charger for 48V 210Ah battery bank

[thastinger]

What charger for a 48V 210Ah battery bank made from 8 Trojan T-605 batteries? I have 3 gas generators I could use to power it, all are slightly different configurations. The genny I took up to the remote garage is a 3500W RV genny, it has a full power 30A RV plug on the front so I could get 27ish amps at 120 out of it or 20A standard plugs. Another genny that is pretty close by is a 3500W split phase genny with a 240V plug on it or duplexed 120 plugs so full power from the 240 plug or half power from the 120 plugs. The third (and heaviest and would need to be hauled in) is a Yamaha 3000ISEB inverter genny which has a twist lock 30A 120 plug or 20A standard plugs.

[Sunking]

With a genny you want to charge at maximum rate to minimize fuel consumption and maximize battery charge efficiency. That point occurs around C/8 of the battery capacity. So you have a 210 AH battery at 48 volts. C/8 is a charge current of 210/8 = roughly 26 to 30 amps. If we take a 75% efficiency of the charger would require a genny of [52 volts x 30 amps] / .75 = 2080 VA. So in practice you need a genny of about 3Kw and a 48 volt 25 to 30 amp charger.

[thastinger]

Thanks, I was kinda hoping that someone who uses one would chime in as well.
Most of the ones I have found tend to be on the golf cart side of things, they only output 15-20A but are advertised as 48V battery bank chargers but seem lite on charging amps. Are there any specific recommendations that work well on PV systems?

[Mike90250]

Iota makes a charger for 48V, but it's not a high amperage one. To get high amps, you will need a 240VAC outlet, and maybe a large golf cart, or forklift charger.

[thastinger]

I have a 240 plug on one of the gennys

[Sunking]

Give you a tip on high power Battery chargers, or I should say Rectifiers. There are thousands of salvaged DC Power Plant Rectifiers out there for sale dirt cheap. You can get them up to 800 amps @ 48 volt DC. Google Lorain Rectifier, or Reltec Rectifiers. Lots of them at 30, 50 and 100 amps. They will most likely require 240 volts larger than 30 amps.

[bcroe]

Big Cheap Chargers

Give you a tip on high power Battery chargers, or I should say Rectifiers. There are thousands of salvaged DC Power Plant Rectifiers out there for sale dirt cheap. You can get them up to 800 amps @ 48 volt DC. Google Lorain Rectifier, or Reltec Rectifiers. Lots of them at 30, 50 and 100 amps. They will most likely require 240 volts larger than 30 amps.

Are a lot of those going to be 3 phase? Good for batteries, but hard for small timers to use; drives the surplus price down. A phase converter can be built, but the cheap ones involve rotating machinery (3
phase motor + some caps). Bruce Roe

[Sunking]

Are a lot of those going to be 3 phase? Good for batteries, but hard for small timers to use; drives the surplus price down. A phase converter can be built, but the cheap ones involve rotating machinery (3
phase motor + some caps). Bruce Roe

No Bruce most 48 volt chargers 100 amp and less will operate from 190 to 290 volts AC. All you need is a 220 to 240 volt AC circuit. 50 amp and less can operate down to 90 volts up to 290 volts. You just select the right tap. YOu can pick up the older ones for a song. They just are not real efficient like the newer sitch modes.

[bcroe]

100A 48V charger

No Bruce most 48 volt chargers 100 amp and less will operate from 190 to 290 volts AC. All you need is a 220 to 240 volt AC circuit. 50 amp and less can operate down to 90 volts up to 290 volts. You just select the right tap. YOu can pick up the older ones for a song. They just are not real efficient like the newer sitch modes.

So 100A can be single phase. The 800A surely are 3 phase, somewhere between must be the changeover. The thing that impresses me the most about the new switchers, is how light & compact they are. Bruce

[Sunking]

So 100A can be single phase.

Not that I am aware of just too many amps at AC would have to be up around 50 amps. Most 120 VAc circuits are 20 amps max. [/QUOTE]30 amps is about as large as you are going to find @ 120 VAC.

The 800A surely are 3 phase, somewhere between must be the changeover.

Yes Sir 480 volt.

The thing that impresses me the most about the new switchers, is how light & compact they are. Bruce

That is because the big heavy input 60 Hz transformer is gone. What they do is rectify the incoming AC to DC, convert it immediately to high frequency AC, then use a high frequency transformer to step the voltage down, then rectify it back to DC. Higher th efrequency, the small and lighter the transformer. That is why aircraft and ships use 400 Hz. Switch mode PS use several Khz.

[bcroe]

Switchers

[Originally Posted by bcroe The thing that impresses me the most about the new switchers, is how light & compact they are. Bruce]

That is because the big heavy input 60 Hz transformer is gone. What they do is rectify the incoming AC to DC, convert it immediately to high frequency AC, then use a high frequency transformer to step the voltage down, then rectify it back to DC. Higher th efrequency, the small and lighter the transformer. That is why aircraft and ships use 400 Hz. Switch mode PS use several Khz. DereckC MSEE, PE
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That is practical because of todays power MOSFETs. The downside is radio interference they generate. When I got my HAM license half a century ago, the only interference in the house was Moms' vacuum cleaner. A couple capacitors soon fixed that. Now the house is full of switchers; can't keep up adding shielding & filters. The new PV array uses a couple 7.5 KW inverters light enough I can pick up. But I fear at max output they will bother the new radio tower nearby. If so I'll have to build shielding with 500VDC & 240VAC line filters (not cheap) at the 15 KW level.

I suppose, the new rectifiers have a much better power factor? The old diodes took quite a bite off the top of the sine wave, with a huge peak current. The switcher could "track" its way up & down the sine, controlling the current to match? Bruce Roe

[Sunking]

What bands do you operate? I am KF5LJW

I understand your frustration with switchers. Unfortunately consumer grade electronics as you know are made with the least amount of components possible to keep cost down at the sacrifice of RFI. With that said the Teloc rectifiers are much higher quality as they are used with very sensitive electronic equipment. Every cell tower has multiple rectifiers. Smallest out there is 600 amp 24 volt DC used in cell towers.

[bcroe]

Interference & rectifiers

What bands do you operate? I am KF5LJW

I understand your frustration with switchers. Unfortunately consumer grade electronics as you know are made with the least amount of components possible to keep cost down at the sacrifice of RFI. With that said the Teloc rectifiers are much higher quality as they are used with very sensitive electronic equipment. Every cell tower has multiple rectifiers. Smallest out there is 600 amp 24 volt DC used in cell towers.

I think I dropped the ball. Doing only VHF here, more listening than transmitting. I suppose cell went 24V as a better direct supply to the radio transmitters? That would imply negative ground systems, as opposed to the 48V telco systems + ground. Bruce Roe K9MQG

[Sunking]

Yes Cell Sites do use 24 volt battery plants with Negative ground reference. However most also have -48 volt converters to operate Microwave and Transport Equipment like optical carriers.

Todays cell site looks much different than say 5 years ago, and no resemblance to say 10 years ago when analog was to still on the air. Analog is history, none exist in the USA today. It was replaced by digital using CDMA and GSM spread spectrum technology. However CDMA and GSM is being antiquated and replaced by 4G LTE.

[Saggys]

What charger for a 48V 210Ah battery bank made from 8 Trojan T-605 batteries? I have 3 gas generators I could use to power it, all are slightly different configurations. The genny I took up to the remote garage is a 3500W RV genny, it has a full power 30A RV plug on the front so I could get 27ish amps at 120 out of it or 20A standard plugs. Another genny that is pretty close by is a 3500W split phase genny with a 240V plug on it or duplexed 120 plugs so full power from the 240 plug or half power from the 120 plugs. The third (and heaviest and would need to be hauled in) is a Yamaha 3000ISEB inverter genny which has a twist lock 30A 120 plug or 20A standard plugs.

Have you thought of replacing your inverter with a inverter/charger?