How to charge 36 volt battery with 12 volt charger

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Re: Charging a 36 volt bank with a 12 volt controller

Quote:

Originally Posted by jeanathon

Deck,

Yes I am only planning on using the electric propulsion for marinas or shooting an inlet. If I decide to do canals or what not I will add a disposable generator to the mix.
The motor is way overpowered at 24 KW at 36 volts with an EV1 controller. Current panels are 2 x 45 watts and a 30 watt. Currently looking at some 200 watt panels.
Not sure yet if I can use this motor for hydroelectric generation via the prop unless I put a manual disconnect to the controller.
36 volt bank is 750 amp hour consisting of 3 batteries.
12 volt bank is yet to be determined. No inverter and minimum electronics ie. no autopilot, fridge, or watermaker. All interior lights are LED.
The boat ways in at 7000 lbs.
Just me and two dogs although I might take current girlfriend, but that is yet to be determined.

Conditions:
Generation-
1. You are now generating a small amount of nominal 12V with solar panels. You plan to greatly increase this solar source.
2. You may use a hydrogenerator (from the propulsion system).
3. You may have an engine-driven alternator 12V source?
4. You may have a shore-power charging source and/or a portable generator.

Storage-
1. You will have/have a small 12V bank (for house, ancillary use, engine/gen starting).
2. You have a large 36V bank (for the electric propulsion system).

Problem:
How to charge the 36V propulsion bank when all your present and future electrical power sources are, or likely will be, 12V?

Solution:
You basically need a 12V DC-DC stepup device capable of 36V battery charging (in other words, a battery-to-battery charger), tightly controlled in order to baby the 36V bank.

The easiest solution is a Sterling Power battery-to-battery charger (BTBC) (I have no connection, other than admiring practical design).

Sterling makes a number of different models in various voltage and amp input/output combinations.

This BTBC device (in your case, 12V in to 36V out, see p/n BBW1236 below) allows your various normal 12V charging sources to feed the 12V (house) bank (large or small, it acts as a buffer).
The BTBC is positioned between the 12V house battery and the 36V battery bank, which receives the BTBC's controlled multistage 36V charging output.
Think of the BTBC as a 12V input smart Duo or Echo type device for passing on a voltage increased charging current to the 36V bank.

You can search for these Sterling BTBC's online, suggest that you look at/download their whole catalog to get the full description of the BTBC and other devices available.

I'll put some selected quotes from the Sterling catalog to further explain:

" The key thing about this product is the ease of installation and the
fact it does not work nor change anything on the standard engine/vehicle system and as such does not raise any warranty or installation issues.
Fully programmable for different battery types."...
... "the best way to charge a battery is using a 4 step battery charging curve (that cannot be achieved from a standard alternator).
This system enables one to simply attach the unit to a standard engine battery and it will fool the alternator into working at it’s maximum ability and ensure all it’s surplus power is used to charge the auxiliary battery bank (your 36V bank) to it’s maximum.
This system is designed to use only the surplus power and ensures that at all times the power required to run the primary system (the vehicle system or the boat engine (your house/starting bank) ) is not affected.
The surplus power is converted into a higher voltage and used to charge a secondary battery bank using a digitally controlled programmable 4 step charging curve (settable for different battery types, SLA/AGM/GEL/LiPo/etc) as per all the other high charge products Sterling makes." ...

... "We also offer a range of 12-24V / 12-36V / 24-24V / 24-36V / 24-12V"...
...
"Battery to Battery chargers / IP68 FULLY WATERPROOF
D/C Input voltage D/C output voltage Amps in Size L x W x D Weight Part nos
12 12 25 230 x 135 x 65
3 BBW1220
12 24 25 230 x 135 x 65
3 BBW1224
12 36 25 230 x 135 x 65
3 BBW1236
24 24 13 230 x 135 x 65
3 BBW2424
No remote control for the above"

Seems like the simplest solution to your overall problem to me. One configurable charging device between your 12V bank and your 36V bank.
Independent from any/all of your 12V charging sources, and a full featured charger for your 36V bank.
And I think they don't cost that much either.

Couldn't reproduce some of the figures for the above, read the Sterling literature (hard to C&P from a pdf doc sometimes).

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Re: Charging a 36 volt bank with a 12 volt controller

Great to see another electric boat.
Can you just operate your motor on 12v instead of 36v?
What kind of motor is it?

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Re: Charging a 36 volt bank with a 12 volt controller

Deck,
That range is acceptable, and thank you for doing the math. Is there a reason I shouldn't charge on the hook? One of the reasons I am going electric is to not have to go into a marina to "refuel".

Tx J Simplicity is elegant. I will read up some more on that device.

Nimble,
It is an old motor out of a forklift. The motor and more importantly controller use either 36 volt or 48 volt. At 12 volts the motor would put out sufficient power, but I am not sure what drawbacks I would have running it lower than rated.

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Re: Charging a 36 volt bank with a 12 volt controller

Quote:

Originally Posted by jeanathon

Deck,
That range is acceptable, and thank you for doing the math. Is there a reason I shouldn't charge on the hook? One of the reasons I am going electric is to not have to go into a marina to "refuel".

Tx J Simplicity is elegant. I will read up some more on that device.

Nimble,
It is an old motor out of a forklift. The motor and more importantly controller use either 36 volt or 48 volt. At 12 volts the motor would put out sufficient power, but I am not sure what drawbacks I would have running it lower than rated.

The controller has a max amps it can operate at, lets say 300 amps. At 48 volts that is 14,400 watts / 746 = 19.3 hp. At 12 volts 4.8 hp.

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Re: Charging a 36 volt bank with a 12 volt controller

Quote:

Originally Posted by Tx J

Conditions:
Generation-
1. You are now generating a small amount of nominal 12V with solar panels. You plan to greatly increase this solar source.
2. You may use a hydrogenerator (from the propulsion system).
3. You may have an engine-driven alternator 12V source?
4. You may have a shore-power charging source and/or a portable generator.

Storage-
1. You will have/have a small 12V bank (for house, ancillary use, engine/gen starting).
2. You have a large 36V bank (for the electric propulsion system).

Problem:
How to charge the 36V propulsion bank when all your present and future electrical power sources are, or likely will be, 12V?

Solution:
You basically need a 12V DC-DC stepup device capable of 36V battery charging (in other words, a battery-to-battery charger), tightly controlled in order to baby the 36V bank.

The easiest solution is a Sterling Power battery-to-battery charger (BTBC) (I have no connection, other than admiring practical design).

Sterling makes a number of different models in various voltage and amp input/output combinations.

This BTBC device (in your case, 12V in to 36V out, see p/n BBW1236 below) allows your various normal 12V charging sources to feed the 12V (house) bank (large or small, it acts as a buffer).
The BTBC is positioned between the 12V house battery and the 36V battery bank, which receives the BTBC's controlled multistage 36V charging output.
Think of the BTBC as a 12V input smart Duo or Echo type device for passing on a voltage increased charging current to the 36V bank.

You can search for these Sterling BTBC's online, suggest that you look at/download their whole catalog to get the full description of the BTBC and other devices available.

I'll put some selected quotes from the Sterling catalog to further explain:

" The key thing about this product is the ease of installation and the
fact it does not work nor change anything on the standard engine/vehicle system and as such does not raise any warranty or installation issues.
Fully programmable for different battery types."...
... "the best way to charge a battery is using a 4 step battery charging curve (that cannot be achieved from a standard alternator).
This system enables one to simply attach the unit to a standard engine battery and it will fool the alternator into working at it�s maximum ability and ensure all it�s surplus power is used to charge the auxiliary battery bank (your 36V bank) to it�s maximum.
This system is designed to use only the surplus power and ensures that at all times the power required to run the primary system (the vehicle system or the boat engine (your house/starting bank) ) is not affected.
The surplus power is converted into a higher voltage and used to charge a secondary battery bank using a digitally controlled programmable 4 step charging curve (settable for different battery types, SLA/AGM/GEL/LiPo/etc) as per all the other high charge products Sterling makes." ...

... "We also offer a range of 12-24V / 12-36V / 24-24V / 24-36V / 24-12V"...
...
"Battery to Battery chargers / IP68 FULLY WATERPROOF
D/C Input voltage D/C output voltage Amps in Size L x W x D Weight Part nos
12 12 25 230 x 135 x 65
3 BBW1220
12 24 25 230 x 135 x 65
3 BBW1224
12 36 25 230 x 135 x 65
3 BBW1236
24 24 13 230 x 135 x 65
3 BBW2424
No remote control for the above"

Seems like the simplest solution to your overall problem to me. One configurable charging device between your 12V bank and your 36V bank.
Independent from any/all of your 12V charging sources, and a full featured charger for your 36V bank.
And I think they don't cost that much either.

Couldn't reproduce some of the figures for the above, read the Sterling literature (hard to C&P from a pdf doc sometimes).

Comparison of Sterling 12 to 36 volt - - - Yandina Trollbridge36.
Identical parameters are not listed:-

List price: $278 - - - $199
Maximum charging current: 30 Amps - - - 100 Amps
Continuous rating: 20 Amps - - - 100 Amps
Automatic switching: 13.3 volts - - - 13.0 volts
Multi stage charging: built-in - - - Echoes charging source
In stock: No - - - Yes
Size: 9x6x2 - - - 4x4x2
Weight: 9 lbs - - - 3 lbs
Warranty: 2 years - - - Unlimited
Override control: optional wired switch - - - Included radio remote
3 battery system using start battery for trolling too: No - - - Yes
Battery equalizing for unmatched batteries: No - - - Yes
Current drain when OFF: Not stated - - - Zero
Current drain when charging: Not stated - - - < 1/2 amp

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Re: Charging a 36 volt bank with a 12 volt controller

OK, so the common brushed series motor, controller is probably from a golf-cart. Given you need little power from it, at 12v you might not need a controller at all, just apply 12v directly from the battery. The standard controller reduces the voltage to the motor at low throttle.
I don't know of any commercially available, but you can boost the voltage in a motor controller instead of reducing it,
then you can keep 12v everywhere instead of special battery and charger for 36v.

Quote:

Originally Posted by jeanathon

It is an old motor out of a forklift. The motor and more importantly controller use either 36 volt or 48 volt. At 12 volts the motor would put out sufficient power, but I am not sure what drawbacks I would have running it lower than rated.

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The controller came out of the same forklift, and controls forward and reverse as well as the speed. The motor has 5 posts, and 3 coils. If I understand correctly at high speed it drops one of the coils to reduce resistance. Although I'm pretty mechanically minded, I think wiring all that from scratch maybe a bit beyond me.
I do like the idea of keeping it 12 volt only though.

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Re: Charging a 36 volt bank with a 12 volt controller

With 5 posts, it would be a brushless motor, so you can't just run it on 12v directly, you need the controller. You could still perhaps convert 12v to 36v just for the controller input and still have the battery and chargers 12v.

Quote:

Originally Posted by jeanathon

The controller came out of the same forklift, and controls forward and reverse as well as the speed. The motor has 5 posts, and 3 coils. If I understand correctly at high speed it drops one of the coils to reduce resistance. Although I'm pretty mechanically minded, I think wiring all that from scratch maybe a bit beyond me.
I do like the idea of keeping it 12 volt only though.

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Join Date: Mar 2012

Location: WNC mountains U.S.

Boat: Boatless

Posts: 969

Re: Charging a 36 volt bank with a 12 volt controller

Quote:

Originally Posted by nimblemotors

With 5 posts, it would be a brushless motor, so you can't just run it on 12v directly, you need the controller. You could still perhaps convert 12v to 36v just for the controller input and still have the battery and chargers 12v.

I wish it were brushless! I believe the problem with this solution is the amount of amps. I did a quick search for such a beast, but only came up with some very lightweight dc to dc converters.

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Re: Charging a 36 volt bank with a 12 volt controller

Quote:

Originally Posted by Andina Marie

Comparison of Sterling 12 to 36 volt - - - Yandina Trollbridge36.
Identical parameters are not listed:-

List price: $278 - - - $199
Maximum charging current: 30 Amps - - - 100 Amps
Continuous rating: 20 Amps - - - 100 Amps
Automatic switching: 13.3 volts - - - 13.0 volts
Multi stage charging: built-in - - - Echoes charging source
In stock: No - - - Yes
Size: 9x6x2 - - - 4x4x2
Weight: 9 lbs - - - 3 lbs
Warranty: 2 years - - - Unlimited
Override control: optional wired switch - - - Included radio remote
3 battery system using start battery for trolling too: No - - - Yes
Battery equalizing for unmatched batteries: No - - - Yes
Current drain when OFF: Not stated - - - Zero
Current drain when charging: Not stated - - - < 1/2 amp

this solution doesn't help him. the boat has a single 36v electric motor. he doesn't have a 12v motor running sometimes to charge the 36. like a trolling boat does. the 36v bank should stay intact. and be charged by 36v. otherwise he can't charge his main engine battery unless the engine is not on. which is silly

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Re: Charging a 36 volt bank with a 12 volt controller

Oops, thanks smac.

The subject was "Charging a 36 volt bank with a 12 volt controller" and others suggested a 12 volt system combined with it.

The Trollbridge36 would actually allow running at 36 volts and charging at 36 volts except when wanting to charge from the 12 volt charging source(s). It would not require an additional 12 volt battery.

However if the 36 volt motor load is rated at more than 100 amps it would not be suitable.