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Updated : 23/11/2017.  

                      Battery charger repairs, most makes catered for. 



"My leisure battery exploded last week. The camper was on EHU at the time. Is it possible for me to send you the CALIRA for diagnostics and repairs? I am based in Oxford. Regards Sarah"


15 years ago, when Lucas was a quality brand, most Leisure Wet Acid batteries were pretty much the same technology. 

These days the best manufacturers have adopted advanced technology, yet the ;Budgets' are generally poor quality versions using outdated 1980's technology.

Things have changed so much in the last few years, that the very best Leisure Wet Acid batteries are exceptionally good and the worst are exeptionally poor. Those batteries that have adopted new technology can last twice as long as a conventional battery, yet cost little more

There is a Habitation Area battery that stands above all others yet is only £95 (November 2017). 

The reason it is like no other is because it is Patented, no one can copy it's very special technology which is called 'Powerframe'.

Johnson Controls build two identical batteries on the same production line, one labelled as Varta LFD and the other built for Bosch : the Bosch L series. 

The Bosch  L version often has a better guarantee and different marketing, but it's specification is identical to the Varta LFD.

They are Wet Lead Acid batteries, so operate with ALL existing chargers and Alternators. They have some special details inside the battery that makes them more appropriate to Motorhome and Caravan use than any other battery in the up to £150 price range. The production process uses 20% less energy than a conventional battery so it costs little more than the usual poor quality 'Leisure' batteries.

Although the batteries are identical, Bosch take a different marketing angle so label theirs Deep Cycle L5 Leisure batteries. Varta describe theirs as Dual Purpose LFD Starter/Leisure batteries. Despite the different marketing approach, they are physically identical and both able to Deep Cycle and start a Truck engine. Both use the Patented Powerframe Technology.

They have unique technology inside that results in higher performance than almost all other Lead Acid batteries : more efficient with faster charging times meaning they can charge up to twice as fast as conventional batteries. They don't self discharge and don't vent ANY Gas or fluid. 

These are safer inside the habitation area than a Gel or AGM battery.

So why is a Varta LFD90 and the Bosch L5 so special?

A conventional battery starts to corrode from the moment it is used, as in the photo on the left above. Corrosion, some times called Grid Growth, acts as a barrier to current flow. 

Where corrosion has usually taken place, so has Fluid loss. 

The Powerframe technology reduces this Corrosion, which also means zero fluid loss. It endows the battery with higher efficiency than anything in it's class, Bosch/Varta claim upto 70% better electrical flow as the batteries age. 

Bosch claims very high charge acceptance. It is one of the fastest charging batteries around on conventional Alternators and mains chargers. 

In the average Motorhome, it charges even faster than an AGM, yet the Varta/Bosch Powerframe doesn't suffer the AGM's charger intolerance, temperature issues and resultant short life.

The lack of Corrosion/Grid Growth also means that the normal loss of adhesion by the Lead Paste is reduced, so there is also less 'Paste shedding'. Therefore the battery AH Capacity does not deteriorate to the extent other batteries do, performing closer to maximum Ah capacity for longer, right up to end of life. 

The advanced, Patented Powerframe Technology means fluid loss will not even occur at the higher temperatures and voltages that would have an AGM battery gasping out dangerous Hydrogen/Oxygen.  

When extreme temperatures are reached, causing even a Powerframe battery to bubble, the Varta LFD90/Bosch L5 special Labyrinth Lid construction is such that the Hydrogen and Oxygen is contained and returns to the cells as Water. 

The Powerframe high Silver content further adds to efficiency at both High and Low temperatures. The Bosch L5 Deep Cycle battery will start a big truck engine in freezing conditions and last better than most batteries in hot Desert temperatures.      

This technology also has very, very low self discharge rates. Put a perfect one in the Garage/Shed in October and it will still be near full charge in March. Although an interim 3 month charge is strongly recommended.

So How Does It Manage To Be So Good?

The special Silver Alloy Grid is manufactured using a 'Rolling' process, not Stamped or Pressed, which changes the molecular structure of the metal resulting in it becoming highly corrosion resistant. 

This combination of the Silver Alloy (Silver is a very efficient electrical conductor with exceptional anti-corrosion properties) and the Rolling process makes a huge difference to the way it behaves. There are several other clever manufacturing touches, but the Powerframe Silver Alloy Grid is the key. 

This resistance to corrosion not only improves battery efficiency, but when corrosion is the primary cause of Wet Acid battery failure, battery life is also dramatically improved. 

See the chart below from a battery Lifetime study of thousands of batteries showing that 86% of Wet Acid batteries go 'End of Life' from Grid Corrosion as the primary cause of failure.

If you take Corrosion out of the equation, you have the potential for one very long life battery where the actual cycle life of the battery will determine it's replacement, not some other side issue :

Two other things you might note about the above chart -

1. That AGM and Gel (VRLA) suffer slightly less from Corrosion, but it still destroyed 60% of all AGM/Gel batteries in the survey 

2. That 30% of AGM and Gel batteries died from 'drying out'. Remember hearing the myth that Gel and AGM's never Gas fluid? 

Together 'Dry Out' and Corrosion accounted for the destruction of 92% of all AGM/Gel batteries. 

So not only does Powerframe technology address the primary form of battery failure but endows it with efficiency streets ahead of anything else. Efficiency that lasts right to EOL. 


The evidence to back up the above :

Varta website : Greater efficiency, up to 70% improved current flow, longer life, more power, faster charging, extreme temperature operation, etc.


Primary benefits of a Varta LFD90 and Bosch L5 over other batteries in the up to £150 price range are : 

Low self discharge : Stays highly charged up for 6 months +. Varta claim a 12 month shel life, but regard that with caution?

High efficiency : Up to 70% better current flow over a similar age older battery. 

Very Low internal corrosion : This makes it more efficient than the opposition, especially after 2 years +. 

Long life and strong performance right to End Of Life

Maintenance free : Zero fluid loss (so as safe inside the MH as Gel/AGM battery, see more below), actually safer, as the LFD is less likely to explode than either Gel or AGM.

Low cost : It's production uses 20% less energy, so lower cost than it's technology would normal merit., 

Faster charge up : Upto twice that of a budget 110Ah battery. See more below on "110Ah Budget batteries". 

Lightest load on a charger of any battery technology : Significant from our point of view, they place a lighter load on the battery charging systems, both Mains 230v and the Alternator.

Exceptional high/low temperature operation rangeTo support this claim of high temperature tolerance, we publish this image below showing a Varta Silver/Bosch Silver Powerframe lasting more than twice as many miles as ordinary batteries in Desert conditions :


We can't verify the tests validity, but 95,000 miles versus 41,000 miles  is a ratio greater than 2 to 1. In other words, at an annual mileage of 10k, a Varta Powerframe starter battery lasts 9.5 years versus just 4 years for a conventional battery in exceptionally punishing conditions.

We think, strong evidence that the Varta LFD90/Bosch L5 will not only out last a conventional wet habiattion battery by a big margin, but do so when used in the Desert like conditions of Morroco

Some budget Leisure's struggle with a Summers day in Brighton. 

Many so called 'Maintenance Free' batteries are actually just low maintenance batteries in relation to fluid loss. To differentiate their product from the 'misuse of the phrase', Bosch have coined the term, 'Absolutely Maintenance Free'

The LFD90 is the same physical size as the Leisure Exide G80 so fits most locations on most Motorhomes and Caravans. 

It is also the same size as that fitted as the Starter Battery of most Fiats, Mercs and Renaults from 2000 to 2017.

Because the LFD90 is also designed to start an Engine, it copes with a short duration high current draw. It is better suited for powering a Motor Mover on a Caravan (some of which can draw over 140amps from the battery) more than almost any other battery. 

However, even an LFD90, AND the Mover Electric Motors, should be rested for 1 minute for every three minutes of use of a powerful Motor Mover setup.

Where to buy a Varta LFD 90/Bosch L5?

This company below sells the LFD90 at around £92, it is a small business with limited stock space so you can be sure the battery has not lost half it's life from sitting on the shelf for months. They can deliver to your door and because the Varta LFD 90 is so well sealed it travels better than most wet batteries. 

However be warned the 'Sales Team' seem to have a brief to sell batteries with the highest profit margin, not those that are the best. They push quite hard their own label batteries, saying they are as good when they are not half the battery the Varta is :

Tayna batteries -  -  01745 823399

Battery Mega store is another good source with a high turnover of Varta Batteries so they should also be 'fresh'. Again watch out for the Sales team pushing higher profit margin batteries.

How can the Varta LFD90/Bosch L5 wet batteries be safer inside the Motorhome than a Gel battery?

                  Because :

                        1. it does not Bubble, but should that occur, the fluid condenses back to Water, remaining inside the battery.

                        2. Gel and AGM batteries operate under pressure, the safety valve can, and does, fail causing explosion.   

                        3. See the section near the bottom of the page on Battery Explosions and Thermal Runaway.


AGM batteries used in the Motorhome environment where an AGM optimised charger is rarely available, have a higher premature failure rate and a higher risk of explosion. See top of page with the email from sarah if you think that is rare.

Note that Gel, like all VRLA batteries, can have a higher 'resting', or 'start' voltage which affects the 'guide' discharge voltage. If you look at the chart below from Yuasa Batteries, a VRLA/Gel battery is 50% discharged at 12.5v, whereas a conventional battery is 50% discharged at 12.1v. 

We suggest you use the Sealed VRLA graphic above as a guide to the discharge level for a Varta LFD/Bosch L5 battery as they have a resting voltage nearer to that of Sealed/VRLA and their characteristics are more on par with a VRLA than a 'conventional' battery.  

You will find many different charts around, but most seem to be based on redundant technology Antimony based batteries, which fell out of favour in the eighties. 

A battery 'State of Charge' chart that doesn't recognise that different technology batteries have different voltages, is clearly out of date. 

A Customer who brought his own LFD90's for us to fit had charged them at home for 24 hours the week before.

When they arrived with us they were showing 12.88v, and once charged/discharged a few times (most batteries only reach their peak after 20 - 30 charge/discharges)  typically reach 12.95v, very close to that of Gel and AGM VRLA batteries and about 0.4v higher than a 'Budget'   

The chart shows just how different this battery is in REAL use :

If you look at the chart above, you will note that the VRLA/Powerframe column has a voltage range of fully charged to discharged of 13.0v to12.0v. A full 1volt range. The chart shows a Yuasa Conventional batteriry has only a 0.8v range from 12.6v down to 11.8v. Remember this is a Yuasa chart of Yuasa quality batteries, don't expect a Numax Battery to perform as well as a Yuasa Conventional battery.

Not only does this suggest a Powerframe LFD 90 is a more usable battery, but when 50% discharged they have almost the same voltage as a fully charged conventional Lead Antimony battery!!  

A HALF discharged Varta Powerframe LFD 90 is 12.5v and a FULLY charged QUALITY conventional battery is 12.6v.

That is useful higher 'voltage' when it comes to Diesel heating, which can  draw so much start-up current it can cause significant voltage drop. Likewise some TV's that require a minimum voltage, will run better on a Varta/Bosch Powerframe.

If nothing else, this demonstrates that the LFD90/L5 is no ordinary 'wet' battery, it's efficient technology translates to real World, visable voltage improvements. 

That is all very well, but a 90Ah battery is too small for me, I like 110Ah batteries?               


Why you should think twice about 110Ah batteries?

When a battery is constructed there are choices that have to be made on Capacity versus Durability. For Deep Discharge strength the plates have to be thicker, this takes up more space effectively reducing the Plate 'capacity'. 

Generally (very broad brush generalisation for Lead batteries) the greater the durability that is required, the lower the battery Ah capacity.  

For example the very durable long life Exide G80 is an 80Ah battery at the physical size of L-353mm, W-175mm, H-190mm of most Motorhome battery boxes

The Deep Cycle Bosh L5/Varta LFD90 is 90Ah, again in the same physical size as a G80. 

The Banner Energy Bull is 100Ah in the same physical package 

The similar physical sized budget Lion leisure is a 110Ah battery. 

So if you are looking for a tough Cycling battery, be cautious about batteries claiming 110Ah in this size, unless it uses some very special technology. We don't mean it says on the label it is 'Super Heavy Duty', take the advertising with a big pinch of Salt. Especially avoid the 'Calcium' batteries being advertised as some kind 'of new technology' when they are Shallow Cycle batteries unsuited to Habitation Area use. 

Ask yourself why Bosch, Exide, Varta, Yuasa, Banner, etc. don't make a 110Ah battery in the above size of  L-353mm, W-175mm, H-190mm

Yet all the budget battery manufacturers 'favour' this capacity in this size.

When we were cutting open batteries in 2012, the budget 110Ah batteries all showed poor quality construction and significant signs of failure. They might start off at 110Ah (although there has been much discussion that the batteries are 'overcharged' to artificially boost their capacity prior to testing) but we would suggest that 'real' capacity drops below 110Ah very quickly once it is used. 

The evaluations of batteries we disected in 2012 led us to conclude, they are so poor, that if a Battery Retailer offers you a 110Ah, it is because of the profit margin he makes, not because he thinks they are any good. 

Again is it in a Battery Retailers interest to sell you the longest life 5 year Bosch battery when he will see you in 2 years time on a 'budget' sale?

Because of the conflict of interest, much advice from Battery Retailers is unsound.

If you find a battery retailer, from the biggest whoilesalers, to the smallest Motorhome or Caravan Dealer pushing, or even being clued up enough to sell, Varta/Bosch batteries then we would suggest their attitude is biased towards the customer, not just pure profit.


We don't sell any batteries, this is as independent as it gets. And no I don't have any links with Varta!!. 

If the new Exide Carbon Boost Battery technology developments advance as we suspect, we may be switching our advice to that. 

We will always publicise what we think is the best habitation battery, we have no allegence to anyone. 


Now more  evidence to back up what we have said, for those not already bored : 

The graphic below from the Bosch website shows the 'Special Lid Structure' that prevents fluid loss outside the battery making it 100% gas tight. We quote : 

"...Labyrinth construction ensures that evaporated liquid remains in the battery. This makes the battery 100% maintenance free, as well as leak-proof and tilt-proof. The Central ventilation opening (as in linking the cells, not as in 'to the atmosphere' ) means it is suitable for installation inside the passenger compartment".

The above Bosch web page twice states "100% Maintenance Free" and "Labyrinth construction ensures that evaporated liquid remains in the battery". 

Despite this statement people still compare Powerframe batteries it to a conventional Wet battery when it really, really isn't.

This battery is safer to use inside the habitation area of a Motorhome/Caravan than even a Gel battery. 


The Bosch PDF, available at the bottom of the same page, states : 

PowerFrame® technology

▶ PowerFrame®: flow optimized grid design for optimum current flow, reduced corrosion and a long service life

▶ Maximum safety through double backfire protection

▶ No leakage of the acid thanks to the sealed design of the battery lid

▶ Absolutely maintenance free

In the notes of the same document it states :

Labyrinth lid : returns condensed water to the battery.


Battery explosion is not common, but does happen, see the email we got from Sarah at the top of this page in Novemeber 2017.

Precautions When Checking/Topping up lost fluid and Battery Explosions 

 According to PREVENT BLINDNESS AMERICA, nearly 6,000 motorists suffered serious eye injuries annually from working around car batteries. 

While rarely fatal, each year battery explosions cause tens of thousands of eye and burn injuries from battery acid globally.

We can't find any similarly good advice from a UK source so we publish this US based guidance :


"Be especially careful when topping up the fluid in a battery,. Hydrogen and Oxygen may be released the minute you unscrew the top. Hydrogen is explosive in just a 4% mixture with Air.

Before topping up a battery, turn off the 12v power and EHU, ensure the battery is not being charged. 

Ideally top up the battery after it has been standing unused for a week when the explosive Gas has had time to disperse. 

Take great care not to make Sparks, by undoing/re-attaching a battery clamp during/after the Top Up process. Ventilate the area well before starting the Check/Top-Up procedure.

Ensure the battery is a wet battery, some AGM batteries have seemingly removable caps which should never be removed.

If it is a Wet Acid battery meant to have maintenance, undo the Battery Caps. If the battery does not have battery caps then it is probably not meant to be topped up so seek advice.

Shine a torch down into the Battery and check the electrolyte is at least covering the Plates. Some batteries have min/max marks which should be used, if available.

If the Plates are visible it is likely the battery has suffered damage.

Add distilled water, or at least de-ionised water. Tap water can shorten the batteries life by years.

Note exactly how much water you need to add as this will be a guide to how often you need to check the battery, but also a guide to the likely damage if the Plates were visable. 

If you need to add significant water to cover the Plates, we would suggest you consider battery replacement. At the very least, monitor the battery carefully and check it more regularly. Also monitor the charging voltages of all the charging systems, Alternator, Mains, Solar, etc to ensure they are all within specification.  

A less common form of battery explosion occurs when the battery is subjected to high temperatures while charging causing thermal runway in AGM or Gel batteries.

Should a battery explosion occur and battery electrolyte (battery acid) gets in the eyes, flush with any drinkable liquid immediately because SECONDS count, continue flushing with water for at least 15 minutes, and seek immediate medical attention. 

In addition, neutralize residual battery acid in the area around the incident, by thoroughly washing the area with a solution of one-pound baking soda (bicarbonate of soda) to one gallon of warm water and rinse thoroughly with water".

Better still use an 100%, Absolutely Maintenance free battery that does not need topping up.


Once again can we point out we do not sell batteries, this is as independent as it gets.

Example battery types and sizes:

The Varta LFD90 is L - 353mm W-175mm H-190mm, Capacity 90ah, MCA 1,000A, CCA/800A, Cost about £95  

The smaller Varta LFD75 is 278mm long, 175mm wide, 175mm high. 12V, capacity 75Ah, cold test current 650A (sometimes called cranking amps).  

Note that the Exide ES900 and the older G80 Gel batteries  are 353 x 175 x 190 (incl. terminals) so a match for a 90Ah Varta LFD90  (information courtesy of David Chambers).

Note 2 : The Varta LFD 90 and Bosch L5 make a better Starter battery than almost any other battery when used in a Motorhome. Motorohome Starter batteries tend to discharge lower when idle for weeks at a time than most Starter batteries are designed for. A load the Varta LFD 90 is designed for.

The size matches most Fiat, Renaults, Mercs made after 1999, direct swap for the OEM battery.

The LFD 75 is a perfect replacement for Ford Transit starter batteries, and more powerful than the originals at half the cost of a Ford OEM.

bosch brochure 2014.pdf bosch brochure 2014.pdf
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