Cheap LiFePO4 BMS?

[Dre]

19 minutes ago, nicknorman said:

Looks great! Could you remind me where they are from, price etc (if you don’t mind). Was the BMS a separate thing?

So it looks like prices have gone up... I only paid 600 gbp (no other costs and including postage tracked with UPS) for 8x 3.2v 150Ah. I would think that after the covid stall there's a lot of demand plus they'll be trying to recover some losses. 

I ordered directly with their website (after a couple of emails with the sales guy in China) because aliexpress wasn't working for me. Ordered on 3rd of February so China was already shutting down but still only took 3 months, two of which they were stuck in Germany! 

As I said the packaging and the voltages seem to indicate the cells are new or at least as advertised. Also being able to email them and get a reply during the height of a pandemic is pretty exceptional on their part and to be able to actually have them delivered puts most European /uk sellers to shame.

[Richard10002]

1 hour ago, Dre said:

So it looks like prices have gone up... I only paid 600 gbp (no other costs and including postage tracked with UPS) for 8x 3.2v 150Ah. I would think that after the covid stall there's a lot of demand plus they'll be trying to recover some losses. 

 

If the price you see is the delivered price, it's still "only" £775 for 300Ah, so not much more per 100Ah than my second hand Valences.

[peterboat]

4 minutes ago, Richard10002 said:

If the price you see is the delivered price, it's still "only" £775 for 300Ah, so not much more per 100Ah than my second hand Valences.

Yes but you have a Bms and possibly the best batteries on the market 

[Dre]

10 hours ago, peterboat said:

Yes but you have a Bms and possibly the best batteries on the market 

I agree! I was thinking of getting those Valences on ebay but I wanted to learn a bit more and also be able to get more matching ones later on. Valences at that price might not always be available and I'd end up mixing very different types of batteries. Also these perfectly fit in the cavity behind the 12v distribition panels where all the cables I need are. I think I might actually get away with just reterminating the existing cables with no new cables to buy or run ?

[Dre]

Also if anybody is interested the bank voltage is 13.20V as they were delivered. 

On the Lifepo4 chart that's over 70% state of charge 

[peterboat]

1 hour ago, Dre said:

I agree! I was thinking of getting those Valences on ebay but I wanted to learn a bit more and also be able to get more matching ones later on. Valences at that price might not always be available and I'd end up mixing very different types of batteries. Also these perfectly fit in the cavity behind the 12v distribition panels where all the cables I need are. I think I might actually get away with just reterminating the existing cables with no new cables to buy or run ?

 

58 minutes ago, Dre said:

Also if anybody is interested the bank voltage is 13.20V as they were delivered. 

On the Lifepo4 chart that's over 70% state of charge 

It's all good then, you are going to enjoy your experience with the batteries as yet I have not heard any complaints from users 

[redwing]

On 05/04/2020 at 12:26, Dr Bob said:

Basically set it up as per this one with the Li's in parallel with the 440Ahr LAs that come with the boat. Initially I will use the BMV to monitor voltage and cut alternator charge at a set point via the BEP switch ....but that will be a day to day occurance not the emergency mode, plus put the temperature sensor from the BMV on the alternator and isolate the BEP when the temp gets too high. I will see how it goes in the very short term. The plan then is either to do surgery on the alternator and fit one of Nick's controllers - or buy a BtoB. As the alternator is 240A then the BtoB (at 120A) would be a simple (if expensive) solution.....but if I turn on the engine and it pumps in 120A to the lithiums then it will be full in an hour ....and the BtoB will have a customisable setting to turn off after the batteries get to 90%. I am not fitting solar as the alternator will cope and we can park under trees.

I have now disconnected all the wires and taken the lithiums off the current boat ready to put on the new one in May.

Bob, I read(but cannot find it) a comment from someone who claimed to be from Sterling on a blog about B to Bs. They were suggesting 2 x 60amp B to Bs in parallel were better than the wateproof 120a one in situations where the waterproofing was not needed. Better cooling I think. Might be worth checking with Sterling. More expensive though.

Edited May 11, 2020 by redwing

[jetzi]

I was a bit put off by the name "Battery to Battery" charger, because that implied to me that it would charge from the lead acid, and my current "bank" is a tiny, and very damaged 110Ah one. However I think that the B to B actually runs directly off my alternator straight to my lithiums? They're also available in a range of sizes - 30A, 60A - so I feel like I could find one appropriate to my 70A alternator (which I've measured at 50A output). https://www.12voltplanet.co.uk/battery-to-battery-chargers.html

 

Is it a problem using a B to B that is slightly too large or too small for my alternator?

 

Can someone remind me of the downside of this approach? Is there a big loss of efficiency going through the B to B rather than having the alternator turn itself off with complicated electronics? The units themselves are quite expensive, but I'm not sure that it would cost that much more than the DIY job all things considered, especially if you factor in a blown alternator!

Edited May 11, 2020 by ivan&alice

[nicknorman]

27 minutes ago, ivan&alice said:

I was a bit put off by the name "Battery to Battery" charger, because that implied to me that it would charge from the lead acid, and my current "bank" is a tiny, and very damaged 110Ah one. However I think that the B to B actually runs directly off my alternator straight to my lithiums? They're also available in a range of sizes - 30A, 60A - so I feel like I could find one appropriate to my 70A alternator (which I've measured at 50A output). https://www.12voltplanet.co.uk/battery-to-battery-chargers.html

 

Is it a problem using a B to B that is slightly too large or too small for my alternator?

 

Can someone remind me of the downside of this approach? Is there a big loss of efficiency going through the B to B rather than having the alternator turn itself off with complicated electronics? The units themselves are quite expensive, but I'm not sure that it would cost that much more than the DIY job all things considered, especially if you factor in a blown alternator!

I have never used a B2B and the instructions are written in Sterlinglish, and Dr Bob is the expert but seems to be in self isolation ( bearing in mind Covid can be got over 5G, he is off-line). But my understanding is that it is designed to be placed between an alternator / battery combination, and another battery. The second battery can of course be your lithiums.

 

If you choose a B2B that is rated at or above your alternator output, the alternator will run flat out and probably cook. If you choose a B2B that is rated somewhat less than the alternator, the alternator won’t be running flat out and will probably last a bit longer! So I would choose a B2B with say 80% of the alternator’s rating.
 

It only cuts in when the first battery is being charged. When you stop the engine, it stops, so you don’t have to worry about a fairly knackered  battery connected to the alternator.

 

The downside is that you are guessing how much to de-rate the B2B compared to the alternator, and the cost. Efficiency must be fairly good, otherwise it would get very hot.

[peterboat]

Hi guys Bob isn't self isolating, we left him behind in the virtual BCN challenge! We made him walk the plank unfortunately he landed on the lock side and ran away! So we left him in 1918, AW says she has sent a search party back for him so it might take awhile as they had a lot of old money and booze and floozies are cheap back then  ?

[redwing]

9 hours ago, nicknorman said:

I have never used a B2B and the instructions are written in Sterlinglish, and Dr Bob is the expert but seems to be in self isolation ( bearing in mind Covid can be got over 5G, he is off-line). But my understanding is that it is designed to be placed between an alternator / battery combination, and another battery. The second battery can of course be your lithiums.

 

If you choose a B2B that is rated at or above your alternator output, the alternator will run flat out and probably cook. If you choose a B2B that is rated somewhat less than the alternator, the alternator won’t be running flat out and will probably last a bit longer! So I would choose a B2B with say 80% of the alternator’s rating.
 

It only cuts in when the first battery is being charged. When you stop the engine, it stops, so you don’t have to worry about a fairly knackered  battery connected to the alternator.

 

The downside is that you are guessing how much to de-rate the B2B compared to the alternator, and the cost. Efficiency must be fairly good, otherwise it would get very hot.

It seems Sterling recommend alternator 30% bigger but Marinehowto recommend 50%     https://marinehowto.com/understanding-the-sterling-power-pro-batt-ultra-battery-to-battery-charger/  

For Ivan , any calc rules out the 60a B2B.  There are 30amp B2B refurbs for sale atm.

 

 the link re temp of 120a B2B https://faroutride.com/b2b-review/

 

[Dre]

2 hours ago, redwing said:

It seems Sterling recommend alternator 30% bigger but Marinehowto recommend 50%     https://marinehowto.com/understanding-the-sterling-power-pro-batt-ultra-battery-to-battery-charger/  

For Ivan , any calc rules out the 60a B2B.  There are 30amp B2B refurbs for sale atm.

 

 the link re temp of 120a B2B https://faroutride.com/b2b-review/

 

I was about to link up the marinehowto page. In the end I think it's a question of suck it and see. I thought I had a 170a alternator but Beta told me it's a 90a so I'll just have to see and hope that it works with my 60a sterling. I think there's a degree of luck also between 30 and 50% ???

[nicknorman]

3 hours ago, Dre said:

I was about to link up the marinehowto page. In the end I think it's a question of suck it and see. I thought I had a 170a alternator but Beta told me it's a 90a so I'll just have to see and hope that it works with my 60a sterling. I think there's a degree of luck also between 30 and 50% ???

A lot is down to the engine bay temperature / ventilation. If the air being sucked in by the alternator fan is very hot, that is obviously worse for alternator life than if it’s cool. Therefore maybe rig up some air inlet pointing near the alternator.

 

Similarly, try not to run the alternator at the minimum speed to get the output you want. If you run it somewhat faster than that, the field current is less (so less heat generated) and the fan speed is more (so better cooling). For a Beta I would be looking at 1200rpm (engine rpm) at least, when the alternator is working hard.

[Dre]

3 hours ago, nicknorman said:

A lot is down to the engine bay temperature / ventilation. If the air being sucked in by the alternator fan is very hot, that is obviously worse for alternator life than if it’s cool. Therefore maybe rig up some air inlet pointing near the alternator.

 

Similarly, try not to run the alternator at the minimum speed to get the output you want. If you run it somewhat faster than that, the field current is less (so less heat generated) and the fan speed is more (so better cooling). For a Beta I would be looking at 1200rpm (engine rpm) at least, when the alternator is working hard.

Great news.... It's all connected and running! 

 

At the moment the battery is getting 13.5v and around 50A

Ive just checked the alternator and it's pretty hot. I have an infrared temp gun and the hottest I can measure pointing into the windings is 150 degrees C.

 

I've just turned the engine off as I'm not sure about the alternator... Need to check temps when charging lead acid bank only. Happy so far though 

[peterboat]

9 minutes ago, Dre said:

Great news.... It's all connected and running! 

 

At the moment the battery is getting 13.5v and around 50A

Ive just checked the alternator and it's pretty hot. I have an infrared temp gun and the hottest I can measure pointing into the windings is 150 degrees C.

 

I've just turned the engine off as I'm not sure about the alternator... Need to check temps when charging lead acid bank only. Happy so far though 

Very nice

[jetzi]

22 hours ago, nicknorman said:

my understanding is that it is designed to be placed between an alternator / battery combination, and another battery. The second battery can of course be your lithiums.

The B2B does sound like the best off the shelf option, to me. I notice that Renogy do a 40A version which seems like a nice compromise, for only 115 GBP (if I can find a way to get it over from America). And that one doesn't work on voltage sensing, but rather an input wire - which the review noted as a negative, but actually I feel gives a better way to control it - from the BMS.

 

 

22 hours ago, nicknorman said:

The downside is that you are guessing how much to de-rate the B2B compared to the alternator, and the cost. Efficiency must be fairly good, otherwise it would get very hot.

The cost is rather minimal when you consider the rest of the system, and sure, there's a bit of a loss in de-rating the alternator - but to be honest when charging lithiums off an alternator the bigger problem seems to be taking too much current / for too long. Are these really the only downsides?

 

 

13 hours ago, redwing said:

For Ivan , any calc rules out the 60a B2B.  There are 30amp B2B refurbs for sale atm.

 

Ooh! Where would I find one of these 30A B2B refurbs?

 

 

10 hours ago, Dre said:

I was about to link up the marinehowto page. In the end I think it's a question of suck it and see. I thought I had a 170a alternator but Beta told me it's a 90a so I'll just have to see and hope that it works with my 60a sterling. I think there's a degree of luck also between 30 and 50% ???

Yeah I don't know exactly what alternator I have - 70A was the figure that was estimated by others on this forum. I've measured 50A coming out of it and it didn't seem overly hot putting out that number, so I feel like though 60A is probably too much, it could probably handle a 30-40A B2B with ease.

 

 

 

3 hours ago, Dre said:

Great news.... It's all connected and running! 

 

At the moment the battery is getting 13.5v and around 50A

Ive just checked the alternator and it's pretty hot. I have an infrared temp gun and the hottest I can measure pointing into the windings is 150 degrees C.

 

I've just turned the engine off as I'm not sure about the alternator... Need to check temps when charging lead acid bank only. Happy so far though

Congratulations, this all sounds very promising! 150 degrees seems far too hot though?

[redwing]

29 minutes ago, ivan&alice said:

 

Ooh! Where would I find one of these 30A B2B refurbs?

 

Here they are Ivan . They've gone up in price since I last looked https://www.ebay.co.uk/itm/BB1230-Battery-to-Battery-charger-12V-12V-30A-EURO-6-REGEN-6-months-warranty/223906425645?hash=item3421dceb2d:g:dhwAAOSwSs1cB-7~

[redwing]

4 hours ago, Dre said:

Great news.... It's all connected and running! 

 

At the moment the battery is getting 13.5v and around 50A

Ive just checked the alternator and it's pretty hot. I have an infrared temp gun and the hottest I can measure pointing into the windings is 150 degrees C.

 

I've just turned the engine off as I'm not sure about the alternator... Need to check temps when charging lead acid bank only. Happy so far though 

 

 

Looking good Dre. 

I think Dr Bob uses a bilge blower and ducting on his alternator

[jetzi]

9 minutes ago, redwing said:

Here they are Ivan . They've gone up in price since I last looked https://www.ebay.co.uk/itm/BB1230-Battery-to-Battery-charger-12V-12V-30A-EURO-6-REGEN-6-months-warranty/223906425645?hash=item3421dceb2d:g:dhwAAOSwSs1cB-7~

Thanks! Still, at 140 squids that's over 40 gbp saving over the new price (not looked hard but I've seen them for 182 GBP on 12voltplanet).

 

Don't think I'm ready to pull the trigger just yet but this does seem like a very, very appealing way to charge lithiums from the alternator with no mess, no fuss and no explosions.

 

Are there really no other disadvantages? I'm struggling to understand why more of us aren't going this route...

[peterboat]

10 minutes ago, redwing said:

Looking good Dre. 

I think Dr Bob uses a bilge blower and ducting on his alternator

He does I use one on my electric motor to give it forced cooling instead of the fan

 Plus you can take cold air from the baseplate so that helps, they are cheap and can move a lot of air 

5 minutes ago, ivan&alice said:

Thanks! Still, at 140 squids that's over 40 gbp saving over the new price (not looked hard but I've seen them for 182 GBP on 12voltplanet).

 

Don't think I'm ready to pull the trigger just yet but this does seem like a very, very appealing way to charge lithiums from the alternator with no mess, no fuss and no explosions.

 

Are there really no other disadvantages? I'm struggling to understand why more of us aren't going this route...

Because people like to make things complicated! Mine is a kiss system and works well, but requires input from me, fully protected systems which are completely automated costalot 

[nicknorman]

17 minutes ago, ivan&alice said:

Thanks! Still, at 140 squids that's over 40 gbp saving over the new price (not looked hard but I've seen them for 182 GBP on 12voltplanet).

 

Don't think I'm ready to pull the trigger just yet but this does seem like a very, very appealing way to charge lithiums from the alternator with no mess, no fuss and no explosions.

 

Are there really no other disadvantages? I'm struggling to understand why more of us aren't going this route...

I think just because of the cost and limited charge control. A lot of modern boats have alternators in the 150-175A range, or more. And of course lithiums can take that sort of current. But to control it all via a B2B of say 120A is an expensive way to do it (£500) and you are still just taking a guess about what the alternator can put out without overheating. For £500 you can have the american alternator regulator (Wakespeed WS500) which has surely got to be better value for £500! (Or make your own of course!)

Edited May 12, 2020 by nicknorman

[jetzi]

13 minutes ago, nicknorman said:

I think just because of the cost and limited charge control. A lot of modern boats have alternators in the 150-175A range, or more. And of course lithiums can take that sort of current. But to control it all via a B2B of say 120A is an expensive way to do it (£500) and you are still just taking a guess about what the alternator can put out without overheating. For £500 you can have the american alternator regulator (Wakespeed WS500) which has surely got to be better value for £500! (Or make your own of course!)

Please could you expand on what you mean by limited charge control? Do you mean you have to make do with the standard LiFePO4 settings regarding voltage stages?

Perhaps this is made more appealing in my situation being that I have a small alternator and only need a 30A B2B (140GBP for the refurb).

[Richard10002]

1 hour ago, ivan&alice said:

Yeah I don't know exactly what alternator I have - 70A was the figure that was estimated by others on this forum. I've measured 50A coming out of it and it didn't seem overly hot putting out that number, so I feel like though 60A is probably too much, it could probably handle a 30-40A B2B with ease.

My alternator is only "small", and seems to put out about 35A when it starts charging the LA bank, but the Amps then tend to half every hour, as the bank is charged up. So it doesn't run at any particular "higher" level of Amps for any length of time. It isn't connected in any way to my lithium bank, and I don't think I foresee this happening in the foreseeable future.

 

If it were connected to the Lithiums via a 30A B2B unit, it would run at 30A constantly. I have no idea whether that would make it too hot, or not. I would think hot.

 

You would think that a constant 30A from a 70A rated alternator ought to be fine, providing it's spinning fast enough.

 

On my boat, experience to date suggests that my solars, (500w), will keep up with power use, (100Ah +/-), most days from April to September and, if I have to run the genny every now and then, it's no big deal. Even in winter, with no solar input, they last about 5-7 days of full time living aboard, so running the genny for 7 hours, every 5 or 7 days is no big deal - in fact, it's a luxury compared to keeping the LAs fully charged at least every second day.

 

I probably differ from many here as I don't do much cruising, so alternator charging would not form a major source of charging, unless something changes in my boating style. Given that I don't go far, or often, I am able to keep the genny and petrol in a shed thing on the mooring.

 

 

6 minutes ago, ivan&alice said:

Please could you expand on what you mean by limited charge control? Do you mean you have to make do with the standard LiFePO4 settings regarding voltage stages?

Perhaps this is made more appealing in my situation being that I have a small alternator and only need a 30A B2B (140GBP for the refurb).

Pretty sure Sterlings B2Bs have a custom setting. My Pro Charge Ultra Charger does.

 

In fact I think the BattleBorn Batteries link above, (somewhere), explains how to set up the custom setting for their batteries.

 

 

[jetzi]

1 minute ago, Richard10002 said:

If it were connected to the Lithiums via a 30A B2B unit, it would run at 30A constantly. I have no idea whether that would make it too hot, or not. I would think hot.

My understanding - which may be wrong - is that it would run at 30A constantly while the lithiums are in bulk charge mode. Once they are "full" (i.e. the voltage at which you terminate charging, representing for example 80% SoC), you should be able to carry on cruising without having to worry about your batteries - the B2B would then switch to float and only supply the amount of power being used by your domestic load. So if you had a 15A load, the B2B would supply 15A (and take a bit more than that due to inefficiencies). If you had no load, the B2B would supply no amps. If you had a 45A load, the B2B would supply 30A, and your lithiums would supply the other 15A.

 

I would expect my alternator to be able to output 30A continuously, even at tickover, and if it couldn't due to overheating I'd certainly want to install a bilge blower or something to make it happen. I don't think 30A is an unreasonable expectation of even a small alternator!

 

I would like to be able to set a terminating SoC for my B2B, which is why I quite liked the idea of an externally switchable B2B like the Renogy. I would not want to just allow the B2B to charge however much it feels it should - that doesn't sound like a recipe for a long and healthy lifepo. That's why I'm interested to hear what @nicknorman means by the limited charge control. Would also love to hear from @Dr Bob on this.

 

13 minutes ago, Richard10002 said:

if I have to run the genny every now and then, it's no big deal. Even in winter, with no solar input, they last about 5-7 days of full time living aboard, so running the genny for 7 hours, every 5 or 7 days is no big deal

I agree with you, this seems like a perfectly reasonable approach for your situation, and I wouldn't add alternator charging to your setup if I were you. We're CCers (CMers at the moment!) so for us, in winter, it's going to be a must. I did consider it at one stage but I have no interest in getting a generator - imho petrol is too risky and diesel gennies are too dear. Besides, I couldn't abide the noise.

 

My engine needs to supply all my electricity from November to February, and a fair amount of it in October and March, so finding a alternator charging solution well before October is a must for me!

 

[nicknorman]

1 hour ago, ivan&alice said:

Please could you expand on what you mean by limited charge control? Do you mean you have to make do with the standard LiFePO4 settings regarding voltage stages?

Perhaps this is made more appealing in my situation being that I have a small alternator and only need a 30A B2B (140GBP for the refurb).

No I wasn’t thinking about the output end, there is a LiFePO4 setting and I think there is also a custom setting. I was thinking about any control over how much current it takes from the alternator. If you bought a 60A B2B to run from a 75A alternator, you couldn’t decide later that you only want it to take 50A because the alternator was getting too hot.

 

Oh and on your point about the external switch to control the B2B, the Sterling datasheet I picked to look at had an optional connection for the ignition switch, which would control when the B2B operated. Not sure if they all do though.

Edited May 12, 2020 by nicknorman