Yandina Trollbridge2400

[john61ct]

I'm pinging Ann-Marie directly to answer a couple Q's, but of course anyone is welcome to join in the discussion.

Re your bigger 24V Trollbridge: can the unit service a generic 24V load, e.g. a DC converter or DC-AC inverter, or is it somehow limited to only certain types of devices?

Also, does it self-protect against overload, if the load is demanding too much current? Or would one need to rely on external fusing?

[john61ct]

From the manual http://www.yandina.com/acrobats/Trollbridge2400.pdf

I plan to set up schematic B, lead reserve/starter "1", plus two equal LiFePO4 "split banks" 2a & 2b.

Note the extreme low resistance of LFP, and very robust connections, large gauge wires.


>Battery 2 is used only for the 24V load

My understanding is, that is only true while TB is active, in 24V mode.

Rest of the time 2a & 2b is parallel functioning as a single bank.

Is that correct?

[john61ct]

> The Trollbridge2400 is suitable for installations with alternators up to 200 amps and 24 volt equipment up to 16 horse power or 500 amps.

If it can handle Loads over 400A, why not a 300A charge source? I can detune with the MC-614 "belt saver" mode, so just asking.

[Andina Marie]

Originally Posted by john61ct

I'm pinging Ann-Marie directly to answer a couple Q's, but of course anyone is welcome to join in the discussion.

Re your bigger 24V Trollbridge: can the unit service a generic 24V load, e.g. a DC converter or DC-AC inverter, or is it somehow limited to only certain types of devices?

Also, does it self-protect against overload, if the load is demanding too much current? Or would one need to rely on external fusing?

The Trollbridges charge 24 and 36 volt batteries by switching them from series to parallel so they can be charged at high current at 12 volts from the alternator without using expensive electronics. 24 volt Trollbridges sit in parallel when idle so both batteries are in parallel and can be used for 12 volt loads. As soon as you draw some current they switch in series to give 24 volts.

The Trollbridge36 is normally in series when idle and only switches to parallel when a charging source is applied. This can be overridden if you need 36 volts at the same time charging is available.

Yes a Trollbridge is somewhat limited to the type of load. The load needs to be intermittent because if it is in series mode only one of the batteries will receive a charge. It works very well with trolling motors since they are rarely running (although they can be) when the main engine is running and charging. An inverter load, however, would have to be manually turned off while charging so the charge reached both batteries.

Although there are inverters that shut down automatically when there is no load, I suspect they draw enough idle current that the Trollbridge24 would stay in series mode. It would NOT be suitable for an inverter with a built-in charging feature.

There is no self-protection in the Trollbridge24, it needs a series breaker or fuse. It can supply 85 amps continuous and about 200 amps shock load so a 100 amp fuse would be about maximum. Typically they use a 60 amp breaker for trolling motors. The Trollbridge2400 comes with a built in 250 amp fuse and a 500 amp fuse is available if needed.

[Andina Marie]

Originally Posted by john61ct

From the manual http://www.yandina.com/acrobats/Trollbridge2400.pdf

I plan to set up schematic B, lead reserve/starter "1", plus two equal LiFePO4 "split banks" 2a & 2b.

Note the extreme low resistance of LFP, and very robust connections, large gauge wires.


>Battery 2 is used only for the 24V load

My understanding is, that is only true while TB is active, in 24V mode.

Rest of the time 2a & 2b is parallel functioning as a single bank.

Is that correct?

Schematic B applies only to the Trollbridge24. The Trollbridge2400 has the Combiner function built in so the starting battery connects directly to it as shown in the link you included.

Correct, when not running a 24 volt load the batteries are in parallel so a 12 volt load can be connected to Battery 1 to use both batteries.

When running a 24 volt load, 12 volt charging current or load current only goes to/comes from battery 1. Although this will unbalance the relative charge levels of the 2 batteries they are put in parallel automatically when the 24 volt load turns off allowing high battery to battery current to equalize them rapidly to the same voltage and charge level.

Obviously nothing should be ever be connected to Battery 2 other than the Trollbridge2400 since its negative terminal is not always at zero volts.

[Andina Marie]

Originally Posted by john61ct

> The Trollbridge2400 is suitable for installations with alternators up to 200 amps and 24 volt equipment up to 16 horse power or 500 amps.

If it can handle Loads over 400A, why not a 300A charge source? I can detune with the MC-614 "belt saver" mode, so just asking.

The high cost 500 amp relay you see on the Trollbridge2400 is used to put the batteries in series, it replaces the traditional jumper between a pair of 12 volt batteries.

Using 300 amp relays, to connect Battery 2 in parallel for charging would more than double the cost. Although load currents when starting a 24 volt motor are expected to be as high as 1200 amps and up to 500 amps continuously it is low duty cycle and running loads at 24 volts are duration limited directly by battery capacity. Charging, on the other hand, takes much longer at lower current and can use more economical relays. Although heavy gauge cables can be used for the 24 volt load, we suggest no heavier than 6 gauge for the charging circuit.

A typical application running a winch or bow thruster has low duty cycle with plenty of time to recharge allowing the use of a 6 or 8 gauge cable running the length of the boat at much lower cost than the high current cables.

[john61ct]

Originally Posted by Andina Marie

Yes a Trollbridge is somewhat limited to the type of load. The load needs to be intermittent because if it is in series mode only one of the batteries will receive a charge.

No problem, all my 24V loads would only be operating for short times when engine / gennie are running.

Solar charging*will sometimes cause a temporary "unbalance" between 2a & 2b, but at*relatively low charge currents

If large-current inrush there when returning to 12V seems like it would be an issue (given very high CAR low resistance of LFP), I could insert a high-amp current-limiting combiner like Sterling's CVSR to safely slow down the "re-balancing".

[john61ct]

Originally Posted by Andina Marie

The Trollbridge2400 has the Combiner function built in.
...
When running a 24 volt load, 12 volt charging current or load current only goes to/comes from battery 1. Although this will unbalance the relative charge levels of the 2 batteries they are put in parallel automatically when the 24 volt load turns off allowing high battery to battery current to equalize them rapidly to the same voltage and charge level.

Wow OK, combiner included makes for (even) better value! The biggest (280A rated) Sterling is not cheap. . .

What sort of inrush amperage do you think the TB2400 can handle?

I'm currently looking at 180AH on each side. Obviously a slight SoC difference is no issue, I'm just wondering if the imbalance goes too far the initial surge may be very hot. Would a large fuse between the two be a good idea for at least testing purposes?

Originally Posted by Andina Marie

Schematic B applies only to the Trollbridge24

so the starting battery connects directly to it as shown in the link

Do you mean there is only one configuration option?

I plan to be able to crank from either Reserve (#1 Lead bank) or House (2a/2b "split" LFP) bank.

So take "starter" terminology out of the picture, both sides of the TB2400 will be the two LFP House "halves", and my Lead Reserve should not be in the TB setup at all, back to separate ACR or DCDC for that?

[john61ct]

Originally Posted by Andina Marie

The high cost 500 amp relay you see on the Trollbridge2400 is used to put the batteries in series, it replaces the traditional jumper between a pair of 12 volt batteries.

Using 300 amp relays, to connect Battery 2 in parallel for charging would more than double the cost.
...
Charging, on the other hand, takes much longer at lower current and can use more economical relays. Although heavy gauge cables can be used for the 24 volt load, we suggest no heavier than 6 gauge for the charging circuit.

OK, so bottom line I should derate my Leece-Neville 320A alt using Balmar's "belt manager", since the large LFP bank's very high CAR will be trying to pull its full output.

So is 200A really the limit?

That does mean longer engine runtimes for charging-only runs, so if you can come up with a workaround that would, be appreciated.

Maybe a switching scheme using Blue Seas HD bank switches? For example, their Dual Circuit version enables switching two high-amp bank circuits ON/OFF with one throw.

I'm thinking maybe bypass the TB connections completely to enable full-bore 300+A Alt charging?

Obviously just spitballin', let me know if it's crazy talk. . .

[Andina Marie]

Originally Posted by john61ct

No problem, all my 24V loads would only be operating for short times when engine / gennie are running.

Solar charging*will sometimes cause a temporary "unbalance" between 2a & 2b, but at*relatively low charge currents

If large-current inrush there when returning to 12V seems like it would be an issue (given very high CAR low resistance of LFP), I could insert a high-amp current-limiting combiner like Sterling's CVSR to safely slow down the "re-balancing".

There are current limiting features already built into the Trollbridge2400. No additional equipment should be needed.

[john61ct]

OK, I just was concerned about the very low resistance of LiFePO4, and perhaps going to a larger bank 2 down the road.

Any suggestions (from anyone) on a relatively low cost tool to measure large-amp in-rushes resulting from joining two banks?

I have a 1000A shunt for my BM just came in, but am not sure how to mount the d^mn thing, huge block of brass no insulation.

And I don't want to risk frying it or my Bogart Trimetric, maybe better just to get a basic clamping ammeter that can measure those sort of current levels?

[Andina Marie]

Although the Trollbridge2400 is limited to a 200 amp charging source there are numerous reasons you don't have to provide any fancy protection.

1. The charging source is typically rated for optimum RPM at low temperature charging very low batteries on a test bench - manufacturers compete to provide better looking numbers - so your charging source doesn't really ever put out "rated" current.

2. The charging source is usually also charging the starting battery so that current can be deducted from its output.

3. We recommend limiting charging cable to 6 gauge and since the 24 volt equipment is typically quite some distance from the charging source the resistance of the cable will provide significant current limit.

4. There is already a current limiting feature built into the TB2400

5. The charging doesn't start until the voltage gets above 13 volts so by then the alternator has had time to heat up and you can't put rated current into a battery that is already up to 13 volts, alternator rating is done on a 10 volt battery.

6. If the load is severe enough to overload the TB2400 the voltage will drop below 13 volts and cause the TB2400 to cycle off and on allowing cooling during the off time.

Please don't make this unnecessarily complicated, the TB2400 is very rugged, just install it per the diagram and see how it works. If it is overloaded you won't destroy it so just monitor temperatures and only start to worry if they get too high.

The KISS principle applies, don't add unnecessary failure modes.

The starting battery does not have to be an independent battery, you can set up a 2 battery system if you want to limit size and weight, where the first battery is also the starting battery.

[Andina Marie]

Originally Posted by john61ct

OK, I just was concerned about the very low resistance of LiFePO4, and perhaps going to a larger bank 2 down the road.

Any suggestions (from anyone) on a relatively low cost tool to measure large-amp in-rushes resulting from joining two banks?

I have a 1000A shunt for my BM just came in, but am not sure how to mount the d^mn thing, huge block of brass no insulation.

And I don't want to risk frying it or my Bogart Trimetric, maybe better just to get a basic clamping ammeter that can measure those sort of current levels?

Don't "sweat" it. Exceeding the limit will not do any damage. The current limit features built in will prevent relay contact welding so at overloads up to 1,000 amps the only downside is momentary heating. But battery to battery inrush currents don't last long enough to cause any significant heating, the voltages equalize in seconds.

[john61ct]

Very good info and fair points, I do tend to be maybe a bit too cautious to compensate for my noobish ignorance.

Originally Posted by Andina Marie

1. The charging source is typically rated for optimum RPM at low temperature charging very low batteries on a test bench - manufacturers compete to provide better looking numbers - so your charging source doesn't really ever put out "rated" current.

2. The charging source is usually also charging the starting battery so that current can be deducted from its output.

Note the custom pulley ratio is set so I get 75% of the 320A rating at pretty low RPM, basically high idle is well above 200A, came off a firetruck/EMS unit designed to put out full rating all day if need be. But as I said with the MC-614, de-rating is easy, I can always start low and measure temps while ramping up.

And since the #1 lead bank (reserve not starter) has very different voltage setpoint requirements, I'll use a DCDC charger rather than a voltage-following combiner between that and the #2 LiFePO4 House bank.

Originally Posted by Andina Marie

3. We recommend limiting charging cable to 6 gauge and since the 24 volt equipment is typically quite some distance from the charging source the resistance of the cable will provide significant current limit.

Wow, now I'm very confused. My understanding is that that small a cable will be a real fire risk carrying even a 200AH current over any distance. And although I will have a separate voltage-sense wire going direct to the #2a House bank positive, I thought I should be minimizing voltage drop?

Originally Posted by Andina Marie

5. The charging doesn't start until the voltage gets above 13 volts so by then the alternator has had time to heat up and you can't put rated current into a battery that is already up to 13 volts, alternator rating is done on a 10 volt battery.

I'm pretty sure you're talking about lead-acid chemistries only?

Resting voltage for LiFePO4 is well above 13V, even under a fair load, right down to 10% SoC.

And my 360AH bank will happily accept over 2C charge rate, so 700+A, it'll continue to pull 200AH right up to 90%, there isn't any resistance until the last few minutes.

Here's an example LFP charge chart

http://d2ojs0xoob7fg0.cloudfront.net...fastcharge.jpg

Originally Posted by Andina Marie

6. If the load is severe enough to overload the TB2400 the voltage will drop below 13 volts and cause the TB2400 to cycle off and on allowing cooling during the off time.

Do you mean a high temperature protective feature will cause the built-in combiner to open?

Because based on the above, I can't see how voltage will drop. And when the combiner isolates #2b (batt 2) that will just exacerbate the SoC difference as #2a (batt 1) rapidly finishes charging to full.

Originally Posted by Andina Marie

The starting battery does not have to be an independent battery, you can set up a 2 battery system if you want to limit size and weight, where the first battery is also the starting battery.

The Reserve (#1) bank being lead-acid, can't be paralleled with the #2 LFP House batteries. Cranking can be switched to either, and I will have a "belt & suspenders" powerpack charged to ensure an emergency won't require self-jumping.

LFP is already under half the weight and space per AH of lead, so no issue there.

[john61ct]

Originally Posted by Andina Marie

Don't "sweat" it. Exceeding the limit will not do any damage. The current limit features built in will prevent relay contact welding so at overloads up to 1,000 amps the only downside is momentary heating. But battery to battery inrush currents don't last long enough to cause any significant heating, the voltages equalize in seconds.

OK, I though that was just because of the higher resistance inherent in lead-acid.

I'll just start out with relatively equal sides of the split bank and limit charge amps to <200A.

Then test incrementally higher rates (greater differences between #2a and #2b, with my infrared temp gun at the ready 8-)

If all that works out OK, try upping from 200A on the Alt, long as things don't get too hot, all is well?

That #6 gauge wire still doesn't seem right though, looking at 30+ feet RT from the alt to the banks, I was planning on at least 2/0, really 4/0 to keep voltage drop below 3%.