Cheap charger destroyed the $1,699 renogy battery

Will Prowse

Admin
Staff member
Moderator

Did some more testing:

1. Cheap transformer based charger probably destroyed the BMS. I measured max voltage at charger output with my scope this morning and I was reading 72V. Average was 36V. Yikes!

2. It is a 15S pack, not a 16S pack. Bms can be used for 15 or 16 cell configurations. Voltage that cells settled to was lower than typical for this reason. I am kicking myself for not noticing this.

Summary: don't use cheap transformer based chargers. I rarely test 48V packs so did not see the need to buy an expensive charger. I was wrong. $1,699 battery is now a brick. Oops 😬
 

EricBarbour

overqualified for this
That's a good point. You could just use a fixed 60v power supply into a 30-amp charge controller (get a model with a "USER DEFINED" setting for different max and low cutoff voltages) and set it for the battery being tested.
 

Steve_S

Offgrid Cabineer, N.E. Ontario, Canada

Did some more testing:

1. Cheap transformer based charger probably destroyed the BMS. I measured max voltage at charger output with my scope this morning and I was reading 72V. Average was 36V. Yikes!

2. It is a 15S pack, not a 16S pack. Bms can be used for 15 or 16 cell configurations. Voltage that cells settled to was lower than typical for this reason. I am kicking myself for not noticing this.

Summary: don't use cheap transformer based chargers. I rarely test 48V packs so did not see the need to buy an expensive charger. I was wrong. $1,699 battery is now a brick. Oops 😬
Damn ! Certainly a cause for some Fred Flinstone Ruckus Stuckus Frickus Fruckus moments I'd say. Fortunately, Renogy sent you the battery to test so it's not out of your pocket as such. Still a painful OUCH and just a terribly shameful waste, fingers crossed that the BMS can be replaced and the battery can continue a happy life.
 

Steve_S

Offgrid Cabineer, N.E. Ontario, Canada
Goodness Gracious, just checked the comments on Will's Video... Oi !
@Will Prowse did you not make a Pt-2 Video or just the other related post in here where you mention the Charger itself was a Culpable at charging way over max volts ?

People like to watch vids and hate to read, maybe a short video as Part-2 to explain the Charger being the culprit.
 

Bill Taylor

Solar Enthusiast
It's difficult to imagine that with all of the technology available today, they did not put a circuit in there that would disconnect if the voltage gets too high. I know there are some batteries on the market that have that built-in. What did they save, $2? I understand that technically it is your fault, but I place the blame squarely on the manufacturer for this failure. Shame.
 

Baserati

Solar Enthusiast
Exactly what I do - Victron MPPT 150/35 and a 60V 8A power supply. Supplies the equivelent of 500W worth of panels on a perfectly bright cloudless sunny day :)
Can you send me details of your setup? What 60V 8A power supply did you use?
 

vk2emp

Solar Enthusiast
Any particular regulated power supply will do, just use the Victron connect app to limit the current to prevent the power supply from going into over current protect. Start low and work up (say 10A). When the over current protection of the power supply kicks in, back it off a few amps to prevent from running the power supply at full noise, extending its life.
 

Scph9002

Solar Enthusiast
Hey Will, please do a full review of that fully die casted aluminum 48v charger you got.

They seem to have extremely good ac to dc conversion efficiency
 

retrodog

Solar Enthusiast
I have a Dakota 54ah battery that came with a 10 amp charger. I built that into my solar generator system on a dolly. But I rarely use it. I usually opt for the 10A power supply that Will showed in his $700 build (something like that) and run it through the victron 100/20 MPPT charger. That's my preferred method, if I don't have panels hooked up. Didn't realize these big power supplies would ruin a battery like that. Makes sense though.
 

Porch

Solar Enthusiast
It's not the fact that it's a big powers supply. It's not even really a "power supply". It's a generic battery charger. They have very poor filtering on the output, but it does not matter as the battery does not care and smooths out all the voltage spikes. Same way on every car. The alternator makes very poor DC power, but the car battery acts as a capacitor and smooths it all out.

It's a cheap, simple, and very reliable type of battery charger. It's not designed for electronics and should not be used as a power supply for them.
 

retrodog

Solar Enthusiast
M
It's not the fact that it's a big powers supply. It's not even really a "power supply". It's a generic battery charger. They have very poor filtering on the output, but it does not matter as the battery does not care and smooths out all the voltage spikes. Same way on every car. The alternator makes very poor DC power, but the car battery acts as a capacitor and smooths it all out.

It's a cheap, simple, and very reliable type of battery charger. It's not designed for electronics and should not be used as a power supply for them.
My bad. I didn't even really read the first post. Just looked like a big power supply. And I haven't personally used any large chargers like that before. I still like charging through the charge controller though.
 

Porch

Solar Enthusiast
Purely for clarification, it's not the size of the charger, but the tech used inside it. This small charger has the same old skool tech and is not for electronics as it could fry them. It will work just fine on a battery tho.
 
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