Anyone been using a pure sine wave inverter to charge your Rad bike?

[Pay Jota]

Just wondering if anyone has done this for an extended period, i.e., plugging the stock charger into a PSW inverter. I don't doubt that it will charge, but wondering if anyone has experienced reduced performance or failure?

I like to do a bit of off-grid camping in the truck camper and try and avoid firing up the genny. Besides, charging takes hours. I will run my genny for a few minutes for toast in the AM or inflating pneumatics or charging a wet cell battery, but that's about it. No TV while camping for us.

Even into a standard house outlet, the charger gets very warm to the touch.

 

[ssichler]

I tested it in our RV and it seemed fine with our Magnum 2000 watt pure sine inverter. Pulled about 7amps.

 

[Pay Jota]

7 amps @ 110/120? Magnums are good inverters and charge controllers. I would trust what they are reading.

I did try charging it with my existing MSW inverter in dodgy clouds-and-sun conditions today and it seemed to take a really long time. My house batt is only a single 105ah wet cell, being fed by a 140w solar panel. My Morningstar charge controller doesnt really read how much a device is pulling in amps, but I could tell it was a load. With less than 3 amps coming into the system from solar, it was dropping the overall DC voltage by a good 0.3-0.5v. That's a lot, really.

Which makes me question the stated 120w @ 120-240v on the charger. Should I be paying more attention to the DC output of 2.0amp @ 48v? That's closer to your readings of 7 amps.

 

[ssichler]

The 7amps is what it was pulling from the batteries. You do look at input of the charger which could be as much as 10amps if I'm doing the math right.

 

[TimJohn]

OK I am charging my 36V 14Ah battery with a 200 watt solar panel system with 2 x 12 volt deep cycle batteries and the 1000 watt inverter. The output from the battery is monitored and the inverter with the 2 amp battery charger that I am using to charge the battery it is drawing 100 watts at 7.8 amps. It takes about 5 to 6 hrs to fully charge my battery... a long time but its part of the solution of reducing my gasoline consumption.

The input from the solar panels on a sunny day right at this moment...17.9 volts and 4.9 amps

 

[ssichler]

OK I am charging my 36V 14Ah battery with a 200 watt solar panel system with 2 x 12 volt deep cycle batteries and the 1000 watt inverter. The output from the battery is monitored and the inverter with the 2 amp battery charger that I am using to charge the battery it is drawing 100 watts at 7.8 amps. It takes about 5 to 6 hrs to fully charge my battery... a long time but its part of the solution of reducing my gasoline consumption.

The input from the solar panels on a sunny day right at this moment...17.9 volts and 4.9 amps

It doesn't seem like you will be able to charge the bike battery and the deep cycle batteries. Going below 50% on the lead-acid batteries will kill them pretty fast.

 

[Pay Jota]

100 watts at 7.8 amps? Arent those both generally figures of consumption of electricity?

At what voltage are you talking about 100 watts being consumed or 7.8 amps being drawn? 7.8 amps at 13v? 7.8 amps @ 120v?

If you know your panels will produce 4.9 amps @ 17.9 volts, there will probably be enough to charge your bike battery and still leave SOME for charging the deep cycles. But not in a quantity that your batteries need to give them their maximum life expectancy.

Your charge controller will not allow 17.9 volts at your battery bank anyway. Most good ones will limit it to no more than about 14.4, unless it is doing some type of desulfation cycle. So, you will get a lot more than 4.9 amps from your panels at 14.4 volts. I have seen my single 140 watt Kyocera/Morningstar combo produce between 7 and 8 amps at 13.5-14-4 volts.

I still question the labeling on the Rad charger. If it is supposedly consuming 120 watts at 120v (as it's listed on a 2019 charger), that's only a 1.0 amp draw at 120v. Yet we are all experiencing a much larger amp draw when we use our inverters. Even assuming an inverter (in)efficiency of 85-90%, we are still talking a draw of less than 1.5a @ 120v.

I cannot directly read what my appliances are drawing from my system in amps. All I can do is read the amount of amps coming into the system from the solar panel at a specific voltage. But I can tell that when my panels are putting out anything over about 4 amps and the Rad charger is charging, my overall voltage will slowing increase. If it was drawing 7 amps, there is no way I would see a voltage increase with my system.

 

[ssichler]

100 watts at 7.8 amps? Arent those both generally figures of consumption of electricity?

At what voltage are you talking about 100 watts being consumed or 7.8 amps being drawn? 7.8 amps at 13v? 7.8 amps @ 120v?

If you know your panels will produce 4.9 amps @ 17.9 volts, there will probably be enough to charge your bike battery and still leave SOME for charging the deep cycles. But not in a quantity that your batteries need to give them their maximum life expectancy.

Your charge controller will not allow 17.9 volts at your battery bank anyway. Most good ones will limit it to no more than about 14.4, unless it is doing some type of desulfation cycle. So, you will get a lot more than 4.9 amps from your panels at 14.4 volts. I have seen my single 140 watt Kyocera/Morningstar combo produce between 7 and 8 amps at 13.5-14-4 volts.

I still question the labeling on the Rad charger. If it is supposedly consuming 120 watts at 120v (as it's listed on a 2019 charger), that's only a 1.0 amp draw at 120v. Yet we are all experiencing a much larger amp draw when we use our inverters. Even assuming an inverter (in)efficiency of 85-90%, we are still talking a draw of less than 1.5a @ 120v.

I cannot directly read what my appliances are drawing from my system in amps. All I can do is read the amount of amps coming into the system from the solar panel at a specific voltage. But I can tell that when my panels are putting out anything over about 4 amps and the Rad charger is charging, my overall voltage will slowing increase. If it was drawing 7 amps, there is no way I would see a voltage increase with my system.

The difference is in the draw is 12 volt DC system vs. 110/120 volt AC. If you looked at an online calculator you would use 12 volts not the current voltage of the battery. 13 volts is full on my AGM bank but it's still a 12 volt system. Based on the label I was expecting to see 10amp DC on my inverter so 7 or 8amp is probably fine.

 

[TimJohn]

......It doesn't seem like you will be able to charge the bike battery and the deep cycle batteries. Going below 50% on the lead-acid batteries will kill them pretty fast.

It doesn't even come close to going below 50%. The output never goes below 12.8 volts the whole time I am recharging the e-bike battery. It does float around though I noticed so sometimes it even creeps up to about 13.5 volts as I am recharging.

I do make a point of charging only on sunny days. The charger does get warm I noticed but with 200Ah deep cycle lead acid batteries I really don't think it's a problem (Golf cart batteries get deep cycled when used to power an electric cart...my application is fairly tame).

.....100 watts at 7.8 amps? Arent those both generally figures of consumption of electricity?

YES

At what voltage are you talking about 100 watts being consumed or 7.8 amps being drawn? 7.8 amps at 13v? 7.8 amps @ 120v?

Well the monitor I use....shows this:

 

[cayjak]

All these confusing numerical calculations are not necessary. Just get yerself a Kill A Watt monitor. Usually under $20 from Amazon or Walmart. Plug it in any AC power outlet (house, RV or the outlet on the inverter). Plug your battery charger into the monitor. Read the power consumption of the battery charger (volts, amps or watts) on the monitor. EASY!

This handy device should be in the tool box of ANYONE who tries to live off the grid. You must know the power consumption of every device you use, before you can properly size your battery bank, inverter and solar array.

http://www.p3international.com/products/p4400.html

 

[Pay Jota]

All these confusing numerical calculations are not necessary. Just get yerself a Kill A Watt monitor. Usually under $20 from Amazon or Walmart. Plug it in any AC power outlet (house, RV or the outlet on the inverter). Plug your battery charger into the monitor. Read the power consumption of the battery charger (volts, amps or watts) on the monitor. EASY!

This handy device should be in the tool box of ANYONE who tries to live off the grid. You must know the power consumption of every device you use, before you can properly size your battery bank, inverter and solar array.

http://www.p3international.com/products/p4400.html

So what does your Kill a Watt meter show the draw of the Rad charger IS at 120v?

Besides, the Kill a Watt meter doesnt DIRECTLY figure the amp draw on our battery bank, which is what we are more concerned with. But it will show what the actual AC draw of the charger is while charging.

So, TJ, that reading is with nothing else being drawn off your battery bank, besides incidentals like your smoke, CO, propane alarms?

 

[TimJohn]

.....So, TJ, that reading is with nothing else being drawn off your battery bank, besides incidentals like your smoke, CO, propane alarms?

YES...the reading of the small box to left is only when the battery is being charged. Nothing else drawing power out of the solar panel system.

Thanks cayjak for the suggestion of the Kill a Watt...I actually have one sitting in a draw so I will place it in line when I am charging the battery. Keep you posted next time I charge.

.....Besides, the Kill a Watt meter doesnt DIRECTLY figure the amp draw on our battery bank

Well my Cycle Analyst (GRIN technologies) does give me this information watts/hr and amps as I am riding. I think most other be-bike displays don't come close to being as informative but give simpler indicators such as estimated range. This maybe simple enough and probably more useful for the general public who buy a turn key e-bike.

 

[cayjak]

Hooked up my Kill A Watt in my garage. Took some photos, which uploaded in reverse order from the way I took them.

Photos show Hertz (frequency), watts, amps, and volts.

First 4 photos with the RAD battery charger plugged in to the Kill A Watt meter, and also plugged into the battery on my RadMini.

Second 4 photos with just the Kill A Watt meter plugged in to extension cord.

In case photos are not clear, the RAD battery charger is drawing 1.54 amps at 120 volts and delivering 116 watts of charging power to the battery.

To generate 116 watts of AC power from a 12 volt (nominal) battery would require approximately 9 amps of current PLUS whatever is required to power the inverter.

 

[TimJohn]

I don't really think this is an issue with my setup. I use a solar panel system and charge my battery from this. Don't use household power.

It would be nice to know the precise draw and I think I do know what it is as pictured in one of the messages but with 2 x 12 Volt 200 Ah it doesn't even flinch. There is enough headroom to charge my e-bike battery for 6 hrs then the batteries are recharged after this time with the solar panels. Do it on sunny days!

So are the concerns because the thinking is the golf batteries with be discharged below 50% and this will eventually ruin them. Doesn't even come close and I don't think it ever will unless I am constantly charging e-bike batteries one after the other and doing them over and over for great lengths of time. There is a limit at some point I guess but not with my usage. Next time I charge I will put the Kill a Watt in line but I think it will demonstrate that the monitor (last couple of messages from me) is fairly accurate.

 

[Pay Jota]

From all this, it certainly appears that the charger is drawing about 1.5 amps at 120v. Which is somewhere around 7-9 amps at 12v, depending on what voltage your batteries are at, due to what the charge controller and the panel(s) are feeding it. An amp is not an amp when you are dealing with 12v being inverted to 120v. It depends on WHERE that amp is being measured and at what voltage.

7-9 amps at ~12v is not an insignificant amount for a single house battery of 105ah (like mine), especially if it was a cloudy day and the solar panel was not boosting the voltage much or mitigating some of that amp draw. Six continuous hours of charging would bring my SOC at or below 50%.

My wife has an ebike, too, and we often ride together. So I would need twice that amount of draw to charge both of our batteries at the same time. Since my truck has TWO starting batteries (in parallel) that probably have an amp hour rating around 90 each, I need to secure another inverter for that battery bank to charge the other Rad battery. Fortunately, my charge controller will charge two separate battery banks at once. I already have it feeding my starter batteries whenever the house voltage goes over 13.2. I can choose to split the charging 50/50 between the two banks or 90/10 favoring the house bank. A battery separator separates either bank from drawing below 13.2v from either bank, so one bank cannot discharge the other.