuse to the Positive Solar Input on the Caravan. The panels are rated as 300W 12V, Voc 21.4V and Isc 18.27A, giving a possible total of 36.54A. Can I also use my Solar Blanket (Regulator removed) by connecting this to the Anderson Plug under the Drivers side of the Caravan? It is a Projecta 120W, 12V, 7.5A Isc, 21V Voc. How does this add to the roof panels for extra Input? Is it using the other Solar Input to the MPPT within the BMS? Will this exceed the allowable Input to the MPPT? Also, I was asked by a friend about connecting the Solar Blanket to the grey Anderson on the Draw Bar when camped. It’s usually used for charging the Caravan Battery from the Car. I don’t believe it to be possible. Hope you can help. Thanks, Bill
To whom it may concern.
My name is Michael Spiteri and I have a question about my Batteryplus35SR.
My question is that it mentions
” FOR USE WITH LEAD ACID BATTERYS”
Can someone explain if I can use a lithium, if not can you explain the reason and what I need to change.
kind regards
Mike.
I have a caravan with an older Diverse Genius and a Morningstar 30m solar controller, this was set up for wet deep cycle batteries. I bought batteries off of I tech , 120x lithium and were told they would be compatible with this system , which is as you know rubbish. Can this system be substituted with BMPRO battery plus35-11-ha? It has 2 x 140 w solar panels. What do you recommend??
Hi Bob,
Darryl here from BMPRO. Happy to jump In a call regarding your question.
You can reach via this number +61 3 9213 8449.
Kind regards,