LiFePo Query

I have 4 LifePO4 batteries in parallel, max rating 150 amps each, max 600 amps total, nominal 5kW hr capacity
They struggled to run the bow thruster 5kW, 12volt, dropping below 11 volts under load of approaching 500amps.
The solution I've used is the fit a 75amp hr AGM in the bow thruster compartment on very short cables, less than 1m, and charge with a Victron 30amp B to B.
The AGM can handle the current for the short period of time the thruster is used.
 
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Ian_Edwards said:
I have 4 LifePO4 batteries in parallel, max rating 150 amps each, max 600 amps total, nominal 5kW hr capacity
They struggled to run the bow thruster 5kW, 12volt, dropping below 11 volts under load of approaching 500amps.
The solution I've used is the fit a 75amp hr AGM in the bow thruster compartment on very short cables, less than 1m, and charge with a Victron 30amp B to B.
The AGM can handle the current for the short period of time the thruster is used.
Click to expand...
I mentioned - I had not realised that bow thrusters were so common place (maybe 'common' is the wrong word) - but equally I had not realised the power requirements.

I assume you run the B2B off the, lead, engine start and the engine is always on when you you use the bow thruster? And - you have another B2B to charge the house Lithiums (along with solar)?

Jonathan
 
Neeves said:
I'm not sure why the NASA shunt option is only 100 amp? and then whether that is sufficient.

Jonathan
Click to expand...
We often hover around 100A load but we are at 24v so in 12v money we are touching 200A. I managed to trip the breaker on the inverter last week pulling 150A by mistake. I didn't realise I had left the 1200w immersion heater on. It's a low frequency 3000w inverter with a peak of 6000w. Running at some thing like 3900w for 20 minutes. It was a good test of our breaker!
 
Neeves said:
I mentioned - I had not realised that bow thrusters were so common place (maybe 'common' is the wrong word) - but equally I had not realised the power requirements.

I assume you run the B2B off the, lead, engine start and the engine is always on when you you use the bow thruster? And - you have another B2B to charge the house Lithiums (along with solar)?

Jonathan
Click to expand...
Not quite, I chose to make the LiFePO4 house battery bank the master. With 5kW hr, and the ability to charge faster and more efficiently, it made sense to me.
The starter battery has B to B powered from the Lithium batteries, as does the bow thruster.
The Lithium is charged by a 120 amp 12v alternator, controlled by a Wake Speed WS500, a Victron 100amp 12v 3kVa inverter charger, which in turn is powered by a shore supply or a Whisper Power generator. The Lithium battery are also charged directly from 180W of solar via a Victrom MPPT.
The starter battery is almost always fully charged from the Lithium, I can't remember member what I set the B to B at but as soon as any charging source is present, it kicks in and the output is set for an AGM charging profile.
The same for the bow thruster battery.
Both B to B's are able of charging when the engine/generator is running, or shore power is available, or the solar gets above its kick off voltage. The solar consists of 2 @ 90W panels, connected is series, so it doesn’t take lot to of sun to kick the Victron MPPT into action.
It amazes me that a relative small solar installation, can take the Lithium from say 50% to close to 100%, in the week or 10days I'm typically away from the boat in the summer, even in NW Scotland. But then we only have about 2hrs of almost complete darkness in mid summer.
 
PaulRainbow said:
Can't beat having equipment that's well made and designed for the job. Beats cheap and nasty any day, IMO.
Click to expand...
I agree but cheap does not necessarily mean nasty.

Kelpie and I both use cheap shunts + monitors - I frankly don't think we are alone. I have no reason to think our shunt and monitor are not adequate. I cannot confirm but our current cheap mon (+ shunt) performs no differently (in terms of its output) to the similar mon and shunt from Xantrex of over 20 years ago - in fact they look identical and the outputs look identical.

Looks can of course be deceptive and I will not know that our shunt and mon are inadequate - until they are.

In the meantime I find cheap and adequate beats expensive and adequate.

Jonathan
 
Ian_Edwards said:
Not quite, I chose to make the LiFePO4 house battery bank the master. With 5kW hr, and the ability to charge faster and more efficiently, it made sense to me.
The starter battery has B to B powered from the Lithium batteries, as does the bow thruster.
The Lithium is charged by a 120 amp 12v alternator, controlled by a Wake Speed WS500, a Victron 100amp 12v 3kVa inverter charger, which in turn is powered by a shore supply or a Whisper Power generator. The Lithium battery are also charged directly from 180W of solar via a Victrom MPPT.
The starter battery is almost always fully charged from the Lithium, I can't remember member what I set the B to B at but as soon as any charging source is present, it kicks in and the output is set for an AGM charging profile.
The same for the bow thruster battery.
Both B to B's are able of charging when the engine/generator is running, or shore power is available, or the solar gets above its kick off voltage. The solar consists of 2 @ 90W panels, connected is series, so it doesn’t take lot to of sun to kick the Victron MPPT into action.
It amazes me that a relative small solar installation, can take the Lithium from say 50% to close to 100%, in the week or 10days I'm typically away from the boat in the summer, even in NW Scotland. But then we only have about 2hrs of almost complete darkness in mid summer.
Click to expand...
Thanks Ian, it is useful to have a cross section of experiences - so your post adds to the fund of knowledge.

We have 2 x 150w panels, actually 4 x 75w, up on the roof of the house and are producing, combined, 25 amps when the sun is un-obscured. I don't bother to move them to 'exactly' face the sun (we are at 33 S) - so still have dawn and dusk. They may produce more than 25amps - at times - but I'd need to be able to monitor full time. Our Lithium battery is only 200a/hrs and it does not take much to charge which is good as we have a rather large gum tree that obscures the direct sun from the solars from about 1pm.

To allow the battery to pay its way we are running various terrestrial appliances through a, cheap, 1500w inverter. The largest draw of our terrestrial appliances include an air fryer, a bread maker and a 65l eskie (which draws 6-7amps when cycled on) which we are running continuously as I 'test' my cheap components and appliances.

Jonathan
 
In looking at other cheap options, other than our Monitor/shunt, I have come across a number of cheap MPPT controllers priced at around A$30 delivered to our home in Sydney, delivery upto 9 days. Their specifications are similar, but not identical and come from a variety of, Chinese, sources. They claim to be compatible with both Lithium and Lead batteries. The devices are sold 'from' Temu in Australia, there is a 30 day return policy (that we have tested - and works).

We 'like' Temu as delivery is swift, payment is in A$, returns are to Australia. So far.....we get what we paid for.

I believe Temu is active in the UK.

Stg:A$ approx 1:2

Upto 100amp solar capacity 12v/24v. (our 300 W panels are producing about 25 amps)

default Float voltage 14.2v variable (one offers 14.4v)
default Discharge voltage 10.5v variable
discharge re-connect 12.6v variable.

No Blue Tooth

They all seem to have USB outlets

There are lots of similar devices - at similar prices + or - 10%


and based on Geem's use of an immersion heater - an instant hot water heater, 220 volt 3,800 W (a bit much for our, 1500W inverter) at A$84. Oddly no flow rate data. Also Temu. On Josepheline we used an instant hot water Bosch propane unit - which worked well.

Jonathan
 
Neeves said:
I agree but cheap does not necessarily mean nasty.

Kelpie and I both use cheap shunts + monitors - I frankly don't think we are alone. I have no reason to think our shunt and monitor are not adequate. I cannot confirm but our current cheap mon (+ shunt) performs no differently (in terms of its output) to the similar mon and shunt from Xantrex of over 20 years ago - in fact they look identical and the outputs look identical.

Looks can of course be deceptive and I will not know that our shunt and mon are inadequate - until they are.

In the meantime I find cheap and adequate beats expensive and adequate.

Jonathan
Click to expand...
I will repeat what I said in an earlier post. The Victron smart shunt is only a little more expensive than you cheap Nasa shunt. The Victron has Bluetooth so you can see SOC on your phone but it's best feature is its ability to link with the Victron MPPTs to provide super accurate measure of voltage at the battery for the MPPTs. This reduces the likelyhood of a HVE since the risks of the MPPTs raising the voltage of the lithium close to their trip settings are much reduced. You only need a small inaccuracy in the solar charge voltage to push a rogue cell in your lithium battery into a high voltage shut downonce you get the lithium battery close to 100% charged. I think using something like the Victron smart shunt combined with their MPPTs would be a sensible move especially if you are using cheap drop in batteries with passive balancers that have a tendency to have cells out of balance over time.
 
Neeves said:
I agree but cheap does not necessarily mean nasty.

Kelpie and I both use cheap shunts + monitors - I frankly don't think we are alone. I have no reason to think our shunt and monitor are not adequate. I cannot confirm but our current cheap mon (+ shunt) performs no differently (in terms of its output) to the similar mon and shunt from Xantrex of over 20 years ago - in fact they look identical and the outputs look identical.

Looks can of course be deceptive and I will not know that our shunt and mon are inadequate - until they are.

In the meantime I find cheap and adequate beats expensive and adequate.

Jonathan
Click to expand...
So you are effectively using 20 yr old tech with the latest Li batteries ? See Geems post about battery monitors and MPPT controllers.
 
Using a Victron BMV to control charging means you also have to use Victron MPPTs, I think?
So for my case it was: £50 monitor plus two 40A MPPTs at £120 each = £290.
Victron route: £130 BMV, £200 each for 30A MPPTs = £530.
That's a fairly big difference.

I didn't use a monitor at all for the first ~18 months, just relied on the BMS. But it wasn't ideal to have to use a glitchy app on my phone every time I wanted to check the batteries.
 
Neeves said:
In looking at other cheap options, other than our Monitor/shunt, I have come across a number of cheap MPPT controllers priced at around A$30 delivered to our home in Sydney, delivery upto 9 days. Their specifications are similar, but not identical and come from a variety of, Chinese, sources. They claim to be compatible with both Lithium and Lead batteries. The devices are sold 'from' Temu in Australia, there is a 30 day return policy (that we have tested - and works).

We 'like' Temu as delivery is swift, payment is in A$, returns are to Australia. So far.....we get what we paid for.

I believe Temu is active in the UK.

Stg:A$ approx 1:2

Upto 100amp solar capacity 12v/24v. (our 300 W panels are producing about 25 amps)

default Float voltage 14.2v variable (one offers 14.4v)
default Discharge voltage 10.5v variable
discharge re-connect 12.6v variable.

No Blue Tooth

They all seem to have USB outlets

There are lots of similar devices - at similar prices + or - 10%


and based on Geem's use of an immersion heater - an instant hot water heater, 220 volt 3,800 W (a bit much for our, 1500W inverter) at A$84. Oddly no flow rate data. Also Temu. On Josepheline we used an instant hot water Bosch propane unit - which worked well.

Jonathan
Click to expand...
Most of those cheap Chinese "MPPT" controllers are actually PWM, plenty of post on here and the 'net to verify this.

It's very difficult to beat Victron MPPT controllers with the SmartShunt.

It's all well and good using some cheaper equipment, as long as a) it's well built and b) if it fails it won't wipe out some other, expensive, equipment. With a well thought out designed and constructed Li installation you cannot afford to fit cheap and nasty charging equipment etc.

For example, i have some cheap (well made) Chinese built DC-DC converters, the drop the boats 24v to a stable 12v for the LED lights. They work really well and i've had some in use for years. If one failed the worse case scenario is a few toasted LEDs. When i bought the boat it had a cheap DC-DC converter dropping the 24v to 12v for some of the electronics. I stripped out all of the old 12v electronics, the new stuff is all 12v/24v, except for my Garmin black box VHF/AIS and this was connected to the 12v circuit. The DC-DC converter failed, putting out 24v and fried the black box. This means a whole new setup, as the one with built in AIS is no longer available and the handsets need replacing as they won't fit the new black box. Total cost, just shy of £2k. Fortunately i was able to acquire a new "old stock" black box for substantially less than that.
 
Kelpie said:
Using a Victron BMV to control charging means you also have to use Victron MPPTs, I think?
So for my case it was: £50 monitor plus two 40A MPPTs at £120 each = £290.
Victron route: £130 BMV, £200 each for 30A MPPTs = £530.
That's a fairly big difference.

I didn't use a monitor at all for the first ~18 months, just relied on the BMS. But it wasn't ideal to have to use a glitchy app on my phone every time I wanted to check the batteries.
Click to expand...
You don't need a BMV. You can use the smart shunt. £114. You then get everything displayed on phone and tablet. Yes you need to use Victron MPPTs as the two devices talk through Victron VE.
For me, Victron is the best solution. Being a 24v boat, we need way smaller MPPTs than a 12v boat as they are all rated in amp. Twice the volts means half the amps for the same size Solar array. Another nice feature of the Victron kit is multiple MPPTs can be linked to the VE network and they function as one. They all work with the same battery voltage provided by the Smart shunt.
 
Kelpie said:
Using a Victron BMV to control charging means you also have to use Victron MPPTs, I think?
So for my case it was: £50 monitor plus two 40A MPPTs at £120 each = £290.
Victron route: £130 BMV, £200 each for 30A MPPTs = £530.
That's a fairly big difference.

I didn't use a monitor at all for the first ~18 months, just relied on the BMS. But it wasn't ideal to have to use a glitchy app on my phone every time I wanted to check the batteries.
Click to expand...
500a Smartshunt is £107. 30A Bluesmart 100/30 £119.20, total £345.40

Not much different to £290 and the MPPTs are more or less the same as than yours. You save £55.40 at the expense of all of the features and functions you're missing by not having Bluetooth and the interconnectivity you could have had with Victron.
 
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PaulRainbow said:
500a Smartshunt is £107. 30A Bluesmart 100/30 £119.20, total £345.40

Not much different to £290 and the MPPTs are more or less the same as than yours. You save £55.40 at the expense of all of the features and functions you're missing by not having Bluetooth and the interconnectivity you could have had with Victron.
Click to expand...
I wasn't able to find Victron MPPTs at that sort of price, where is that from? It's the same as an Epever, which is inferior in many respects. At the time I was building my system the cost difference was substantial.
 
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