So we are heading over to France next week for a week with the van and I want to look at getting, for pricing reasons, a few LiFePO4 leisure batteries [LB] to replace the existing AGM one.
Am thinking 2 by 200 Amp
My existing LB charger [Schaudt booster 121525] is only suitable for Gel/AGM/Li so I will need to change it.
So looking for
1: any insights on the idea itself
2: recommendations for a suitable LiFePO4 charger
I presume my existing on board mains chargers will not need replacing
[which I assume charges the starter battery directly as well as the LBs, but through the schaudt?
I also have a PV panel, with its "gizmo" in with all the other electrical kit
Thanks as always
1. Consider what you want from lithium batteries.
2. What is the capacity in Ah (Ampere hours) of your existing AGM battery? (Battery capacity is measured in Ampere hours, not Amperes (A) which is a measurement of current flow).
3. Normal advice is not to discharge a lead acid below 50% depth of discharge (DoD). So if you have a nominal 100Ah AGM battery, which is a lead acid battery, there is only about 50Ah of useable capacity. You can discharge further, but battery life will be shortened.
4. Lithium batteries have a much longer, perhaps 10 times the charge/discharge cycle life when taken to 80% DoD. This means that a 200Ah lithium battery will have more than 3 times the useable capacity of a 100Ah lead acid battery. Do you really need over six times you probable present useable battery capacity.
5. Lead acid batterries generally have a maximum advised charge rate of C/10 (capacity in Ah/10), so 10A for a 100Ah battery. At this rate, and allowing for the losses in the battery, it would take about six hours to recharge a !00Ah lead acid battery that had been discharged to the recommended 50% DoD. Another advantage of lithium batteries is the recharge rate of C/4, or 50A for a single 200Ah battery. This is double the rated output of the existing Schaudt 121525 "booster" or B2B, but a recharge time of less than 4 hours seems possible, with a larger B2B.
6. Your Schaudt Electroblok, is probably fused at 50A on the habitation battery side. It would not be sensible to connect a larger B2B than the existing unit via the EBL. A larger B2B would have to be connected directly to the batteries via suitable fuses close to the batteries. Extensive rewiring with thicker cables would be needed.
7. Is the alternator suitable for the increased load when recharging the lithium batteries? OK for the existing B2B, but if going higher, it may need changing for a model with a higher rating. I have read that alternator ratings are for maximum, and not sustained current.
8. The existing mains charger will not fully charge lithium batteries unless it has a lithium profile, but I have seen recommendations for storing lithium batteries at below 100% state of charge. Possibly rated at 16A it would take over 10 hours flat out to recharge one 200Ah battery from 80% DoD. It may not survive that duty. There is a facility in the Electroblok for providing a low rate charge to the starter battery, but this depends on a "Mains ON" signal from the Schaudt charger.
9. Solar panels are a useful way of charging lithium batteries, but in the you will need as large an area as possinle with an MPPT (maximum power point tracking) regulator for maximum gain. No details were submitted.
10. For prices about £600 upwards for one 200Ah lithium battery in UK.
11. Fom your use of the abbreviation "A" to denote battery capacity, the term "gizmo" for your solar regulator, and your unfamiliarity with the common abbreviation, B2B, it seems that your electrical knowledge is limited. Perhaps you should seek the advice of a competant installation technician. A charged battery contains a lot of energy, and while 12V is in itself not dangerous, the possible high currents flowing can cause fires, and personal injury.