Battery charger efficiency?

[wpns]

I've got a golf cart charger from Allied Lithium that puts a fixed 15 amps into a 48V battery, and (for instance) over the course of 191 minutes where it put probably 2.3 KWHR into the battery, it drew 4.5 KWHR from the wall, for an efficiency of around 50% AC->DC. Is this normal? Is there a better charger I could use that would plug into a 20A 120V outlet and would deliver up to 30A into the battery at a higher efficiency?

The Lithium cart is the red line here, green is a lead-acid cart that hadn't finished.

This is the charger:

https://cdn.shopify.com/s/files/1/0240/6314/8096/files/48V_Charger_Data_Sheet_7-27-23.pdf?v=1691594053

This is the next generation battery, which has BT and a much better BMS, mine is similar:

https://cdn.shopify.com/s/files/1/0240/6314/8096/files/Data_Sheet_48V_30Ah.pdf?v=1707429316

 

[timselectric]

Normally I would say chargeverter, all day long.
But the V1 has been discontinued and the V2 is too expensive.
So I don't have any good recommendations, at the moment.

 

[OzSolar]

My gut is that Golf cart chargers are built around keeping the cost down with little consideration for efficiency. Still I don't think you're going to get anything better than 90%. It may be easier to add a few more solar panels to your system and accept the losses, just a thought.

I've got a 5 AMP 60v power supply. Later today I'll try to hook it up to a server rack battery plug into Kill-A-Watt meter into. I'm curious how efficient it is.

 

[seneysolar]

AC Converter/Battery Charger 36/48V: The Inverter Store

Offering a large charging capacity, the AIMS AC Converter/Battery Charger 36V and 48V, 25/18 amps, handles multiple battery types across a range of applications.

theinverterstore.com

These are advertised at 80% efficiency but its only 18A @ 48v

 

[wpns]

Normally I would say chargeverter, all day long.
But the V1 has been discontinued and the V2 is too expensive.
So I don't have any good recommendations, at the moment.

Well, I do have 2 new Chargeverters on order for backup use (charging batteries from grid/generators), so maybe I'll have a third use for them. 8*)

 

[MattiFin]

Something wrong with your measurements unless the charger was literally in flames.

There is no way that size of heat sink would be able to cool 700w losses(~2,1kWh in 3 hours or so)

 

[wpns]

Something wrong with your measurements unless the charger was literally in flames.

There is no way that size of heat sink would be able to cool 700w losses(~2,1kWh in 3 hours or so)

I haven't felt it while running, but it's got a fan in the middle of the heatsink, so wouldn't expect it to get that hot...

 

[MattiFin]

I haven't felt it while running, but it's got a fan in the middle of the heatsink, so wouldn't expect it to get that hot...

Even with a fan 700w losses are not plausible.

What did you use to measure AC side watts? Does it measure correctly between real power(W) and apparent power(VA)?

Same/similar looking charger sold under different name claims up to 95% efficiency. That sounds maybe a bit optimistic but nothing unusual.

 

[MattiFin]

My gut is that Golf cart chargers are built around keeping the cost down with little consideration for efficiency. Still I don't think you're going to get anything better than 90%. It may be easier to add a few more solar panels to your system and accept the losses, just a thought.

modern (last 30years) switch-mode 48V power supplies are all probably at least 75% efficient. Would need utterly incompetent designer for 50% efficiency and the end result would be lot more expensive as the single most expensive item in the charger is the cooling&heatsinks.

 

[gotbeans]

Where were you getting their drawing wattage? I've noticed my inverters are saying a draw of X but the actual measured draw is lower. They're including their consumption and the losses and who knows what else?

Do you have one of the AC plug in meters to monitor their actual usage of your battery chargers? That's what I'd recommend




must be space age stuff

I haven't felt it while running, but it's got a fan in the middle of the heatsink, so wouldn't expect it to get that hot...

Would you put your hand on a space heater when it is on the low setting?
This is the same heat

 

[hwy17]

I just tested my EG4 18A charger, which is a very similar design to yours.

Measuring with a kill a watt at the wall and DC as read from the Lifepower4 BMS I got a result of 88% efficiency.

It is too low to use in my double conversion system, I tried it for half a day the other day and you could feel in the utility room that it was generating an unnecessary amount of heat. My HEP-2300-55 claims 95% and I believe it, only gets lukewarm to the touch. But I don't have an easy way to test that one for myself I'd have to pull some wiring out to get a clamp on it.

Are you measuring the boat house circuit from some distance away? Voltage drop does add up to relevant losses.

My measurement was also cold, it's possible efficiency drops once it heats up. But as mentioned in this thread, they'd have to be trying to do worse than 80% nowadays.

 

[upnorthandpersonal]

For reference, a R48 Rectifier (as some of us use in our DIY chargeverter) sits over 90% efficiency.

 

[DougfromdaUP]

I too suspect a measurement error. Did you just multiply volts x Amps for the AC power? That won't work, because of the low power factor of the charger.

 

[wpns]

I’m getting the readings from an SC20 energy monitor as seen at https://www.saelig.com/product/DLPO002.htm but will try my Watts Up Pro to confirm. It doesn’t get 700W warm, so there’s something else going on here…

 

[wpns]

So My Watts Up Pro (by the same company) shows the power from the wall at 878 watts, so definitely something wrong with my metering. I'm going to convert over to Shelly Pro 1PM devices, because they never fail (except twice so far, sigh), and because the SC20s are long obsolete and require a lot of configuration and setup that I have to reinvent each time I touch them...
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