After fitting a lithium battery and a B2B, what final checks do I do before fitting fuses...

[growly_bear]

Hello All

I've cracking on with fitting a Renogy B2B (with solar), busbars, 2000W inverter, shunt and lithium battery. I'll check all connections , but before I fit the fuses what electrical tests can I do to make sure that all is well?

Once it's powered up, I know that I'll have to set (or check the lithium profile in the B2B) and look for hot spots.
As I'm not anticipating using EHU much do I set the EBL to the gel setting?
Is it a good idea to check the tightness of the electrical connections once in a while?

If there is anything else please tell me.

Does anyone else get nervous before the big switch on, or is it just me!

 

[LostInSpace]

First, check that the split charge relay is disabled or the appropriate fuse removed and the connection labelled.

Set the EBL to GEL,

Set the B2B to lithium before powering up.

I would fit a lowish value fuse for the inverter to check it powers up giving 240 volts (no load) and if all is well fit the correct value fuse.

Fit the fuses one at a time and check each circuit before proceding.

 

[growly_bear]

LostInSpace Thank you.

First, check that the split charge relay is disabled or the appropriate fuse removed and the connection labelled.

Good point. I've used the starter battery +ve as the feed for the B2B, so it won't catch out whoever owns it in the future.

Set the B2B to lithium before powering up.

mmm can't do that as there is no mechanical DIP switches or the like. It's software driven. But, I'm thinking of using the LA battery to do basic tests (not running up the inverter though), so I can then set it to lithium.

I would fit a lowish value fuse for the inverter to check it powers up giving 240 volts (no load) and if all is well fit the correct value fuse.

Is that in case the inverter is faulty?

Fit the fuses one at a time and check each circuit before proceding.

Good idea.

I was thinking of doing a check of +ve to -ve busbars to test for a short.

Thanks for your help

 

[Outdoors Dad]

Last year I fitted a Renogy b2b I used a LA first to check everything worked ok. I think the Renogy B2B automatically detects the battery type???

 

[ChrisL]

Set the EBL to GEL

Can anyone tell me why? The absorption voltages are the same but the gel setting absorption time is 8 hours, lithium batteries need very little absorption time maybe an hour or so.

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[eddie]

If there is anything else please tell me.

Check the “Use by date” and operation of your fire extinguisher?

 

[growly_bear]

Check the “Use by date” and operation of your fire extinguisher?

Fire extinguisher, goggles and insulated gloves at the ready (truly i hope not though)!

 

[growly_bear]

Last year I fitted a Renogy b2b I used a LA first to check everything worked ok. I think the Renogy B2B automatically detects the battery type???

There's no mention of that in the manual..

 

[Lenny HB]

Can anyone tell me why? The absorption voltages are the same but the gel setting absorption time is 8 hours, lithium batteries need very little absorption time maybe an hour or so.

A good charger with lead batteries will adjust the absorbtion time depending on the state of discharge when the batteries put on charge.
EBL`s older one had a fixed 8 hours newer ones 16 hours for Gel.

That is why it is not a good idea to a lead charger like an EBL if you use EHU on more than the odd occasion.

The latest CBE chargers have a automatic exitation phase so not suitable for Lithium.

 

[jumar]

I was advised to use a resistor on the positive side whilst powering up large capacity Invertor...this I did....lots of YouTubes showing this

I also was unsure on powering up the system after my conversion...but all went well.

Due to vibration I check everything frequently for tightness...

I checked and checked again all cable runs...sometimes just looking in my battery seat box prior to powering up...this was the first time for me...being guided all the way by Knowledgeable Funsters...Good luck...

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[growly_bear]

I was advised to use a resistor on the positive side whilst powering up large capacity Invertor...this I did....lots of YouTubes showing this

I also was unsure on powering up the system after my conversion...but all went well.

Due to vibration I check everything frequently for tightness...

I checked and checked again all cable runs...sometimes just looking in my battery seat box prior to powering up...this was the first time for me...being guided all the way by Knowledgeable Funsters...Good luck...

Thank you. I was unaware of the invertor power up. Does it need this each time it's switched on?

 

[Lenny HB]

Thank you. I was unaware of the invertor power up. Does it need this each time it's switched on?

If is advisable with inverters over 2000 watts.
I have a 3000va inverter I fitted a 4 way isolator switch so I can connect a 10 ohm resistor in series before switching the power direct.

 

[growly_bear]

If is advisable with inverters over 2000 watts.
I have a 3000va inverter I fitted a 4 way isolator switch so I can connect a 10 ohm resistor in series before switching the power direct.

Thanks Lenny HB. Is there a formula to calculate the resistance and wattage?

 

[Raul]

Thanks Lenny HB. Is there a formula to calculate the resistance and wattage?

Yes Ohms law V/IxR
A 10 ohm resistor will give 15.6w at 12.5v
Or take a builders pencil, cut in half and sharpen both ends. Now you have a nice graphite resistor, use it in line for 5-10 seconds to pre charge the caps, and within one sec make the connection.

If inverter is switched of by the low power switch, and the 12v side is permanently connected, then the caps will always stay charged. If you break the 12v supply via an isolator switch, then you need a switch with pre charge resistor for each time power up; as Lenny explained.

 

[growly_bear]

Yes Ohms law V/IxR
A 10 ohm resistor will give 15.6w at 12.5v
Or take a builders pencil, cut in half and sharpen both ends. Now you have a nice graphite resistor, use it in line for 5-10 seconds to pre charge the caps, and within one sec make the connection.

If inverter is switched of by the low power switch, and the 12v side is permanently connected, then the caps will always stay charged. If you break the 12v supply via an isolator switch, then you need a switch with pre charge resistor for each time power up; as Lenny explained.

Thanks. If no idea what current to charge them at as my invertor is only 2000w. Now thinking it through w = vxv/r which is what you calculated above.

Good to know I'll not need to do this every time

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[Raul]

This capacitors pre charge, is necessary on any items with large caps IE: inverters, big charge controllers etc. when you make a connection to a lithium battery. Reason is the bms short circuit protection, most bmses trip on inrush as it senses a large load similar to short circuit. If you change the setting to hold the inrush for caps, you render the bms short circuit protection useless. Hence the need for resistor precharge. Or remember to re set the bms to original value after the connection is made.

 

[growly_bear]

This capacitors pre charge, is necessary on any items with large caps IE: inverters, big charge controllers etc. when you make a connection to a lithium battery. Reason is the bms short circuit protection, most bmses trip on inrush as it senses a large load similar to short circuit. If you change the setting to hold the inrush for caps, you render the bms short circuit protection useless. Hence the need for resistor precharge. Or remember to re set the bms to original value after the connection is made.

Got it. Thanks

I'm snapping my pencils and reading 20 Ohms. Is that too high and shall I halve again!

 

[Speve]

For my Victron 2000 a multiples I had a 50w 7 Ohms resistor that worked fine

 

[LithiumConvert]

Is that in case the inverter is faulty

Or the wiring.

 

[growly_bear]

Or the wiring.

of course. Sometimes the most obvious isn't thought of!

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[Raul]

Got it. Thanks

I'm snapping my pencils and reading 20 Ohms. Is that too high and shall I halve again!

No, thats fine, you will be charging with 8w approximately 4-5 seconds, then make the connection. It's my preferred method, quick and to the point.

 

[LostInSpace]

I was unaware of the invertor power up. Does it need this each time it's switched on?

Probably not when it is just switched on having already been on - and then switched off.

It is usually the act of connecting which powers up the capacitors.

 

[Pausim]

Set the EBL to GEL,

I have decided to set my EBL to Säure (acid). The main charge voltage seems to be the same 14.3V as Gel but the absorption time is much shorter than the extended 16 hours. Does anyone know why Gel is usually suggested? I did the same on my CBE DS to avoid the long hours of absorption.