Looking for an MPPT solar charge controller without BMS

[Nick Gatel]

My solar system has blocking diodes in each panel so they cannot discharge a battery when there is no sun. With a large, but mobile system, I am not constrained by weight or weather and have a high end battery monitor/meter. The function I use the most is the % of Battery function. It is programmed to know how many useful amp hours a full battery bank has, and it calculates amps in and out. For example, in the early morning it may show 89% left and at 10 am usually shows 100% capacity. The other thing I monitor at times are amps. My meter will show both charging amps or discharging amps — whatever the current state is. In full sun it is over 10 amps. Turn on the microwave and it drops to more than -100 amps. I rarely look at voltage unless the camper has been sitting for a couple weeks. When the camper is in storage I disconnect the battery bank via a push/pull switch so consumers like the CO and smoke detectors don’t draw.

[Dave C]

Okay, my system is assembled and passed initial testing.  Tomorrow I’ll give the battery a full charge if the weather is good.  The battery is in one IP67 enclosure and the controller, power meter and switches are in another.  (The enclosures are in the Bud Industries PTS Series, available at digikey.com.).  The whole power system, including panel, battery, controller, other hardware, custom EMI/EMP protective bag and waterproof nylon bag weighs 5-1/2 lbs. and it all fits in one of the external, cylindrical pouches on my Osprey Xenith 105 pack.  Not exactly backpacking light, but it’s the lightest, most compact 12V 4.5 Ah LiFePO4 waterproof solar setup I could find.  I’ve seen Li-Ion charging systems that are much lighter and more compact and about 4 times the Ah rating.  But they weren’t waterproof, and didn’t use LiFePO4, which has a much longer cycle life, better discharge curve and is safer.

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