Low Budget Lifepo4 Experiences anyone?

[Franziska]

Interesting thoughts here on the terminals and bus bars.
The logic to minimize the number of materials seems plausible to me.

Now here are two more thoughts on this.

Most of these blue batteries come with smallish busbar straps made from tinned copper.
I can see the thought of replacing those by more substantial busbars.
As the actual poles are from aluminum I can follow the use of aluminum for this too.

The main point of contact are the about 1" pole surfaces and not the studs as far as I understand this.

The studs which get delivered with the batteries are stainless I guess, and most of us use studs with inbus stainless heads instead.
We all know that they need to be screwed in lightly as to not damage the aluminum threads in the poles.

Here is my question, as we screw in stainless stud bolts and the main connector is the top surface of the poles, how about using a drop of Tefgel on the studs to separate the stud bolt from the actual pole when screwing it in.
Alternatively a drop of medium or low Loctite.

Than place the busbar on top and put another drop of Tefgel under the washer and nut which tighten the busbar down onto the actual pole.
Obviously avoid any Tefgel between busbar and pole!!!

That way corrosion should be the minimum. If you want spray the complete assembly with conformal coating as a last step.

Thoughts on this?

[Scubaseas]

Originally Posted by Franziska

Interesting thoughts here on the terminals and bus bars.
The logic to minimize the number of materials seems plausible to me.

Now here are two more thoughts on this.

Most of these blue batteries come with smallish busbar straps made from tinned copper.
I can see the thought of replacing those by more substantial busbars.
As the actual poles are from aluminum I can follow the use of aluminum for this too.

The main point of contact are the about 1" pole surfaces and not the studs as far as I understand this.

The studs which get delivered with the batteries are stainless I guess, and most of us use studs with inbus stainless heads instead.
We all know that they need to be screwed in lightly as to not damage the aluminum threads in the poles.

Here is my question, as we screw in stainless stud bolts and the main connector is the top surface of the poles, how about using a drop of Tefgel on the studs to separate the stud bolt from the actual pole when screwing it in.
Alternatively a drop of medium or low Loctite.

Than place the busbar on top and put another drop of Tefgel under the washer and nut which tighten the busbar down onto the actual pole.
Obviously avoid any Tefgel between busbar and pole!!!

That way corrosion should be the minimum. If you want spray the complete assembly with conformal coating as a last step.

Thoughts on this?

If you want to electrically isolate the ss stud tefgel would work fine. If you want a conductive anti seize use copper anti sieze.

If you are worried about corrosion the tefgel route should be fine as long as you have good contact between bar and post of the cell.

If the connections are clean and dry I doubt electrolysis will be that much of an issue.

From CRC:

Copper Grade Anti-Seize a combination of copper (10%) flake, graphite and other extreme pressure additives. Copper Grade Anti-Seize is copper in color and is not recommended for applications where copper is prohibited. Like Silver Grade, Copper Anti-Seize protects metal parts against rust, corrosion, galling and seizure at temperatures up to 1800° F. It is electrically conductive and does not compromise the integrity of soft metals.

[Franziska]

Hmm. That's exactly the opposite of what I suggested.

The idea is to use only two materials instead of 4 and separating the material which is primarily only a mechanical fastener (the stainless studs and washers) from the other material which is the main conductor (the aluminum poles and busbars).

That leaves very limited chances for corrosion at the battery studs.

The studs cross-section is fairly small when compared to the actual busbar to pole contact areas.

Originally Posted by Scubaseas

From CRC:

Copper Grade Anti-Seize a combination of copper (10%) flake, graphite and other extreme pressure additives. Copper Grade Anti-Seize is copper in color and is not recommended for applications where copper is prohibited. Like Silver Grade, Copper Anti-Seize protects metal parts against rust, corrosion, galling and seizure at temperatures up to 1800° F. It is electrically conductive and does not compromise the integrity of soft metals.

[Scubaseas]

Originally Posted by Franziska

Hmm. That's exactly the opposite of what I suggested.

The idea is to use only two materials instead of 4 and separating the material which is primarily only a mechanical fastener (the stainless studs and washers) from the other material which is the main conductor (the aluminum poles and busbars).

That leaves very limited chances for corrosion at the battery studs.

The studs cross-section is fairly small when compared to the actual busbar to pole contact areas.

I don't disagree with your idea of using tefgel. Or Blue 242 Loctite.

Or just use all aluminum. Studs, nuts, washers and bars all the same alloy as the post of the cell if you're worried about it. I don't think corrosion for dissimilar metals on the cells is an actual problem. It's not being exposed to any electrolytes like if it were a stainless screw in an aluminum mast which is exposed to seawater.

[newhaul]

Originally Posted by Scubaseas

I don't disagree with your idea of using tefgel. Or Blue 242 Loctite.

Or just use all aluminum. Studs, nuts, washers and bars all the same alloy as the post of the cell if you're worried about it. I don't think corrosion for dissimilar metals on the cells is an actual problem. It's not being exposed to any electrolytes like if it were a stainless screw in an aluminum mast which is exposed to seawater.

Funny part is ( at least in my cells ) the bolts screw into a stainless nut on my cells so using tined copper straps and ss bolts is not an issue but adding aluminum into the mix would increase the likelihood of corrosion at that exact point where you really don't want any .

[Franziska]

6mm aluminum studs don't sound very reliable to me, so they will be stainless, but yes, probably with blue loctite.
That would perhaps even allow screwing the studs in by hand and eliminate the need to tighten the studs themselves with a torque wrench.

The nuts will then be tightened while preventing the studs from rotation by the inbus and the Loctite.

Originally Posted by Scubaseas

I don't disagree with your idea of using tefgel. Or Blue 242 Loctite.

Or just use all aluminum. Studs, nuts, washers and bars all the same alloy as the post of the cell if you're worried about it. I don't think corrosion for dissimilar metals on the cells is an actual problem. It's not being exposed to any electrolytes like if it were a stainless screw in an aluminum mast which is exposed to seawater.

[Franziska]

Thanks, will decide once mine have arrived...

Originally Posted by newhaul

Funny part is ( at least in my cells ) the bolts screw into a stainless nut on my cells so using tined copper straps and ss bolts is not an issue but adding aluminum into the mix would increase the likelihood of corrosion at that exact point where you really don't want any .

[hzcruiser]

Originally Posted by CaptainRivet

[...]
1st and last cell of each 4 cell series pack will see much higher loads, age faster and differ much more. Balancer cannot work properly like this too as it lS not recognizing rhe whole battery, just the one 4 series pack. 3rd more
[...]

Do you have some links to support such statements that the first and last cell are seeing higher loads and all those other alleged side effects?

[Franziska]

Another question (all equipment is purchased and fixed, so no need to discuss alternative equipment or its benefits!!!):

We have 840Ah of 12V LiFePo4 batteries.
We have renewable energy (wind & solar) charging through several controllers on a + and- busbar.
Absolute maximum renewable charging 155A@12V at very best.
A 400A BMS capable of a charging current of 200A at most.

Shore/genset charging of 35A (which might get upgraded later).

QUESTION:
Can we attach the shore/genset charger of 35A to the charging busbar, or do we have to keep the two charging methods separate by adding a high Amp switch.

If we would add it right now, we stay below the max of 200A charging which the BMS can handle. 155+35=190A. It is unlikely that the renewable ever really achieve 155A output.

If we upgrade the shore/genset charging later we would install a switch or upgrade the BMS.

So, do we need a switch?

[newhaul]

Originally Posted by Franziska

Another question (all equipment is purchased and fixed, so no need to discuss alternative equipment or its benefits!!!):

We have 840Ah of 12V LiFePo4 batteries.
We have renewable energy (wind & solar) charging through several controllers on a + and- busbar.
Absolute maximum renewable charging 155A@12V at very best.
A 400A BMS capable of a charging current of 200A at most.

Shore/genset charging of 35A (which might get upgraded later).

QUESTION:
Can we attach the shore/genset charger of 35A to the charging busbar, or do we have to keep the two charging methods separate by adding a high Amp switch.

If we would add it right now, we stay below the max of 200A charging which the BMS can handle. 155+35=190A. It is unlikely that the renewable ever really achieve 155A output.

If we upgrade the shore/genset charging later we would install a switch or upgrade the BMS.

So, do we need a switch?

Short answer yes you can just hook it up to the busbar no problem .

No you don't need a switch but the charger should be running through your shore power breaker panel so there is the switch if ever needed.

[Franziska]

Ok, one more issue we need a solution for.


Following information from here and elsewhere we decided to get the 400A "non-smart" BMS from Daly.
We have it already delivered & received.
I like the fact that it is less complicated then the smart version and, some suggested its better tried and tested than their smart version.

Now, it turns out, that the Rutland 1200 Windgen controller needs not only be reprogrammed, but now they also said we need a zero volt type signal from the BMS to switch that controller on or off in a coordinated manner.

Specifically Marelec writes:

"...If the BMS operates and disconnects all of the loads from the battery we don't want it to simply disconnect the wind turbine controller as well. This could potentially damage the controller. Instead we need the controller to shut down the wind turbine in a controlled manner. Hopefully your BMS is equipped with a signal output in the form of a volt free contact which you can use that to send a signal to the 1200 controller. This signal will tell the controller to soft stop the wind turbine before the controller is disconnected by the BMS.
You connect the output of the volt free contact to the terminals on the remote temperature sensor. When the BMS closes the contact both the wind turbine and the solar panel will be shut down. The wind generator will go through its soft stall routine first. This mode will remain for the duration of the contact closure. When the BMS opens the external contacts the controller and charge sources will revert to the state they were in before the shutdown..."

Bummer, the non smart BMS does not offer that.

Marelec suggest a work around via our small lead acid outboard starter battery:

"...If your BMS does not have a signal output there is another work around. The controller takes it's power from the Battery 1 output so it is only a problem if the BMS disconnects the controller if the lithium batteries are connected to battery bank 1.

So you could connect the lithium batteries via the BMS to battery bank 2 on the controller. You would then need to connect a lead acid battery or similar (for example a leisure battery) to battery bank 1. If this is on a boat for example you might keep a lead acid battery for the starter battery and use the lithium batteries for your domestic supply.

With regards to your other question I recommend you connect the 40Ah lead acid batteries to Batt1 on the controller and the Lithium batteries to Batt2. The controller will naturally deliver the most power to the batteries with the lowest voltage until the voltage of both battery banks is the same so the lead acid batteries will not overcharge..."

Does that not mean the wind controller shuts the wind off once the lower voltage of the lead acid batteries has been reached? Charging current for LiFePo4 is higher than for FLA, no?

The issue is that we want to primarely charge the LiFePo4 batteries from it.
Ideally I wanted to have the lead acid battery completly of the system, it gets charged by the outboards anyway.

So, I wonder if there is not a small electronic component / black box we could put in between the wind controller and LiFePo4 batteries which would supply the required zero voltage signal even with our "dumb-non smart BMS".
I'd really prefer not to need to change the new BMS for another one and spending several 100€ again.
Spending say 50€ for an extra black box/sensor would be absolutely ok for us.

Maybe one of the clever electric guys here (newhaul?) can point me to a solution / black box to add?

Thanks so much.

[newhaul]

Originally Posted by Franziska

Ok, one more issue we need a solution for.


Following information from here and elsewhere we decided to get the 400A "non-smart" BMS from Daly.
We have it already delivered & received.
I like the fact that it is less complicated then the smart version and, some suggested its better tried and tested than their smart version.

Now, it turns out, that the Rutland 1200 Windgen controller needs not only be reprogrammed, but now they also said we need a zero volt type signal from the BMS to switch that controller on or off in a coordinated manner.

Specifically Marelec writes:

"...If the BMS operates and disconnects all of the loads from the battery we don't want it to simply disconnect the wind turbine controller as well. This could potentially damage the controller. Instead we need the controller to shut down the wind turbine in a controlled manner. Hopefully your BMS is equipped with a signal output in the form of a volt free contact which you can use that to send a signal to the 1200 controller. This signal will tell the controller to soft stop the wind turbine before the controller is disconnected by the BMS.
You connect the output of the volt free contact to the terminals on the remote temperature sensor. When the BMS closes the contact both the wind turbine and the solar panel will be shut down. The wind generator will go through its soft stall routine first. This mode will remain for the duration of the contact closure. When the BMS opens the external contacts the controller and charge sources will revert to the state they were in before the shutdown..."

Bummer, the non smart BMS does not offer that.

Marelec suggest a work around via our small lead acid outboard starter battery:

"...If your BMS does not have a signal output there is another work around. The controller takes it's power from the Battery 1 output so it is only a problem if the BMS disconnects the controller if the lithium batteries are connected to battery bank 1.

So you could connect the lithium batteries via the BMS to battery bank 2 on the controller. You would then need to connect a lead acid battery or similar (for example a leisure battery) to battery bank 1. If this is on a boat for example you might keep a lead acid battery for the starter battery and use the lithium batteries for your domestic supply.

With regards to your other question I recommend you connect the 40Ah lead acid batteries to Batt1 on the controller and the Lithium batteries to Batt2. The controller will naturally deliver the most power to the batteries with the lowest voltage until the voltage of both battery banks is the same so the lead acid batteries will not overcharge..."

Does that not mean the wind controller shuts the wind off once the lower voltage of the lead acid batteries has been reached? Charging current for LiFePo4 is higher than for FLA, no?

The issue is that we want to primarely charge the LiFePo4 batteries from it.
Ideally I wanted to have the lead acid battery completly of the system, it gets charged by the outboards anyway.

So, I wonder if there is not a small electronic component / black box we could put in between the wind controller and LiFePo4 batteries which would supply the required zero voltage signal even with our "dumb-non smart BMS".
I'd really prefer not to need to change the new BMS for another one and spending several 100€ again.
Spending say 50€ for an extra black box/sensor would be absolutely ok for us.

Maybe one of the clever electric guys here (newhaul?) can point me to a solution / black box to add?

Thanks so much.

Just add the little sacrificial fla battery to the system as they recomend it is the cheapest way to protect your system. We do that all the time with our inboards to protect the alternator from damage due to an HVD situation . Which if your charge controllers are propperly setup will not ever happen . You dont want to charge to 100% . Lfp actually doesnt like to be full for any period of time. Hence my chargers are set to 13.8vdc . Or 92% approx charge .

[Franziska]

Thanks, so that confirms what they suggested is the best way of doing this. Thank you!!

Batt 2 from the wind controller will then go to the Lifepo4 charging busbar (wind, solar and optionally shore / genset.)
Even when all of these are combined they do not get over the max 400A capacity of our BMS.

Originally Posted by newhaul

Just add the little sacrificial fla battery to the system as they recomend it is the cheapest way to protect your system. We do that all the time with our inboards to protect the alternator from damage due to an HVD situation . Which if your charge controllers are propperly setup will not ever happen . You dont want to charge to 100% . Lfp actually doesnt like to be full for any period of time. Hence my chargers are set to 13.8vdc . Or 92% approx charge .

[rgleason]

Franziska great thread with good questions and advice. I have followed but not read it all 384 posts.
Wholybee had a diagram here
https://www.cruisersforum.com/forums....php?p=3402385

Is has your system as built changed from that much? Some pictures and description of your system and equipment as it is ending up would be very helpful when you get a chance.

[CarlF]

Too many posts to see if it's already be mentioned but here are two good ways to protect the alternators against a BMS shutoff:

- A simple relay that parallels the Lithium house and lead acid start banks whenever the ignition switch is on - obviously this only works if the lead acid bank is happy at the lithium charge voltages (which is usually true of both AGM and flooded start batteries that are usually at almost 100% charge) https://shop.marinehowto.com/product...ction-solenoid

- The Sterling alternator protection device that will dissipate any surge
https://shop.marinehowto.com/product...tection-device

There's no reason not to use both.