Lithium Upgrade Process Dilemna

[alanfw]

I’ve been tying my brain in knots for 2 days trying to decide on an electricity upgrade for my sailing boat (after one of my two marine lead acid batteries died).
I’ve decided to keep the remaining battery as a dedicated start battery and replace the other with a 140Ah lithium house battery (https://www.aussiebatteries.com.au/g...ithium-battery). Now I’m trying to decide on the charging configuration.
The boat already has a Statpower Truecharge 20A 240V charger that was keeping the batteries charged and fridge etc running while berthed. It also has 200W of solar panels and an Epever 20A solar MMPT controller (that has user-settable configuration that will allow me match it to the Lithium battery). Unfortunately, a previous owner installed it far from the battery with WAY under-spec cable resulting in roughly 0.5V+ difference between controller and battery when charging, reducing the solar yield significantly.

So here’s my dilemma: Do I…

1: simply place a lithium compatible DC-DC isolated charger between the starter battery and the new lithium house battery and keep the existing solar controller (maybe upgrade the cables if I can find where they are – the wiring is a MESS!) eg: https://www.outbackmarine.com.au/vic...0w-isolated-dc

2: get a DC-DC with solar input (preferably with a remote monitoring ability) and ditch the Epever controller. This will place my solar controller in the battery storage compartment, eliminating the problem of voltage drop.

3: Forget about the DC-DC and just use a battery isolator that will allow the house battery to charge (when the alternator is running or when the shore power is plugged in). The Giant battery site says their batteries will charge safely with old-style alternators as long as the voltage is <14.6V, which seems to be what my system has. (This approach seems to have problems related to spikes created when the lithium BMS switches off charging, suddenly dropping the load on the alternator - but I would have thought the lead acid starter battery would absorb those...)

PS: Ideally, I'd like more than 140Ah of house power, but the space in my battery storage compartment is limited. I did a LOT of looking at alternatives to the 100Ah marine battery I'm keeping as a dedicated start battery - like a compact high CCA low AH start battery I could place in a different location near the engine but without knowing the current demands of the Bukh DV24 I decided to stick with the good battery I have. This one looked possible: https://itechworld.com.au/products/i...t&_ss=e&_v=1.0 If anyone has any useful thoughts here I'd love to hear them!

[newhaul]

Originally Posted by alanfw

I’ve been tying my brain in knots for 2 days trying to decide on an electricity upgrade for my sailing boat (after one of my two marine lead acid batteries died).
I’ve decided to keep the remaining battery as a dedicated start battery and replace the other with a 140Ah lithium house battery (https://www.aussiebatteries.com.au/g...ithium-battery). Now I’m trying to decide on the charging configuration.
The boat already has a Statpower Truecharge 20A 240V charger that was keeping the batteries charged and fridge etc running while berthed. It also has 200W of solar panels and an Epever 20A solar MMPT controller (that has user-settable configuration that will allow me match it to the Lithium battery). Unfortunately, a previous owner installed it far from the battery with WAY under-spec cable resulting in roughly 0.5V+ difference between controller and battery when charging, reducing the solar yield significantly.

So here’s my dilemma: Do I…

1: simply place a lithium compatible DC-DC isolated charger between the starter battery and the new lithium house battery and keep the existing solar controller (maybe upgrade the cables if I can find where they are – the wiring is a MESS!) eg: https://www.outbackmarine.com.au/vic...0w-isolated-dc

2: get a DC-DC with solar input (preferably with a remote monitoring ability) and ditch the Epever controller. This will place my solar controller in the battery storage compartment, eliminating the problem of voltage drop.

3: Forget about the DC-DC and just use a battery isolator that will allow the house battery to charge (when the alternator is running or when the shore power is plugged in). The Giant battery site says their batteries will charge safely with old-style alternators as long as the voltage is <14.6V, which seems to be what my system has. (This approach seems to have problems related to spikes created when the lithium BMS switches off charging, suddenly dropping the load on the alternator - but I would have thought the lead acid starter battery would absorb those...)

PS: Ideally, I'd like more than 140Ah of house power, but the space in my battery storage compartment is limited. I did a LOT of looking at alternatives to the 100Ah marine battery I'm keeping as a dedicated start battery - like a compact high CCA low AH start battery I could place in a different location near the engine but without knowing the current demands of the Bukh DV24 I decided to stick with the good battery I have. This one looked possible: https://itechworld.com.au/products/i...t&_ss=e&_v=1.0 If anyone has any useful thoughts here I'd love to hear them!

First thing is if your solar wiring is not right then make it right cheapest use for your problem 200 watts solar through my epever 30 mppt does a great job maintaining my 250 ah lfp bank . Just upgrade the wiring and locate the controller close to the bank it is charging. Cheapest and most beneficial to you . Will have to do it eventually so may as well do it now .

[PUDDLE JUMPER II]

Wiring recommendations? Brands?

[newhaul]

Originally Posted by PUDDLE JUMPER II

Wiring recommendations? Brands?

The manual calls for 8agw for your controller but if you can get 6agw to fit then better.
https://www.amazon.com/Gauge-Wire-iG...Q%3D%3D&sr=8-8
Or similar.
And move controller as close as practicable to where you are installing your bank .

[SOLAR SUPPORT]

In order to make the safe charging you need for the lithium battery with old-style AC battery chargers, it is necessary to use charge interrupter voltage sensitive relays. Epever solar regulator, I think, allows you to adjust the charge cut-off voltage. However, it is not certain that there will be no problems with this. If you do not want to use the old devices on the boat, an economical alternative can be a hybrid device. You can use a smart off-grid device that combines solar mppt, AC battery charger and full sine inverter in the same box, with 12 volt, 800-1200 Watt powers, sold for $250-$300. These hybrid devices are widely used in RVs. Mppt and AC battery charging settings can be adjusted very flexibly and they are sufficient in terms of capacity. Is there a way to safely charge this smart hybrid inverter device with an alternator, I'm looking into it. To understand the details of this topic, you can follow the link below.

https://www.cruisersforum.com/forums...ml#post3700721

[newhaul]

Originally Posted by SOLAR SUPPORT

In order to make the safe charging you need for the lithium battery with old-style AC battery chargers, it is necessary to use charge interrupter voltage sensitive relays. Epever solar regulator, I think, allows you to adjust the charge cut-off voltage. However, it is not certain that there will be no problems with this. If you do not want to use the old devices on the boat, an economical alternative can be a hybrid device. You can use a smart off-grid device that combines solar mppt, AC battery charger and full sine inverter in the same box, with 12 volt, 800-1200 Watt powers, sold for $250-$300. These hybrid devices are widely used in RVs. Mppt and AC battery charging settings can be adjusted very flexibly and they are sufficient in terms of capacity. Is there a way to safely charge this smart hybrid inverter device with an alternator, I'm looking into it. To understand the details of this topic, you can follow the link below.

https://www.cruisersforum.com/forums...ml#post3700721

Yes the Epever mppt controller does that. As does my 1992 trace 2512 inverter charger. From a top end of 14.7 and a low end of 14.2volts also amps adjustable from 1 amp to 120 amps infinite set. Float is 13.2 to 13.6 volts. Also has a manually operated Equalization that I don't use.

[Pete7]

Alan, are you still going ahead with this?

Pete