Charging a Torqeedo Using Solar

[Curmudgeon]

My apologies if this topic has been addressed before. I'm seriously considering a Torqeedo travel 801. I like the light weight, absence of gasoline and ease of starting. It will power a 9' Avon "roll up" tender.

The battery comes with an 80 watt charger that plugs into a standard 110 a/c plug. I believe there is also an adapter for European 220v sockets. I'm told the battery takes 7-8 hours to charge.

Suppose I wanted to leave the battery on my boat and charge it there? I have a 2000 watt Heart interface inverter, so I suppose I could plug in the charger while the diesel was running.

But what about "trickle charging" the battery using a solar panel? I could keep the battery on the boat; I sail mostly on weekends and could keep it charging all week when I'm not there. A little 80 watt inverter that plugs into a vehicle cigarette lighter costs about 30 dollars. Would that work with a solar panel? How big a solar panel would I need? Has anyone tried this before? I called Torqeedo USA but no one there seems to know.

[Pblais]

If an 80 watt charger takes 7 hours at 110 Volts. Volts X Amps = Watts. You can do the math at 12 volts less the inefficiency of going DC to AC to the inverter(20%). You are charging a battery so you need to think in those terms. Given the battery is more than likely 12 volts it's just another charging chore you need to do. It does depend on how much you run it.

Do you have a lot of charging ability going to waste? This might be a great idea.

[Curmudgeon]

Actually I think the battery on the 801 is 24 volt.

I don't know what you mean about charging ability going to waste. I have plenty of charging ability ashore, but I don't want to run down the boat's batteries charging the Torqeedo.

Instead, I want to use a dedicated solar panel, similar to the ones that people use to charge d/c devices such as the typical 12v battery. I understand that 12v is also a typical output for a solar panel of reasonable size.

My question is, will it work (albeit slowly)? Could it damage the battery?

[Pblais]

My question is, will it work (albeit slowly)? Could it damage the battery?

No it's only how long it takes. You do want to fully recharge the battery. If it took 3 days then you'll be replacing the battery sooner than you want to do so. If you are at shore power you probably don't need it's use either.

[witzgall]

The 801 uses a 24v battery. There are some panels that will give you 24v output. However, they may not output a voltage that is high enough for charging. I have just purchased an 801, but I have not had a chance to give it a try. I do know that the charger is rated at 40v. It would make sense to pose the question to Torqueedo. If you do, please post their response.

BTW, I am looking at building a 24v 40ah LIFEPO4 battery. This is 4x the capacity of the battery supplied. It should weigh less than 30 lbs and fit into one of those shorty plastic waterproof ammo boxes. If I follow throug with it, I'll post here. When cruising the idea is one could use this and when it is depleted, take it ashore and charge it while using the original battery. Something like that.

Chris

[Curmudgeon]

I talked to a technical support person at Torqeedo today. Yes, the problem is that if the solar panel is too small, the charging process may not begin at all. He said that Torqeedo has been investigating this issue but there is no resolution yet.

So if I get the Torqeedo I will either charge it using shore power or with my inverter. My boat has 4 6-Volt deep cycle batteries. The question now is, how much will charging the Torqeedo deplete the batteries?

[44'cruisingcat]

How about connecting the solar panel to the boat's house batteries? With a small charge regulator.

Then run the small inverter and charger from the house batteries.

[Curmudgeon]

Well yes. I already have a 2000 watt inverter and solar panels to recharge the house batteries. The question is how much recharging the Torqeedo will draw my batteries down.

[44'cruisingcat]

From the website it seems the 801 has a 300 Watt hour battery. To fully charge from a 12 volt battery that would take 300/12 = 25 amp hours.

You'd allow for a bit more (say 20%) due to various losses though.

Your 80 Watt charger should pull around 7 amps, for around 4 hours to charge the battery.

It might be worth buying a smaller inverter for this job, the 2000 watt one might have a fairly high no load current draw.

[witzgall]

Here is a possible solar solution to charging a higher voltage battery, such as the Torqueedo 801:

1. Kanena Solar panel: Kaneka G-SA060 60 watt solar panel. Lead-free. High efficiency
BZ products MPPT500hv controller: MPPT Charge Controls

The controller is switchable between 12-24-48 volt output. It is designed for high output panels, such as the 60v Kaneka. THe panel is a big one for it's output, but shade resistant. I was wondering if something like this could be rigged to charge the house bank, and then with some kind of disconnects, charge the Toqueedo. THis is assuming that the charge brains are in the battery, not the charger they provide. I think their charger is just a 40v 2a power supply. It gets hot, like most of these inefficient power supplies.

Chris

[witzgall]

Putting my money where my mouth is, I have placed an order for eight, 3.2v 40ah LIFEPO4 cells. These will wire up to make a 24v, 40ah battery. This is 4x the capacity of the Torqueedo battery. Now I need to find and purchase a BMS board. The cells should be here in ~ a month, I think. I got in the tail end of a group buy from http://www.evcomponents.com

Chris

[Curmudgeon]

Originally Posted by witzgall

Here is a possible solar solution to charging a higher voltage battery, such as the Torqueedo 801:

1. Kanena Solar panel: Kaneka G-SA060 60 watt solar panel. Lead-free. High efficiency
BZ products MPPT500hv controller: MPPT Charge Controls

The controller is switchable between 12-24-48 volt output. It is designed for high output panels, such as the 60v Kaneka. THe panel is a big one for it's output, but shade resistant. I was wondering if something like this could be rigged to charge the house bank, and then with some kind of disconnects, charge the Toqueedo. THis is assuming that the charge brains are in the battery, not the charger they provide. I think their charger is just a 40v 2a power supply. It gets hot, like most of these inefficient power supplies.

Chris

Wow, that Kanena solar panel is almost as big as my staysail.

Which gets me to thinking... maybe 100 years from now, someone will have developed a sail that is also a solar panel. You just raise the sail, plug it into your house bank, and go.

[Curmudgeon]

Originally Posted by witzgall

Putting my money where my mouth is, I have placed an order for eight, 3.2v 40ah LIFEPO4 cells. These will wire up to make a 24v, 40ah battery. This is 4x the capacity of the Torqueedo battery. Now I need to find and purchase a BMS board. The cells should be here in ~ a month, I think. I got in the tail end of a group buy from http://www.evcomponents.com

Chris

That's alot of money, and the charger for those batteries costs $2,000 on top of what you pay for the batteries. Plus you'd have to haul that additional wieght around in your tender.

For $2,000 you could buy 4 additional Torqeedo batteries and have 5x the original capacity.

[witzgall]

Curmudgeon;
You don't need one of those chargers! The company is selling mostly to folks converting cars. Those chargers would be serious overkill for this application. The batteries will be ~$400 + perhaps $70 for the BMS board.. It will be light, small, and last over 2000 cycles. I am also looking at an e-bike 24 kit, to commute with, so I would also use the pack for that. So far I have found a 15a 24v charger for $175

The Kaneka panel is big - I think I would be able to fit only one + a wind genny on our arch. They do handle high temps realy well, output does not drop as much as mono and poly cell panels.

However, I am not ready to go down this route. I want to experiment with just plugging in their charger to an inverter first, and seeing how that goes.

BTW, I am a solar guy. We live in a passive and active solar house. It has a 2kw solar array, and 2kw of hot water heat.

Chris

[witzgall]

Some more Torqueedo info:

Although the cells in their battery pack will accept a high rate of charge, the battery management circuitry in the pack will only accept 2A of current. Any more and you will damage the electronics. The "Charger" they supply is nothing more than a power supply, it has no battery management brains in it at all.

So something like the Kaneka panel solution I outlined above won't work - it will put out too much amps and damage the battery pack.

One 50-60 watt 24v nominal panel might do the trick for a slow charge. The trick would be to ensure that it did not output more power than the supplied charger. I did mention to the Torqeedo tech guy that being able to charge these at a higher rate would be advantageous to cruisers.

I hope to have my 40ah battery built up by the end of the season. I will report any success or failure here.

Chris