Problem with Lithium battery charging

[colinm]

I don't know if I would bother with upgrading the EBL99 with the Apuljack change. Lots of folk seem happy with putting it into GEL mode.

If of interest, have a look at this thread ... https://wildcamping.co.uk/threads/for-sale-100ah-lithium-batteries.98574/
Pair of top quality 100Ah Lithiums and other bits for sale.
I would bundle the pair of batteries together with the Schaudt 25A B2B (perfect partner to the Schaudt EBL giving an improved charge rate and has a Lithium setting) plus a custom factory support that allows you to fit the B2B behind the EBL on a ducato/relay/boxer mount for an all-in price of £460 (plus any shipping costs)

I have a invertor under the seat, so only room for 2x75Ah, or 1x100Ah.

 

[Chasn]

For those willing to consider the DIY approach to lithium I bought 8 lithium cells and a BMS direct from China for £750 including all taxes and shipping. These just fitted in in the habitation battery recess in my Carthago which is designed for two 100Ah lead acid batteries. The net result is 610Ah with a weight less than two 90Ah lead acid batteries. The only other major costs were a Victron lithium mains battery charger and a smart shunt. This now enables me to run my 3 way fridge (which takes 15A when on electric) and stay off-grid with minimal gas usage for an extended period. Of course items like electric kettle, toaster and microwave are easy add-ons.

With regards to lithium operating I have the following comments. Unlike lithium ion which are best between 20 and 80% SOC, these are LFP which are fine 10 to 100%. With regards to battery protection a good BMS is essential. If any cell drops significantly below 2.5v for an extended period that cell is toast. As it takes a minimum of four cells for a 12v system allowing the system voltage to drop to 10v would be bad news. The other major no no is to charge below 0degC battery temperature but the BMS will look after all these issues and will keep the cells balanced.

 

[merl]

For those willing to consider the DIY approach to lithium I bought 8 lithium cells and a BMS direct from China for £750 including all taxes and shipping. These just fitted in in the habitation battery recess in my Carthago which is designed for two 100Ah lead acid batteries. The net result is 610Ah with a weight less than two 90Ah lead acid batteries. The only other major costs were a Victron lithium mains battery charger and a smart shunt. This now enables me to run my 3 way fridge (which takes 15A when on electric) and stay off-grid with minimal gas usage for an extended period. Of course items like electric kettle, toaster and microwave are easy add-ons.

With regards to lithium operating I have the following comments. Unlike lithium ion which are best between 20 and 80% SOC, these are LFP which are fine 10 to 100%. With regards to battery protection a good BMS is essential. If any cell drops significantly below 2.5v for an extended period that cell is toast. As it takes a minimum of four cells for a 12v system allowing the system voltage to drop to 10v would be bad news. The other major no no is to charge below 0degC battery temperature but the BMS will look after all these issues and will keep the cells balanced.

B2B charger or direct from the alternator?

 

[wildebus]

For those willing to consider the DIY approach to lithium I bought 8 lithium cells and a BMS direct from China for £750 including all taxes and shipping. These just fitted in in the habitation battery recess in my Carthago which is designed for two 100Ah lead acid batteries. The net result is 610Ah with a weight less than two 90Ah lead acid batteries. The only other major costs were a Victron lithium mains battery charger and a smart shunt. This now enables me to run my 3 way fridge (which takes 15A when on electric) and stay off-grid with minimal gas usage for an extended period. Of course items like electric kettle, toaster and microwave are easy add-ons.

With regards to lithium operating I have the following comments. Unlike lithium ion which are best between 20 and 80% SOC, these are LFP which are fine 10 to 100%. With regards to battery protection a good BMS is essential. If any cell drops significantly below 2.5v for an extended period that cell is toast. As it takes a minimum of four cells for a 12v system allowing the system voltage to drop to 10v would be bad news. The other major no no is to charge below 0degC battery temperature but the BMS will look after all these issues and will keep the cells balanced.

Not sure about the cost-effectiveness of getting sufficient lithium to run a 3-way fridge off the battery? it will use about 4kWh per day. Sure, the 610Ah Lithium Battery - 7,800kWh of power - will have enough energy for a day no worries, but then you have to have 4kWh of recharge power - good luck attaining that with Solar even on a great summers day!
It makes far more sense IMO to switch to a compressor fridge, which is around around 3,200kWh less consumption per day. Can make up the power used by a compressor fridge very easily with a pretty basic solar setup and would need nowhere near as big a lithium bank. The money saved would pay for the fridge as well - that really would be "free power" in comparison

 

[Chasn]

On a 4 day trip with just 1 hour driving between nightstops and good solar there was no problem. The B2B gives about 60A. The overall plan was to give flexibility and reduce gas consumption. In winter we will probably use gas for the fridge overnight. We now always use an electric kettle and the use of a toaster and microwave are no issue even with the high current draw. I would also like to switch to a compressor fridge but the MH is only 6 years old and the existing fridge is tall and narrow so probably difficult to find a compressor alternative that fits the space neatly. The LFP batteries will probably never need changing so £750 is not much to pay to have a fit and forget solution. The efficiency of LFP charging (about 95%) means that the solar and B2B output is put to better use particularly at higher SOCs when lead acid charging drops below 80% efficiency.